The Urinary SystemI.
Introduction
A. The Kidneys. Position
1. Are reddish organs that are shaped like “kidney beans”. There are
two, a right and left, located above the waist, between the
peritoneum and the posterior wall of the abdomen. Since the
kidneys are behind the abdominal peritoneum they are said to be
retroperitoneal (others being the adrenal gland and the ureters for
the urinary system).
2. Partially protected by the 11th and 12th pair of ribs.
3. The Left Kidney is slightly higher the the Right Kidney.
B. Kidney tissue layers. Three layers surround the kidney (Going deep to
superficial)
1. The Renal Capsule- smooth ,transparent, fibrous membrane
continuous with the outer coat of the Ureter. Deepest of the three
layers. This layer serves to protect against trauma and maintains
the shape of the kidney.
2. Adipose Capsule- the intermediate layer is fatty tissue surrounding
the renal capsule. Also serves to protect against trauma.
3. Renal Fascia is a thin layer of dense, irregular connective tissue.
Anchors kidneys to surrounding structures and abdominal walls.
Fascia is Latin (the language of the Roman empire) for a sheet or
band of fibrous connective tissue which envelopes, separates, and
or binds soft structures of the body.
II.
External and Internal Anatomy
A. Size. The Kidney is approx. 12 cm (5inches) long, 12-15 cm wide and
2-3 cm thick.
B. Renal Hilus is a deep vertical fissure near the center of the concave
border in which the ureter leaves the kidney. Blood and lymphatic
vessels also enter and exit the kidney via the hilus.
C. Renal Sinus is a cavity within the kidney. Contains the renal pelvis
and minor & major calyces
D. Renal Cortex is one of three general regions of the internal kidney.
The most outermost region.
E. Renal Medulla is the innermost layer with eight to eighteen cone
shaped structures called pyramids.
F. Renal Pyramids,are located in the renal medulla. The base of the
pyramid faces the renal cortex, the apex called the renal papilla points
toward the center of the kidney. Straited due to the presence of tubules
G. Renal Columns are projections of the renal cortex extending between
the pyramids.
H. Renal Parenchyma is The Renal Cortex + The Renal Pyramids. The
functional portion of the kidney. Parenchyma is a term denoting the
tissue characteristic of an organ excluding connective or supporting
tissue. This term applies to both plants and animals.
I. Nephron is the functional unit of the kidney. There are approx 11.25 million nephrons in each parenchyma. A person is born with all
the nephrons they possess. Nephrons can grow larger.
J. Collecting ducts are ducts which receive filtrate from many nephrons
which in turn drain into papillary ducts (Ducts of Bellini). Papilla is a
term to denote “small disturbances”. Papillary ducts are not really
disturrbing anything. It is an anatomical term given by early anatomists.
The Ducts of Bellinin empty into the minor calyces
K. Minor Calyces are ducts that drain into Major calyces. Each kidney has
8 to 18 minor and 2 to 3 major calyces. Located in the Renal Sinus.
III.
Main Functions of the Kidney
A. Cardiovascular and blood.
1. Regulation of blood pressure via the secretion of Renin
2. Regulation of blood volume and ion composition.
3. Regulation of blood pH.
4. Erythropoiesis
B. Excretion and Elimination
IV.
Blood supply to the kidneys.
A. Introduction. The Kidneys make up 1% of total body mass but renal
blood flow accounts for 20-25% of Resting cardiac output. Total resting
blood flow is approx 1200mls/min.
1. Arterial Blood
2. Two Renal arteries (a right and left) branch off the descending
aorta.
3. Within the kidney the renal arteries divide into several segmental
arteries
4. Segmental arteries give off several branches labeled Lobar
arteries which in turn branch into the Interlobar arteries. The
Interlobar arteries pass through the renal columns between the
renal pyramids.
5. At the base of the renal pyramids the interlobar arteries arch
between the medulla and cortex and become Arcuate arteries.
6. Arcuate arteries divide and produce a series of Interlobular
arteries which enter the renal cortex and give off branches called
afferent arterioles.
Renal Artery
Segmental Lobar Interlobar
Arcuate
Arcuate Artery
Interlobular Afferent Arteriole
Glomerular Capillary
Glomerular capillary
V.
Efferent Arteriole
Peritubular capillaries
The Nephron
A. Introduction.
1. The Nephron consists of two portions :
a. Renal corpuscle. The renal corpuscle consists of a
i.
Bowman’s capsule
ii.
The Glomerulus
b. Renal tubules have three general regions
i.
The Proximal convoluted tubule (PCT)
ii.
The Loop of Henle:descending and ascending limbs
iii.
The Distal Convoluted Tubule (DCT)
c. The nephron performs three basic functions
d. Glomerular filtration
e. Tubular secretion (blood to filtrate)
f. Tubular reabsorption (filtrate to blood)
B. The three basic functions in detail
1. Glomerular filtration. Small substances pass across the wall of the
glomerular capillaries into the renal tubules.
2. Tubular Reabsorption. Substances move from the nephron to the
blood.
3. Tubular Secretion. Substances move from blood to nephron.
C. Renal Corpuscle.
1. All lie in the renal cortex. Each corpuscle has two components
a. Bowman’s (Glomerular) capsule. A double walled epithelial cup.
The parietal layer consists of simple squamous epithelium. The
Visceral layer consists of podocytes.
b. The Glomerulus- the capillary network.
2. Filtration of substances through the glomerulus must pass through
three layers.
a. Endothelial fenestrations (pores) of the glomerulus. Pores
allow small substances to pass through but not RBC’s.
b. Basement membrane of the glomerulus prevents loss of large
proteins.
c. Pedicels are distinct plasma membrane foot-like projections of
Podocytes, which cover glomerular capillaries. Pedicels cover
the basement membranes of glomerular capillaries except for
spaces called filtration slits.
d. The slit membranes extend across filtration slits preventing the
loss of medium sized proteins during filtration.
e. After fluid filters out of the glomerular capillaries, it is first in the
Capsular Space. The fluid moves into the nephron and follows
the general route of
1. PCT
2. Loop of Henle
3. DCT
4. Collecting ducts ( Cortical and Medullary)
5. Minor Cayces
6. Major Calyces
7. Renal Pelvis
8. Ureters
9. Urinary Bladder
10. Ureters
f. Renal corpuscle and both convoluted tubules lie in the renal
cortex.
g. Loop of Henle extends into the renal medulla
D. Two types of nephrons
1. Cortical nephrons. Make up 80-85% of all nephrons. Penetrates
only the superficial region of the renal medulla. Receives blood
from peritubular capillaries, which arise from efferent arterioles.
