chapter 21 Flashcards
1
Q
The vascular system consists of
A
arteries, capillaries and veins. These vessels must be resilient and flexible to withstand pressure and move with tissues
2
Q
Function of vascular system
A
exchange of material between blood and tissues
transporting blood between the capillaries and the heart
3
Q
Three layers of a vessel
A
- tunica intima
- tunica media
- tunica externa
4
Q
tunica intima
A
smooth, innermost layer made of endothelium and a surrounding layer connective tissue
5
Q
tunica media
A
middle layer, made of smooth muscle and external elastic membrane; structure varies pending vessel; important for maintenance of normal bp in arteries
6
Q
smooth muscle allows
A
arteries to constrict or dilate but is too thick to allow difussion between tissues and blood
7
Q
tunica externa
A
fibrous connective tissue, strong t prevent rupture or larger arteries, thinner in veins
8
Q
Arteries and veins run
A
side by side, arteries have thicker walls and higher bp than veins
9
Q
has small rounds lumen (internal space)
A
collapsed artery
10
Q
has a large, flat lumen
A
vein
11
Q
lining contracts
A
veins
12
Q
lining does not contract
lining folds
A
artery
13
Q
more elastic
A
arteries
14
Q
have valves
A
veins
15
Q
Arteries
A
responsible for vasodilation and vasoconstriction; blood travels through elastic arteries, muscular arteries and arterioles, lrgest vessels that carry blood away from heart
16
Q
Elastic arteries
A
conducting arteries
17
Q
artery walls are resillient due to
A
elastic fibers in the tunica media
18
Q
elastic rebound
A
cushions the sudden rise in pressure during ventricular systole and the recoil during ventricular diastole slows the drop in pressure
19
Q
Muscular Arteries
A
medium sized arteries with thick tunica media, distribution arteries, distributes blood to skeletal muscles and organs
20
Q
examples of muscular arteries
A
exernal carotid artery, brachial artery, mesenteric artery and femoral
21
Q
major arterial pressure points
A
common carotid, radial, brachial, femoral, popliteal, posterior tibial, dorsal pedal
22
Q
arterioles
A
small arteries; resistance vessels with poorly defined tunica externa
23
Q
tunica media consists of
A
smooth muscle to allow vasoconstriction/dialation in response to O2 levels
24
Q
arterioles have more resistance to blood flow because
A
more pressure is required to push blood through a small diameter
25
capillaries
exchange vessels, only vessels that permit exchange between blood and tissue, one cell layer thick
26
blood flow is slowest in capillaries to
allow time for two-way exchange
27
There are no capillaries in
cartilage and epithelial tissue
28
capillaries prevent
blood loss and keeps plasma proteins in the blood
29
Fenestrated capillaries
contain pores that allow rapid exchange
30
sinusoids
large and more permeable than other capillaries to allow exchange of larger molecules like protein and blood cells to leave and enter blood stream
31
precapillary sphincters
regulated by smooth muscle cells, found at the beginning of each network, regulate blood flow into capillary network based on the needs of tissue
32
collaterals
multiple arteries supplying one capillary bed; the fusion exemplifies an arterial anastomosis to provide alernate routes of blood flow
33
metarteriole
precapillary arteriole
34
thoroughfare channel
normal passageways of capillary bed
35
vasomotion
blood flow in capillaries occurs in pulses
36
veins
collect blood from tissues and organs and return it to the heart; LARGER in diameter than arteries, thinner walls because no blood pressure
37
venules
small veins that collect blood from capillary beds
38
medium sized veins
few smooth muscle cells with a sturdy tunica externa
39
large veins
all three layers present
