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BIOL 1190 > Ch. 21 - Blood Vessels and Hemodynamics > Flashcards

Ch. 21 - Blood Vessels and Hemodynamics Flashcards

1
Q

What are the 5 classes of blood vessels?

A

arteries, arterioles, capillaries, venules, veins

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2
Q

What are the 3 layers of a BV wall? What are they each composed of?

A
  1. tunica interna - simple squamous epithelium, basement membrane (collagen fibers), internal elastic lamina
  2. tunica media - smooth muscle cells and elastic fibers, external elastic lamina
  3. tunica externa - elastic and collagen fibers
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3
Q

Why do arteries have a thick tunica media?

A

to stretch easily; plays role in vasoconstriction (squeezing V wall, narrow lumen) and vasodilation (lumen diameter increases)

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4
Q

What are the 2 types of arteries?

A
  1. elastic (conducting)

2. muscular (distributing)

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5
Q

How do the form of elastic arteries relate to their function?

A
  • can receive blood under pressure and propel it onward
  • conduct blood from heart to medium sized muscular arteries

**aorta & initial branches, pulmonary trunk

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6
Q

What are the aorta’s major initial branches?

A

brachiocephalic, subclavian, common carotid, common iliac

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7
Q

How do the form of muscular arteries relate to their function?

A
  • capable of greater vasoconstriction and vasodilation to adjust rate of flow; have thick walls
  • direct blood flow and distribute blood to specific parts of body
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8
Q

What are anatomses?

A

union of 2 or more arteries supplying the same body region; blockage of one pathway has no effect

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9
Q

What is collateral circulation?

A

alternate route of blood flow through an anastomosis

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10
Q

What is the Circle of Willis? (cerebral arterial circle)

A
  • ring of arteries forming an anastomosis at the base of brain
  • internal, carotid, basilar arteries
  • supply cerebral cortex
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11
Q

What is a key role of arterioles?

A

regulating blood flow from arteries into capillaries and altering arterial BP via vasoconstriction/vasodilation

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12
Q

What are capillaries?

A

microscopic vessels that connect arterioles to venules; function in exchange of nutrients and wastes bt blood and tissue fluid

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13
Q

What are the components of a microcirculation?

A

metarterioles (branches off arteriole into C bed), through capillaries and into a postcapillary venule

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14
Q

What are the 3 types of capillaries?

A
  1. continuous capillaries
  2. fenestrated capillaries
  3. sinusoids
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15
Q

How do the form of each type of capillary relate to its function?

A
  1. continuous - found in brain, lungs, skeletal/smooth muscle, CT
  2. fenestrated - small holes to allow for material exchange in kidneys, small I, endocrine glands
  3. sinusoids - large fenestrations to allow proteins/some blood cells to pass from a tissue into blood in liver, RBM, spleen
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16
Q

Describe the walls of veins and venules

A

relatively thin; not designed to withstand high pressure, but can adapt to changing volume and pressure of blood

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17
Q

Where is the largest portion of your blood?

A

in systemic veins and venules bc they act as blood reservoirs where it can be diverted quickly if needed

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18
Q

What are the 3 mechanisms of capillary exchange?

A
  1. diffusion
  2. transcytosis
  3. bulk flow
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19
Q

What is moved in diffusion?

A

solutes; O2, glucose, AA, hormones diffuse down [gradient] out of capillaries –> into interstitial fluid –> into body cells

wastes/CO2 have high conc in fluid, then released by body cells to diffuse into blood

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20
Q

How do substances diffuse in capillary exchange?

A

through lipid bilayers of endothelial cells, fenestrations, intercellular clefts

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21
Q

What is transcytosis?

A

passage of large lipid-insoluble materials into endothelial cells via endocytosis followed by exocytosis

(proteins, hormones such as insulin entering bloodstream and maternal antibodies from maternal to placental circulation)

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22
Q

How does bulk flow function?

A

bulk flow of multiple solutes by filtration and reabsorption in response to pressure (high to low)

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23
Q

How is bulk flow regulated?