2. Juxtamedullary nephrons comprise 15-20% of all nephrons.
Glomeruli are deep in the renal cortex close to the renal medulla.
The long Loop of Henle stretch into the renal medulla. Receives
blood from peritubular capillaries and the Vasa Recta.
3. Ascending loop has two parts.
a. Thin descending limb
b. Thick ascending limb
4. Histology of a Nephron.
a. The PCT. Cells are cubodial with a brush border of microvilli on
the apical surface (analagous to small intestine). 100% of
filtered glucose and amino acids are reabsorbed.
b. Descending limb of Henle’s loop and the thin ascending limb is
simple squamos epithelium
c. Thick ascending limb is cuboidal to columnar epitheliumwith
some microvilli.
d. DCT and collecting duct the cells are cuboidal with few
microvilli. At the late segment of the DCT two different cell
types are present.
* Principal cells which respond to Anti-diruetic hormone
(ADH) and Aldosterone
• Intercalated cells which secrete protons into the tubule
e. Bowman’s capsule. The Parietal layer is made up of simple
squamos epithelium and the visceral layer is made up of
podocytes.
5. Juxtaglomerular apparatus (JGA)
Final portion of the ascending limb of the loop of Henle contacts the
afferent arteriole. The cells in the ascending limb in contact with the
afferent arteriole are tall crowded mass called the Macula
densa.(osmo-receptors) . Macula densa cells are sensitive to the
osmolarity of filtrate. Modified smooth muscle cells called the
Juxtaglomerular cells are baroreceptors. JG cells secrete
Renin during low blood flow or low blood pressure.. In addition
Mesangial cells surround the glomerular capillaries and enter into
the JGA. Mesangial cells also phagocytize glomerular basal lamina
components and immunoglobulins. They are an unusual example
of phagocytic cells derived from smooth muscle and not
monocytes. Have phagocytic and contractile properties.
Macula densa + Juxtaglomerular Cells = Juxtaglomerular
Apparatus.
6. Functions of various cells and structures
a. PCT cells have high absorptive capacity. Make the largest
contribution to reabsorption. Reabsorbs 100% filtered
glucose, and amino acids, 80-90% bicarb, 65% water,
sodium, and potassium, 50% of chlorine and urea.
a. Macula densa. Cells are very sensitive to concentrations of
sodium, chloine, in filtrate solution within the tubule lumen.
b. JGA regulates arterial blood pressure and blood filitration by
kidneys
c. Principal cells respond to ADH and aldosterone
d. Intercalated cells secrete H+. Helps rid body of excess acids.
VI.
Renal Physiology
A. Glomerular Filtration. Factors which influence the rate of glomerular
filtration or Net Filtration Pressure (NFP)
NFP= GBHP-(CHP+BCOP) or
NFP= GBHP- CHP- BCOP
1. GBHP stands for Glomerular Blood Hydrostatic Pressure
a. Promotes filtration
b. GBHP is approx. 55mmHg
c. It is the pressure of fluids pushing against the walls of the
capillaries*
•
Glomerular capillaries are 50X more permeable than capillaries
elsewhere. Endothelial pores are large (50-100nm in diameter).
Basement membrane of endothelia and slit membranes only
allow passage of substances smaller than 6-7nm. Very little
albumin, diameter 7.1 nm, passes through.
2. Capsular Hydrostatic Pressure (CHP) is approx 15 mmHg.
Opposes filtration. CHP is due to the pressure of fluid in the
capsular space.
3. Blood Colloid Osmotic (Oncotic) Pressure (BCOP) also opposes
filtration. Increases in osmotic pressure are caused by increases in
solute concentration as the solute filters out of the glomerular
capillaries to the tubules.. As solute concentration increases, the
drop in water concentration acts as an inhibition on filtration.
4. Common Values for NFP
GBHP=55mmHg
CHP=15mmHg
BCOP=30mmHg
Therefore NFP=10mmHg
5. Amount of filtration/day. 180 liters (48 gallons) filtrate enters the
capsular space. This is 65X the blood volume. Approx 178-179
liters are re-absorbed. 1 to 2 liters are excreted.
6. Tubular Reabsorption
a. PCT. Make the largest contribution to reabsorption.
Reabsorbs 100% filtered glucose, and amino acids, 80-90%
bicarb, 65% water, sodium, and potassium, 50% of chlorine
and urea.
b. Descending (Thin) limb of the Loop of Henle-simple
squamous epithelia. High water permeability. Low solute
permeability. As fluid descends down the loop osmolarity
increases.
c. Ascending (Thick) limb of the Loop of Henle and the Early
segment of the Distal Collecting Tubule. Cuboidal epithelia
with some microvilli. High solute permeability, Low water
permeability. As filtrate ascends the loop osmolarity decreases.
d. Late DCT and Collecting ducts. Principal cells which have
receptors for ADH and Aldosterone and Intercalated cells which
secrete hydrogen ions
7. Reabsorption of Nutrients in the Loop of Henle. The Loop of Henle
reabsorbs approx. 30% of filtered potassium, 20% of Na, 35% Cl,
and 15% water. Chemical composition of the fluid entering the
LOH is different from fluid in the PCT.
8. Reabsorption in the DCT and Collecting ducts. Principal cells
respond to ADH and aldosterone. ADH is anti-diuretic hormone.
When water levels are low, Osmoreceptors in the hypothalamus
are stimulated sending signals to the posterior pituitary. The
posterior pituitary secretes ADH which acts on the Principal cells
causing increased water absorption from the tubule to the blood.
Intercalated cells located in collecting ducts can reabsorb some
potassium and secrete hydrogen ion via an H+ ATPase.