40
valves
present in venules and medium veins of the limbs that have to fight gravity to return blood to the heart; prevent backflow
41
varicose vein
swollen and distended veins found in superficial veins of the legs...prego=blood pools in veins, valves no longer work=stretched
42
hemorrhoids
constipation or child birth...vessels in digestive tract irritated and swollen
43
exchange in capillaries, 3 steps
1. diffusion=gasses move from greater to lesser concentration
2. filtration=high pressure forces plasma out of caps to tissue distributing nutrients
3. colloid osmotic pressure=attracting pressure caused by proteins in blood, when blood reaches venous end, proteins pull tissue fluid/waste into capillaries
44
venoconstriction
systemic veins constrict to shunt blood to arteries, this maintains normal bp during blood loss
45
venous reserve
blood reserved in liver, skin and lungs...taken to general circulation after blood loss
46
pressure and resistance
increased pressure=increased flow, increased resistance=decreased flow
47
blood pressure
arterial pressure pressure is highest in arterial circulation due to the elevated resistance of the arterioles
48
capillary hydrostatic pressure
fluid pressure
49
venous pressure
low pressure of venous system
50
vascular resistance
friction between blood and the wall of the vessel; length and diameter of vessel affect resistance
51
vessel length
longer blood vessels experience more friction which increases resistance
52
vessel diameter
smaller diameters increase friction slowing the flow of blood; diameter has more of an affect on resistance than does vessel length
53
viscosity
normal blood viscosity is dependent on the presence of protein and RBC friction, too much increases friction, too little lower friction
54
turbulence
upsetting the flow of blood die to sudden changes in vessel diameter or vessel wall damage
55
blood pressure
the force blood exerts against the walls of the blood vessels
56
filtration in capillaries depends on
blood pressure
57
pressure is measured in
mmHg
58
systolic pressure
blood pressure when the left ventricle is contraction, higher of the two numbers
normal range: 120mmHg or below
59
diastolic pressure
when left ventricle is relaxed, the lower bp #
| normal range: 80mmHg or below
60
pulse pressure
the difference between the systolic and dyostolic pressures
61
mean arterial pressure (MAP)
diastolic pressure + (pulse pressure / 3)
62
**Hypertension
high blood pressure
63
Hypotension
low blood pressure
64
brachial artery
most common place to take normal bp. readings. pressure decreases as distance from the heart increases
65
capillary beds
bp decreases as it travels through the capillary beds of the organs and tissues. it is high enough for filtration but low enough to prevent rupture
66
veins-pressure
decreases further and approaches zero as blood enters the right atrium
67
pulmonary bp
see notes, pg. 6
68
elastic rebound
arteries recoil to their original dimensions during ventricular diastole
69
elasticity of large arteries
normal elasticity lower systolic pressure and increase diastolic pressure
70
elasticity in the aortic wall
absorbs some of the force of ventricle systole and recoils to maintain diastolic pressure when there is no blood flow
71
1. venous return, "starlings law"
the heart pumps only the blood it receives, if venous return decreases, cardiac muscle fibers will not be stretched, cannot contract as forcefully
72
2. resistance to blood flow
decreases as it travels through larger veins; increases velocity of blood
73
3. constriction of veins
smooth muscle allows veins to constrict and force blood toward the heart and valves prevent backflow
74
4. skeletal muscle pump, contraction of leg muscles...
