CH 21 Blood Vessels & Hemodynamics Flashcards
(111 cards)
1
Q
How many layers does a blood vessel have
A
3
2
Q
What are the three layers of a blood vessel
A
Tunica interna, tunica media, tunica externa
3
Q
Tunica interna
A
innermost layer, adjacent to lumen
4
Q
Tunica media
A
middle layer, smooth muscle and elastic fibers
5
Q
Tunica externa
A
outermost layer, adjacent to surrounding tissue
6
Q
Arteries carry blood away from the BLANK and to the BLANK
A
heart, tissues
7
Q
Components of elastic arteries
A
1- large thick walled arteries with elastin in all 3 tunis 2- aorta is one 3inactive in vasoconstriction 4-act as pressure reservoirs–expand and recoil as blood ejected from heart= smooth pressure downstream
8
Q
Largest arterie
A
aorta
9
Q
Components of muscular arteries
A
1)distal to elastic arteries 2)deliver blood to organs 3)thick tunic media with more smooth muscle 4) active in vasocontriction
10
Q
What are the smallest arteries
A
arterioles
11
Q
Arterioles lead to
A
capillary beds
12
Q
Arterioles control
A
flow into capillary beds via vasodialation and vasoconstriction
13
Q
Anastomoses
A
the union of the branches of 2 or more arteries supplying the same region of the body
14
Q
Anastomoses components
A
1)provides an alternate route for blood flow
15
Q
Arteries that do not form an anastomoses are called
A
end arteries
16
Q
Necrosis occurs when
A
an artery is blocked and blood cannot get to that particular region of the body
17
Q
Capillaries are
A
microscopic vessels that usually connect arterioles and venules
18
Q
capillary walls are composed of
A
a single layer of cells and a basement membrane
19
Q
Because their walls are so thin, capillaries permit:
A
the exchange of nutrients and wastes between blood and tissue cells
20
Q
Continous capillaries are formed by
A
endothelial cells
21
Q
Venules are
A
the small vessels formed by the union of several capillaries
22
Q
Venules drain blood from BLANK into BLANK
A
capillaries into veins
23
Q
Veins are formed from the union of several
A
venules
24
Q
compared to arteries, veins have a thinner BLANK and BLANK and a thicker BLANK
A
tunica interna and media and a thincker externa
25
Veins have less blank and blank than arteries
elastic tissue and smooth muscle
26
veins contain
valves
27
At rest, the largest portion of the blood is in:
systemic veins and venules (blood reservoirs)
28
Substances cross capillary walls by (3)
diffusion, transcytosis and bulk flow
29
Diffusion
(passes through walls easily)substances such as oxygen, carbon dioxide, glucose, amino acids and hormones cross capillary walls via simple diffusion
30
Transcytosis
(endocytosis on one side and exocitosis on another) large, lipid-insoluble molecules (like insulin) cross capillary walls in vesicles via transcytosis
31
Bulk Flow
(goes between cells, how most things are moved such as nutrients and gases) a passive process in which large number of ions, molecules or particles in a fluid move together in the same direction
32
bulk flow is more important for
regulation of the relative volumes of blood and interstitial fluid
33
Starling's law of capillaries
under normal conditions, the volume of fluid and solutes reabsorbed is almost as large as the volume filtered
34
Blood flow is
the volume of blood that flows through any tissue in a given time period
35
Total blood flow is
cardio output, the volume of blood that circulates through systemic (or pulmonary) blood vessels each minute
36
Cardio output =
heart rate X stroke volume
37
What generates BP
contraction of the ventricles
38
BP is determined by (3)
CO, blood volume and vascular resistance
39
the higher the BP the greater the
blood flow
40
systolic pressure
pressure exerted in aorta during ventricular contraction
41
average systolic pressure
120 mmhg in normal human
42
diastolic presure
lowest level of aortic pressure
43
pulse pressure
difference between systolic and diastolic pressure
44
throwing of arteries =
pulse
45
Vascular Resistance (R)
is the opposition to blood flow due to friction between blood and the walls of blood vessles
46
The higher the R (vascular resistance)
the smaller the blood flow
47
R (vascular resistance) depends on (3)
1) size of the blood vessel lumen 2) blood viscosity 3)total blood vessel length
48
Blood factors that remain relatively constant (2)
1) viscosity 2)blood vessel length
49
blood viscosity
the "stickiness" of blood due to formed elements and plasma proteins
50
Increased viscosity =
increased resistance
51
Longer blood vessel=
greater resistance encountered
52
Greatest influence on resistance
blood vessel diameter
53
Venous Return
the volume of blood flowing back to the heart through the systemic veins, occues due to the pressure generated by contractions of the heart's left ventricle
54
Venous return is assisted by
valves, respiratory pump and skeletal muscle pump
55
Where is the cardiovascular center located
medulla oblongata
56
what is the cardiovascular center
the group of neurons that regulate heart rate, contractility and blood vessel diameter
57
Baroreceptors
Important pressure-sensitive sensory neurons that monitor stretching of the walls of blood vessels and the atria
58
2 types of blood pressure controls
1) short term neural and hormonal controls 2)long-term renal regulation
59
short term neural and hormonal control of BP
counteract fluctuations in blood pressure by altering peripheral resistance and CO
60
long-term renal regulation
contracts fluctuations in blood pressure by altering blood volume
61
Direct renal mechanism
alters blood volume independently of hormones.
