Phys Chapter 14

the pressure gradient across the vessel and inversely related to resistance of the vessel

what is the rate of blood movement through the cardiovascular system related to?

85 mmHg

what is the median arterial pressure?

aorta

where is the median arterial pressure measured?

2-8 mmHg

what is the central venous pressure?

veins that lead to the right atrium

where is the central venous pressure measured?

• vessel radius

• vessel length

• blood viscosity

what factors influence resistance of blood vessels to blood flow?

a decrease in blood vessel radius, which increases resistance

what is vasoconstriction?

increase in blood vessel radius, which decreases resistance

what is vasodilation?

have a greater resistance but is not a major factor for adults

what effect do longer blood vessels have on blood pressure?

increases resistance but is not a major determinant of resistance over the short term

how does an increase in blood viscosity affect blood pressure?

the total cross-sectional area of the vessels

what is the primary determinant of velocity?

arteries and arterioles

what carries blood away from the heart?

arteries

which is bigger, arteries or arterioles?

veins and venules

what carries blood to the heart?

veins

which is bigger, veins or venules?

the smallest blood vessels

what are capillaries?

arterioles, capillaries, and venules

what is the microcirculation composed of?

epithelium cells

what lines all vessel lumens?

aorta

what is the largest artery?

elastic material, also known as connective tissue

what allows for high pressure and expansion-contraction with changes in blood pressure in the thick walls of the arteries?

the wall becomes thinner and the amount of smooth muscle increases

what happens when arteries get smaller?

low resistance to blood flow

what does a large artery diameter provide?

pressure reservoirs

what do arteries function as?

diastole

what phase of the cardiac cycle do arteries ensure blood flow?

expansion of arteries during systole

what does the elastic connective tissue of the arteries allow for?

recoil during diastole

what functions to “pump” the blood forward in arteries?

pulse detected in the radial artery of the wrist

what does recoil during diastole contribute to?

link arteries to capillaries

what is the function of arterioles?

changes in smooth muscle activity

what controls arteriole diameter and functions to regulate blood flow?

partial contraction without external factors

what generates “arteriolar tone” in arterioles?

smooth muscle contraction

what is vasoconstriction in arterioles?

smooth muscle relaxation

what is vasodilation in arterioles?

change in blood flow not due to neuronal or hormone signaling

what is intrinsic control?

increase in blood flow following metabolic activity

what is active hyperemia?

if blood flow is higher than metabolic demand

when does vasoconstriction in arterioles occur?

regulation by chemicals secreted by neighboring cells or blood vessel endothelial cells

what is local regulation in arterioles?

• oxygen

• endothelin-1

which chemicals cause vasoconstriction in the arterioles?

• carbon dioxide

• potassium ions

• acids

• adenosine

• nitric oxide

• bradykinin

• prostacyclin

which chemicals cause vasodilation in the arterioles?

the smooth muscle of arterioles

what do sympathetic neurons innervate?

to divert blood flow to the heart and skeletal muscle

what is the function of the flight-or-fight response?

vasopressin and angiotensin II

which two hormones also control arteriole activity by promoting vasoconstriction?

capillaries

what is the primary site for the exchange of solutes between the plasma and tissues?

metabolic activity of the tissue

what is capillary density related to?

capillaries

what has the thinnest walls?

single layer of flattened endothelial cells, lack smooth muscle

what is the capillary walls composed of?

basal lamina

what are capillaries supported by?

single cell passage

what is the purpose of the cross-sectional diameter of capillaries?

exchange of materials by passive diffusion due to the leakiness of the epithelial membrane

what does slow blood flow allow for in capillaries?

smooth muscles and metarterioles

what controls blood flow through capillaries?

a “bypass” that moves blood from an arteriole to a venule without moving through capillaries

what is the function of metarterioles?

continuous

what is the most common type of capillary?

tight junctions

how are endothelial cells joined in continuous capillaries?

slow permeability

what is the permeability of continuous capillaries for ions and amino acids?

gases and lipid soluble material

what can pass through the continuous capillary cell membrane?

transcytosis

how do large molecules like proteins move through the endothelial cell of continuous capillaries?

fenestrated capillaries

What type of capillary has endothelial cells with large pores that allow the movement of large molecules?

kidneys, intestine, and endocrine glands

where are fenestrated capillaries abundant?

sinusoidal capillaries

what type of capillaries are highly porous with gaps between endothelial cells that allows for the passage of blood cells and proteins from tissue into the bloodstream?

bone marrow, liver, and spleen

where are sinusoidal capillaries found?

allows albumin and clotting factors to enter the plasma

what is the function of the sinusoidal capillaries found in the liver?

allows blood cells to enter

what is the function of sinusoidal capillaries found in the spleen?

allows blood cells to leave

what is the function of the sinusoidal capillaries in blood marrow?

vena cava

what is the largest vein?

a “volume reservoir”

what is the function of veins?

blood; lower

veins hold more ________ than arteries and at a _________ pressure

pressure gradient between peripheral veins and the right atrium

what is venous return driven by?

one-way

what type of valve do veins have to promote blood flow to the heart?

skeletal muscle

what type of muscle contraction compresses veins to promote movement towards the heart?

contraction

what opens proximal valves and closes distal valves?

relaxation

what opens distal valves and closes proximal valves?

alternating activity of contraction-relaxation

what pumps blood toward the heart?

to return fluid and protein to the cardiovascular system

what is the function of the lymphatic system?

filter bacteria and foreign matter

what do lymph nodes do?

lymph nodes

where is the site of lymphocyte accumulation

• system contains “valves” that ensure unidirectional fluid movement

• driven by smooth muscle contraction in lymphatic vessel walls and skeletal muscle compression

• unidirectional movement of fluid

what are the similarities between the lymphatic and systemic cardiovascular system?

• no single pump

• lymph vessels can “blind-end”

• thinner endothelial layer

what are the differences between the lymphatic and systemic cardiovascular system?