Lesson 10 Flashcards
1
Q
fluid filter out of the ___ end of the capillary and osmotically reenters ____ end
A
- arterial
- venous
2
Q
what does fluid do as it filters in and out of the cell?
A
- delivers materials to the cell
- remove metabolic waste
- maintain balance between osmosis and hydrostatic pressure
3
Q
what are the two types of hydrostatic pressure
A
- capillary hydrostatic pressure
- interstitial hydrostatic pressure
4
Q
capillary hydrostatic pressure
A
drives fluid out of capillary
5
Q
interstitial hydrostatic pressure
A
drives fluid into capillary
6
Q
hydrostatic pressure is usually high on ____ and low on ____ end
A
- arterial
- venous
7
Q
hydrostatic pressure equation
A
HP = CHP - IHP
8
Q
colloid osmotic pressure
A
draws fluid into capillary
9
Q
what does osmotic pressure result from
A
plasma proteins being more abundant in blood than in fluid
10
Q
oncotic pressure
A
net colloid osmotic pressure
10
Q
colloid osmotic pressure equation
A
COP = bloodCOP - tissueCOP
11
Q
net filtration pressure is the difference between
A
net hydrostatic pressure and net osmotic pressure
12
Q
net filtration pressure equation
A
NFP = (CHP - IHP) - (BCOP - ICOP)
13
Q
usually in normal condition the IHP and ICOP are
A
equal
14
Q
capillary exchange at the arterial end characteristicers
A
- NFP>0
- net hydrostatic pressure > net osmotic pressure
- fluid moves out of capillary and into the interstitial fluid
15
Q
capillary exchange at venous end of capillary characteristics
A
- NFP<0
- net osmotic pressure > net hydrostatic pressure
- fluid moves into capillary and out of interstitial fluid
16
Q
what is the resulting out net filtration pressure at the arterial end
A
13mmHg out
17
Q
what is the resulting inward net filtration pressure at the venous end
A
7mmHg inward
18
Q
why is the net hydrostatic pressure lower at the venous end than at the arterial end
A
blood pressure is lower so oncotic pressure overrides hydrostatic pressure
19
Q
what is the overall result of the NFP being lower at the venous end than at the arterial end
A
capillary gives off fluid at arterial end and reabsorbs it at the venous end
20
Q
capillaries reabsorb about ___ of the fluid they filter
A
85%
21
Q
what is done with the remaining fluid that does not get reabsorbed by the capillaries
A
reabsorbed by lymphoid system and ultimately returned to the blood
22
Q
____ liter of fluid filtered. ___ liters of fluid reabsorbed.
A
- 24
- 20.4
23
Q
___ liters of fluid drained away by the lymphoid capillaries.
A
3.6
24
glomeruli of kidneys devoted to
filtration
25
alveolar capillaries in lungs devoted to
absorption so fluid doesn't fill air spaces
26
characteristics of resting tissue
- most precapillary sphincters constricted
- capillaries are collapsed
- BP low
27
when does reabsorption dominate?
resting tissue
28
characteristics of active tissue
capillary pressure rises
29
when does filtration dominate?
active tissue
30
what happens to fluid filtration/reabsorption in traumatized tissue?
release substances that increase permeability and filtration
31
edema
accumulation of excess fluid in a tissue
32
what is happening in the body during edema?
fluid filters into tissue faster than it is absorbed back into the capillary
33
three primary causes of edema
1. increased capillary filtration
2. reduced capillary reabsorption
3. obstructed lymphatic drainage
34
increased capillary filtration is caused by
- kidney failure
- histamine
- old age
- poor venous return
35
reduced capillary reabsorption caused by
- hypoproteinemia
- liver disease
- dietary protein deficiency
36
obstructed lymphatic drainage caused by
surgical removal of lymph nodes
37
pathological causes of edema
- tissue death
- pulmonary edema
- cerebral edema
38
severe edema can cause
circulatory shock
39
what causes tissue death
oxygen delivery and waste removal impaired
40
what causes pulmonary edema
fluid in lungs
41
pulmonary edema poses a threat for
suffocation
42
what are the signs and symptoms of cerebral edema
- headaches
- nausea
- seizures
- coma
43
what causes circulatory shock resulting from severe edema
excess fluid in tissue spaces causes low blood volume and low blood pressure
44
venous return
flow of blood back to the heart
45
what are the five mechanisms used to achieve venous return
- pressure gradient
- gravity
- skeletal muscle pump
- thoracic pump
- cardiac suction
46
____ is the most important force in venous return
blood pressure
47
venules have a pressure of
12-18 mmHg
48
central venous pressure
point where the venae cavae enter the heart
49
what is the central venous pressure
5mmHg
50
overall venous pressure gradient of ____ towards heart
7-13mmHg
51
gravity does what as a mechanism of venous return
drains blood from head and neck
52
how is fluid moved in the skeletal muscle pump
contracting limb muscles squeeze blood out of compressed part of vein
53
what keeps moving blood towards the heart in the skeletal muscle pump
valves
54
how is blood moved through the thoracic pump (4)
- inhalation expands thoracic cavity
- thoracic pressure on the inferior vena cava decreases
- abdominal pressure on the VC increases
- blood is forced upward towards heart
55
blood flows faster with ___ in the thoracic pump
inhalation
56
central venous pressure fluctuates during respiration due to
thoracic pump
57
what is central venous pressure during inhalation
2mmHg
58
what is the central venous pressure during exhalation
6mmHg
59
what are the steps of cardiac suction affecting venous return
- during ventricle contraction valves pulled slightly downward by chordae tendineae and atrial space expands
- slight suction draws blood into atria from venae cavae and pulmonary veins
60
what are the reasons exercise increases venous return?
