Resistance Regulation

Question 1

how to calculate MAP?

Answer 1

MAP= CO * TPR

Question 2

How to determine flow

Answer 2

Q = P/R

Question 3

What are the three ways to regulate MAP?

Answer 3

1. Within the heart
2. Resistance vessels
3. Blood Volume

Question 4

Difference between chronotropic and ionotropic

Answer 4

chronotropic- changes in performance by increasing heart rate
ionotropic- changes in performance w/o increasing heart rate (ie changing contracility)

Question 5

What are the intrinsic mechanisms for increasing heart performance via the heart?

Answer 5

1. heterometric- changing the CO by changing the length of the fibers in the muscle
2. homometric- changing the CO w/o changing the fiber length- changing contracility

Question 6

What are extrinsic mechanisms for regulating cardiac performance in the heart?

Answer 6

autonomic innervation- sympathetic- increases HR, CO, contracility, conduction velocity; parasympathetic- decreases HR and contractility. balance of sympathetic and parasympathetic is important.
humoral factors- norepinephrine, epinephrine, aldosterone, cortisol, thyroid hormone

Question 7

What are the key factors of intrinsic regulation of VSM

Answer 7

1. basal tone (independent of innervation)
2. myogenic stretch reflex (contraction)
3. local metabolites (dilation)

Question 8

autoregulation

Answer 8

regulation of flow via the vessels just proximal to the tissue

Question 9

what are the two ways VSM can be extrinsically regulated?

Answer 9

1. nervous innervation

2. humoral factors

Question 10

describe the autonomic regulation of VSM

Answer 10

1. tonic sympathetic innervation promoting constriction contributing to basal tone (along with intrinsic factors)
2. sympathetic innervation promoting dilation (minor; primarily in skeletal muscle)
3. parasympathetic dilation in GI and genitalia

Question 11

describe the humoral factors regulating VSM

Answer 11

norepinephrine- constrictor
epinephrine- low amounts dilation, high amounts constriction
ADH/Vasopressin- fluid retention, constriction
angtiotensin II- constriction
Histamine- dilator

Question 12

what is the difference between the pressor and the depressor

Answer 12

pressor- increases sympathetic innervation- increasing HR, resistance, contractility, basal tone, venomotor tone (in large veins, no effect on resistance but increases VR and therefore CO)

depressor- inhibits the pressor and has vagus innervation to heart, lowering HR

Question 13

Where are the high pressure barometric sensors?

Answer 13

carotid sinus and aortic sinus

Question 14

What does the carotid body do? what effects does it have?

Answer 14

it senses hypoxia. has the affect of

1. Increasing HR
2. increasing respiration
3. increasing resistance
4. arousal from sleep

Question 15

what is the factor that determines perfusion pressure?

Answer 15

mean arterial pressure MAP