microcirculation

Question 1

controls flow into and out of capillary bed

Answer 1

i. Arteriole -

Question 2

as vessel size goes down pressure

Answer 2

also goes down

what’s important to pressure is the total cross section diameter of the vascular system

aorta is the biggest artery in the body but there is only one of them

If you add up the total diameter of the capillaries in the system, the diameter of the system is way bigger than the diameter of the one single aorta

Question 3

Coming off the arteriole there are small muscular rings called

Answer 3

precapillary sphincters

these dictate flow into the capillary bed

based on the needs of that organ

Question 4

i. Vasomotion

Answer 4

contraction or relaxation of the small arterioles and the precapillary sphincters and the result of that is intermittent flow

Question 5

b. Vasomotion regulation

Answer 5

Oxygen content/tension - tissues that are O2 starved will be dilated and will have more flow

nutrient demand theory

Question 6

why does lipid or water soluble have to do with it?

Answer 6

Lipid soluble substance able to move through the membranes (CO2 can do this as well)

in order to move water soluble molecule you need a pore or transport molecule

Question 7

what determines how a molecule might move across a capillary membrane

Answer 7

concentration: driving force
molecular size
solubility
presence or absence or a transport protein or channel that allows them to flow

Question 8

what is interstitial fluid

Answer 8

Fluid like plasma with no proteins

i. Collagen fibers
ii. Polyuronic acid
iii. Glycose amino glycan
iv. These form the brush border and make the interstitial gelatinous

Only 1% free fluid

this is what get’s filtered out of the blood stream and proteins are big and negatively charged

Question 9

Blood entering on the left from the arterial side, leaving on the right to enter the venous return back to the heart what will come out

Answer 9

Water, glucose w/ transport molecule , CO2 moving in and out of the bloodstream and into the tissue

this is going to happen at the front of the capillary and movement will be determined by STARLING FORCES

Question 10

Balance of ______ is going to determine whether it has net filtration or absorption at this capillary bed

Answer 10

3. Balance of starling forces is going to determine whether it has net filtration or absorption at this capillary bed

Question 11

most important starling force

Answer 11

hydrostatic pressure

1. Causes outward pressure
2. Tend to filter fluid out and increase pressure in the vessel

Question 12

Interstitial fluid pressure (Pif) is going to oppose

Answer 12

the capillary fluid pressure

Question 13

when would you have high interstitial pressure

Answer 13

with edema

Question 14

Plasma colloid pressure (IIp) comes from

Answer 14

non diffusible elements in the blood

cells
proteins

Question 15

pressure from nondiffusable elements in the plasma that would tend to _____

Answer 15

pressure from nondiffusable elements in the plasma that would tend to draw the fluid in (inward pressure)

Question 16

Donnan equilibrium effect

Answer 16

Pressure is a little bit higher than you would expect b/c proteins are negatively charged which attracts Ca++ ions around it and that makes the Ca++ attached to the proteins nondiffusable and enhances the amount of nondiffusable elements in the plasma

halo of Ca
donna with a halo

the theory is that the Ca is being sequestered in the blood because it is attracted to proteins

for this reason we see less movement of Ca

Question 17

Interstitial fluid colloid osmotic pressure (IIif) . tends to

Answer 17

ii. Tend to pull fluid out of the vessel (outward pressure)

Question 18

describe starling forces in the capillary

Answer 18

two fluid pressures oppose

two colloid pressures oppose

this balance determined filtration of absorption

Question 19

why do we see negative interstitial fluid pressure

Answer 19

because the lymphatics are constantly pulling fluid back

Question 20

Average capillary filtration pressure

Answer 20

~ 0.3 mmHg
1. Over our entire circulatory system, there is a small amount of fluid that does not get absorbed–> get it back through the lymphatic system

Question 21

XIII. Starling Equilibrium - what is this

Answer 21

balancing of filtration and absorption

a. Fluid volume leaving capillaries is balanced by absorption at other capillaries and by lymphatic return

Question 22

Normal net filtration about

Answer 22

b. Normal net filtration about 2ml/min

Question 23

how does ascites and edema work?

Answer 23

i. The more pressure goes up, the more we filter, the bigger the demand on the lymphatic system to return that volume and the greater risk of ascites and edema when we overwhelm the lymphatic system’s ability to return that volume

Question 24

lymphatic channels are characterized by there __ directional flow

Answer 24

i. There are valves to ensure one way flow
ii. No pumps
iii. Open ended tubes to collect the lymph

Question 25

nodes in the lymph system

Answer 25

prevent pathogens from getting dumped into the circulatory system

Question 26

increase of 20 mmHG in SBP and 10 mmHG DBOM

Answer 26

2x increase risk of death from

stroke
heart dz
other vascular dz

Question 27

these structures transport blood under high pressures to the tissues and have strong vascular walls and rapid flow

Answer 27

arteries

Question 28

these are the last small branches of the arterial system and act as control conduits through which blood is released into the capillaries

Answer 28

the arterioles

Question 29

this is the site of fluid exchange nutrients and other substances in the blood and the interstitial fluid

Answer 29

capillaries

Question 30

these structures collect blood from the capillaries

Answer 30

venules

Question 31

these structures function as conduits to transport blood from the tissues back to the heart

Answer 31

veins

Question 32

compared to the arteries, veins have ____walls and ____ pressure

Answer 32

thin walls and low pressure

Question 33

arteriel pressure is controlled by what

Answer 33

independent of CO or local flow but rather nervous reflexes that increase HR
contraction of venous reservoirs (more blood to the heart) and constriction of most of the arterioles throughout the body

also the kidenys play a role via hormones

Question 34

what is the equation for determining blood flow through a vessel

Answer 34

Flow= change in pressure over resistance

Question 35

the percentage of blood that is composed of cells is called the ______ and is usually around _____

Answer 35

hematorcit

40

which is to say that 40 % of the blood is cells

Question 36

___________ attenuates the effect of aterial pressure on tissues

Answer 36

autoregualation

through changes in vascular resistance

Question 37

the two most important factors that can influence pulse pressure

Answer 37

1) increased stroke volume

2) decreased arterial compliance usually due to arteriosclerosis

Question 38

what changes in pulse pressure would we see with a patent ductus arteriosus

Answer 38

some of the blood pumped through the aorta flows immediately through the patent ducuts into the pulmonary artery causing the diastolic pressure to be very low

which means a very great pulse pressure would be observed and

Question 39

what changes in pulse pressure would we see with a aortic valve stenosis

Answer 39

you would see a diminished pulse pressure because of the inability of blood to make it through the valve

Question 40

what changes in pulse pressure would we see with aortic regurgitation

Answer 40

aortic pressure would fall very low because of back flow leading to an increase in pulse pressure

Question 41

kortkoff sounds

Answer 41

sounds heard with auscultation when the bp cuff is sufficient to close an artery during part of the cycle
when the blood pressure cuff falls below the systolic pressure you can hear a sound