Microcirculation, venous blood flow and venous return

Question 1

What does the intersitium consist of?

Answer 1

Collagen and proteoglycan filaments

Question 2

What are crystalloids?

Answer 2

Low molecular water solutes

Question 3

What are colliods?

Answer 3

Plasma proteins

Question 4

What is the permeability of albumin through the capillary wall in comparison to water?

Answer 4

1/1000th

Question 5

What is the oncotic pressure generated by plasma proteins?

Answer 5

~ 28 mmHg

Question 6

What is the interstitial oncotic pressure?

Answer 6

~ 5 - 8 mmHg

Question 7

What is the capillary hydrostatic pressure at the arterial end?

Answer 7

~ 30 - 40 mmHg

Question 8

What is the capillary hydrostatic pressure at the venous end?

Answer 8

10 - 15 mmHg

Question 9

How much water do capillaries lose?

Answer 9

2-3 L per day

Question 10

What is the lymphatic system important for controlling?

Answer 10

• The concentration of proteins in interstitial fluid
• Volume of interstitial fluid
• Interstitial fluid pressure
• Immune response

Question 11

What is the blood pressure in the venous system?

Answer 11

3 - 18 mmHg

Question 12

What percentage of blood is contained in the venous system?

Answer 12

~ 60%

Question 13

How is venous return increased?

Answer 13

• Sympathetic innervation
• Skeletal muscle pumps
• Inspiratory movements
• Blood volume

Question 14

What is orthostatic (postural) hypotension?

Answer 14

• When moving from supine to upright
• Around 500 ml of blood drains from the upper body to the legs
• Decreased venous return and therefore decreased Cardiac Output and decreased blood pressure.

Question 15

What are the most common types of capillaries in the body?

Answer 15

Continous

Question 16

What capillaries contain pores which allow small lipophobic molecules to pass through?

Answer 16

Fenestrated capillaries

Question 17

What capillaries are you more likely to find in skeletal muscle?

Answer 17

Fenestrated capillaries

Question 18

What capillaries are more likely to be found in the liver?

Answer 18

Sinusoidal or discontinous capillaries

Question 19

What are the features of sinusoidal or discontinous capillaries?

Answer 19

Large gaps between endothelial cells

Question 20

What plasma proteins generate oncotic pressure?

Answer 20

Mostly albumin, to a lesser extent globulins