Create a functional study guide that covers Chapters 9.
Rachel Carey
Ch.13 exam 3 study guide
CH. 13 The Cardiovascular System: Cardiac Function
13.1: An Overview of the Cardiovascular System…Rachel Carey
o Cardiovascular System: organ system consisting of the heart, blood
vessels, and blood.
· the heart—a muscular pump that drives the flow of blood
through blood vessels; (2)blood vessels—conduits through which the
blood flows; and (3) blood—a fluid that circulates around the body,
carrying materials to and from the cells.
o Atria: the hearts two upper chambers, which retrieve blood carried to
the heart in veins; singular is the atrium.
o Ventricles: two lower chambers, pumped blood into the arteries; in the
brain, chambers that contain cerebrospinal fluid.
o The vasculature is all the blood vessels in the body.
o Capillaries are the smallest blood vessels in the body. They permit
material exchange between blood and tissues.
o Arteries: large vessels that carry blood away from the heart
o Arterioles: small blood vessels that carry blood to the capillaries.
o Venules: blood vessels that carry blood from capillaries to veins
o Veins: large blood vessels that carry blood toward the heart
o Blood consists of a liquid (plasma) in which the other components
(erythrocytes, leukocytes, and platelets) are suspended.
o Blood acts as a medium that carries oxygen and nutrients to the body’s
cells while it carries away carbon dioxide and other waste products.
13.2 The Path of Blood Flow Through the Heart and
Vasculature….Rachel Carey
o Pulmonary circuit: the portion of the vasculature that encompasses the
blood vessels within the lungs and those connecting the lungs with the
heart
o Systemic circuit: the portion of the vasculature that encompasses all of
the body’s blood vessels, except those belonging to the pulmonary circuit.
o The right heart supplies blood to the pulmonary circuit, whereas the left
heart supplies blood to the systemic circuit. Notice that blood on one side
of the heart never mixes with blood on the other side.
o Aorta: majory artery whose branches carry blood to all organs and
tissues in the systemic circuit.
o Vena cava: one of the two large veins that carry blood into the right
atrium; plural, venae cavae
o Pulmonary arteries: arteries that carry blood to the lungs from the heart
o Pulmonary veins: veins that carry blood from the lungs to the heart
o Blood returns to the heart by way of the venae cavae, which carry it to
the right atrium, where the blood then enters the right ventricle.
o In contrast to the series flow of blood through the right and left sides of
the heart, blood flow through the systemic circuit takes the form of parallel
flow, with different arteries supplying fresh blood to different organs.
o The branching of blood vessels ensures that each capillary bed receives
fresh blood.
13.3 Anatomy of the Heart….Rachel Carey
o AV (atrioventricular valve): one of the valves that separate the atrium
and the ventricle on either side of the heart
o Bicuspid valve: the AV on the left side of the heart, which possesses two
cusps; also called the mitral valve.
o Tricuspid valve: the AV on the right side of the heart; has three cusps.
o The heart is located in the thoracic cavity and is surrounded by a peri-cardial
sac.
o The heart wall is made up of the epicardium, the myocardium, and the
endothelium; most of the heart consists of the myocardium.
o Valves in the heart ensure unidirectional flow of blood. Atrioventricular valves
allow blood to flow from atrium to ventricle, whereas semilunar valves allow
blood to flow from ventricle to artery (left ventricle to aorta and right ventricle to
pulmonary trunk).
13.4 Electrical Activity of the Heart….Rachel Carey
o Internodal pathways: systems of conducting fibers that run from the sinoatrial
node (SA node) to the AV node through the walls of the atria.
o Bundle of His: part of the conduction system of the heart located in the
interventricular septum
o Normally the heartbeat is driven by pacemakers in the sinoatrial (SA) node,
located in the upper right atrium.
o Following each action potential, pacemaker cells exhibit slow, spontaneous
depolarizations (pacemaker potentials) that eventually depolarize the membrane
to threshold and trigger the next action potential.
o In most cardiac contractile cells, action potentials are characterized by a broad
plateau phase that largely results from an increase in the cell membrane’s
calcium permeability; the flow of calcium into the cells is important in triggering
heart muscle contractions.
o The heart’s electrical activity can be recorded using electrodes placed on the
skin surface, yielding an electrocardiogram (ECG), which consists of three
phases: a P wave, corresponding to atrial depolarization; a QRS complex,
corresponding to ventricular depolarization; and a T wave, corresponding to
ventricular repolarization.
13.5 The Cardiac Cycle…..Rachel Carey
o The cardiac cycle: is a series of mechanical and electrical events occurring within
the heart during a single beat.
o (1) the various phases in the pumping action of the heart; (2) periods of valve
opening and closure; (3) changes in atrial, ventricular, and aortic pressure, which
reflect contraction and relaxation of the heart muscle; (4) changes in ventricular
volume, which reflect the amount of blood entering and leaving the ventricle during
each heartbeat; and (5) the two major heart sounds.
o Aortic pressure varies throughout the cardiac cycle; it rises to a maximum (systolic
pressure, SP) during systole and falls to a minimum (diastolic pressure, DP) during
diastole.
o The average pressure throughout the cycle, which represents the driving force for
blood flow through the systemic circuit, is the mean arterial pressure (MAP).
o Ventricular volume falls to a minimum at the end of systole (end-systolic volume,
ESV) and rises to a maximum at the end of diastole (end-diastolic volume, EDV).
o The difference between these volumes is the stroke volume (SV), the volume
pumped by each ventricle in a single heartbeat.
o The pressure-volume curve provides information about how well the heart is
functioning.
