L11: Arterial, Venous & Lymphatic Systems Flashcards
define distensibility
the ability of veins to be stretched
= increase in vol.
inc. pressure x org. vol.
compare distensibility between veins and arteries
veins:
8x more distensible
p vein dis. = systemic vein dis.
p art dis is 6x > than systemic art.
veins carry __x more blood than arteries
3x
summary of vein distensibility
are much more distensible than arteries
with little force we can stretch veins
define compliance
= capacitance
compliance describes the distensibility of BVs
tells us the total quantity of blood that can be stored in a given portion of circulation per 1 mmHg rise in pressure
capacitance = ?
= distensibility x volume
inversely related: elastance and pressure
directly related to volume
artery compliance decreases with ______ .
age
how does greater amount of elastic tissue effect compliance?
= higher elastance
= lower compliance
define pulse pressure
PP = SV/arterial compliance
what are the 2 major factors of pulse pressure
- SV output
2. compliance of artery tree
pulse pressure: stroke volume
- most important factor
- PP increases = systolic pres. increase
pulse pressure: arterial compliance
decreased compliance = increased PP
ex. = aging
list some conditions that cause abnormal contours in pulse pressure
- aortic valve stenosis
- arteriosclerosis
- patent ductus arteriosus
- aortic regurgitation
aortic valve stenosis
- valve diameter is greatly reduced
- aortic pp decreased greatly
- blood flow diminished
arteriosclerosis
thickening/hardening of arterial walls
patent ductus arteriosus
- at least half of CO flows back into pulmonary artery, lungs, or left ventricle
- diastolic pressure falls very low before next systole
aortic regurgitation
- aortic valve is absent or not fully closing
- allows backward flow
- aortic pressure falls to 0 between beats
how does pulse pressure line graph change when traveling form large vessels to capillaries?
graph shows pressure per time
graph becomes a horizontal line when reaching capillaries
define systolic pressure
highest arterial pressure due to systole/contraction
define diastolic pressure
lowest arterial pressure due to filling period
when taking blood pressure what tells you when to read a measure?
Korotkoff sounds
define mean pressure
= average arterial pressure with respect to time
= diastolic pressure = (1/3)pp
why does mean pressure lie closer to diastolic pressure than systolic pressure?
because mean pressure includes the variable of time since we spend more time in diastole than systole
define central venous pressure
= pressure in the right atrium
name 2 factors that regulate right atrial pressure
- ability of heart to pump blood out of right side of heart
2. tendency of blood to flow into the right atrium at constant rate
name some factors that increase venous return and the result
result = increased right atrial pressure
- increased blood vol.
- incre. peripheral venous pressure
- dilation of arterioles
peripheral vein pressure in a person lying down
= +4 to +6 mmHg > than right atrial pressure
when intra-abdominal pressure increases ….. ?
- venous pressure in legs must increase above abdominal pressure before blood can flow from legs to heart thru abdominal veins
peripheral pressures in a person standing up
cranial pressure is neg. — because it must resist gravity’s pull in order to stay consistent
= -10
leg pressure is pos. — must oppose gravity to get back to heart
= +90
in graph 15-2, how do changing blood volumes alter pressure?
volume changes are instantaneous followed by a period of delayed compliance reacting to the volume change
volume can change quickly but pressure reacts slowly to change in vol.
varicose veins
- veins are not working properly
- veins become enlarged/twisted
- blood is allowed to flow backwards
microcirculation is in the ….. ?
capillaries and arterioles
vessel areas beyond arterioles but not yet considered apart of capillaries
metarterioles
arterioles are highly ______, which controls blood flow to tissues but ______ coat is lost in _______ .
highly muscular
muscular coat
lost in metarterioles
define precapillary sphincter
smooth muscle fiber encircles capillary where it originates from metarteriole and aids in blood flow
capillary walls
- monocellular layer of endothelium = 0.5 thickness
- thin BM
- internal diameter = 4-9 micrometers
cyclical opening and closing of precapillary sphincters
vasomotion
capillaries slit pores
- vesicular channels
2. allow rapid diffusion of water, water-soluble ions, small solutes
capillary plasmalemmal vesicles
- formed from caveolins
2. role in endo- trans- cytosis
capillaries in certain organs have pores: list some locations
liver
GI tract
kidneys
what is the most important factor in regulating vasomotion?
