33. Pulmonary circulation. Special circulation

Question 1

Venous blood from the whole body passes through what circulation

Answer 1

Pulmonary circulation

Question 2

What are some characteristics of the pulmonary vessels compared w the systemic vessels

Answer 2

Short, wide highly distensible

Thinner walls

Lesser smooth muscle

Pulmonary arterioles has 1/5 of the pressure as systemic

Question 3

Pressure in Pulmonary artery is lower than in aorta
How deos this affect stroke volume of right ventricle compared w left

Answer 3

EQUAL stroke volume

Question 4

What is pulmonary arterial pressure in systole compared w aorta

Answer 4

25 mmHg in p.a

125 mmHg aorta

Question 5

Does pulmonary capillaries form tissue fluid

Answer 5

No

Pressure too low (6-7mmHg)

Question 6

Pulmonary Blood vessels have high compliance
What does this mean

Answer 6

Blood passing through them can change but does this not significantly change the pressure

Question 7

Compare the blood flow through the apices of the lung to the base of lung

Answer 7

Much less blood flow to apices than bases

Question 8

For regulation, what are pulmonary vessels strongly dependent on the changes on

Answer 8

alveolar pO2 and pCo2

Question 9

What happens in an area of low pO2 but high pCO2

Answer 9

Arteriolar resistance increases
Therefore reduces blood flow

Blood is redirected to areas where ventilation is better and gas exchange is improved

Question 10

WHch organ constantly needs a rich supply of blood

Answer 10

brain

Question 11

Compared to total oxygen supply, how uch of it is consumes by brain

Answer 11

20%

Question 12

What happens when interruption of 10-12 mins of O2 supplied to brain

Answer 12

Structural changes in neurons

Brain cant survive

Question 13

What type of regualtion is very well expressed in cerebral bloood

Answer 13

Autoregulation

Eveen w/o the changes in carotid artery pressure, cerebral blood flow is still constant

Question 14

Does neural and sympathetic incluences affect cerebral blood flow

Answer 14

Not really

Question 15

What are the main regulators of cerebral blood flow

Answer 15

pCO2, pO2 blood pH

Question 16

When is blood flow increased to an area in the brain

Answer 16

When cerebral activity is increased

Total blood flow not altered tho

Question 17

When can cerebrl vessels becomes compressed and impair blood flow to brain

Answer 17

When increased production/ decreased outflow of cerebral spinal fluid causes increase in intracranial pressure

Question 18

Corornary blood flow is about how much of the cardiac output

Answer 18

5%

Question 19

What advantageous abt the heart capillary network

Answer 19

10 times denser than skeletal muscle so east to transport substances

Question 20

What do cardiomyocytes contain to allow them to have a high affinity for oxygen

Answer 20

myoglobin

Question 21

CAn the heart function in hypoxic conditions

Answer 21

no, very limited anaerobic capacity

Question 22

WHy during systole, the blood flow to the left ventricle is reduced

Answer 22

Due to compression on coronary vessels by the ventricular muscle

receives most of its blood flow at diastole

Question 23

when pO2 decreases and pCO2 increases- hypoxemia, how can you increase coronary blood flow

Answer 23

adenosine, Nitric oxide, lactate, H2CO3 are vasodilators that dilate the coronary vessels

Question 24

Changes in cutaneous blood flow is due to what

Answer 24

thermoregualtion

Question 25

What is the cardiac output for cutaneous blood flow ( temperature in comfort zone)

Answer 25

5%

Question 26

What are the 2 types of resistance vessels in the skin

Answer 26

arterioles

arterio-venous anastomoses

Question 27

Aretrio-venous anastomoses: what nerves are tey controlled by? WHere are they found?

What activates their refelx mechanism

Answer 27

Only under sympathetic control - ( cutaneous vessels have no parasymoathetic control)

Skin of palms, soles,pinna, nose, lips

Thermoreceptors

Question 28

What happens when artertio-venous anastomoses constrict/ open

Answer 28

constrict: Blood flows through capillary networks with large surface area, allows heat loss

Open: blood bypasses capillary network and flows directly in venous vessels. doesnt allow heat loss

Question 29

What is the blood flow throug the digestivesystem

Answer 29

20-25% of Cardiac output

Question 30

Which parts of digestive system is best supplied with blood flow

Answer 30

muscosa of digestive tube and upper compartments

Question 31

What happens in fasting condtions compared to feeding

Answer 31

fasting: capillary pressure favours filtration

Feed: Splanchnic capillaries reabsorb, they dilate

Question 32

What innervation regulates digestive organs

Answer 32

sympathetic

arterioles has lots of a-adrenergic receptors that causes vasocontriction and decreases splanchnic blood flwo