Lecture 32

Question 1

What is hemodynamics

Answer 1

how blood flows through the circulatory system

Question 2

what is chronotropy

Answer 2

timing of the heartbeat

Question 3

positive vs negative chronotropic effect

Answer 3

positive: increase in heart rate. Tachycardia: hr > 100 bpm due to increased sympathetic activity

negative: decrease in heart rate. Bradycardia: hr< 60 bpm due to increased parasympathetic activity

Question 4

what is ionotropy

Answer 4

contraction strength of myocardium

Question 5

positive vs negative ionotropic effect

Answer 5

positive: increased strength of contraction
negative: decreased strength of contraction

Question 6

describe sympathetic modulation of pacemaker rhythm on sinoatrial node

Answer 6

(nor)epinephrine from postganglionic fibers of sympathetic NS

binds to B-receptor, activates adenylate cyclase, cAMP,

PKA to phosphorylate funny channel allowing Na+ in (first depolarizing)

PKA phosphorylate T-type Ca2+ channel creating full action potential

Question 7

describe parasympathetic modulation of pacemaker rhythm

Answer 7

ACh binds to muscarinic receptors
activates signal transduction closes Ca2+ opens K+ causing net hyperpolarization

increases time needed for pacemaker potential to depolarize the cell to threshold

Question 8

Describe the modulation of heart muscle contractility (ionotropy)

Answer 8

(nor)epinephrine, B1 receptor, Adenylate cyclase, cAMP,

phosphorylates protein kinase activating it

protein kinase activates L-type Ca2+ channel (20%)

protein kinase activates Ca2+-ATPase on SR to bring Ca2+ in speeding the removal of Ca2+ from cytoplasm during relaxation

protein kinase activates tropomyosin on muscle fibers

Question 9

how is the SA node, AV node stimulated

Answer 9

parasympathetic Vagus nerves (X) and sympathetic nerves

Question 10

what 4 nerves are purely parasympathetic for short term regulation of the heart

Answer 10

CN III: oculomotor
CN VII: facial
CN IX: glossopharyngeal
CN X: Vagus

Question 11

what is the short term/long term regulation of the heart

Answer 11

short: baroreceptor reflex
long: fluid regulation by kidneys

Question 12

when does the atria repolarize

Answer 12

QRS

Question 13

what are fenestrated capillaries

Answer 13

capillaries perforated by minute physical pores

Question 14

what is the starling and landis principle

Answer 14

states that fluid movement across capillary walls is determined by the balance between hydrostatic and oncotic pressures

Question 15

describe blood flow

Answer 15

can be laminar or turbulent

Question 16

what does laminar flow result from

Answer 16

higher viscosity
lower velocity

Question 17

what is the mean arterial pressure

Answer 17

average pressure in artery during cardiac cycle

Question 18

describe the sound from stethescope at different cuff pressures

Answer 18

> 120: no sound heard
80-120: Korotkoff sounds are created by pulsatile blood flow through the compressed artery
<80 blood flow is silent when artery is no longer compressed

Question 19

what is the Reynolds #

Answer 19

helps quentify flow and predict transition from laminar to turbulent flow

dimensionless
< 2000 = laminar
>3000 = turbulent

Question 20

how is the blood pressure meausred

Answer 20

over the brachial artery (close to heart)
sphygomomanometer
(systolic) 120/90 (diastolic)

Question 21

what is pulse pressure

Answer 21

systolic - diastolic

Question 22

wht is NR influenced by

Answer 22

fluid density (rho)
speed
vessel radius
fluid viscosity (eta)

= 2pvr/n

Question 23

what is blood density proportional to

Answer 23

hematocrit (increases viscosity) and total blood proteins

Question 24

what can cause high NR

Answer 24

narrowing of vessles due to buildup of plaqu (atherosclerosis
hypertension (high BP)
low blood viscosity (anemia)

Question 25

what is poiseuille's equation for

Answer 25

using largest diameter and shortest length of tubing possible. infused fluid should be the lowest possible viscosity delivered under maximum possible pressure

Question 26

what has the highest effect on flow

Answer 26

vessel radius

Question 27

describe LaPlace Law and the tension on the walls of a blood vessel

Answer 27

the tension in the wall of a hollow structure or cylinder is proportional to the product of the internal pressure and radium T=r deltaP

Question 28

what is directly related to aneurysm formation and rupture

Answer 28

blood vessel wall stress

Question 29

what is the mean arterial pressure

Answer 29

the average arterial pressure throughout one cardiac cycle influenced by the product of CO and TPR