CVS 3

Question 1

Key features of arteries:

Answer 1

• Low resistance vessels conducting blood to organs with little loss in pressure
• Act as pressure reservoirs for maintaining blood flow between ventricular contractions
• Walls have a lot of elastic tissue

Question 2

Key features of arterioles:

Answer 2

• Major sites of resistance to blood flow
• Responsible for the pattern of blood flow distribution
• Participate in the regulation of arterial blood pressure

Question 3

Key features of capillaries:

Answer 3

• Site of exchange between blood and tissue

- Walls are made up of a single layer of endothelium

Question 4

Key features of veins:

Answer 4

• Low resistance vessels for blood flow back to the heart

- Their capacity for blood is adjusted to facilitate flow

Question 5

What are the three tissue layers of an artery

Answer 5

• Tunica externa (adventitial later)
• Tunica media (medial layer)
• Tunica intima (intimal layer)

Question 6

What cells make u the tunica externa

Answer 6

Connective tissue

Question 7

What cells make u the tunica media

Answer 7

Smooth muscle cells

Question 8

What cells make u the tunica intima

Answer 8

Endothelial cells

Question 9

Which blood vessel contains the most endothelium

Answer 9

Capillaries

Question 10

Which blood vessel contains the most smooth muscle

Answer 10

Artery

Question 11

Which blood vessel contains the most elastic tissue

Answer 11

Elastic artery

Question 12

Which blood vessel contains the most connective tissue

Answer 12

Venule

Question 13

What is hydrostatic pressure

Answer 13

The pressure exerted by a fluid

Question 14

What are the units of flow

Answer 14

l/min or ml/min

Question 15

What is resistance

Answer 15

Friction impeding the flow

Question 16

What two factors determine resistance

Answer 16

• Pressure difference between two points (ΔP)

- Resistance to flow (R)

Question 17

What is the driving force of blood flow?

Answer 17

The pressure generated by contractions of the heart

Question 18

What is the equation for flow

Answer 18

F=ΔP/R

Question 19

What are the three factors affecting resistance?

Answer 19

• Viscosity of blood (n)
• Vessels length (L)
• Vessel radius (r) =MAJOR

Question 20

Describe the relationship between vessel radius and resistance

Answer 20

Slight change in radius brings about ta notable change in flow
e.g two fold change in radius = 16 fold change in flow

Question 21

How is the radius of an arteriole changed?

Answer 21

By the contraction of smooth muscle

Question 22

What is the poiseuille equation

Answer 22

Flow = πΔPr⁴/8nL

Question 23

What is the equation for mean arteriole pressure?

Answer 23

MAP = Diastolic pressure = 1/3 pulse pressure

Question 24

Why does blood pressure not drop to 0 during diastole

Answer 24

Passive recoil of the elastic tissue of the arteries continues to push blood down stream into the vascular system from arteries to arterioles

Question 25

Why is high arteriolar resistance important?

Answer 25

The pressure gradient helps drive blood from the heart to the tissue capillary beds -The arteriolar resistance also converts pulsatile arterial pressure into non-fluctuating capillary pressure

Question 26

Describe arteriolar vasoconstriction

Answer 26

Increased contraction of the smooth muscle in the arteriolar wall leads to increased resistance and decreased flow through the vessel.

Question 27

Describe arteriolar Vasodilation

Answer 27

Decreased contraction of the smooth muscle in the arteriolar wall leads to decreased resistance and increased flow through the vessel.

Question 28

What is vascular tone?

Answer 28

a state of partial constriction (arteriolar smooth muscle plays a big part in this)

Question 29

What factors influence vascular tone?

Answer 29

- Myogenic activity | - Sympathetic activity

Question 30

Why is vascular tone important?

Answer 30

Tonic activity makes it possible to either decrease or increase contractile activity.