Lesson 10 Flashcards
fluid filter out of the ___ end of the capillary and osmotically reenters ____ end
- arterial
- venous
what does fluid do as it filters in and out of the cell?
- delivers materials to the cell
- remove metabolic waste
- maintain balance between osmosis and hydrostatic pressure
what are the two types of hydrostatic pressure
- capillary hydrostatic pressure
- interstitial hydrostatic pressure
capillary hydrostatic pressure
drives fluid out of capillary
interstitial hydrostatic pressure
drives fluid into capillary
hydrostatic pressure is usually high on ____ and low on ____ end
- arterial
- venous
hydrostatic pressure equation
HP = CHP - IHP
colloid osmotic pressure
draws fluid into capillary
what does osmotic pressure result from
plasma proteins being more abundant in blood than in fluid
oncotic pressure
net colloid osmotic pressure
colloid osmotic pressure equation
COP = bloodCOP - tissueCOP
net filtration pressure is the difference between
net hydrostatic pressure and net osmotic pressure
net filtration pressure equation
NFP = (CHP - IHP) - (BCOP - ICOP)
usually in normal condition the IHP and ICOP are
equal
capillary exchange at the arterial end characteristicers
- NFP>0
- net hydrostatic pressure > net osmotic pressure
- fluid moves out of capillary and into the interstitial fluid
capillary exchange at venous end of capillary characteristics
- NFP<0
- net osmotic pressure > net hydrostatic pressure
- fluid moves into capillary and out of interstitial fluid
what is the resulting out net filtration pressure at the arterial end
13mmHg out
what is the resulting inward net filtration pressure at the venous end
7mmHg inward
why is the net hydrostatic pressure lower at the venous end than at the arterial end
blood pressure is lower so oncotic pressure overrides hydrostatic pressure
what is the overall result of the NFP being lower at the venous end than at the arterial end
capillary gives off fluid at arterial end and reabsorbs it at the venous end
capillaries reabsorb about ___ of the fluid they filter
85%
what is done with the remaining fluid that does not get reabsorbed by the capillaries
reabsorbed by lymphoid system and ultimately returned to the blood
____ liter of fluid filtered. ___ liters of fluid reabsorbed.
- 24
- 20.4
___ liters of fluid drained away by the lymphoid capillaries.
3.6
glomeruli of kidneys devoted to
filtration
alveolar capillaries in lungs devoted to
absorption so fluid doesn’t fill air spaces
characteristics of resting tissue
- most precapillary sphincters constricted
- capillaries are collapsed
- BP low
when does reabsorption dominate?
resting tissue
characteristics of active tissue
capillary pressure rises
when does filtration dominate?
active tissue
what happens to fluid filtration/reabsorption in traumatized tissue?
release substances that increase permeability and filtration
edema
accumulation of excess fluid in a tissue
what is happening in the body during edema?
fluid filters into tissue faster than it is absorbed back into the capillary
three primary causes of edema
- increased capillary filtration
- reduced capillary reabsorption
- obstructed lymphatic drainage
increased capillary filtration is caused by
- kidney failure
- histamine
- old age
- poor venous return
reduced capillary reabsorption caused by
- hypoproteinemia
- liver disease
- dietary protein deficiency
obstructed lymphatic drainage caused by
surgical removal of lymph nodes
pathological causes of edema
- tissue death
- pulmonary edema
- cerebral edema
severe edema can cause
circulatory shock
what causes tissue death
oxygen delivery and waste removal impaired
what causes pulmonary edema
fluid in lungs
pulmonary edema poses a threat for
suffocation
what are the signs and symptoms of cerebral edema
- headaches
- nausea
- seizures
- coma
what causes circulatory shock resulting from severe edema
excess fluid in tissue spaces causes low blood volume and low blood pressure
venous return
flow of blood back to the heart
what are the five mechanisms used to achieve venous return
- pressure gradient
- gravity
- skeletal muscle pump
- thoracic pump
- cardiac suction
____ is the most important force in venous return
blood pressure
venules have a pressure of
12-18 mmHg
central venous pressure
point where the venae cavae enter the heart
what is the central venous pressure
5mmHg