Lecture 10 - Art-Ven-Lymph

Question 1

How do distensible arteries “even out” pressure pulsations in pulsatile blood flow?

Answer 1

Their distensible nature allows them to expand to the extra volume, which causes smooth velocity to blood flow.

Question 2

Compare venous distention to arterial distention.

Answer 2

Veins are 8x more distensible (lack the smooth muscle of arteries)

Question 3

Why is pulmonary vein distensibility the same as systemic arteries.

Answer 3

“The left heart pumps out what the right heart receives.”

Question 4

Describe vascular compliance

Answer 4

An increase in volume over an increase in pressure. This gives the amount of blood that can be “stored” in a vessel for each mmHg rise in pressure.

Question 5

Describe the concept of “elastance.”

Answer 5

Elastance is the ability for a deformed object to “return to normal.” For example, rubber band with high elastance will readily return to its shape.

Question 6

Elastance is higher in (arteries/veins). Why?

Answer 6

Arteries. They contain more elastic tissue (tunica media) and can readily “snap back” to shape after distention.

Question 7

Compliance is said to be the “…measure of the ease with which a hollow viscus may be _____.”

Answer 7

distended

Question 8

Describe the changes in flow due to aortic valve stenosis.

Answer 8

There is decreased flow, as flow is directly proportional to a vessel’s radius

Question 9

Describe how patent ductus arteriosis changes blood flow.

Answer 9

The opening of the ductus arteriosus forms a “shunt” from the left to right heart, reducing volume pumped with each pulse, and therefore reduces pressure wave.

Question 10

Explain the incisure found in pressure pulse contour waves.

Answer 10

Backflow of the blood into the aortic semilunar valve cusps produces a slight “increase” in pressure contour.

Question 11

The progressive reduction of pressure pulsations due to muscular arterial walls

Answer 11

damping

Question 12

The ability for a vessel to increase its volume in response to pressure.

Answer 12

Vascular distensibility

Question 13

The central venous pressure is measured in the _______

Answer 13

Right atrium

Question 14

Two factors which regulate right atrial pressure

Answer 14

• Ability of heart to pump blood to pulmonary circuit

- Venous return to right atria

Question 15

Describe factors increasing venous return

Answer 15

• increased blood volume
• increased peripheral venous pressures (SNS stimulation)
• dilation of arterioles

Question 16

Describe the effect of increased Intra-abdominal P on venous return

Answer 16

The venous system must overcome the Intra-abdominal P before blood flow can resume to the heart

Question 17

Explain the pathophysiology of varicose veins.

Answer 17

Veins have increased capacitance. However, when they are engorged with blood, the leaflets of their valves no longer prevent backflow of blood.

Question 18

Describe the structure of a capillary (width, thickness, etc.)

Answer 18

Unicellular, thick B.M., 0.5micrometer wall, 4-9 micrometer diameter

Question 19

Slit pores in capillaries allow for _______

Answer 19

Extravasation of water and water-soluble solutes.

Question 20

Explain the role of calveolins.

Answer 20

Proteins similar in structure to clathrin. Allow for transcytosis.

Question 21

What is the most important factor in regulating vasomotion?

Answer 21

Tissue [oxygen]

Question 22

Describe the means of diffusion of water, oxygen, and carbon dioxide in capillaries.

Answer 22

These water soluble substances diffuse through the endothelial cells

Question 23

Describe the diffusion of non-lipid soluble compounds in blood.

Answer 23

Utilize the intercellular pores

Question 24

Compare water diffusion into/out of the vessel to plasma flow through the vessel.

Answer 24

Water diffuses 80x more rapidly

Question 25

Explain how the interstitium forms a barrier to bulk flow of liquids.

Answer 25

Large amounts of proteoglycan fibers.

Question 26

List the forces that are responsible for filtration from capillaries

Answer 26

Capillary pressure (out), interstitial osmotic pressure (out), plasma osmotic pressure (in), interstitial fluid pressure (in)

Question 27

What is the f(x) of lympatic vessels

Answer 27

to return filtrate to the circulation and prevent edema

Question 28

What may increase lymph flow?

Answer 28

Elevate capillary hydrostatic pressure, decreases plasma osmotic pressure, increased interstitial osmotic pressure, increased capillary permeability

Question 29

What is the function of the lymphatic system?

Answer 29

To return fluid filtered from the capillaries to the circulation. If no such mechanism existed, the interstitium would become swollen (edema).

Question 30

What causes lymphatic capillary collapse?

Answer 30

The increase of atmospheric pressure above lymphatic hydrostatic pressure

Question 31

What factors increase lymph flow?

Answer 31

• Elevated capillary hydrostatic P
• Decreased plasma oncotic P
• Increased interstitial oncotic P
• Increased capillary permeability

Question 32

How do you calculate rate of lymph flow?

Answer 32

Interstitial fluid P x activity of lymphatic pump

Question 33

Drains right head, RUE, R axilla, R thorax

Answer 33

Right lymphatic duct

Question 34

Drains left head, LUE, abdomen, L thorax, bilateral LE

Answer 34

thoracic duct

Question 35

Explain the role of “anchoring filaments” in lymphatic capillary flow

Answer 35

Anchoring filaments connect to the capillary endothelial cells; as interstitial pressure increases, the capillaries are “compressed” inward, causing the anchoring filaments to open the valves

Question 36

What two factors influence the pulse pressure?
A. Cardiac output and TPR
B. SV and Arterial compliance
C. Venous return and SNS stimulation

Answer 36

B. SV & Arterial compliance

Question 37

How does an increase in blood volume alter blood pressure?

Answer 37

Initially, the increase in blood volume increases blood pressure. However, certain responses return it to normal.

1) Increased Pc forces blood out of the tissues
2) Increased Pc causes a stress-relaxation, dilating venous reservoirs to hold more blood
3) Increased TPR, decreasing venous return