circulation (midterm 2) Flashcards
what portions is circulation divided into
systemic and pulmonary circulation
what is circulation
transport of nutrients and O2 to tissues
waste and CO2 from tissues
what are the fundamental parts of circulation
arteries -> arterioles -> capillaries -> venules -> veins
what do arteries do
transport blood under high pressure
large diameter
what do arterioles do
control blood flow transported into the capillaries, decrease pressure
what do capillaries do
exchange site of fluid, nutrients, electrolytes, hormones, and other substances
what do venules do
collect blood from the capillaries back to heart; lower pressure
what do veins do
transport of blood from tissues back to heart and reservoir of blood; low pressure
what does blood flow to tissues match
needs of tissues (oxygen, nutrients)
what do microvessels regulate
the flow of blood via contraction/dilation, allowing tissues in need to receive more blood flow
how is arterial pressure controlled
independently of local blood flow control and cardiac output control
what happens when arterial pressure decreases
contraction and constriction increases, then arterial pressure increases
how much resistance to flow in peripheral circulation in the small arterioles
2/3
what is the resting diameters of small arterioles
5-25 um
what are the major proteins in blood and what do they do
albumin - regulates pH and osmotic pressure
globulins - immune mlcs
fibrinogen - involved in clotting
what are the major cell types in blood
erythrocytes (red blood cells) direct oxygen transport
platelets involved in blood coagulation and hemostasis
leukocytes (white blood cells) are the cellular participants in the immune response
what is hematocrit and what are they in men and women
percentage of blood that’s cells
men - 42-47%
women - 38-42%
what is the marginal plasma layer
a thin cell free layer created within vessels because RBCs accumulate along the axis of the vessel
what do blood cells provide
friction during vascular flow which leads to viscosity, which varies with vessel diameter
what is the equation for resistance to flow
1/R^4
what is the fahraeus-lindquist effect
as vessel diameter decreases, the apparent viscosity of blood decreases
how are blood vessels distensible
- increased diameter, decreases resistance, increases blood flow
- acts to smooth pulsatile flow
are veins or arteries more distensible
veins
Dv ~ 8x Da
what is compliance
amount of blood that can be held with increased pressure
what is delayed compliance
acts to maintain pressure with changes in volume
increased volume = quick increased pressure, then slow decreased pressure
what is pulse pressure
- difference between systolic and diastolic pressure
- determined by stroke volume output and arterial compliance
- function of cardiac output compliance
what does increasing compliance imply
a decrease in the transmission rate of the pressure pulse
what factors change pulse pressure
arteriosclerosis (increases pp)
aortic stenosis (decreased pp)
aortic regurgitation (decreased pp)
what does dampening lead to
increased resistance and decreased compliance - almost non-existent at capillaries
what happens with measuring blood pressure
- stethoscope and cuff placed over upper arm over brachial artery
- cuff pressure increases > 200 mmHg therefore collapses branchial and NO sound
- cuff pressure slowly decreases and when pressure = diastolic pressure brachial opens at systolic and can hear sound
- when Pcuff = P diastolic, brachial always opens and constant sound
what does pressure equal
120 (systole)/80 (diastole)
pressure increases with age
what is central venous pressure regulated by
- increase in cardiac output decreases central venous pressure
- increase in venous flow increases central venous pressure
what does hydrostatic pressure do
column of liquid exerts pressure due to the weight of liquid
13.6 mm H2O = 1 mmHg
CVP = 0 mmHg
what is venous pressure in the feet, hands, and sagittal sinus
90 mmHg
35 mmHg
-10 mmHg
what is the venous pump
veins contain one-way valves that direct blood -> heart via tissue compression