13.6 Cardiac Output and Its Control…Rachel Carey
o Cardiac Output (CO): the volume of blood ejected from each ventricle per minute
o Extrinsic control: regulation of an organ or tissue by neural input, circulating
hormones, or any other factor originating from outside the organ.
o Intrinsic control: regulation of an organ tissue by factors originating from within the
organ or tissue itself; also known as autoregulation or local regulation
o The heart is regulated by sympathetic and parasympathetic neurons and hormones
(extrinsic control) as well as by factors -operating entirely within the heart -(intrinsic
control).
o Heart rate, which is determined by the firing frequency of the SA node, is entirely
under extrinsic control.
o Stroke volume is under extrinsic and intrinsic control and is affected by three major
factors: ventricular contractility, end-diastolic volume, and afterload.
o The influence of end-diastolic volume on stroke volume is the basis of Starling’s law of
the heart, an example of intrinsic control of cardiac function.
o End-diastolic volume is primarily determined by end-diastolic pressure
(preload).
14.1 Physical Laws Governing Blood Flow and Blood Pressure-Daniel Cavallo
· The vasculature is much like an elaborate system of pipes that runs through the body, so the
fundamental physical laws that describe the flow of any liquid through a system of pipes also pertain to
blood flow in the cardiovascular system. The rule that is pertinent to our discussion here states that the
flow rate of a liquid (the volume flowing per unit of time) through a pipe is directly proportional to the
difference between the pressures at the two ends of the pipe (the pressure gradient) and inversely
proportional to the resistance of the pipe:
o
Resistance in the Cardiovascular System
• The pressure gradient in the systemic circuit is much greater than the pressure gradient in
the pulmonary circuit
• Flow through both circuits is equal
• Flow = ∆P/R
• Thus resistance through the pulmonary circuit is much less than resistance through the
systemic circuit
Resistance in the Cardiovascular System
• Factors affecting resistance to flow
•
Radius of vessel
•
In arterioles (and small arteries)—can regulate radius
•
Length of vessel
•
Viscosity of fluid = η
•
Blood viscosity depends on amount of RBCs and
• Poiseuille’s Law
•
A fluid flowing through a tube or blood vessel encounters resistance, some of which is due to
frictional forces acting between the fluid and the walls of the tube or vessel. Friction within the fluid itself
also contributes to the resistance, which explains why some fluids, such as molasses, flow more slowly
than others, such as water. The speed at which a fluid moves varies from one location to another within
the moving liquid. As a consequence, layers of fluid moving at different speeds rub against each other,
which creates friction and dissipates energy. For a fluid moving smoothly through a cylindrical tube, the
resistance (R) is given by the following equation, which is called Poiseuille’s law:
14.2 Overview of the Vasculature-Daniel Cavallo
• Arteries: carry blood away from heart
• Microcirculation-The arterioles, capillaries, and venules can be seen only with the aid of a
microscope and, therefore, are called the microcirculation.
• Arterioles-carry blood from the heart and to capillaries
• Capillaries- site of exchange, smallest of the blood vessels-consist of a layer of endothelial cells
and a basement membrane; the walls of all other blood vessels contain various amounts of smooth muscle
and fibrous and/or elastic connective tissue
• Veins: return blood to heart
Overview of the Vasculature
14.3 Arteries
• Storage site for pressure
•
A Pressure Reservoir-The thickness of arterial walls, coupled with the relative abundance of
elastic tissue, gives arteries both stiffness and the ability to expand and contract as the blood pressure rises
and falls with each heartbeat. This combination of stiffness and flexibility enables arteries to perform one
of their major functions—acting as pressure reservoirs to ensure a continual, smooth flow of blood
through the vasculature even when the heart is not pumping blood (diastole)
• Thick, elastic arterial walls
•
Low compliance
•
Expand as blood enters arteries during systole
•
Recoil during diastole
• Compliance- measure of how the pressure of a vessel will change with a change in volume
•
To serve as a pressure reservoir, arteries must have low compliance which, it is a measure of the
relationship between pressure and volume change. In vessels with low compliance, such as arteries, a
small increase in blood volume causes a large increase in blood pressure (or a large increase in pressure
causes only a small degree of expansion of the blood vessel walls). Therefore, when the heart ejects blood
into the arteries during systole and causes these vessels to expand, the resulting rise in pressure is greater
than it would be if arteries’ compliances were higher. The low compliance of arteries is a function of the
elasticity of the vessel walls.
•
Arterial Blood Pressure-Pressure in the Aorta
Measuring blood pressure
•
Pressure cuff and sphygmomanometer
•
Compressed artery
•
Turbulent flow produces Korotkoff sound
•
Pressure at first Korotkoff sound = systolic blood pressure
•
Uncompressed artery
•
Laminar flow, no sound
•
Pressure when sound disappears = diastolic blood pressure
Arterial Blood Pressure
•
Blood pressure determinations
•
The measured BP is shown as SP/DP
•
Example: 110/70
•
Pulse pressure = SP – DP
•
Example: 110 – 70 = 40 mm Hg
•
MAP = SP + (2 × DP)/3
•
Example: (110 + 140)/3 = 83.3 mm Hg
14.4 Arterioles-Daniel Cavallo
The smallest arteries branch into even smaller arterioles, which lead either into a capillary bed or into
metarterioles, which in turn lead into capillary beds. Thus arterioles serve as the passageway for blood to
enter the capillaries, where exchange between blood and tissue takes place. The walls of arterioles contain
little elastic material but have an abundance of circular smooth muscle that forms rings around the
arterioles. Because this smooth muscle can contract or relax, thereby changing the diameter of arterioles,
arterioles are best known as the site where resistance to blood flow can be regulated.
•
Arterioles provide greatest resistance to blood flow
•
Greater than 60% of TPR
Order an Essay Now & Get These Features For Free:
Turnitin Report
Formatting
Title Page
Citation
Outline
