Overview and function of the CVS

Question 1

What are the functions of the CVS?

Answer 1

• buLK FLOW SYSTEM:
  o2 + co2, nutrients, metabolites, hormones, heat
• Very flexible:
  Pump varies output, vessels care redirect blood and vessels can store blood

Question 2

What is the structure of the CVS?

Answer 2

• 2 pumps Lies in series. Right side/pulmonary circulation=Left side/systemic circulation.
• Output must be equal.
• However, most vascular beds are in parallel.

Question 3

What does it mean that vascular beds are in parallel?

Answer 3

• All tissues get oxygenated blood and allows he regional redirection of blood

Question 4

Where does our 5l of blood/cardiac output go at rest?

Answer 4

• Skeletal muscle 20%
• Abdominal cavities 24%
• Brain 13%
• Other 10%

Question 5

What is Mean Arterial Pressure?

Answer 5

The average pressure throughout the whole cardiac cycle.

Question 6

How do you calculate Change in pressure?

Answer 6

Mean Arterial Pressure- Central venous pressure

Question 7

What is resistance controlled/affected by?

Answer 7

Radius, which has big effect on blood flow

• Think of taps being turned off and on at the head, arms, legs, gut-> liver.

Question 8

What is resistance controlled/affected by?

Answer 8

Radius, which has big effect on blood flow

• Think of taps being turned off (increase resistance) and on at the head, arms, legs, gut-> liver.

Question 9

Relate vascular beds being in parallel to controlling resistance.

Answer 9

• It explains their ability of regional redirection of blood.
• Constrict/ dilating the vessels.

Question 10

What are the vessels we constrict/dilate to control regional redirection of blood?

Answer 10

Arterioles. By increasing/decreasing resistance, we control resistance and therefore blood flow to each vascular bed.

Question 11

Explain the order of vessels from the heart, back to the heart.

Answer 11

Arteries -> arterioles -> capillaries -> venules -> veins -> BACK TO THE HEART.

Question 12

Describe the structure of the aorta.

Answer 12

• Big tube, wide radius, very low resistance so lets blood flow through it very easily. Elastic wall
• Elastic artery.
• Damps pressure variations- by accomodating some of the pressure during ejection phase when aorta stretches and during diastolic phase it releases some of that elastic energy

Question 13

Describe the structure of arteries.

Answer 13

• Muscular arteries
• wide lumen
• Strong, non elastic wall
• low resistance conduit

Question 14

Describe the structure and function of arterioles.

Answer 14

• Resistance vessels
• Very small lumen, big resistance
• Thick, contractile wall (can vary resistance)
• Resistance vessel means Allows regional redirection of blood

Question 15

Describe the structure and function of capillaries?

Answer 15

• Exchange vessels:
• Narrow lumen => Big surface area:Volume ratio
• Really thin wall- small barrier to diffusion

Question 16

Describe the strucutre and function of venules and veins.

Answer 16

-Capacitance vessels

• Get blood back to the heart as easily as possible.
• Storing the blood.

-Wide lumen, distensible wall. This means low resistance. but also means can store all the blood.

Question 17

What is the main importance of veins during exercise?

Answer 17

Allows the fractional distribution of blood between the veins and rest of circulation (esp the heart).

• push that spare capacitance back to the heart

Question 18

Name…

• Aorta
• Artery
• Venules

Answer 18

aorta- elastic artery

artery- muscular artery

arterioles- resistance vessels

venules- capacitance vessels

Question 19

Name artery.

Answer 19

-muscular artery