- heart beats faster and harder increasing CO and BP
- vessels of skeletal muscles, lungs, and heart dilate and increase flow
- increase respiratory rate, increased action of thoracic pump
- increased skeletal muscle pump
61
venous pooling
- accumulation of blood in limbs venous pressure
- not enough to force blood upward
62
venous pooling can occur with
inactivity
63
with prolonged standing CO may be low enough to cause ____
dizziness and syncope
64
venous pooling can be prevented by
periodically tensing leg muscles
65
circulatory shock
any state in which cardiac output is insufficient to meet body's needs
66
what are the two forms of circulatory shock
- cardiogenic shock
- low venous return shock
67
cardiogenic shock
- inadequate pumping of heart
- usually result of MI
68
low venous return shock
cardiac output low because too little blood returns to heart
69
what are the three forms of low venous return shock
- hypovolemic shock
- obstructed venous return shock
- venous pooling shock
70
hypovolemic shock
loss of blood volume
71
what is the most common form of low venous return shock
hypovolemic shock
72
what are the three main reasons for hypovolemic shock
- trauma
- burns
- dehydration
73
obstructed venous return shock
tumor or aneurysm compressed a vein impeding blood flow
74
venous pooling shock is caused by
long periods of standing, sitting, or widespread vasodilation
75
neurogenic shock results from
sudden loss of vasomotor tone and vessels dilate
76
what are the possible causes of neurogenic shock?
- brainstem trauma
- emotional shock
77
other types of shock share characteristics with ____
venous pooling and hypovolemic shock
78
septic shock
bacterial toxins trigger vasodilation and increased capillary permeability
79
anaphylactic shock
severe immune reaction to antigen, histamine release, generalized vasodilation, increased capillary permeability
80
responses to circulatory shock
- compensated shock
- decompensated shock
81
compensated shock
several homeostatic mechanisms bring about spontaneous recovery
82
what is an example of compensated shock
is a person faints and falls to a horizontal position, gravity restores blood flow to the brain
83
decompensated shock
- when compensation fails
- life-threatening positive feedback loops occur
- condition gets worse causing damage to cardiac and brain tissue
84
what is an example of decompensated shock
myocardial ischemia causes MI and decrease CO which slows blood flow to cause disseminated intravascular coagulation to reduce venous return
85
normal blood flow to the brain
700 mL/min
86
does blood flow to the brain fluctuate?
yes
87
what happens when there is blood deprivation for a few seconds in the brain
loss of consciousness
88
what happens when there is blood deprivation for 4-5 minutes?
irreversible brain damage
89
though total flow to the brain is constant what happens to blood?
shifted to active brain areas from moment to moment
90
____ regulates its own blood flow
brain
91
how does the brain regulate its own blood flow?
cerebral arteries dilate or constrict as systemic BP drops or rises respectively
92
what is the main chemical stim of blood?
pH
93
poor perfusion leads to ____ accumulation in the brain
CO2
94
what happens when there is CO2 accumulation in the brain
- pH decreases
- triggers vasodilation
95
low CO2 in brain leads to what?
- pH increases
- stims vasoconstriction
96
when does low CO2 concentration in the brain occur
hyperventilation
97
what can low CO2 concentration in the brain cause
- ischemia
- dizziness
- syncope
98
hypercapnia
CO2 accumulation in the brain
99
hypocapnia
low levels of CO2 in the brain
100
Transient ischemic attacks
brief episodes of cerebral ischemia
101
what are transient ischemia attacks caused by
spasms of diseased cerebral arteries
102
what can transient ischemia attacks cause
- dizziness
- vision loss
- weakness
- paralysis
- headache
- aphasia
103
how long do transient ischemia attacks last
a few moments to a few hours
104
what can transient ischemia attacks be early warning signs for
impending stroke
105
cerebral vascular accident aka
stroke
106
what is a stroke?
sudden death of brain tissue caused by ischemia
107
what can cause a stroke
- atherosclerosis
- thrombosis
- ruptured aneurysm
108
what are the possible side effects of a stroke?
- blindness
- paralysis
- loss of sensation
- loss of speech
109
what is the most common effect of a stroke
loss of speech
110
what does recovery from a stroke depend on?
surrounding neurons and collateral circulation
111
variable blood flow depends on
state of exertion
112
what is variable blood flow at rest?
- arterioles constrict
- most capillary beds shut down
- total flow about 1L/min
113
what is variable blood flow during exercise?
- arterioles dilate in response to muscle metabolites
- blood flow can increase 20-fold as blood is diverted from the digestive and urinary organs
114
muscle metabolites include
- lactate
- CO2
- H+
115
how does muscular contraction impede blood flow?
by compressing blood
116
_____ contractions cause fatigue faster
isometric contraction
117
lungs have ___ pulmonary blood pressure
low
118
pressure in pulmonary arteries
25/10 mmHg
119
____ overrides blood pressure
oncotic pressure
120
pulmonary capillaries ___ fluid
absorb
121
why do pulmonary capillaries absorb fluid
prevent fluid accumulation in alveoli
122
what is the pulmonary response to hypoxia?
pulmonary arteries constrict in diseased area or areas of the lung that are receiving less oxygen from outside redirecting blood to better-ventilated region of lung
123
what is the systemic arteries response to hypoxia
dilate to increase tissue perfusion
124
