Peripheral Vasculature

Question 1

What happens to blood flow after you eat a big meal?

Answer 1

It is shunted to the GI system.

Question 2

Are capillaries different in each system?

Answer 2

YES. They are different in the liver, skin, brain, and muscle. (ex. capillaries are tight in the brain (BBB) and testes (BTB), but leaky in the kidney).

Question 3

How do the pulmonary and systemic circuits compare in terms of pressure?

Answer 3

The systemic circuit is higher in pressure than the pulmonary circuit.

Question 4

Should we think about the arteries as a separate organ system?

Answer 4

YES

Question 5

Should we think about the veins as a separate organ system?

Answer 5

YES, they are very compliant.

Question 6

Should we think about capillaries as their own system?

Answer 6

YES

Question 7

Why shouldn’t you jump in the pool after eating a big meal?

Answer 7

because the blood in your body is shunted to your GI tract and when you recruit the muscles you need for swimming, there is less blood flow and therefore less O2 being delivered to them, making cramps much more likely.

Question 8

What happens to blood flow when you work out and start to overheat?

Answer 8

the blood flow gets dissipated to the extremities to release heat.

Question 9

Does the arterial or venous system have higher O2 tension?

Answer 9

arterial

Question 10

In what system does high BP occur?

Answer 10

the arterial system (not the venous system)

Question 11

Is the arterial or venous system more compliant?

Answer 11

venous system

Question 12

**What is the most important characteristic of the aorta?

Answer 12

it is elastic and acts as a secondary pump!

Question 13

Where is the greatest cross sectional area?

Answer 13

capillaries because there are billions of them

Question 14

**What is the most important characteristic of the vena cava?

Answer 14

it is compliant (can hold large volumes at LOW pressure)

Question 15

Is elasticity the inverse of compliance?

Answer 15

YES

Question 16

What happens to the amount of smooth muscle as we move toward the precapillary sphincter?

Answer 16

it increases. This is good, because if you are in shock due to a major car accident and have internal bleeding, you need blood flow to be shunted toward the internal organs, so the precapillay sphincters of the skin will constrict, reducing blood flow to the skin where it isn’t needed.

Question 17

Do the capillaries have smooth muscle?

Answer 17

NO. they are very thin and only have a single layer of endothelium.

Question 18

Where is blood volume greatest?

Answer 18

in the venous compartment

Question 19

What is the hematocrit?

Answer 19

% of RBCs per unit volume. The hemoglobin is what makes up this hematocrit.

Question 20

Where is the greatest pressure in the vasculature at any one time?

Answer 20

In the aorta.

Question 21

Where is the largest pressure drop at any one time?

Answer 21

at the level of the arterioles

Question 22

Is there still pressure at the level of the capillaries?

Answer 22

YES because you need some pressure for filtration

Question 23

Where is velocity the greatest and lowest, respectively?

Answer 23

velocity is greatest in the aorta, and lowest in the capillaries.

Question 24

What is the velocity of blood in the vena cava (relative to the velocity of the aorta)?

Answer 24

about 2/3 that of aortic velocity (so it picks back up after the capillaries). biphasic looking curve (looks like a water glass)

Question 25

Where is pressure the lowest?

Answer 25

vena cava

Question 26

What is the Windkessel effect?

Answer 26

accounts for the shape of the arterial blood pressure waveform in terms of the interaction between the SV and the compliance of the aorta and large elastic arteries
Aka: buffers pressure changes of the aorta

Question 27

How does pulse pressure?

Answer 27

difference between systolic and diastolic pressure (120-80= 40).

Question 28

What is pulse oximetry?

Answer 28

method to quantitatively evaluate the % of arterial blood hemoglobin that is saturated with O2 after leaving the heart by using 2 different LEDs that are placed on the finger. One LED emits red light (660nm) and the other emits an infrared light (940nm). These lights pass through tissue and are absorbed by oxy-hemoglobin differently than deoxy-hemoglobin. The photometer can then detect a % based on the ratio of light absorbed.

Question 29

Does more or less light pass through the pulse oximeter if you are hypoxic?

Answer 29

LESS, and therefore you will see a lower O2 saturation %.

Question 30

What will you hear when taking BPs at peak systolic pressure?

Answer 30

turbulent flow (Korotkoff sounds)

Question 31

Do the kidneys have tight or leaky capillaries?

Answer 31

leaky

Question 32

What do the kidneys regulate?

Answer 32

volume, electrolytes, and BP

Question 33

Do cortical and medullary nephrons have similar or different vascular beds?

Answer 33

different. These are involved in reabsorbing fluids and electrolytes so we don’t waste them.

Question 34

What pressure is at work when blood enters the capillaries?

Answer 34

hydrostatic pressure, responsible for filtration

Question 35

What pressure is at work when blood exits the capillaries?

Answer 35

osmotic pressure, responsible for reabsorption

Question 36

How can we get CVP (central venous pressures)?

Answer 36

using a SWAN catheter placed right outside of the heart in the SVC

Question 37

When does greatest coronary blood flow occur?

Answer 37

during diastole!