Cardiovascular System Flashcards
In the systemic circuit, blood leaves the left ventricle via a single large artery
Aorta
The arteries of the systemic circulation branch off the aorta, dividing into progressively smaller vessels. The smallest arteries branch into
arterioles
arterioles branch into a huge number (estimated at 10 billion) of very small vessels which unite to form larger diameter vessels
capillaries
larger diameter vessels venules
venules
The arterioles, capillaries, and venules are collectively termed
microcirculation.
the veins from the various peripheral organs and tissues unite to produce two large veins, It is by way of these two veins that blood is returned to the right atrium.
inferior vena cava & superior vena cava
blood leaves the lungs via four
pulmonary veins
the two ____ one supplying the right lung and the other the left.
pulmonary arteries
Blood leaves the right ventricle via a single large artery, which divides into
Pulmonary trunk, pulmonary arteries
Lungs receive all the blood pumped by the
Right ventricle, right side of the heart
each of the peripheral organs and tissues receives only a fraction of the blood pumped by
Left ventricles, left side of the heart
exceptions, for the liver, kidneys, and pituitary In those organs, blood passes through two capillary beds, arranged in series, before returning to the heart. This pattern is known as a
portal system
F
blood Flow
pressure exerted by any fluid, it denotes the force exerted by the blood. This force is generated in the blood by the con- traction of the heart,
hydrostatic pressure
equation for blood flow
F = triangleP/R
flow=
_how difficult it is for blood to flow between two points at any given pressure difference. ___ is the measure of the friction that impedes flow.
resistance (R)
One determinant of resistance is the fluid property known as
Viscosity
_____is a function of the friction between molecules of a flowing fluid; the greater the friction, the greater the
Viscosity
Three things that determine resistance
fluid Viscosity, length of tube, and inside radius of tube
Chambers through which blood flows from veins to ventricles. Atrial contraction adds to ventricular filling but is not essential for it.
Atria
Chambers whose contractions produce the pressures that drive blood through the pulmonary and systemic vascular systems and back to the heart.
Ventricles
Low-resistance tubes conducting blood to the various organs with little loss in pressure. They also act as pressure reservoirs for maintaining blood flow during ventricular relaxation.
Arteries
Major sites of resistance to flow; responsible for the pattern of blood flow distribution to the various organs; participate in the regulation of arterial blood pressure.
Arterioles
Sites of nutrient, metabolic end product, and fluid exchange between blood and tissues.
Capillaries
Sites of nutrient, metabolic end product, and fluid exchange between blood and tissues
Venules
Low-resistance conduits for blood flow back to the heart. Their capacity for blood is adjusted to facilitate this flow
Veins
liquid portion of blood that contains dissolved nutrients, ions, wastes, gases, and other substances. Its composition equilibrates with that of interstitial fluid at the capillaries.
Plasma
Includes erythrocytes that function mainly in gas transport, leukocytes that function in immune defenses, and platelets (cell fragments) for blood clotting.
Cells
heart is a muscular organ enclosed in a fibrous sac, the located in the chest (thorax)
Pericardium
fibrous membrane is closely affixed to the heart and is called the
epicardium
The walls of the heart are composed primarily of cardiac muscle cells called
myocardium
inner surface of the cardiac chambers, as well as the inner wall of all blood vessels, is lined by a thin layer of cells
endothelial cells
between the atrium and ventricle in each half of the heart are the ____ which permit blood to flow from atrium to ventricle but not from ventricle to atrium
atrioventricular (AV) valves,
The left AV has two flaps and is thus called the bicuspid valve.
bicuspid valve.
right AV valve is called the ___ because it has three fibrous flaps
tricuspid valve
Adjacent cells are joined end to end at structures called
Intercalated disk
1 percent of cardiac cells do not function in contraction, but have specialized features that are essential for normal heart excitation. These cells constitute a network known a
Conduction System
The ____ initiates the heartbeat and helps spread the impulse rapidly throughout the heart.
conducting system
sympathetic postganglionic fibers re- lease primarily
norepinephrine
the parasympathetics release primarily
acetylcholine
arteries supplying the myocardium
coronary arteries
the blood flowing through them is termed the
coronary blood flow
The number of times the heart contracts per minute.
heart rate
The inability of the heart to generate tetanic contractions is the result of the long absolute defined as the period during and following an action potential when an excitable mem- brane cannot be re-excited.
refractory period
he period of ventricular contraction and blood ejection is called
systole
a period of ventricular relaxation and blood filling
diastole
During the first part of systole, the ventricles are con- tracting but all valves in the heart are closed, and so no blood can be ejected. This period is termed ____ contraction because the ventricular volume is constant
isovolumetric ventricular
Once the rising pressure in the ventricles exceeds that in the aorta and pulmonary trunk, the aortic and pulmonary valves open, and the ____ period of systole occurs.
ventricular ejection
he volume of blood ejected from each ventricle during systole is termed the
stroke volume (SV).
At this time the AV valves are also closed. Thus, no blood is entering or leaving the ven- tricles since once again all the valves are closed. Ventricular volume is not changing, therefore, and this period is termed
isovolumetric ventricular relaxation
Two ___ resulting from cardiac contraction are normally heard through a stethoscope placed on the chest wall. The first sound, a soft low-pitched lub, is associated with closure of the AV valves; the second sound, a louder dup, These sounds, which result from vibrations caused by the closing valves, are perfectly normal
heart sounds
- first sound, a soft low-pitched ___ is associated with closure of the AV valves;
- marks the onset of systole
lub
second sound, a louder __, is associated with closure of the pulmonary and aortic valves
-onset of diastole.
dup
Other sound, sign of heart disease
heart murmurs
____ can be produced by blood flowing rapidly in the usual direction through an abnormally narrowed valve (stenosis), by blood flowing backward through a damaged, leaky valve (insufficiency), or by blood flowing between the two atria or two ventricles through a small hole in the wall separating them (called a septal defect)
Murmurs
blood flowing rapidly in the usual direction through an abnormally narrowed valve. a murmur heard throughout
stenosis
blood flowing backward through a damaged, leaky valve
Insufficiency
blood flowing between the two atria or two ventricles through a small hole in the wall separating them
septal defect
The volume of blood pumped by each ventricle per minute is called the
cardiac output (CO)