Cells in the Renal Tubules can raise blood pH by A) secreting H+
into the tubule, or B) Reabsorbing bicarbonate.
9. Secretion of K.
Principal cells in the final portion of the DCT secrete K into the
lumen. Secretion is controlled by
a. Aldosterone. Increase Aldo causes increased K secretion
b. Increased [Na] DCT leads to Increased Na absorption into blood
which leads to increased K secretion
10. Tubular Secretion.
a. Reabsorption is the movement of filtered substances from
tubule to blood.
b. Secretion is the movement of filtered substances from blood to
tubule
VII.
Regulatory Mechanisms
A. Renin-Angiotensin regulation of blood pressure and
Glomerular filtration
B. Atrial Natriuetic Peptide (ANP). Secreted by the atrial
cells of the Heart in response to increased blood volume.
Increased stretch of atrial cells leads to increase
secretion of ANP
Increased ANP in turn leads to increase excretion of
water and Na which leads to increased GFR
ANP has the opposite effect of the Renin-Angiotensin
mechanism regarding GFR.
C. Neural Regulation.
Sympathetic leads to decreased GFR. Parasympathetic
to increased GFR.
c. Myogenic Controls: Increased blood pressure in the
afferent arterioles lead to a reflexive contraction of
smooth muscle around the arteriole.
1
Chapter 19
Reproductive System
Lecture Outline
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The Reproductive System
The human species could not survive without
functional male and female reproductive systems.
The reproductive systems play essential roles in
the development of the structural and functional
differences between males and females,
influence human behavior, and produce offspring.
However, a reproductive system, unlike other
organ systems, is not necessary for the survival of
an individual human.
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Reproductive System Functions
1. Production of gametes
2. Fertilization
3. Development and nourishment of a new
individual
4. Production of reproductive hormones
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Major Reproductive Organs
Figure 19.1
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Formation of Gametes
Gametes:
• sex cells
• sperm in males
• oocytes (eggs) in females
Meiosis:
• a special type of cell division that leads to formation
of sex cells
Each sperm cell and each oocyte contains 23
chromosomes
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Meiosis
1
1. Before meiosis begins, all the chromosomes are
duplicated.
2. At the beginning of meiosis, each of the 46
chromosomes consists of 2 chromatids connected
by a centromere.
3. The chromosomes align as pairs in a process called
synapsis.
4. Because each chromosome consists of 2 chromatids,
the pairing of the chromosomes brings 2 chromatids
of each chromosome close together.
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Meiosis
2
5. Genetic material is exchanged on occasion,
when a part of a chromatid of 1 chromosome
breaks off and is exchanged with part of
another chromatid from the other
chromosome, in a process termed, crossing
over.
6. Meiosis I produces 2 cells, each having 23
chromosomes composed of 2 chromatids
joined at a centromere.
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Meiosis
3
7. During Meiosis II, each of the 2 cells divide
into 2 cells and the centromere breaks, giving
separate chromosomes.
8. The final result from meiosis are four cells,
each having 23 chromosomes.
Since the number of chromosomes are reduced
during the process of dividing into 4 cells, the
process is a reduction division process.
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Meiosis
4
Figure 19.2
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From Fertilization to Fetus
Fertilization:
• union of sperm and oocyte
Zygote:
• what develops after fertilization
• develops into an embryo 3 to 14 days after fertilization
Embryo:
• 14 to 56 days after fertilization
Fetus:
• 56 days after fertilization
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Male Reproductive System
The male reproductive system consists of the
testes, a series of ducts, accessory glands, and
supporting structures.
The ducts include the epididymis, the ductus
deferens, and the urethra.
Accessory glands include the seminal vesicles,
the prostate gland, and the bulbourethral glands.
Supporting structures include the scrotum and
the penis.
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Male Reproductive Structures
Figure 19.3
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Male Reproductive Organs
1
Scrotum:
• contains testes
• contains dartos muscle that moves scrotum and
testes close to and away from body depending on
temp.
• sperm must develop at temp. less than body temp.
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Male Reproductive Organs
2
Testes:
• primary male reproductive organ
• produces sperm
• in scrotum
• contain seminiferous tubules: where sperm is
produced
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Male Reproductive Organs
3
Testes continued:
• contain interstitial cells: secrete testosterone
• contain germ cells: cells that sperm cells arise from
• contain sustentacular cells: nourish germ cells and
produce hormones
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Male Reproductive Organs
4
Epididymis:
• thread-like tubules on side of each testis
• where seminiferous tubules empty new sperm
• where sperm continue to mature develop ability to
swim and bind to oocytes
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Male Reproductive Organs
5
Ductus deferens:
• “vas deferens”
• extends from epididymis and joins seminal vesicle
• cut during a vasectomy
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Male Reproductive Organs
6
Urethra:
• extends from urinary bladder to end of penis
• passageway for urine and male reproductive fluids
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Male Reproductive Organs
7
Penis:
• corpus cavernosum, corpus spongiosum, spongy
urethra:
• 3 columns of erectile tissue which fill with blood for
erection
• transfer sperm from male to female
• excrete urine
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Male Reproductive System Glands
Seminal Vesicles:
• next to ductus deferens
• helps form ejaculatory duct
Prostate gland:
• surrounds urethra
• size of a walnut
Bulbourethral gland:
• small mucus secreting glands near base of prostate
gland
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Male Reproductive Structures
Figure 19.3
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Male Reproductive Organs
1
Figure 19.6a
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Male Reproductive Organs
2
Figure 19.6b
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Secretions
1
Semen:
• mixture of sperm and secretions from glands
• provides a transport medium and nutrients that
• protect and activate sperm
• 60% of fluid is from seminal vesicles
• 30% of fluid is from prostate gland
• 5% of fluid is from bulbourethral gland
• 5% of fluid is from testes
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Secretions
2
Seminal vesicles:
• provide fructose
• contain prostaglandins which decrease mucus
thickness around cervix and uterine tubes and help
sperm move through female repro. tract
• contains coagulants that help deliver semen into
female
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Secretions
3
Prostate gland:
• contains enzymes to liquefy semen after it is inside
female
• neutralizes acidity of vagina
Bulbourethral gland:
• neutralize acidity of male urethra and female vagina
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Secretions
4
Testicular secretions:
• include sperm and small amount of fluid
2 to 5 milliliters of semen is ejaculated each time
1 milliliter of semen contains 100 million sperm
Sperm can live for 72 hours once inside female
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Path of Sperm
1. Sperm develop in seminiferous tubules
(testes)
2. Epididymis (mature)
3. Ductus deferens
4. Receive secretions from seminal vesicles,
prostate gland, and bulbourethral gland
5. Urethra where semen (sperm) exit body
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Spermatogenesis
Spermatogenesis:
• formation of sperm cells
• begins at puberty
• interstitial cells increase in number and size
• seminiferous tubules enlarge
• seminiferous tubules produce germ cells and
sustentacular cells
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Production of Sperm Cells
1. Germ cells
2. Spermatogonia
3. Primary spermatocytes
4. Secondary spermatocytes
5. Spermatids
6. Sperm cells
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Spermatogenesis
Figure 19.5
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Sperm Cell Structure
Head:
• contain a nucleus and DNA
Midpiece:
• contain mitochondria
Tail:
• flagellum for movement
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Structure of the Testis and Sperm Cell
Figure 19.4
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Male Sex Hormones
1
Gonadotropin-releasing hormone (GnRH) is
produced in the hypothalamus and stimulates
secretion of LH and FSH.