A

blood hydrostatic pressure

blood and interstitial fluid osmotic pressure

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24
Q

What is blood hydrostatic pressure and how does it function in bulk flow?

A

force blood exerts against walls of vessels generated by pumping of heart

  • highest in arteries, drops as blood enters capillaries
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25
Q

What is osmotic pressure and how does it function in bulk flow?

A

force created by solutes; pulls water and solutes out of fluid into the capillaries

osmotic pressure is higher in the blood than the interstitial fluid

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26
Q

Which pressures promote filtration and reabsorption?

A

filtration - BHP

reabsorption - BOCP

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27
Q

As 85% of fluid is reabsorbed in capillary exchange, what happens to the remaining 15%?

A

it is returned to the blood via lymphatic vessels

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28
Q

What is edema and what can cause it?

A
  • abnormal increase in interstitial fluid
  • occurs when filtration > absorption
  • excess F: increased BP, permeability of capillaries
  • inadequate A: decreased [plasma proteins] lowering BOCP
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29
Q

What is lymphedema?

A

when lymph vessels fail to work properly

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30
Q

What is blood flow? What causes changes in blood flow?

A

volume of blood moving past a point in a given amount of time (mL/min)

  • greater the pressure difference, greater the BF
  • more resistance, the less BF
31
Q

What are factors affecting blood flow?

A
  1. pressure difference between aorta and capillaries
  2. vascular resistance to flow
  3. venous return
32
Q

What is blood pressure and what is influenced by/dependent on?

A
  • force exerted by blood against BV walls due to contraction of heart
  • influenced by elasticity of BV walls
  • dependent on amount of blood in system
33
Q

Where is BP highest?

A

highest in aorta and large arteries; falls as distance from heart increases (O mmHg at right atrium)

34
Q

What is vascular resistance?

A

the force opposing blood flow due to friction between blood and BV walls

35
Q

What is the strength of vascular resistance dependent on?

A
  1. diameter of vessel lumen (vasoconstriction/vasodilation)
  2. viscosity of blood
  3. total length of vessels
36
Q

How does blood viscosity affect resistance, and ultimately BP?

A
  • depends mostly on ratio of RBC to plasma volume

* high viscosity –> high resistance –> increased BP

37
Q

How does being overweight increase BV length?

A

more BV in adipose tissue; increases total BV length in circulatory system

**300 km more BV for every pound of fat!

38
Q

How does venous return affect blood flow?

A
  • dependent on good return of venous blood back to right atrium
39
Q

Because gravity opposes flow up to heart, what helps the return of blood to heart?

A

skeletal muscle pump & respiratory pump

40
Q

How does the skeletal muscle pump affect blood flow?

A

valves in large veins in legs prevent backflow of blood

  • contraction of leg muscles squeeze veins, pushing blood up and down
41
Q

How do the valves function in the skeletal muscle pump?

A
  • while standing still, valves are open

- proximal valves open while distal valves catch blood and close; blood moves upward

42
Q

How does the respiratory pump affect blood flow?

A
  • breathing helps bring blood back to heart
43
Q

What aspects of breathing help bring blood back to the heart?

A
  • diaphragm contracts and moves downward –> expands thorax (lower pressure) and compresses abdomen (higher pressure)
  • this creates area of lower pressure around heart, and area of higher pressure in abdomen which moves blood up increasing venous return
44
Q

Which veins are compressed during inhalation and exhalation?

A

I - abdominal veins

E - thoracic veins

45
Q

Where is velocity fastest and slowest?

A

F - aorta (where cross-sectional area is lowest)

S - capillaries (where cross-sectional area is greatest)

46
Q

Where is the cardiovascular centre located and what does it regulate?

A
  • medullar oblongata (part of brainstem)

- heart rate, contractility, BV diameter

47
Q

Where is the input to the CV centre sent from?

A
  1. parts of brain (cerebral cortex, limbic system, hypothalamus –> body temp, emotions)
  2. proprioceptors (joint movement)
  3. baroreceptors (pressure change in BV)
  4. chemoreceptors ([chemicals] in blood H+, O2, CO2)
48
Q

What are possible output from the CV centre? (to what it regulates)

A
  1. heart rate - increase/decrease
  2. contractility - increase/decrease
  3. BV - vasoconstriction/vasodilation
49
Q

Which hormones regulate BP?