squeeze the veins to force blood to the heart
75
5. respiratory pump
inhillation and exhillation of the lungs expand and compress veins to return blood to heart
76
6. heart rate and force
if heart rate and force increase, blood pressure increases (exercise)
77
7. peripheral resistance
vessels offer to the flow of blood (resistance to blood flow)
78
8. blood loss
small loss of blood (donation) temp. drop in pressure, followed by a rapid compensation in the form of a rapid heart rate and greater vasoconstriction
79
Diffusion
movement of ions from an area of greater concentrationto an area of lesser concentration
80
Use Diffusion
water, ions and small molecules such as glucose
81
some ions diffuse through channel in plasma membrane
Na+, K+, Ca+, CI-
82
large water souluable compounds diffuse through
fenestrated capillaries
83
Plasma proteins are
senusoid, which are very permeable
84
Filtration
* driven by hydrostatic pressure
* water and small solutes forced through capillary wall
* leaves larger solutes in blood stream
85
reabsorption
* the result of osmotic pressure
* equals pressure to prevent osmosis
* caused by suspended blood PROTEINS that are too lrg to cross capillary walls
86
net capillary colloid osmotic pressure is the difference between:
1. blood colloid osmotic pressure
2. interstitial fluid colloid osmotic pressure
(pulls water and solutes into a capillary from interstitial fluid)
*both control filtration and reabsorption through capillaries
87
forces water out of solution
net hydrostatic pressure
88
forces water into solution
net osmotic pressure
89
capillary exchange at arterial end
fluid moves out of capillary and into interstitial fluid
90
capillary exchange at venous end
fluid moves into capillary and out of interstitial fluid
91
transition point between filtration and reabsorption is closer to
venous end
92
capillaries filter more than
they absorb
93
excess fluid enters
lymph vessels
94
hemorrhaging
increases reabsorption of interstitial fluid
95
dehydration
accelerates reabsorption
96
increase in hydrostatic or decrease in colloid osmotic pressure within vessels causes fluid to
move out of blood and build up periphreal tissues=edema (swelling)
97
autoregulation of blood flow
factors that promote the dilation of precapillary sphincters are called vasodilators; relax the smooth muscle
98
local vasodilators:
```
decrease tissue O2 levels
increasee Co2
nitric oxide release from endothelial cells
increase in potassium or hydrogen ions
chemicals release during inflammation
elevated local temp
```
99
local vasoconstrictors
prostaglandins and thromboxanes; stimulate platelet aggregation and constrition of damaged vessels
100
baroreceptor reflexes
cardiovascular reflex that responds to change in pressure
101
chemoreceptor reflexes
cardiovascular reflex respond to changes in chemicals in blood
102
antidiuretic hormone
causes vasoconstriction that elevates bp, reabsorbs water from kidneys adding to blood volume
103
angiotensin II
responds to fall in renal bp, stimulates production of aldosterone, stimulates secretion of ADH, stimulates thirst, cardiac output, constriction of atrioles
104
erythropoetin
responds to a drop in blood O2 levels, causes vasoconstriction and stimulates the production and maturation of RBCs
105
Natriuretic peptide
respond to excessive stretching of arterial wall during diastole; reduces blood volume and pressure by sodium exchange in the kidneys, increase urine production
106
Norepiniphrine
stimulates vasoconstriction; raises bp
107
epinephrine
stimulates vasoconstriction; increases heart rate and force of contraction increasing bp
108
cardiovascular response to light exercise
* extensive vasodilation occurs increasing circulation
* venous return increases with muscle contraction
* cardiac output increases
109
Cardiovascular response to heavy exercise
* activates sympathetic nev. system
* cardiac output increases to maximum
* restricts blood flow to non essential organs
* redirects blood flow to heart, lungs and muscles
* blood supply to brain is not affected
110
**circle of willis (fig 21-24)
circle of arteries around the pituitary gland
111
**Hepatic portal circulation
blood from abdominal digestive organs and spleen circulate through the liver before returning to the heart
Purpose + anastomosis
112
fetal circulation
1. umbilical vein carries oxygenated blood from placenta to fetus
2. umbilical arteries carry oxygen deficient blood from the fetus to placenta
3. placenta contains fetal and maternal blood vessels that are close to one another but do not mix, but allows gases, wastes and nutrients in and out
113
ductus venosus
from the placenta the blood is taken to the inferior vans cava, after birth, these fetal vessels constrict and become nonfunctional
114
foramen ovale
opening in the interatrial septum that permits some blood flow from the R. atrium to L. atrium in the fetal heart, bypassing the R. ventricals
115
ductus arteriosus
a short vessel that diverts most of the blood in the pulmonary artery to the aorta and then to the body, bypassing lungs
116
when an infant is born, the intake of O2 and inflation of lungs
closes a flap over the foramen ovale and constricts the ductus arteriosis
117
Pulse
heartbeat found at an atrial site; the force of ventricular contraction transmitted through the arterial wall
118
Pulse sites, 7
```
radial=wrist, thumb side
carotid=neck
temporal=temple
femoral=top of thigh
popliteal=back of knee
dorsal pedis=top of foot
apical=the heart
```