Luteinizing Hormone (LH) is produced in the
anterior pituitary and stimulates secretion of
testosterone.
Follicle-stimulating hormone (FSH) is produced in
the anterior pituitary and prompts
spermatogenesis.
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Male Sex Hormones
2
Testosterone is produced in the interstitial cells
in the testes and is involved in development and
maintenance of reproductive organs.
Inhibin secreted by cells of the seminiferous
tubules and inhibits FSH secretion.
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Male Reproductive Hormone
Regulation
36
Figure 19.7
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Male Puberty
Male puberty:
• sequence of events in which a boy begins to produce
male hormones and sperm cells
• begins at 12 to 14 and ends around 18
• testosterone is major male hormone
• secondary sexual characteristics develop:
Example – skin texture, fat distribution, hair growth,
skeletal muscle growth, and larynx changes
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Male Sex Act
1
The male sex act is a complex series of reflexes that
result in erection of the penis, secretion of mucus
into the urethra, emission, and ejaculation.
Emission is the movement of sperm cells, mucus,
prostatic secretions, and seminal vesicle secretions
into the prostatic, membranous, and spongy
urethra.
Ejaculation is the forceful expulsion of the
secretions that have accumulated in the urethra to
the exterior.
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Male Sex Act
2
Sensations, normally interpreted as pleasurable,
occur during the male sex act and result in an
intense sensation called an orgasm.
A phase called resolution occurs after
ejaculation in which the penis becomes flaccid,
an overall feeling of satisfaction exists, and the
male is unable to achieve erection and a second
ejaculation.
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Penile Erection
Erection is the first major component of the male sex
act.
Neural stimuli cause the penis to enlarge and
become firm.
Specifically, parasympathetic action potentials from
the sacral region of the spinal cord cause the arteries
that supply blood to the erectile tissues to dilate.
Blood then fills small venous sinuses called sinusoids
in the erectile tissue and compresses the veins,
which reduces blood flow from the penis.
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Penile Ejaculation
Ejaculation results from the contraction of smooth
muscle in the wall of the urethra and skeletal
muscles surrounding the base of the penis.
Just before ejaculation, action potentials are sent to
the skeletal muscles that surround the base of the
penis.
Rhythmic contractions are produced that force the
semen out of the urethra, resulting in ejaculation.
In addition, muscle tension increases throughout
the body.
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Female Reproductive System
The female reproductive organs consist of the
ovaries, the uterine tubes, the uterus, the
vagina, the external genitalia, and the mammary
glands.
The internal reproductive organs of the female
are located within the pelvis, between the
urinary bladder and the rectum.
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Female Pelvis
Figure 19.18
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Female Reproductive Organs
1
Figure 19.9
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Female Reproductive Organs
2
Ovaries:
• primary female reproductive organ
• produces oocytes and sex hormones
• one on either side of uterus
• ovarian ligaments: anchor ovaries to uterus
• suspensory ligaments: anchor ovaries to pelvic cavity
• ovarian follicle: cells in ovaries that contain oocytes
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Structure of Ovary and Ovarian
Follicles
46
Figure 19.10
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Female Reproductive Organs
3
Uterine (Fallopian) tubes:
• part of uterus which extends toward ovaries and
receive oocytes
• fimbriae are fringe-like structures around opening of
uterine tubes that help sweep oocyte into uterine
tubes
• tubal ligation (sterilization of female)
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Female Reproductive Organs
4
Uterus:
• pear sized structure located in pelvic cavity
• functions: receive, retain, and provide nourishment
for fertilized oocyte, where embryo resides and
develops
• body: main part
• cervix: narrow region that leads to vagina
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Female Reproductive Organs
5
Uterus wall layers:
• perimetrium (serous): outermost layer
• myometrium (muscular): middle layer
• composed of smooth muscle
• endometrium: innermost layer that is sloughed off
during menstruation
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Female Reproductive Organs
6
Vagina:
• extends from uterus to outside of body
• female copulation organ that receives penis during
intercourse
• allows menstrual flow
• involved in childbirth
• contains very muscular walls and a mucous membrane
• very acidic to keep bacteria out
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External Female Genitalia
1
Vulva:
• external female sex organs
• mons pubis, labia majora and minora, clitoris, and
vestibule
Mons pubis:
• fatty layer of skin covering pubic symphysis
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External Female Genitalia
Labia majora:
• larger, outer folds of skin
• equivalent to male scrotum
Labia minora:
• thin, inner folds of skin
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External Female Genitalia
3
Clitoris:
• small erectile structure located in vestibule
• equivalent to male penis
Prepuce:
• where 2 labia minora unite over clitoris
Vestibule:
• space in which vagina and urethra are located
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Female External Genitalia
Figure 19.12
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Maturation of the Oocyte and Follicle
Figure 19.11
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Ovulation
Ovulation:
• release of an oocyte from the ovary
• due to LH secreted from the anterior pituitary
Corpus luteum:
• mature follicle after ovulation
• degenerates if egg is not fertilized
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Oogenesis and Fertilization
1
Females are born with all of their oogonia (2
million), unlike males that only begin to
produce sperm during puberty.
