A&P Ch 20 Vessels and Circulation
Which statement accurately compares filtration and reabsorption?
Filtration involves bulk flow of fluid out of the blood, whereas reabsorption is bulk flow back into the blood.
What factors influence these two values, and how can their values change?
Heart rate and stroke volume Increase end systolic pressure and decrease end diastolic pressure
Movement of large amounts of fluids and dissolved substances down a pressure gradient
bulk flow
Homeostatic mechanisms to maintain a normal blood pressure respond to:
cardiac output, resistance, blood volume (increase in any of these increases blood pressure)
Valves in veins:
cause venous blood flow to go in only one direction.
High carbon dioxide levels and low pH in blood of the carotid arteries will stimulate:
chemoreceptors to activate the vasomotor center.
Signals white blood cells where to go
chemotaxis
Which is the most common type of capillary?
continuous
Excitation of the vasomotor center results in:
increased sympathetic activity and predominantly more vasoconstriction than vasodilation.
Increased cardiac output ______ the blood pressure.
increases
Concerning the exchange between blood and interstitial fluid at systemic capillaries:
more fluid is filtered than reabsorbed.
Blood colloid osmotic pressure is largely due to:
the proteins in the blood, and it promotes reabsorption.
Cardiac output depends on blood pressure and resistance.
true
Epinephrine, aldosterone, and antidiuretic hormone each cause an increase in blood pressure.
true
The contraction of skeletal muscles plays an important role in the movement of blood in the veins.
true
The two major factors affecting blood flow (and adequate tissue perfusion) are resistance and the blood pressure gradient.
true
_____ make up the bulk of the capillary bed.
true capillaries
The ________ is composed of an endothelium and a subendothelial layer made up of a thin layer of areolar connective tissue.
tunica intima
The ________ is composed of circularly arranged layers of smooth muscle cells.
tunica media
Movement of blood from capillaries back to heart
venous return
Smallest veins from 8 to 100 micrometers diameter
venules
The major way resistance is regulated
vessel radius
Peripheral resistance is affected by:
viscosity, vessel length, lumen size
A vasodilator causes a decrease in local blood flow at a capillary bed.
false
Blood pressure is lowest in:
veins
If someone's blood pressure were listed as 110/65 mmHg, then their mean arterial pressure (MAP) would be:
80 mm Hg
_____ allows for an increase in the perfusion of a local tissue.
Angiogenesis
Give an example of an elastic artery.
Aorta
Baroreceptors are found where?
Aortic arch, carotid sinuses
Located in arch of aorta send signals via vagus nerve
Aortic bodies
The smallest of the 3 arteries?
Arterioles
Lower blood pressure when too high
Atrial natriuretic peptide (ANP)
During exercise, blood flow to skeletal muscles increases. What other blood flow changes occur?
Blood flow to coronary vessels increases, and flow to abdominal organs decreases.
Imagine yourself sitting in an awkward position in an uncomfortable chair that is depriving part of your leg from normal blood flow. This deprivation of adequate perfusion will result in what sort of local changes in your leg?
Build up of carbon dioxide and hydrogen ions will cause vasodilation.
Located within external carotid artery send signals via glossopharyngeal nerve
Carotid body
Involved in regulating blood pressure, but they are more important in regulating respiration
Chemoreceptor reflexes
Raise blood pressure when too low
Epinephrine and norepinephrine Angiotensin II Antidiuretic hormone (ADH) Aldosterone
Most common of the 3 arteries?
Muscular arteries
Movement of fluid back into blood on venous end
Reabsorption
Blood flow inversely related to resistance
Resistance
Blood flow directly related to pressure gradient
Systemic blood pressure gradient
Which statement accurately describes total blood flow?
Total blood flow equals cardiac output and can vary significantly over time with activity levels.
If someone suffered from hypertension, such that the blood pressure in their capillaries was elevated, then net filtration pressure would be:
above normal
Multiple alternative pathways possible, differ in number of arteries, capillary beds, or veins
alternating pathway
In general, as an artery's diameter decreases, the artery walls show:
an increase in the relative amount of smooth muscle and a decrease in the relative amount of elastic fibers.
Filtration dominates at the ____ end of a capillary bed, and is driven by ____ pressure.
arterial, hydrostatic
If someone were to have abnormally low levels of protein in their blood, then net filtration pressure would:
be higher than normal.
Sinusoids are found in:
bone marrow, spleen, and liver
As blood moves from the arterial end to the venous end of a capillary, net filtration pressure:
decreases, as blood hydrostatic pressure decreases.
Term that describes white blood cells leaking out of capillaries
diapedesis
-pressure in arteries during ventricular diastole -lowest pressure generated in arteries, but not that low -artery maximally recoiled (used energy to keep pressure relatively high
diastolic pressure
Equation to calculate MAP
diastolic pressure + 1/3 pulse pressure E.g., with blood pressure 120/80 MAP = 80 + 40/3 = 93
Oxygen and carbon dioxiode are transported between the blood and interstitial fluid by way of:
diffusion from areas of higher concentration to lower concentration.
Blood flow is _____ related to the pressure gradient but _____ related to the resistance.
directly, inversely
Peripheral resistance is _____ related to vessel length and _____ related to vessel radius.
directly, inversely
The largest arteries of the body are classified as:
elastic arteries
Arteries that provide only one pathway for blood to organ
end arteries
Stimulators of chemoreceptors
high carbon dioxide, low pH, very low oxygen
How is blood pressure regulated over longer-terms (hours and days)?
hormones
A portal system:
is one in which blood flows through two capillary beds before being sent back to the heart.
Give an example of a fenestrated capillary.
kidney glomerulus
Average of blood pressure forces on arteries
mean arterial pressure (MAP)
Aldosterone and atrial natriuretic peptide have ________ effects on blood pressure.
opposite
_____ of the blood in the body is in the veins.
over half
Amount of blood entering capillaries per unit time per gram of tissue
perfusion
Blood flowing through two capillary beds, one after the other
portal system
Smooth muscle ring at true capillary origins
precapillary sphincter
-measures elasticity and recoil of arteries -highest in arteries closest to the heart -may change temporarily with exercise -difference between systolic and diastolic blood pressure
pulse pressure
One major artery delivering blood to organ or region
simple pathway
At a capillary bed, a vasoconstrictor:
stimulates precapillary sphincters and decreases local blood flow.
Vasodilation and vasoconstriction controlled by
sympathetic division of ANS
Which part of the circulatory system holds the largest amount of blood?
systemic veins
-pressure in arteries during ventricular systole -highest pressure generated in arteries -elastic arteries maximally stretched (storing energy)
systolic pressure
Angiotensin II causes:
vasoconstriction, decrease urine formation, and increased thirst.
Cycle of contracting and relaxing of precapillary sphincters
vasomotion
The constant slight constriction of the arterioles
vasomotor tone