cardiovascular - lecture 4

Question 1

what do right and left pulmonary arteries do

Answer 1

blood from right side of heart goes to right lung

Question 2

what do right and left pulmonary veins do

Answer 2

blood from lungs which is now oxygenated returns to heart - left side

Question 3

describe arteries and veins

Answer 3

arteries = move blood from heart, carry oxygenated blood (mostly)
veins = bring blood back to heart, carry deoxygenated blood (mostly)

Question 4

describe walls/septums

Answer 4

inter atrial septum
inter ventricular septum = boundary between right and left halves
right ventricular free wall = 1/10th, low pressure system
left ventricular free wall = v thick, lots of power, high pressure system

Question 5

describe coronary circulation - gen

Answer 5

heart has own circulation
coronary arteries = branch off above valve that feeds aorta
blood returns through veins and goes back to right atrium

Question 6

describe coronary arteries

Answer 6

branch off just above aortic valve
supply the heart muscle with oxygenated blood

Question 7

describe coronary veins

Answer 7

coronary veins and coronary sinus empty deoxy blood into right atrium

Question 8

what happens when blockage of coronary arteries

Answer 8

myocardial infarction = heart attack
plaque if lodged = turbulent flow
intervention needed

Question 9

name cardiac valves

Answer 9

tricuspid - right heart
pulmonary valve (pulmonic)
mitral valve (bicuspid) - left heart
aortic valve
make sure blood is not back flowing

Question 10

describe cardiac valves

Answer 10

left av = bicuspid = 2 leaflets
right av = tricuspid = 3 leaflets
left aortic semi lunar valve
right pulmonary semi lunar valve
semilunar = looks like half moon

Question 11

describe chordae tendinae and papillary muscles

Answer 11

chordae = connect to muscle and holds on
prevents prolapse from massive amounts of pressure

papillary muscle = contracts when ventricle contracts

both make structure strong

Question 12

what is pericardium

Answer 12

bag that surrounds heart
pericardial sac
does not expand, but v flexible, prevents overfilling
protects heart physically from damage and rest of body
provides pericardial fluid (~70ml)= lubricant to allow heart to freely contract with no friction, generated from serous membranes

Question 13

what is epicardium

Answer 13

outer layer of heart tissue
epithelial cells

Question 14

what is myocardium

Answer 14

muscle
specialized cells

Question 15

what is endocardium

Answer 15

inner layer of heart tissue
endothelial cells

Question 16

what is fibrous ring

Answer 16

between atria and ventricles = thick part
electrically isolates it
except av small node

Question 17

sinus node aka

Answer 17

sinoatrial node
sa node

Question 18

av node aka

Answer 18

atrioventricular

Question 19

bundle of his aka

Answer 19

his bundle
av bundle
atrioventricular bundle

Question 20

purkyne fibers aka

Answer 20

purkinje fibers

Question 21

his purknje system aka

Answer 21

bundle of his + left and right bundle branches + purkinje fibers

Question 22

what is pace making activity

Answer 22

sa node = main pacemaker
av node and cells of his purkinje system can beat spontaneously if sa node fails to fire

his purkinje system = 1/700ms
purkinje alone = 1/2secs or so

Question 23

describe activation sequence - 1

Answer 23

sinus node
small cluster cells specialized = electrical properties allow them to beat on their own, even if take heart out of body
beat 1/sec
electrical cascade = end up with wave of propagation and propagates through atria

Question 24

describe activation sequence - 2

Answer 24

wave from sa node now propagates through atria

Question 25

describe activation sequence - 3

Answer 25

hits av node
transmits electrical signals to ventricles
conducts signals slowly = delay so atria can empty blood into ventricles

Question 26

describe activation sequence - 4

Answer 26

bundle of his
specialized cardiac cells - v quick

Question 27

describe activation sequence - 5

Answer 27

left and right bundle branches
left bundle branch somewhat leaky = so septum becomes activated = have wave of propagation through system
septum - left to right and down

Question 28

describe activation sequence - 6

Answer 28

purkinje fibers
connect with all myoctes in ventricle then ventricles contract

Question 29

describe activation sequence - 7

Answer 29

left and right ventricular myocardium
endo to epi

Question 30

describe bundle branches

Answer 30

right bundle branch well insulated by ct
left bundle branch not completely isolated from the septum = so propagation in septum left to right and top to bottom

Question 31

describe Purkinje Fibre structure

Answer 31

large tree like structure

Question 32

describe sinus node

Answer 32

initiate an impulse (with every heartbeat – 1/sec)

Question 33

describe atrioventricular node

Answer 33

transfer the signal from the atria to ventricles (via the
bundle branches)
Impose a delay between atrial and ventricular contraction
Acts as a secondary pacemaker

Question 34

describe bundle branches

Answer 34

Rapidly conduct signal from AV node to Purkinje fibers
anatomy causes septum to activate first

Question 35

describe purkinje fibers

Answer 35

Branching network running just under endocardium
activate all cells in both ventricles at roughly same time
conduction from endo to epi - inside out
coordinated contraction maximizes pressure (and force *efficient)

Question 36

describe impulse propagation between myocytes

Answer 36

how signal travels between myocytes
electrically connected

Question 37

describe intercalated disk

Answer 37

many gap junctions found near intercalated disks
connection between cells via gap junctions occur primarily longitudinally - at ends of cells
makes tiny pore between cells = very tiny
cells form hemi channels on their own
ions flow freely through

Question 38

describe local circuit currents = numbers

Answer 38

hyperpolarized then
depolarized cell = +20mv
resting cell = -80mv
+ve ions move due to electrical gradient between cells
K+= cell A–>B cytoplasmic
Na+= cell B–>A interstitial

Question 39

describe local circuit currents - generally

Answer 39

sodium = net flow outside cells, low concentration
net pos charge on cell with ap
K+ net flow inside cells, high concentration to cell B
pos to neg attraction
sodium channels open and change in conformation and depolarizes
cells coupled by gap junctions

Question 40

describe having local circuits during repolarization

Answer 40

cell A repolarizes before cell B
B now +vs 20mv while A is -ve 80mv
local currents flow in opp direction

Question 41

where can interstitial currents be sensed

Answer 41

currents on outside can be sensed by electrodes on body
interstitial currents can be sensed at the surface of the body