Heart- Sum 6

Question 1

cardiovascular system

contents

Answer 1

heart +
blood vascular system +
lymph vascular system

Question 2

CV system

function

Answer 2

maintain and regulate continuous movement of body fluids

aka heart pumps blood toward capillary beds

Question 3

heart wall layers

Answer 3

endocardium
myocardium
epicardium

epi and endo have sublayers

Question 4

epicardium

outer layer

Answer 4

1. visceral pericardium (shiny)- covers entire outer surface
   aka visceral layer of serous pericardium
2. subepicardium- layer of fibroelastic CT (equal collagen and elasic fibers) + adipose CT (epicardial fat in AV and IV grooves + surrounding coronary vessels)

if fat in others layers then maybe pathologica

Question 5

endocardium

layers

Answer 5

endothelium- lines atria
subendothelium
myoelastic CT
subendocardium

Question 6

visceral pericardium

of epicardium

Answer 6

simple squamous epithlium

secretes lubricating fluid for pericardial cavity to reduce friction

Question 7

subepicardium

of epicardium

Answer 7

layer of fibroeleastic to connect epithelium to underlying fat or myocardium

layer of adipose CT to cushion coronary vessels and store energy

Question 8

coronary vessels

Answer 8

healthy levels = fat restricted to grooves around vessels, 20% ventricular mass

-recessed from the heart surface aka in grooves

unhealthy levels = more than 20%, extends beyond grooves/covers heart surface, obesity, diabetes 2, vascular aging, atherosclerosis

Question 9

myocardium

muscular layer

Answer 9

main cell type = contractile cardiomyocytes

heart pumps by coordinating cells contraction and relaxation

heart wall is mostly myocardium

Question 10

myocardial infarction

Answer 10

physical damage to/necrosis of contractile cells releases troponin T or I into ECM

serum troponin levels elevated 2-3 hrs after pain onset, peaks at 12-48, 4-10 days to return to normal

Question 11

contractile cardiomyocytes

appearance

Answer 11

-Y shaped
-1-2 nuclei
-weak striations
-intercalated discs aka gap junctions for rapid ion transfer, allow depolarizationi current to flow

Question 12

myoendocrine cells

Answer 12

@ myocardium

modified contractile cardiomyocytes + secrete peptide hormones
-atria = ANP (atrial natriuretic peptide)
-ventricles = BNP (B type natriuretic peptide)

Question 13

congestive heart failure

Answer 13

ANP and BNP inc (weak heart beat so can’t pump enough blood to meet O2 demands)

inc kidney filtration =
inc sodium excretion aka natriuresis
inc fluid excretion aka diuresis

ANP and BNP vasodilator indirectly via renin

BNP more sensitive = left vent dysfunction

Question 14

purkinje fibers

location

Answer 14

@ myocardium

modified contractile cardiomyocytes + rapid impulse conduction

mostly travel in subendocardium layer of endocardium but terminate in myocardium
-location makes vulnerable to infections of endocardium

Question 15

COVID

Answer 15

can trigger myocarditis = reduce ability to pump bc extra fluid, rapid heartbeat

can occur in asymptomatic, children, athletes OR after vaccination

also fibrin clots and microclots (local tissue damage/ischemia) + recruit megakaryocytes to myocardium

Question 16

endocardium - subendocardium

sub layers

Answer 16

deepest layer
loose CT + blood vessels + nerves + purkinje

CT anchors endocardium to myocardium and give pathway for purkinje fibers

Question 17

myoelastic CT layer

sub layer endocardium

Answer 17

smooth muscle cells + elastic fiber + some collagen I

facilitate contraction/expansion of endothelium

Question 18

subendothelial layer

sub layer endocardium

Answer 18

collagenous or fibroelastic CT, always lots of collagen I

anchors endothelium to rest of endocardium

Question 19

endothelium

sub layer endocardium

Answer 19

layer closest to chamber lumen
simple squamous epithelium
lines heart chambers

Question 20

conduction system

Answer 20

1.SA node
2.atrial walls
3.AV node
4.fibrous skeleton
5.AV bundle of His
6.R and L bundle branches
7.purkinje fibers

conduction fibers v close to inner layer = faster impulse

Question 21

SA Node

Answer 21

pacemaker
normal rate of depolarization is faster than other cells

SA nodal cells= smaller than other atrial cardiomyocytes, fewer myofibrils, lack intercalated discs
-# of SA nodal cells = maximum HR
-will reduce with age, not related to activity

Question 22

purkinje fiber

appearance

Answer 22

x2 diameter of normal contractile cells

x3 more gap junctions in intercalated discs

lighter staining bc lots of glycogen (unstained in H&E)

more resistant to hypoxia bc of glyogen protection

Question 23

cardiac skeleton

Answer 23

R ring + L ring +CT part of IV and AV septum

fibrous > dense irregular collagenous CT

flexible anchor for cardiac muscle tissue to withstand pulling from several directions during contraction

Question 24

heart valves

Answer 24

valves maintain unidirectional flow thru heart aka prevent backflow

need to be intact, mobile, pliabe, avascular

Question 25

valve layers

Answer 25

1. endothlieum inflow
2. elastic layer (inflow)-dense for rapid recoil
3. spongiosa (central core)- loose compressible to absorb force
4. fibrosa (outflow) -dense col I to resist stretching/breaking
5. endothelium outflow

Question 26

valvular degeneration

clinical relevance

Answer 26

compromised structure = compromised function

less efficient flow:
-too much flow (patent valve)
-too little flow (stenosis)
-regurgitation (backflow)

muscle tissue weakened from strain

Question 27

AV node

Answer 27

delays transmission of signals from atria to ventricles

atrial contraction precedes ventricular contraction