62
arterial system
heart-->elastic arteries -->muscular arteries --> arterioles--> capillaries ---> venous system
63
venous system
capillaries-->post capillary venule-->small veins -->large veins-->heart
64
Elastic arteries are known as
conducting arteries
65
muscular arteries are known as
distributing arteries
66
arterioles are known as
resistance vessles
67
capillaries
exchange vessels
68
small and large veins are known as
capacitance veins
69
largest arteries are known as
elastic arteries
70
the aorta is located off the
left ventricle
71
second largest arteries are known as
muscular arteries
72
the purpose of muscular arteries
to deliver blood to the body
73
muscular arteries are _____ in vasoconstriction
active
74
elastic arteries are _______ in vasoconstriction
inactive
75
elastic arteries act as pressure reservoirs by
expanding and recoiling as blood is filled and ejected from the heart
76
elastic arteries are associated with which part of BP
ventricular systole
77
muscular arteries work to get blood to
the head, upper and lower extremities
78
which are the smallest arteries
arterioles
79
the control system for vasomotor control (vasodialation and vasoconstriction)
autonomic system response located in the medulla oblogata
80
when there is sufficient oxygen in the arteries, the precapillar sphinters are
contracted
81
when there is insufficient oxygen in the arteries precapillaries sphincters are
relaxed
82
thoroughfare channel
where blood flows when precapillary sphincters are contracted -- space between arterioles and venules
83
3 types of capillaries (3)
continuous, fenestrated, sinusoid
84
continous capillaries
continuous capillary formed by endothelial cells, tight junctions, commonly found in the brain
85
fenestrated capillaries
have medium large holes allowing for quicker transfusion of gas and substances, found where we pick up and drop off waste like the liver and kidneys
86
sinusoid capillaries
large holes called sinusoids, found in places of a lot of dead RBC transport like the spleen
87
tunica interna is made of
endothelium
88
tunica media is made of
smooth muscle
89
veins and venules have a _____ due to ______
valve - low pressure of blood
90
hydrostatic pressure in capillaries
pushes fluid out of capillaries
91
osmotic pressure in capillaries
pulls fluid into capillaries
92
there is more pressure inside the ____ than the ______
blood vessels than the tissue
93
net filtration occurs at the
arteriolar end of a capillary
94
NFP =
outward force
95
NFP in net filtration =
10mmHg
96
NFP in net reabsorption
-8mmhg
97
Net reabsorption occurs at the
venous end of a capillary
98
why does pressure slow in net reabsorption
due to surface area and coming in contact with arterial walls.
99
vasocontriction does what to resistance
increases
100
if resistance is doubled
the resistance is 1/16 as much
101
input to cardiovascular center (nerve impulses) come from
higher brain centers, proprioreceptors (monitor joint movement) and chemoreceptors (measuring blood acidity)
102
parasympathetic effects of cardiac output
vagus nerves (para) cardiac accelerator nerves (symp) vasomotor nerves (symp)
103
direct renal mechanism is mainly responsive to
higher BP
104
the renin-angiotensin-aldosterone mechanism kicks in when BP is
Low
105
pathway of renin-angiotensin- aldosterone mechanism
renin -->angiotensinogen-->angiotensin 1--->angiotensin 2
106
angiotensin converting enzyme comes especially from
lungs
107
where does the conversion of angiotensinogen to angiotensin 1 occur
in the liver
108
functions of angiotensin II- how it triggers an increase in BP
increases blood volume by stimulating aldosterone (vasoconstriction), causing ADH release, triggering hypothalamic thirst center.
109
hormone released by vasodialation
atrial nautriuretic peptide - released by heart with high BP
110
hormone released to increase blood volume
aldosterone, antidiuretic hormone
111
hormone released to decrease blood volume
atrial natriuretic peptide