A
  1. epinephrine and norepinephrine
  2. renin-angiotensin-aldosterone system
  3. antidiuretic hormone (ADH)
  4. atrial natriuretic peptide (ANP)
50
Q

How do epinephrine/norepinephrine regulate BP?

A

increases heart rate and contractility

51
Q

How does renin-angiotensin-aldosterone system regulate BP?

A
  • causes vasoconstriction, leads to increased blood volume and BP
  • decreases urine production by kidneys
52
Q

How does ADH regulate BP?

A
  • causes vasoconstriction, leads to increased blood volume and BP
  • increases water absorption by kidneys + decreased urine production
53
Q

How does ANP regulate BP?

A
  • causes vasodilation and increased BP

- increases urine production

54
Q

What triggers each hormone to regulate BP?

A
  1. E/NE - by sympathetic NS, secreted by adrenal medulla
  2. R-A-A - by decrease in BP/blood flow to kidneys
  3. ADH - low blood volume or high osmotic pressure
  4. ANP - stretching of atrial walls due to high blood volume
55
Q

What is autoregulation?

A

matching tissue blood flow and metabolic demands

–> increase in metabolic activity (more ATP used) in an organ will trigger increased blood flow

56
Q

In response to low O2 levels, how do the effects on BV vary?

A
  • system vessels dilate

- pulmonary vessels constrict

57
Q

What is shock?

A

failure of CV system to deliver adequate amounts of O2 and nutrients to body tissues

58
Q

What does shock result in?

A
  • inadequate perfusion (supply of blood)
  • cells forced to switch to anaerobic resp
  • lactic acid buildup
  • damage and death of cells/tissues
59
Q

What are 4 types of shock and what are they caused by?

A
  1. hypovolemic - decreased blood volume
  2. cardiogenic - poor heart function
  3. vascular- excessive vasodilation
  4. obstructive - obstruction of blood flow
60
Q

What is the route of systemic circulation?

A

O2 blood from L ventricle –> aorta –> body –> returns de-O2 blood to R atrium

61
Q

What is the route of pulmonary circulation?

A

R side of heart –> lungs –> back to heart

62
Q

What is hepatic portal circulation?

A

detouring of venous blood from GI tract to liver on its way to heart

63
Q

How do pulmonary arteries differ from systemic arteries?

A

larger diameter, thinner walls, less elastic tissue

  • less pressure needed to move blood to lungs due to less distance
64
Q

What is the route of hepatic portal circulation?

A

venous blood from GI tract (pancreas, spleen, stomach, intestines, gallbladder) –> hepatic portal vein/sinusoids of liver –> heart

65
Q

What is the benefit of venous blood going to the liver before going to the heart?

A

allows for nutrient storage/modification & blood detoxification by liver

66
Q

What are some changes in the CV system associated with aging?

A
  • decreased compliance of aorta
  • reduced cardiac output & max heart rate
  • increase in systolic pressure –> hypertension
  • coronary artery disease, atherosclerosis, congestive heart failure
67
Q

What is hypertension?

A

chronic systolic BP and diastolic BP (140mmHg/90mmHg or greater)

68
Q

What are treatment options for hypertension?

A

various drugs such as diuretics, beta blockers, vasodilators, calcium channel blockers

69
Q

How can diuretics treat hypertension?

A

cause the kidneys to remove odium and water helping BV walls to relax

70
Q

How can beta blockers treat hypertension?

A

blocking effects of epinephrine (hormone that increases heart rate) and therefore lowers BP

71
Q

How can vasodilators treat hypertension?

A

triggered by high blood volume, leads to decreased BP

72
Q

How can calcium channel blockers treat hypertension?

A

slow down/prevent Ca2+ from entering cells of heart and BV walls

73
Q

What are some lifestyle changes to treat hypertension?

A

losing weight, exercising, limiting alcohol/sodium intake, managing stress

BIOL 1190 (18 decks)

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