At puberty about 300,000 to 400,000 oogonia
are left.
Puberty to menopause, FSH stimulates several
follicles to begin developing during each
menstrual cycle but only 1 follicle should be
ovulated.
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Oogenesis and Fertilization
2
Oocytes are swept into one of uterine tubes by
fimbriae.
If sperm is present in uterine tube during
ovulation oocyte could be fertilized.
If fertilization occurs then zygote implants in
uterus.
Oocyte only lives for 24 hours, so if no sperm is
present at ovulation no zygote develops, and
oocyte dies.
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Female Puberty
Begins between 11 to 13 and is usually
completed by 16
Menarche first episode of menstrual bleeding
Vagina, uterus, uterine tubes, and external
genitalia to enlarge and fat is deposited in
breast and hips
Elevated levels of estrogen and progesterone
are secreted by ovaries
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Mammary Glands
Organs of milk production in breasts
Modified sweat glands
Female breasts begin to enlarge during puberty
Consists of lobes covered by adipose
Lobes, ducts, lobules are altered during lactation
to expel milk
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Anatomy of the Breast
Figure 19.13
© 2019 McGraw-Hill Education
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Female Sex Hormones
1
Gonadotropin-releasing (GnRH) hormone is
produced in the hypothalamus and stimulates
secretion of LH and FSH.
Luteinizing Hormone (LH) is produced in the
anterior pituitary and causes ovulation.
Follicle-stimulating hormone (FSH) is produced in
the anterior pituitary and prompts follicles in the
ovaries to begin development.
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Female Sex Hormones
2
Estrogen:
• proliferation of endometrial cells
• development of mammary glands (especially duct
system)
• control of LH and FSH secretion
• development and maintenance of secondary sex
characteristics
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Female Sex Hormones
3
Progesterone:
• enlargement of endometrial cells and secretion of
fluid from uterine glands
• maintenance of pregnancy state
• development of mammary glands (especially alveoli)
• control of estrogen, FSH, and LH secretion
• development of secondary sex characteristics
© 2019 McGraw-Hill Education
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Menstrual Cycle
Menstrual cycle:
• series of changes that occur in sexually mature,
nonpregnant females
Menses:
• time when endometrium is shed from uterus
Average is 28 days and results from cyclical
changes that occur in endometrium
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Stages of Menstrual Cycle
1
Days 1 to 5 Menses (shedding of endometrium)
• menstrual bleeding (menses)
• estrogen and progesterone levels are low
• follicle begins to mature
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Stages of Menstrual Cycle
2
Days 6 to 13 Proliferative (between end of
menses and ovulation)
• endometrium rebuilds
• estrogen levels begin to increase
• progesterone levels remain low
• follicle matures
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Stages of Menstrual Cycle
Day 14 Ovulation
• oocyte is released due to LH
• estrogen levels high
• progesterone levels are increasing
• cervical mucus thins
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69
Stages of Menstrual Cycle
4
Days 15 to 28 Secretory (between ovulation and
next menses)
• endometrium is preparing for implantation
• estrogen levels decrease (low)
• progesterone levels high
• cervical mucus thickens
© 2019 McGraw-Hill Education
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Menstrual Cycle
Figure 19.14
© 2019 McGraw-Hill Education
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Menopause
Menopause
• time when ovaries secrete less hormones and number
of follicles in ovaries is low
• menstrual cycle and ovulation are less regular
• hot flashes, fatigue, irritability may occur
• estrogen replacement therapy may be used to
decreases side effects
© 2019 McGraw-Hill Education
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Female Sexual Behavior
1
Sexual drive in females, like sexual drive in males,
is dependent on hormones.
Testosterone-like hormones, and possibly
estrogen, affect brain cells (especially in the area
of the hypothalamus) and influence sexual
behavior.
Testosterone-like hormones are produced
primarily in the adrenal cortex.
© 2019 McGraw-Hill Education
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Female Sexual Behavior
2
Psychological factors also play a role in sexual
behavior.
The sensory and motor neural pathways involved
in controlling female sexual responses are similar
to those found in the male.
© 2019 McGraw-Hill Education
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Female Sex Act
1
During sexual excitement, erectile tissue within
the clitoris and around the vaginal opening
becomes engorged with blood.
The mucous glands within the vestibule secrete
small amounts of mucus, with larger amounts
extruded into the vagina through its wall.
Stimulation of the female’s genitals during sexual
intercourse and psychological stimuli normally
trigger an orgasm, or climax.
© 2019 McGraw-Hill Education
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Female Sex Act
2
The vaginal and uterine smooth muscle, as well as
the surrounding skeletal muscles, contract
rhythmically, and muscle tension increases
throughout much of the body.
After the sex act, there is a period of resolution,
which is characterized by an overall sense of
satisfaction and relaxation.
© 2019 McGraw-Hill Education
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Contraception
1
Many methods are used to prevent pregnancy,
either by preventing fertilization (contraception)
or by preventing implantation of the developing
embryo.
Methods include behavioral, barrier, chemical,
and surgical.
© 2019 McGraw-Hill Education
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Contraception
© 2019 McGraw-Hill Education
2
(a,b,d) ©McGraw- Hill Education/Jill Braaten; (c) ©Aaron Haupt/Science Source; (e) ©Martin Shields/Alamy
1
Chapter 18
Urinary System
and Fluid Balance
Lecture Outline
© 2019 McGraw-Hill Education
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Urinary System
1
The urinary system is the major excretory
system of the body.
Some organs in other systems also eliminate
wastes, but they are not able to compensate in
the case of kidney failure.
