the heart Flashcards
describe how deoxygenated blood flows through the different parts of the heart
- deoxygenated blood flows in through superior and inferior vena cava into the right atrium and through the atrioventricular valve/ tricuspid valve into right ventricle
- then it flows out of heart into the lungs through the pulmonary artery
describe the flow of blood through the different parts of the heart (oxygenated)
- oxygenated blood from lungs enter heart through pulmonary veins into left atrium
- then through atrioventricular / bicuspid valve into the left ventricle
- then it flows through the aortic/ semi lunar valve to the aorta and out of the body
why is the pulmonary artery and pulmonary veins special
pulmonary artery -carry deoxygenated blood out
pulmonary veins carry oxygenated blood in
draw and label the structure of the heart
interior and exterior
describe the cardiac muscle cells
-made of fibres that branch producing cross bridges
-numerous mitochondria between muscle fibrils (myofibrilles)
-muscle cells separated by intercalated discs= allow synchronised contraction
what does diastole and systole mean in the cardiac cycle?
diastole- muscle relaxing
systole- muscle contraction
what happens during Atrial systole of the cardiac cycle
-atria contract
-ventricles relax
-AV valves open
-semi-lunar valves open
-blood flowing into ventricles
-highest pressure in the atrium
what happens during ventricular systole in the cardiac cycle
-Atria relax
-ventricles contract
-AV valves closed (prevent back flow)
-semi lunar valves open
-blood flows to arteries (pulmonary and aorta)
-highest blood pressure in ventricles
what happens during diastole day n the cardiac cycle
-Atria and ventricles relax
-AV valves open
-Semi lunar valves close
-blood flows into heart atria and ventricles
-highest pressure in arteries
why is the heart described as myogenic
controls it’s own regular heartbeat by initiating electrochemical impulse
explain how the heart initiates it’s own heart beat
1) SAN initiates a wave of excitation
2)wave of excitation spreads over walls of both atria along the membranes of the muscle tissue
3) cardiac muscle cells of atria contract (depolarise), causing atrial systole
4) wave of excitation reaches AVN delay at node, allows atria to empty blood into ventricles
5) wave of excitation, carried away from AVN down to Purkyně tissue (bundle of His) in inter ventricular septum
6) at base of septum it’s spread out over walls of ventricles
7) the wave spreads up from Apex, causing ventricular systole
8) ventricles contract from base up, causing blood to be pushed up to arteries
what is an electrocardiograph
when electrical activity moves from the SAN to AVN it is detected by sensors attached to the skin and convert it into a trace
draw a normal ECG and explain each part
p-wave = SAN wave to the atria (atrial systole)
QRS complex = AVN wave to ventricles (ventricular systole)
T-wave = diastole
what is a normal heart trace called?
what are the abnormal heart traces?
1) Sinus rhythm
2) -rapid heart rate = tachycardia
-slow heart rate = bradycardia
-atria contracting more frequently than ventricles = Atrial fibrillation
-irregular = ectopic
