cardiovascular - lecture 4 Flashcards
what do right and left pulmonary arteries do
blood from right side of heart goes to right lung
what do right and left pulmonary veins do
blood from lungs which is now oxygenated returns to heart - left side
describe arteries and veins
arteries = move blood from heart, carry oxygenated blood (mostly)
veins = bring blood back to heart, carry deoxygenated blood (mostly)
describe walls/septums
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
describe coronary circulation - gen
heart has own circulation
coronary arteries = branch off above valve that feeds aorta
blood returns through veins and goes back to right atrium
describe coronary arteries
branch off just above aortic valve
supply the heart muscle with oxygenated blood
describe coronary veins
coronary veins and coronary sinus empty deoxy blood into right atrium
what happens when blockage of coronary arteries
myocardial infarction = heart attack
plaque if lodged = turbulent flow
intervention needed
name cardiac valves
tricuspid - right heart
pulmonary valve (pulmonic)
mitral valve (bicuspid) - left heart
aortic valve
make sure blood is not back flowing
describe cardiac valves
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
describe chordae tendinae and papillary muscles
chordae = connect to muscle and holds on
prevents prolapse from massive amounts of pressure
papillary muscle = contracts when ventricle contracts
both make structure strong
what is pericardium
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
what is epicardium
outer layer of heart tissue
epithelial cells
what is myocardium
muscle
specialized cells
what is endocardium
inner layer of heart tissue
endothelial cells
what is fibrous ring
between atria and ventricles = thick part
electrically isolates it
except av small node
sinus node aka
sinoatrial node
sa node
av node aka
atrioventricular
bundle of his aka
his bundle
av bundle
atrioventricular bundle
purkyne fibers aka
purkinje fibers
his purknje system aka
bundle of his + left and right bundle branches + purkinje fibers
what is pace making activity
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
describe activation sequence - 1
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
describe activation sequence - 2
wave from sa node now propagates through atria
describe activation sequence - 3
hits av node
transmits electrical signals to ventricles
conducts signals slowly = delay so atria can empty blood into ventricles
describe activation sequence - 4
bundle of his
specialized cardiac cells - v quick
describe activation sequence - 5
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
describe activation sequence - 6
purkinje fibers
connect with all myoctes in ventricle then ventricles contract
describe activation sequence - 7
left and right ventricular myocardium
endo to epi
describe bundle branches
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
describe Purkinje Fibre structure
large tree like structure
describe sinus node
initiate an impulse (with every heartbeat – 1/sec)
describe atrioventricular node
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
describe bundle branches
Rapidly conduct signal from AV node to Purkinje fibers
anatomy causes septum to activate first
describe purkinje fibers
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)
describe impulse propagation between myocytes
how signal travels between myocytes
electrically connected
describe intercalated disk
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
describe local circuit currents = numbers
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
describe local circuit currents - generally
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
describe having local circuits during repolarization
cell A repolarizes before cell B
B now +vs 20mv while A is -ve 80mv
local currents flow in opp direction
where can interstitial currents be sensed
currents on outside can be sensed by electrodes on body
interstitial currents can be sensed at the surface of the body
