The Heart Flashcards
Singled celled organisms and mass transport system
-can rely on simple diffusion
-to obtain all nutrients and remove all waste across cam
-as they have large SA:vol ratio
why do multicellular organisms need a mass transport system
-higher demand for nutrients and greater production of waste
-due to higher metabolic rate
-SA:vol ratio too small to deliver nutrients at appropriate rate and remove waste
-Simple diffusion would be too slow
what is meant by a double circulatory system
blood goes through the heart twice per complete cycle
what is another name for there left atrioventricular valve
Bicuspid. LABRAT. (LA-B)
what is another name for the right atrioventricular valve
Tricuspid. LABRAT. (RA-T)
Heart structure
-cardiac muscle which does not get fatigued
-coronary artery supplies cardiac muscle with oxygenated blood (cardiomyocyte)
-Myogenic= contract without nerve stimulation
-Interconnected= contract simultaneously
what is the function of the chordae tendinae
prevent valves from being inverted when under pressure
aorta function
-carries oxygenated blood from left ventricle to the body at high pressure
pulmonary artery function
-carries deoxygenated blood from right ventricle to the lungs
pulmonary vein
carries oxygenated blood from lungs to LA
Ventricles
LV: wall is the thickest (most cardiac muscle), forces blood into aorta at high pressure
RV: forces blood into pulmonary artery at lower pressure than LV (otherwise pressure would be too high and would rupture alveoli)
Pulmonar Semilunar valve
prevents backflow of blood from pulmonary artery into right ventricle during ventricular diastole
aortic semilunar valve
prevents backflow of blood from aorta into left ventricle during ventricular diastole
Atrioventricular Tricuspid valve
-prevents backflow of blood from RV to RA during ventricular systole
-closes when pressure in RV> RA
atrioventricular bicuspid valve
-prevents backflow of blood from LV to LA during ventricular systole
septum
separates RHS from LHS of heart
keeps oxygenated blood separated from deoxygenated
vena cava
carries deoxygenated blood from body to RA
when do valves open
when pressure behind it is greater than pressure in front
when do valves close
when the pressure in front of it is greater than the pressure behind it
Outline the cardiac cycle
-Atria contract simultaneously using atrial systole
-Pressure is higher in A than in V so AV valves open & blood flows into ventricles
-Ventricles contract simultaneously during ventricular systole
-Pressure is higher in V than in A, so AV valves close
-Pressure is higher in V than in arteries, so SL valves open
-Blood forced into the aorta and pulmonary artery
-Walls of A and V are relaxed during diastole
-pressure is higher in arteries than V, so SL valves shut
-Blood returns to atria through veins
-Atria fill with blood
-Pressure inc and AV valves open
-Blood slowly and passively enters ventricles
why is the muscular wall of the LHS of the heart much thicker than RHS
L needs to pump blood to the lungs
R needs to pump blood to extremities of the body
More muscle is able to contract with greater force to generate high pressure
LubDub
LUB- AV valves closing as V contract
DUB- SL valves closing from backflow of blood (from aorta and PA) as V relax
what is meant by myogenic
contracts w/o nerve stimulation
Diagram
SL opens, SL shuts
AV shuts, AV opens
Control of cardiac cycle
-Wave of impulses sent from sinoatrial node (SAN) across atria causing atrial systole
-Layer of non-conducting tissue prevents impulses from reaching ventricles
-Wave passes through atrioventricular node (AVN) which imposes a slight delay (allows atria to empty and ventricles to fill)
-AVN sends wave along Bundle of His through the septum to the base of V where it branches out in Pukinje fibres
-Ventricles contract from apex upwards
Stroke volume
V of blood pumped out of LV each cardiac cycle
cardiac output
V of blood pumped out of LV each minute
HR equation
CO= SV X HR
What causes pulses
Expansion of the arteries during ventricular systole, followed by elastic recoil during diastole
What happens to HR during exercise
-Skeletal muscles contract at higher rate
-Higher demand for oxygen & glucose
-so volume of blood being circulated needs to be increased dramatically. HR inc, SV inc.
-Cardiac muscle also contracts more strongly- greater force of ejection
Why do athletes have low HR
With a lot of exercise, there is an increased strength in cardiac muscle
stroke volume increases
so cardiac output can be achieved with fewer bpm
Factors affecting HR
-age, children higher HR
-diseases, CF inc HR
-smoking, nicotine inc HR
how are cardiac monitors used to analyse heart activity?
-electrodes placed on skin
-electrocardiogram
-corresponds to electrical activity
-can help diagnose heart problems
How can a persons diet impact their HR
rich in fruit, veg, CBH dec HR
rich in saturated lipids, inc HR
stages of electrocardiogram
P- Depolarization of A (>atrial systole)
QRS- Depolarization of V (>ventricular systole)
T- Repolarisation of V (>ventricular diastole)
how can an electrocardiogram indicate heart abnormalities?
no regular pattern- ventricular fibrillation
no distinct P wave- atrial fibrillation
long gaps- bradycardia
short gaps- tachycardia
raised ST wave- myocardial infarction
what is a myocardial infarction
when blood supply to cardiac muscles is cut off, preventing aerobic respiration
What is atheroma
Build up of fatty deposits in the wall of coronary artery
restricted blood flow-> myocardial infarction
What is SAN
specialised patch of muscle found in the wall of the right atrium (pacemaker)
Symptoms of heart attack
-chest pain
-shortness of breath
-rapid, weak pulse
-lightheadedness
-Nausea
What to do if you suspect heart attack
Call 999
Sit person in W position
Give 300mg of aspirin
Monitor breathing and pulse rate until ambulance arrives
Signs of cardiac arrest
not moving
not breathing
don’t respond to stimulation
CPR
Check for breathing by tilting head backwards
Place interlocked hands in centre of chest
Keep elbows straight and press down firmly at rate of 100bpm
Do this 30 times and give 2 rescue breaths
Repeat 30:2 until ambulance arrives
Difibrillator
Difib applies electric shock to momentarily stop electrical activity so the heart can recover to normal rhythm
how do high levels of saturated fats lead to coronary heart disease?
-Raises LDL
-LDLs deposit cholesterol in walls of coronary artery
-Can lead to atheroma
-reduces lumen size
-reduced oxygen supply to cardiac muscle
-myocardial infraction
