BIPN 100 Lecture Notes - Lecture 24: Pulse Pressure, Mechanoreceptor, Calcitriol
28 Jun 2018
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BIPN100 Lecture 24 Notes 6/4/18
- Capillary exchange
ocan calculate the flux or flow of fluid in or out of capillary
oStarling equation
K = filtration coefficient
Constant; varies between tissues
Higher K means easier for fluid to move out/in capillary. Kidneys have higher K,
brain has lower K
(Pc + πi) consider filtration, or things moving out of capillary
(Pi + πc) consider absorption, or things moving into the capillary
if flux is positive, the fluid leaves the capillary (net filtration)
if flux is negative, there’s an influx of fluid into the capillary (net absorption)
Pc from arterial to venous decreases: there should be a pressure gradient to allow
flow. Resistance is also a factor, according to Ohm’s Law
πc stays constant because there shouldn’t be any big solutes like albumin or red
blood cells that cross the capillary walls at the arteries or the venous sides
Pi should be 0 mmHg on both sides, unless something goes wrong
πi should stay constant because there shouldn’t be any big solutes that cross the
capillary walls on the artery or venous sides
in healthy system, there’s net filtration on arterial side and net absorption on
venous side
- Lymphatic system
oReturns fluid and proteins to the circulatory system
oWhen things have moved into interstitial area and there’s net filtration, not all the fluid
is absorbed back into the circulation. Lymphatic picks up remaining fluid
oLymph vessels collect excess fluid from interstitial to return to venous circulation
oAlso filters pathogens
- Edema
oOccurs when normal exchange between the circulatory system and the lymphatic
system is disrupted
oAccumulation of fluid in interstitial compartment. Fluid is filtered, but not completely
absorbed
oCan be fully body edema or localized edema
o2 main causes
inadequate drainage of lymph: obstruction of the lymphatic system (parasites,
cancer)
filtration much greater than absorption
can occur due to increase in hydrostatic pressure (elevated venous pressure,
caused by heart failure) which causes excess filtration
if there’s a discrepancy in the amount of blood pumped through heart, there’s
an accumulation of blood in one chamber, which increases its pressure
find more resources at oneclass.com
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can occur due to decrease in plasma protein concentration from sever
malnutrition or liver failure. If liver fails, it cannot produce proteins like albumin,
and the interstitial pressure cannot be maintained
can occur due to increase in interstitial proteins
- summary: functional model of the cardiovascular system
oLA and LV pumps oxygenated blood into aorta,
which is elastic. When ventricle contracts
(systole), pressure causes semilunar valve to open
and blood pushed into aorta and aorta expands
oAorta stores pressure (potential energy). When
heart relaxes (diastole), the aorta recoils
oblood moves to arterioles (resistance blood
vessels with most smooth muscles). These can
vasoconstrict or vasodilate easily. Change in radius
is main determinant in change of resistance
oarterioles constrict or dilate smooth muscle,
changing the distribution of blood flow throughout the circulation
oblood goes into capillary beds, which are one cell thick to allow exchange of materials
oblood goes into venules, which converge into veins
ovenous system: volume reservoir. Veins are very compliant and flexible. They store 60%
of blood. When needed, there’s increase of venous return to heart so heart can contract
more forcefully
oblood enters right side of heart to pulmonary capillaries
- Blood pressure
oSystolic BP: When ventricle contracts, it is in systole.
Semilunar aortic valve opens and blood is pushed into
aorta and arteries, which expand and store pressure
in elastic walls
oDiastolic BP: When heart relaxes, it is in diastole.
Semilunar valve closes and pressure in aorta is high,
so it recoils and pushes blood into rest of the system
- Arterial blood pressure
oPulse pressure = Systolic P – Diastolic P
best indication of contractility of heart, or force of
contraction
oDiastolic pressure is best indication of total peripheral
resistance of the system
oCan correlate flow with cardiac output, or how effective
heart is pumping blood (mL/min)
oChange in pressure = mean arterial pressure
= change in pressure from aorta to vena cava / total
peripheral resistance
mean arterial pressure: described the average arterial BP during one cardiac cycle
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Capillary exchange: can calculate the flux or flow of fluid in or out of capillary, starling equation. Higher k means easier for fluid to move out/in capillary. Pc from arterial to venous decreases: there should be a pressure gradient to allow flow. Resistance is also a factor, according to ohm"s law. C stays constant because there shouldn"t be any big solutes like albumin or red blood cells that cross the capillary walls at the arteries or the venous sides. Pi should be 0 mmhg on both sides, unless something goes wrong. I should stay constant because there shouldn"t be any big solutes that cross the capillary walls on the artery or venous sides in healthy system, there"s net filtration on arterial side and net absorption on venous side. Lymphatic system: returns fluid and proteins to the circulatory system, when things have moved into interstitial area and there"s net filtration, not all the fluid is absorbed back into the circulation.
