Circulatory System

Question 1

What are platelets derived from?

Answer 1

derived from megakaryocytes

- while they are cell fragments, platelets have own ribosomes and can make proteins. But have no nucleus to make mRNA

Question 2

Order of decreasing vascular resistance in capillaries, arterioles, artery, veins and venule

Answer 2

Arterioles (smallest diameter)
Capillary (smaller diameter, but vast amount make them not as resistant compared to arterioles)
arteries
veins and venules (larger diameter vs arteries)

Question 3

what are the three layers of arteries and veins?

what is the innermost layer made of and relate this to capillaries?

Answer 3

Tunica:
externa, media, intima
intima is made of endothelial cells, simialr to capillaries which are one cell thick endothelial cells

Question 4

how are cardiac muscles cells connected?

Answer 4

• intercalated discs

- purpose is for the heart to function as a single organizational unit

Question 5

how do cardiac fibers in atria contract simult?

Answer 5

due to gap junctions

- located in intercalated disks

Question 6

What are the R and T states of hemoglobin?

Answer 6

r: relaxed
t: taut

R: relaxed, O2 bound and has higher affinity
T: taut, O2 unbound and lower affinity

Question 7

Examples of hemoglobin right vs left shift:

why? think respiration

Answer 7

Right shift:

• high CO2, low pH, high temp due to low affinity for O2
• release of O2 is necessary in high respiration

Left shift:
- low CO2, high pH, low temp

Question 8

how does fetal hemoglobin incr O2 affinity?

Answer 8

• decr affinity for2,3 BPG

- note cooperativity or MOA of hemoglobin is unchanged

Question 9

what does 2,3 BPG normally do?

Answer 9

• normally decr O2 affinity for

- a reduction in 2,3 BPG binding would increase O2 affinity

Question 10

Out of reptiles, human, kangaroo rat, and camel, which would have the higheest body temp when environmental temp is 45 degrees C?

Answer 10

Reptile, they lack mechanisms of vasodilation and sweating - impermeable integumentary. Eliminating options for cooling

Question 11

What are the two primary factors that normally determine level of blood pressure?

Answer 11

Cardiac output and resistance to blood flow
CO = SV x HR > blood pumped into system by heart per unit time
Resistance > arteries, mostly arterioles, and precapillary sphincters

BP = Peripheral resistance x CO (analogous to ohm’s law)