Lecture 1 - Introduction to the CVS

Question 1

Why do we need a CVS? (7)

Answer 1

• Circulates hormones and immune mediators
• Transport nutrients to muscles and organs
• Pump blood through the lungs and carry oxygen to various parts of the body
• Transports nutrients to muscles and organs
• Defence system
• Connection to Lymphatic system
• Human reproduction
• Temperature regulation

Question 2

Passive diffusion (2)

Answer 2

time proportional distance2.

um

Question 3

Cardiac output (2)

Answer 3

CO = HR X SV

Volume of blood ejected from the heart per minute

Question 4

CO - Values (2)

Answer 4

o Rest = 70/min x 70 ml = 5 litres/min

o Exercise = 180/min x 120 ml = 20 litres/min

Question 5

What controls cardiac output? (3)

Answer 5

Filling pressure - Starlings law
Para(Sympathetic) autonomic nerves
Chemical factors and hormones

Question 6

What controls blood flow and determines blood pressure? (3)

Answer 6

Resistance
Blood flow proportional to pressure
Blood flow inversely proportional to resistance of blood vessels

Question 7

Blood flow formula

Answer 7

(Pa-Pv)/ Resistance

Question 8

Resistance through vessels (3)

Answer 8

Aorta has a low cross-sectional area so low resistance and high pressure, faster flow.
Arterioles are RESISTANCE vessels which control arterial BP by determining TPR (total peripheral resistance).
In capillaries, the velocity is slow allowing gaseous/nutrient exchange to occur.

Question 9

Blood velocity formula

Answer 9

BV (cm/s) = Blood flow (cm3/s) / Cross sectional area (cm2) x (Pie r2 per vessel)

Question 10

Structure of blood vessel - capillaries (2)

Answer 10

Endothelium - lines BV. Releases NO, vasodilation.

Tunica media - Smooth muscle, NA a1 adrenorecptors, vasoconstriction.

Question 11

Structure of blood vessel - veins (2)

Answer 11

Not innervated by nerves.

Capacitance vessels can expand more if needed.