Cardiology 4: Vascular System Flashcards
(89 cards)
1
Q
what is flow (q)
A
volume of fluid displaced through a vessel with respect to time (L/min)
2
Q
flow is determined by what 2 things?
A
- pressure difference (Pi - Po)
2. resistance (R) across a vessel
3
Q
resistance is ____ proportional to flow
A
inversely
4
Q
pressure difference is ____ proportional to flow
A
directly
5
Q
resistance is primarily determined by the ____ of the vessel
A
radius
6
Q
a small change in radius results in a ___change in resistance
A
very large
7
Q
whenever the radius decreases, the flow decreases to the power of ___
A
4
8
Q
what is velocity?
A
distance fluid travels along a vessel with respect to time
9
Q
velocity is determined by what 2 things?
A
- flow through the vessel
2. cross-sectional area of vessel
10
Q
velocity is ____ proportional to flow
A
directly
11
Q
veloccity is ____ proportional to cross sectional area
A
inversly
12
Q
as the cross-sectional area increases, the velocity of blood ____
A
decreases
13
Q
vasculature plays an active role in regulating ____ and ___ for efficient matching of flow and demand
A
blood pressure and distribution of flow
14
Q
each vessel type has a specific function that is determined by its ____
A
structure
15
Q
structural feature of arteries
A
elastic
16
Q
structural feature of arterioles
A
can change radius
17
Q
structural feature of capillaries
A
material exchange
18
Q
structural feature of veins
A
expandable
19
Q
what is the one common structural feature of all the vasculature of the circulatory system?
A
a smooth, single-celled layer of endothelium
20
Q
___ arteries have thick walls with 3 layers
A
systemic
21
Q
what are the 3 layers of the systemic arteries?
A
- intima
- media
- adventitia
22
Q
describe the structure of the intima
A
single layer of endothelial cells acting as a metabolically active barrier between blood and the vessel wall
23
Q
describe the structure of the media
A
thick layer of elastin and collagen (strength) and vascular smooth muscle (for contraction)
24
Q
there are 2 main structures of arteries that give them their characteristic functions, what are these structures and their functions?
A
- large radius: low resistance tubes conductine blood to organs
- elasticity: pressure reservoir for maintaining blood flow during diastole
25
the arteries store ___ to maintain blood flow during diastole
pressure
26
what is the function of arterioles?
regulate rate and distribution of blood flow
27
arterioles are composed of ___ and ____ arranged in rings that allow for vasoconstriction and vasodilation
endothelium and smooth muscle
28
what are the 2 control systems of the arterioles and what systems control those systems?
1. Intrinsic (local conditions surrounding BV control)
| 2. extrinsic (nervous system input controls)
29
what are the 3 sources of intrinsic control of blood flow?
1. autoregulation / myogenic regulation
2. endothelium-mediated regulation
3. metabolic regulation
30
in autoregulation / myoregulation, blood flow is adjusted to _____ based on _____
local pressure; vessel stretch
31
in autoregulation / myoregulation, changes in local blood pressure cause changes in arteriolar radius and resistance to maintain _____
stable local flow
32
arterioles ___ with increased local blood flow and ____ with decreased pressure
constrict; dilate
33
in endothelium mediated regulation, endothelium lining produces substances that ___ or ___ arteriole smooth muscle
relax; contract
34
give 2 substances that the endothelium produces to induce relaxation of arteriole smooth muscle
nitric oxide; prostacyclin
35
give 2 examples of substances that the endothelium produces to induce contraction of the ateriole smooth muscle
angiotensin 2 and endothelin
36
in metabolic regulation, inadequate O2 supply by increased metabolic rate or decreased O2 delivery results in accumulation of ___ which locally ____ the arterioles
metabolites; dilates
37
give 4 examples of metabolites that can accumulate in metabolic regulation
1. lactic acid
2. CO2
3. H+
4. adenosine
38
what are the 3 sources of extrinsic control of flow?
1. sympathetic regulation
2. hormonal regulation
3. reflex regulation
39
sympathetic regulation involves what areas of the cerebral medulla to influence vessel tone?
1. pressor region
| 2. depressor region
40
stimulation of the pressor region causes____ resulting in ___
sympathetic outflow; vasoconstriction
41
stimulation of depressor region causes ____ resulting in ___
inhibition of pressor region, resulting in vasodilation
42
what 2 hormones released by the adrenal medulla influence arteriole tone?
NE and Epi
43
a low concentration of Epi causes ___ of arterioles by stimulating ___ receptors
dilation ; beta
44
high concentration of Epi causes ____ of arterioles by stimulating ___ receptors
constriction ; alpha
45
NE casues ____ of arterioles by stimulating ___ receptors
constriction; alpha
46
in reflex regulation, the cerebral medulla is under influence of neuronal impulses from what 5 places?