concentration of oxygen in the tissues
define vasomotion
the opening and closing of precapillary sphincters
what is the most important means of exchange between blood and interstitial fluid?
diffusion
_______ substances can diffuse readily thru the capillary cell membranes: list examples
lipid-soluble substances
oxygen
carbon dioxide
in capillary exchange, _____ substances diffuse thru the intercellular _________ .
non-lipid soluble
intercellular pores/clefts
relate water diffusion and flow of plasma within a capillary
rate of water diffusion is 80x faster
than flow of plasma in capillaries
rate of diffusion is directly proportional to ________ of the diffusing substances
concentration differences
structure of interstitium
gel like material
with rivulets of free flowing fluid
collagen bundles
why is passage of substances thru the interstitium mostly due to diffusion and not flow?
- due to large number of proteoglycan filaments
but rivulets that allow fluid flow can sometimes form
what do starling forces determine in capillary exchange
the direction of diffusion into or out of capillary
list the four starling forces
- capillary pressure
- interstitial fluid pressure
- capillary plasma colloid osmotic pressure
- interstitial fluid colloid osmotic pressure
list the inward vs. outward starling forces
inward: interstitial fluid press and capillary plasma colloid osmotic pressure
outward: capillary pressure and interstitial fluid colloid osmotic pressure
define net filtration pressure
the sum of all starling forces of capillary exchange
the overall pressure needed for flow in or out of capillaries to occur
another name for capillary pressure
hydrostatic pressure
what is the significance of the capillary filtration coefficient
takes into consideration the number and size of pores
not all capillaries have the same size/number of pores
leakiness
describe lymph vessels
- like veins but thinner walls
- semilunar valves
- pick up fluid lost from veins
- slow moving
- stop edema
- failure = edema
when fluid enters the lymphatics ….. ?
- lymph vessel walls contract
- causes fluid to be pumped into blood circulation
- creates a slight neg. pressure in interstitial spaces
describe blood at the arterial end of capillaries
nutrient rich
oxygenated
forces moving fluid outward at arterial end of capillary
pulling fluid out of capillaries into tissue
- capillary pressure = 30
- neg. interstitial free fluid pressure = 3 (lymphatics)
- interstitial fluid colloid osmotic press. = 8
total outward force at arterial end of capillaries
= 41 mmhg
forces moving fluid inward at arterial end of capillary
pulling fluid into blood stream
1. plasma colloid osmotic pressure = 28
total inward force at arterial end of capillaries
= 28
net outward force at arterial end of capillaries
= 13 mmhg
forces moving fluid inward at venous end
- plasma colloid osmotic pressure = 28
total inward force at venous end
= 28
forces moving fluid outward at venous end
- capillary pressure = 10
- neg. interstitial free fluid pressure = 3
- interstitial fluid colloid osmotic pressure = 8
total outward force at venous end
= 21
net inward force at venous end
= 7 mmhg
= net reabsorption force
force of capillaries to regain fluid from interstitial fluid to put back in veins
describe the direction of the interstitial forces
inter. fluid press. = pushing into capillary
inter. fluid colloid osmotic press. = pulling out of capillary
describe the direction of the intracapillary forces
cap. pres. = pushing out of capillary
plasma colloid osmotic pres. = pulling into capillary
lymph vessels contain _____ valves.
one way
list 4 factors that increase lymph flow
- elevated capillary hydrostatic pressure
- decreased plasma colloid osmotic pressure
- increased interstitial fluid colloid osmotic pres.
- increased permeability of capillaries
way stations of the lymphatic system
lymph nodes
cells test lymph here to see if there is a problem in the body and can result in an immune response
mass of lymphocytes and macrophages