© 2019 McGraw-Hill Education
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Urinary System
2
Figure 18.1
© 2019 McGraw-Hill Education
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Urinary System Functions
1. Excretion
2. Regulation of blood volume and blood
pressure
3. Regulation of blood solute concentration
4. Regulation of extracellular fluid pH
5. Regulation of red blood cell synthesis
6. Regulation of Vitamin D synthesis
© 2019 McGraw-Hill Education
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Components of the Urinary System
Two kidneys
Two ureters
One urinary bladder
One urethra
© 2019 McGraw-Hill Education
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Urinary System
Figure 18.2a
© 2019 McGraw-Hill Education
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Kidney Characteristics
Bilateral retroperitoneal organs
Shape and size:
• bean shaped
• weighs 5 ounces (bar of soap or size of fist)
Location:
• between 12th thoracic and 3rd lumbar vertebra
© 2019 McGraw-Hill Education
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Kidney Structures
1
Renal capsule:
• connective tissue around each kidney
• protects and acts as a barrier
Hilum:
• indentation
• contains renal artery, veins, nerves, ureter
© 2019 McGraw-Hill Education
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Kidney Structures
2
Renal sinus:
• contains renal pelvis, blood vessels, fat
Renal cortex:
• outer portion
Renal medulla:
• inner portion
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Kidney Structures
Renal pyramid:
• junction between cortex and medulla
Calyx:
• tip of pyramids
Renal pelvis:
• where calyces join
• narrows to form ureter
© 2019 McGraw-Hill Education
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11
Longitudinal Section of the Kidney
Figure 18.3
© 2019 McGraw-Hill Education
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Nephron
The nephron is the functional unit of the kidney.
Each kidney has over one million nephrons.
There are two types of nephrons in the kidney:
•
juxtamedullary
•
cortical
Approximately 15% are juxtamedullary
The nephron includes the renal corpuscle, proximal
tubule, loop of Henle, distal tubule and collecting duct
© 2019 McGraw-Hill Education
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Nephron Components
1
Renal corpuscle:
structure that contains a Bowman’s capsule and
glomerulus
Bowman’s capsule:
• enlarged end of nephron
• opens into proximal tubule
• contains podocytes (specialized cells
• around glomerular capillaries)
Glomerulus:
• contains capillaries wrapped around it
© 2019 McGraw-Hill Education
Renal Corpuscle and Filtration
Membrane
14
Figure 15.5
© 2019 McGraw-Hill Education
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Nephron Components
2
Filtration membrane:
• in renal corpuscle
• includes glomerular capillaries, podocytes, basement
membrane
Filtrate:
• fluid that passes across filtration membrane
© 2019 McGraw-Hill Education
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Nephron Components
3
Proximal tubule:
• where filtrate passes first
Loop of Henle:
• contains descending and ascending loops
• water and solutes pass through thin walls by
diffusion
© 2019 McGraw-Hill Education
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Nephron Components
4
Distal tubule:
• structure between Loop of Henle and collecting duct
Collecting duct:
• empties into calyces
• carry fluid from cortex through medulla
© 2019 McGraw-Hill Education
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The Nephron
Figure 18.4
© 2019 McGraw-Hill Education
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Flow of Filtrate through Nephron
1. Renal corpuscle
2. Proximal tubule
3. Descending loop of Henle
4. Ascending loop of Henle
5. Distal tubule
6. Collecting duct
7. Papillary duct
© 2019 McGraw-Hill Education
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Blood Flow through Kidney
1. Renal artery
2. Interlobar artery
3. Arcuate artery
4. Interlobular artery
5. Afferent arteriole
6. Glomerulus
7. Efferent arteriole
8. Peritubular capillaries
9. Vasa recta
10. Interlobular vein
11. Arcuate vein
12. Interlobar vein
© 2019 McGraw-Hill Education
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Blood Flow Through the Kidney
Figure 18.6
© 2019 McGraw-Hill Education
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Urine Formation
1
Urine formation involves three processes:
• Filtration – occurs in the renal corpuscle
• Reabsorption – it involves removing substances
from the filtrate and placing back into the blood
• Secretion – it involves taking substances from the
blood at a nephron area other than the renal
corpuscle and putting back into the nephron tubule
© 2019 McGraw-Hill Education
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Urine Formation
2
Figure 18.7
© 2019 McGraw-Hill Education
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Urine Formation-Filtration
1
Movement of water, ions, small molecules
through filtration membrane into Bowman’s
capsule
19% of plasma becomes filtrate
180 Liters of filtrate are produced by the
nephrons each day
1% of filtrate (1.8 liters) become urine rest is
reabsorbed
© 2019 McGraw-Hill Education
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Urine Formation-Filtration
2
Only small molecules are able to pass through
filtration membrane
Formation of filtrate depends on filtration
pressure
Filtration pressure forces fluid across filtration
membrane
Filtration pressure is influenced by blood
pressure
© 2019 McGraw-Hill Education
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Filtration Pressure
Figure 18.8
© 2019 McGraw-Hill Education
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Urine Production-Reabsorption
99% of filtrate is reabsorbed and reenters
circulation
Proximal tubule is primary site for reabsorption
of solutes and water
Descending Loop of Henle concentrates filtrate
Reabsorption of water and solutes from distal
tubule and collecting duct is controlled by
hormones
© 2019 McGraw-Hill Education
Reabsorption in the Proximal
Convoluted Tubule
28
Figure 18.10
© 2019 McGraw-Hill Education
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Urine Concentration
1
The descending limb of the loop of Henle is a
critical site for water reabsorption.
The filtrate leaving the proximal convoluted
tubule is further concentrated as it passes
through the descending limb of the loop of
Henle.
The mechanism for this water reabsorption is
osmosis.
© 2019 McGraw-Hill Education
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Urine Concentration
2
The renal medulla contains very concentrated
interstitial fluid that has large amounts of Na+, Cl−,
and urea.
The wall of the thin segment of the descending limb
is highly permeable to water.
As the filtrate moves through the medulla
containing the highly concentrated interstitial fluid,
water is reabsorbed out of the nephron by osmosis.
The water enters the vasa recta.
