Microcirculation

Question 1

What blood vessel group is considered the “stopcocks” of circulation?

Answer 1

Arterioles

Question 2

Which vessel group is considered storage vessels?

Answer 2

Veins

Question 3

Which vessel group takes part in exchange of gases, water, and solutes?

Answer 3

Capillaries

Question 4

Which vessels are in between arterioles and capillaries?

Answer 4

Metarterioles

Question 5

What is the role of metarterioles?

Answer 5

Sphincters that regulate flow into the capillaries.

Question 6

Which group of vessels has the greatest cross-sectional area and surface area?

Answer 6

Capillaries

Question 7

How do precapillary sphincters regulate blood flow?

Answer 7

If one area within the capillary bed requires blood, the other areas will constrict their sphincters to redirect blood flow.

Question 8

Is capillary distribution the same from tissue to tissue?

Answer 8

No; some areas have more dense capillary beds.

Question 9

Do true capillaries have smooth muscle?

Answer 9

No; they are incapable of active constriction or relaxation.

Question 10

Why can capillaries withstand high intravascular pressures?

Answer 10

The Law of LaPlace. Radius is directly proportional to wall tension

Question 11

What are the four methods of exchange across the capillary endothelium?

Answer 11

1. Diffusion.
2. Bulk Flow.
3. Vesicular transport.
4. Active transport

Question 12

What substances are exchanged across the endothelium via diffusion?

Answer 12

Oxygen.
Carbon dioxide.
Lipid-soluble substances.

(from high to low concentration)

Question 13

What substances are exchanged across the endothelium via bulk flow?

Answer 13

Water, electrolytes, small molecules.

via intercellular clefts or “pores”

Question 14

What substances are exchanged across the endothelium via vesicular transport?

Answer 14

Proteins

larger molecules

Question 15

What substances are exchanged across the endothelium via active transport?

Answer 15

Ions, glucose, amino acids.

low to high/across chemical gradients, must use ATP

Question 16

What is the normal distribution of fluid in the body by liter?

Answer 16

3L Plasma.
11L Interstitial Fluid.
28L Intracellular Fluid

Question 17

How many liters of extracellular fluid?

Answer 17

14L

Question 18

What three things does interstitial volume depend on?

Answer 18

1. Rate of filtration.
2. Rate of reabsorption.
3. Lymph flow

Question 19

Which substance is the major determinmant of oncotic pressure?

Answer 19

Proteins

Question 20

What is capillary hydrostatic pressure (Pc)?

Answer 20

Pressure in the capillary that forces fluid OUTWARD through the capillary membrane

Question 21

What is interstitial fluid hydrostatic pressure (Pif)?

Answer 21

Normally a negative pressure which creates an outward force (from capillary to interstitial) for fluid

Question 22

What factor creates a negative interstitial fluid hydrostatic pressure?

Answer 22

Lymphatics create negative pressure via pumping action

Question 23

What is the more abundant plasma protein?

Answer 23

Albumin

Question 24

How are proteins similar to sodium in the body?

Answer 24

Proteins want to pull fluid to themselves. Similar to salt (water follows salt), fluid follow proteins as well

Question 25

What is plasma colloid osmotic pressure (Pie-p)?

Answer 25

aka- Plasma oncotic pressure. | Tends to cause inward (into capillary) movement of fluid.

Question 26

What is interstitial fluid osmotic pressure (Pie-if)?

Answer 26

aka- Interstitial fluid oncotic pressure. | Tends to cause outward (out of capillary) movement of fluid

Question 27

What is the Gibbs-Donnon effect?

Answer 27

Albumin exerts a greater osmotic force than can be accounted for solely on the basis of the number of molecules dissolved in the plasma. (Albumin attracts Na+ which attracts Cl-, which ultimately increases osmotic force and pulls fluid towards them).

Question 28

Which two ions does albumin naturally attract?

Answer 28

Sodium (Na+) and Chloride (Cl-)

Question 29

Does the Gibbs-Donnan effect increase or decrease osmotic/oncotic pressure (pulling power)?

Answer 29

Increases

Question 30

What is filtration the sum of?

Answer 30

The sum of the hydrostatic and osmotic forces favor the net movement of water from the capillary to the interstitial space.

Question 31

Does filtration or reabsorption happen more on the arterial side? Venule side?

Answer 31

Filtration- Arterial side Reabsorption- venule side

Question 32

What is reabsorption the sum of?

Answer 32

The sum of the hydrostatic and osmotic forces favors the net movement of water from the interstitial space to the capillary

Question 33

What is the net driving force of filtration?

Answer 33

Net driving force >0

Question 34

What is the net driving force of reabsorption?

Answer 34

Net driving force<0

Question 35

Over time, is there a net overage or deficit of filtration and how does the body compensate for this?

Answer 35

There is an overage over time. | This is all equaled out because of the lymphatic system

Question 36

Describe dehydration in how it correlates to filtration/reabsoprtion?

Answer 36

Decrease capillary hydrostatic pressure Increase oncotic pressure. More fluid being pulled from interstital

Question 37

What is the Starling Forces equation?

Answer 37

Net driving force= (Pc-Pif) - rc(Pie-c-Pie-if)

Question 38

What does the Starling equation conclude?

Answer 38

That there is more fluid going out of the capillary than going in

Question 39

What does muscular contraction do to lymphatics?

Answer 39

Distortion of and opening of spaces.

Question 40

What is the cause for the negative pressure in the interstitial fluid space?

Answer 40

Lymphatics

Question 41

How is plasma filtrate returned via the lymphatic circulation?

Answer 41

1. Tissue pressure. 2. Intermittent skeletal muscle activity. 3. Lymphatic vessel contraction. 4. System of one-way valves

Question 42

What does the lymphatic system return to circulation?

Answer 42

Protein. Bacteria. Fat. Excess fluid

Question 43

What four things can cause edema?

Answer 43

1. Increased capillary hydrostatic pressure. 2. Decrease plasma oncotic pressure. 3. Increased capillary permeability. 4. Lymphatic obstruction

Question 44

What is an example of something that increases capillary hydrostatic pressure?

Answer 44

Heart failure (High CVP) or venous obstruction

Question 45

What is an example of something that decreases plasma oncotic pressure?

Answer 45

Hypoproteinemia from malnutrition. | Or low albumin in elderly

Question 46

What is an example of something that increases capillary permeability?

Answer 46

Proinflammatory mediators- - Histamine - Bradykinin Damage to structural integrity of kidneys- - trauma - burns - severe inflammation

Question 47

What is an example of lymphatic obstruction?

Answer 47

Filariasis