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