© 2019 McGraw-Hill Education
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Urine Concentration
3
The ascending limb of the loop of Henle dilutes
the filtrate by removing solutes
The thin segment of the ascending limb is not
permeable to water, but it is permeable to
solutes
Consequently, solutes diffuse out of the
nephron
© 2019 McGraw-Hill Education
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Urine-Concentrating Mechanism
Figure 18.9
© 2019 McGraw-Hill Education
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Reabsorption in the Loop of Henle
Figure 18.11
© 2019 McGraw-Hill Education
Reabsorption in the Thick Segment of
the Ascending Limb
34
Figure 18.12
© 2019 McGraw-Hill Education
Distal Convoluted Tubule and
Collecting Duct Reabsorption
35
Figure 18.13
© 2019 McGraw-Hill Education
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Urine Production—Secretion
1
Tubular secretion removes some substances
from the blood.
These substances include by-products of
metabolism that become toxic in high
concentrations and drugs or other molecules
not normally produced by the body.
Tubular secretion occurs through either active or
passive mechanisms.
© 2019 McGraw-Hill Education
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Urine Production—Secretion
2
Ammonia secretion is passive.
Secretion of H+, K+, creatinine, histamine, and
penicillin is by active transport.
These substances are actively transported into
the nephron.
The secretion of H+ plays an important role in
regulating the body fluid pH.
© 2019 McGraw-Hill Education
Urine Concentration and Volume
Regulation
Three major hormonal mechanisms are involved
in regulating urine concentration and volume:
1. renin-angiotensin-aldosterone
2. the antidiuretic hormone (ADH)
3. the atrial natriuretic hormone
© 2019 McGraw-Hill Education
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Renin-Angiotensin-Aldosterone
Mechanism
1
1. Renin acts on angiotensinogen to produce
angiotensin I
2. Angiotensin-converting enzyme converts
angiotensin I to angiotensin II
3. Angiotensin II causes vasoconstriction
© 2019 McGraw-Hill Education
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Renin-Angiotensin-Aldosterone
Mechanism
2
4. Angiotensin II acts on adrenal cortex to
release aldosterone
5. Aldosterone increases rate of active transport
of Na+ in distal tubules and collecting duct
6. Volume of water in urine decreases
© 2019 McGraw-Hill Education
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41
Aldosterone Actions
Figure 18.14
© 2019 McGraw-Hill Education
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Antidiuretic Hormone Mechanism
1. ADH is secreted by the posterior pituitary
gland
2. ADH acts of kidneys, causing them absorb
more water (decrease urine volume)
3. Result is to maintain a normal blood volume
and blood pressure
© 2019 McGraw-Hill Education
ADH and the Regulation of
Extracellular Fluid
43
Figure 18.15
© 2019 McGraw-Hill Education
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Atrial Natriuretic Hormone
1
1. ANH is secreted from cardiac muscle in the
right atrium of the heart when blood
pressure increases
2. ANH acts on kidneys to decrease Na+
reabsorption
3. Sodium ions remain in nephron to become
urine
4. Increased loss of sodium and water reduced
blood volume and blood pressure
© 2019 McGraw-Hill Education
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Atrial Natriuretic Hormone
2
Figure 18.16
© 2019 McGraw-Hill Education
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Homeostatic Control of Blood and Urine
Volumes
Figure 18.17
© 2019 McGraw-Hill Education
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Ureters and Urinary Bladder
1
Ureters:
• small tubes that carry urine from renal pelvis of
kidney to bladder
Urinary bladder:
• in pelvic cavity
• stores urine
• can hold a few ml to a maximum of 1000 milliliters
© 2019 McGraw-Hill Education
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Urethra
Urethra:
• tube that exits bladder
• carries urine from urinary bladder to outside of body
© 2019 McGraw-Hill Education
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Ureters and Urinary Bladder
2
Figure 18.18
© 2019 McGraw-Hill Education
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Urine Movement
Micturition reflex:
• activated by stretch of urinary bladder wall
• action potentials are conducted from bladder to
spinal cord through pelvic nerves
• parasympathetic action potentials cause bladder to
contract
• stretching of bladder stimulates sensory neurons to
inform brain person needs to urinate
© 2019 McGraw-Hill Education
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Micturition Reflex
Figure 18.19
© 2019 McGraw-Hill Education
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Body Fluid Compartments
The intracellular fluid compartment includes the
fluid inside all the cells of the body.
Approximately two-thirds of all the water in the
body is in the intracellular fluid compartment.
The extracellular fluid compartment includes all the
fluid outside the cells.
The extracellular fluid compartment includes,
interstitial fluid, plasma, lymph, and other special
fluids, such as joint fluid, and cerebrospinal fluid.
© 2019 McGraw-Hill Education
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Composition of Fluids
Intracellular fluid contains a relatively high
concentration of ions, such as K+, magnesium
(Mg2+), phosphate (PO43−), and sulfate (SO42−),
compared to the extracellular fluid.
It has a lower concentration of Na+, Ca2+, Cl−,
and HCO3− than does the extracellular fluid.
© 2019 McGraw-Hill Education
Exchange Between Fluid
Compartments
The cell membranes that separate the body fluid
compartments are selectively permeable.
Water continually passes through them, but ions
dissolved in the water do not readily pass through
the cell membrane.
Water movement is regulated mainly by hydrostatic
pressure differences and osmotic differences
between the compartments.
Osmosis controls the movement of water between
the intracellular and extracellular spaces.
© 2019 McGraw-Hill Education
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Regulation of Extracellular Fluid
Composition
Thirst Regulation
Ion Concentration Regulation
© 2019 McGraw-Hill Education
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56
Thirst Regulation
Water intake is controlled by the thirst center
located in the hypothalamus
When the concentration of ions in the blood
increases, it stimulates the thirst center to cause
thirst
When water is consumed, the concentrations of
blood ions decreases, due to a dilution effect; this
causes the sensation of thirst to decrease
© 2019 McGraw-Hill Education
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Thirst Regulation of Extracellular Fluid
Concentration
Figure 18.20
© 2019 McGraw-Hill Education
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Ion Concentration Regulation
1
Regulating the concentrations of positively
charged ions, such as Na+, K+, and Ca2+, in the
body fluids is particularly important.
