Lecture 12: Capillaries & Veins

Question 1

What are “Capillaries?”

Answer 1

Site of exchange of materials between the blood and tissues

Question 2

What are the 3 factors that enhance diffusion?

Answer 2

1) Diffusing molecules only have a short distance to travel
2) Incredible numbers of capillaries (10-40 billion)
3) Slow moving blood

Question 3

What organs would you find the Continuous Capillaries?

Answer 3

• muscles
• skin
• lungs
• CNS

Question 4

What organs would you find the Fenestrated Capillaries?

Answer 4

• Kidneys

- Intestines

Question 5

What organs would you find the Sinusoidal Capillaries?

Answer 5

• Liver

Question 6

What is Fick’s Law?

Answer 6

the rate of diffusion of one material in another is proportional to the negative of the gradient of the concentration of the first material.

Question 7

What are Veins?

Answer 7

serve as a blood reservoir and passageways back to the heart

Question 8

Veins have small radii, so they offer little resistance to flow.
T/F

Answer 8

False, they have large radii

Question 9

Veins that serve as a blood reservoir is often referred to as:

Answer 9

-Capacitance Vessels

Question 10

Veins have ____walls with less _____muscle than arteries

Answer 10

Thinner; Smooth

Question 11

Veins have very _____ elasticity

More _____ than elastin

Answer 11

Little;

Collagen

Question 12

What is “Venous Return?”

Answer 12

Volume of blood entering each atrium per minute from the veins

Question 13

What is the mean pressure average when blood enters the venous system?

Answer 13

17 mm Hg

Question 14

Atrial pressure is around 0 mm Hg, there’s still a driving pressure.
T/F

Answer 14

True

Question 15

What are the 5 factors that enhance venous return?

Answer 15

1) Cardiac Contraction (suction)
2) Sympathetically Induced Venous Tone
3) Skeletal Muscle Activity
4) Venous Valves
5) Respiratory Activity

Question 16

During Ventricular contraction:

The ___ valve are drawn ______. enlarging the atrial cavities

Answer 16

AV;

Downwards

Question 17

During Ventricular contraction:
The atrial pressure drops BELOW 0 mm Hg.
T/F

Answer 17

True

Question 18

During Ventricular contraction:

Increase in ___to_____ pressure gradient so venous return is _______

Answer 18

vein; atria

enhanced

Question 19

Sympathetic Stimulation produces _____ venous tone.
Modesty _____ venous pressure.
Increases the _____ _______ to drive more ______ into the Right Atrium

Answer 19

Increased
Increases
Pressure Gradient; blood

Question 20

Many ____ veins in the extremities lie between ______ muscle, so when the muscles _____, the veins are _______

Answer 20

Large
Skeletal; Contract
Compressed

Question 21

Venous Valves on Venous Return:
Blood can only move in a __________ fashion in the veins due to ______ way valves spaced about 2-4 cm intervals.
When these valves fail, we get _______ veins

Answer 21

Unidirectional
one
varicose

Question 22

Due to ____ activity. the pressure within the chest cavity is _____ mm Hg less than ______ pressure

Answer 22

Respiratory

5; atmospheric