1. baroreceptors (arterial and cardiopulmonary)
2. chemoreceptors (peripheral and central)
3. hypothalamus that directly sense chemical
4. cerebral cortex (emotional reflexs)
5. skin (responds to pressure)
47
reflex regulation is also affected by blood concentrations of ___ and __
CO2 and O2
48
____ of peripheral vessels allowsdirection of blood flow to areas with greatest need
dual control
49
in the brain and heart is intrinsic or extrinsic dominant? why?
intrinsic; vital structures with limited tolerance for reduced blood flow
50
in the skin is intrinsic or extrinsic dominant? why?
extrinsic; important to homeostasis
51
in skeletal muscle is intrinsic or extrinsic dominant? why?
both interact allowing for tuned response to large changes in metabolic activity
52
when resting, skeletal muscle is mostly using ___ mechanisms, but with the onset of exercise, ___ mechanisms take over
extrinsic; intrinsic
53
neural regulation of the vascular system is primarily done by what branch of the NS?
sympathetic nervous system
54
autoregulation is mediated by a ____ mechanism whereby an increases in _____ induces vasoconstriction
myogenic; transmural pressure
55
____ are the smallest blood vessels in the body, composed of only 1 endothelial layer thick
capillaries
56
capillaries allow for the exchange of ___, ___ and ___ with interstitial fluid
gases, water , solutes
57
blood flow in the capillaries depends on the contractile state of the ____, which can constrict to the point of stoppinf flow completely
arterioles
58
capillaries have a large ___ and a ___ velocity
cross-sectional area; slow
59
capillary exchange of solutes occurs in what 3 ways?
1. diffusion
2. filtration
3. pinocytosis
60
the rate of diffusion of water across capillary walls is ~40 x greater than the rate at which water is brought to the capillaries by __
blood flow
61
diffusion of ____ molecules such as O2 and Co2 occurs directly through the lipid membrane
lipid-soluble
62
diffusion of ___ molecules occurs through water filled pores in the membrane of the capillary
lipid-insoluble
63
filtration at capillaries typically occurs through ____ and water movemnet is determined by balance of ___ across capillary wall
pores; starling forces
64
____ in capillary is the principal force of filtration
hydrostatic pressure
65
hydrostatic pressure (Pc) depends on what 2 things?
1. arterial (upstream) and venous (downstream) pressures
| 2. resistance of arterioles and venules
66
increases arterial / venous pressure results in ___ hydrostatic pressure
increased
67
increased arteiole resistance results in ___ hydrostatic pressure
decreased
68
increased venule pressure results in ____ hydrostatic pressure
increased
69
what force opposes Pc?
hydrostatic pressure of interstitial fluid Pif
70
osmotic pressure in the plasma of the capillary is called __ pressure
oncotic
71
___ is the principle force of absorption (fluid movement) into the capillary
oncotic pressure
72
oncotic pressure is generated by ___ due their inabilty to cross memnranes
plasma proteins (such as albumin)
73
oncotic pressure is a key factor in preventing __
fluid loss from capillary
74
oncotic pressure is opposed by what force?
osmotic pressure of interstitial fluid
75
small amount of movement of ____ occurs through tiny pinocytotic vesicles formed by pinching off endothelial cell membrane
large lipid insoluble molecules
76
the venous system returns blood to the heart from the tissue by ___
venous return
77
the large resevoir of the venous system is due to ____ and contains ___% of the blood volume
high compliance; 70
78
volume changes in the venous system results in ___ changes
pressure
79
the venous system regulates flow of blood back to the heart by adjusting ____. This is called ___
stiffness; venomotor tone
80
venous pressure is ____ by an increase in venomotor tone (constriction) with sympathetic sympathetic stimulation of smooth muscle
increased
81
unlike with arterioles, constriction of veins ____ flow
increases
82
venous pressure and venous return are ____ by skeletal muscle pump and respiratory pump
increased
83
____ Is the driving pressure for venous return difference between peripheral venous pressure and right atrial pressure
venous pressure and flow
84
explain the process of the skeletal muscle pump
muscle contraction compresses veins, forcing blood toward the heart as backward flow is prevented by one-way venous valves
85
explain the process of the respiratory pump
during inspiration, intra-thoracic pressure is decreased while intra-abdominal pressure increased, increasing pressure difference between peripheral veins and the heart (and thus venous return)
86
what happens to lymph vessels when muscle contraction
muscle contraction pulls on lymph vessels to open spaces between endothelial cells and permit proteins and large proteins and large particles into system
87
t/f flow of lymph occurs by pressure, muscle/lymphatic contraction and one-way valves
true
88
the lymphatic system is important for return of ___ and removal of ___
proteins; foreign particles (like bacteria)
89
when the lymphatic system is overwhelmed / blocked, ___occurs
edema