Action potentials, muscle contraction, and
normal cell membrane permeability depend on
the maintenance of a narrow range of these
concentrations.
© 2019 McGraw-Hill Education
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Ion Concentration Regulation
2
Negatively charged ions, such as Cl−, are
secondarily regulated by the mechanisms that
control the positively charged ions.
The negatively charged ions are attracted to the
positively charged ions; when the positively
charged ions are transported, the negatively
charged ions move with them.
© 2019 McGraw-Hill Education
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Sodium Ions
Sodium ions (Na+) are the dominant ions in the
extracellular fluid.
About 90 to 95% of the osmotic pressure of the
extracellular fluid results from sodium ions and
from the negative ions associated with them.
Stimuli that control aldosterone secretion influence
the reabsorption of Na+ from nephrons of the
kidneys and the total amount of Na+ in the body
fluids.
Sodium ions are also excreted in sweat.
© 2019 McGraw-Hill Education
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Potassium Ions
Electrically excitable tissues, such as muscles
and nerves, are highly sensitive to slight changes
in the extracellular K+ concentration.
The extracellular concentration of K+ must be
maintained within a narrow range for these
tissues to function normally.
Aldosterone plays a major role in regulating the
concentration of K+ in the extracellular fluid.
© 2019 McGraw-Hill Education
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Regulation of Blood Potassium Levels
Figure 18.21
© 2019 McGraw-Hill Education
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Calcium Ions
The extracellular concentration of Ca2+ is maintained
within a narrow range.
Increases and decreases in the extracellular
concentration of Ca2+ have dramatic effects on the
electrical properties of excitable tissues
Parathyroid hormone (PTH), secreted by the
parathyroid glands, increases extracellular Ca2+
concentrations.
Calcitonin reduces the blood Ca2+ concentration
when it is too high.
© 2019 McGraw-Hill Education
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Phosphate and Sulfate Ions
Some ions, such as phosphate ions (PO43−) and
sulfate ions (SO42−), are reabsorbed by active
transport in the kidneys.
The rate of reabsorption is slow, so that if the
concentration of these ions in the filtrate exceeds
the nephron’s ability to reabsorb them, the excess
is excreted into the urine.
As long as the concentration of these ions is low,
nearly all of them are reabsorbed by active
transport.
© 2019 McGraw-Hill Education
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Regulation of Acid-Base Balance
1
Buffers
• chemicals resist change in pH of a solution
• buffers in body contain salts of weak acids or bases
that combine with H+
• three classes of buffers: proteins, phosphate buffer,
bicarbonate buffer
© 2019 McGraw-Hill Education
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Regulation of Acid-Base Balance
2
Respiratory system involvement in acid-base:
• responds rapidly to changes in pH
• increased respiratory rate raises blood pH (more
alkalotic) due to increased rate of carbon dioxide
elimination from the body
• reduced respiratory rate reduces pH (more acidic)
due to decreased rate of carbon dioxide elimination
from the body
© 2019 McGraw-Hill Education
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Regulation of Acid-Base Balance
3
Kidney Involvement in acid-base:
• nephrons secrete H+ into urine and directly regulate
pH of body fluids
• more H+ secretion if the pH is decreasing and less H+
secretion if pH is increasing
© 2019 McGraw-Hill Education
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Regulation of Acid-Base Balance
4
Figure 18.22
© 2019 McGraw-Hill Education
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Acidosis and Alkalosis
Acidosis occurs when the pH of blood falls below
7.35
There are two types of acidosis based upon the
cause: respiratory and metabolic
Alkalosis occurs when the pH of blood increases
above 7.45
There are two types of alkalosis based upon the
cause: respiratory and metabolic
© 2019 McGraw-Hill Education
Biology 2404
Assignment VII
1.
2.
Trace the flow of filtrate from Renal capsule to urethra
Describe the blood flow through the kidney starting at
the Renal artery and ending at the renal vein.
.
3.
4.
5.
1.
2.
3.
4.
5.
6.
7.
8.
6.
1.
List the percent absorptive or secretion of sodium,
potassium, water, bicarbonate, glucose for different
regions of the nephron.
Describe the filtration membrane. What does it allow
and not allow to filter through (in healthy conditions)
Define the terms
Renal cortex
Renal Pyramids
Renal Columns
Renal Sinus
Major Calyx
Minor Calyx
Renal medulla
Ureters
Define the following terms:
Autosomes
Sex Chromosomes
3. Gametes
4. Gonads
5. Meiosis
6. Mitosis
7. Sertoli Cells
8. Haploid
9. Diploid
7. Starting with One Cell describe and draw step by step
the process of Meiosis I in males and females (they
have different end results). How many viable cells are
there for the male and for the female.at the end of
Meiosis I?
8. Describe in detail the process of spermatogenesis
including cells involved and time length.
9. Describe where sperm are stored and all the ducts,
ampullae which it traverses on its way out.
10. Describe the three glands: their secretions,
composition of fluids, and volume of secretions, the
functions, and the ducts traversed during male
ejaculation.
11. Define the following:
1. Uterus
2. Cervix
3. Fallopian tubes
4. Fimbrae
5. Endometrium
2.
Follicle
7. Corpus Luteum
12. Describe the process of Oogenesis all the way to the
Graafian follicle and secondary oocyte. Include
hormones involved in this process.
13. Describe the process of ovulation, the hormone
involved and what is released into the Fallopian tube
(It isn’t just the oocyte) . At what stage of meiosis is
the secondary oocyte? What is the life expectancy of
the secondary oocyte?
14. When do females form all their ova (eggs)? At stage
of Meiosis I are they halted? Can the life style choices
of a person’s grandmother potentially impact the
genetics of her grandchildren?
15. What happens to the remainder of the Graafian follicle
after ovulation? Does it perform any role in
pregnancy? If so what?
16. Describe what happens when the secondary oocyte is
fertilized by a sperm. Read the textbook and notes
carefully. The process is Not straight forward.
17. Describe the blastocysts, when and where it implants,
and what must occur for the mother’s immune system
Not to destroy it.
6.
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