The Heart Flashcards by Francisco Campino

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

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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

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what is meant by a double circulatory system

blood goes through the heart twice per complete cycle

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what is another name for there left atrioventricular valve

Bicuspid. LABRAT. (LA-B)

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what is another name for the right atrioventricular valve

Tricuspid. LABRAT. (RA-T)

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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

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what is the function of the chordae tendinae

prevent valves from being inverted when under pressure

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aorta function

-carries oxygenated blood from left ventricle to the body at high pressure

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pulmonary artery function

-carries deoxygenated blood from right ventricle to the lungs

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pulmonary vein

carries oxygenated blood from lungs to LA

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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)

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Pulmonar Semilunar valve

prevents backflow of blood from pulmonary artery into right ventricle during ventricular diastole

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aortic semilunar valve

prevents backflow of blood from aorta into left ventricle during ventricular diastole

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Atrioventricular Tricuspid valve

-prevents backflow of blood from RV to RA during ventricular systole
-closes when pressure in RV> RA

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atrioventricular bicuspid valve

-prevents backflow of blood from LV to LA during ventricular systole

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septum

separates RHS from LHS of heart
keeps oxygenated blood separated from deoxygenated

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vena cava

carries deoxygenated blood from body to RA

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when do valves open

when pressure behind it is greater than pressure in front

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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