8. heart

mass transport system

bulk movement of fluid in one direction

factors requiring mass transport system

SA:V ratio

metabolic rate

size

surface are to volume ratio

as the size increases the ratio decreases, as volume increases faster than surface area

unicellular organism

able to rely on diffusion across outer face membrane to supply oxygen and nutrients as large SA:V ration and low metabolic rate allow diffusion to be fast enough

large multicellular organism

diffusion across outer surface is not sufficient to provide all cels with oxygen and nutrients so require specialised exchanged surfaces and a mass transport system. due to small SA:V ratio, cells deep within and high metabolic rate

specialised exchange surfaces

increase surface area for exchange with enviroment eg alveoli in lungs and villi in small intestine

plants

large multicellular organisms which have stomata in leaves to exchange gas, no need to further mass transport system for gas was short diffusion distance but is for water and mineral ions in the form of xylem and phloem

circulatory system

mammalian mass transport system composed of blood vessels (closed system) filled with blood which the heart pumps in one direction

double circulatory system

describes like this as blood is pumped by the heart twice in two circuits (pulmonary and systemic)

pulmonary circulation

circulation that transports blood to the lungs

systemic circulation

circulation that transports blood to the body

superoir vena cava

A,

right pulmonary vein

B,

right atrium

C,

inferior vena cava

D,

right ventricle

E,

Aorta

F,

left pulmonary vein

G,

left ventricle

H,

left pulmonary vein

I,

left ventricle

j,

A

semilunar valve

B

right atrium

C

right atrioventricular valve which prevents back flow of blood form ventricle to the atria

D

right ventricles

E

ventricular septum

F

left ventricle

G

left atrio-ventricular valve

H

semilunar valve

I

left atrium

J

pulmonary artery

K

aorta

right ventricle to the left atrium

movement of blood in the heart via the lungs

left ventricle to the right atrium

movement of blood in the heart via the body

pulmonary artery to the pulmonary vein

blood vesicles the blood flows through from the heart to the the lungs and back

aorta to vena cava

blood vesicles the blood flows through from the heart to the the rest of the body and back 

ventricular systole

ratio relax

ventricles relax to decrease volume and increase pressure, as pressure exceeds atria the atrioventricular valve close, making ‘lub’ noise

pressure continues to increase it exceeds pressure in arteries and opens semilunar valve and blood flows out

atria systole

ventricles relaxed

atria wall muscles contract to push any last blood out in ventricle (atrial kick)

diastole

both atria and ventricles relaxed

semilunar valves close ‘dub’ sound, prevents back flow of blood

atrioventricular valve open allowing atria and ventricles to passively fill with blood

atrial systole, ventricular systole

order of cardiac cycle after diastole

Y

semilunar valve closes, as ventricle walls relax and pressure in ventricles drops below arteries, DUB sound

z

atrioventricular valve open, as both atrio and ventricle walls are relaxed so pressure of ventricle pressure falls below atrium

w

atrioventricular valve closes, as ventricle walls begin to contract increasing pressure in ventricles until it exceeds atrial pressure, cause LUB sound

x

semilunar valve opens, as pressure form ventricles exceeds pressies in aorta and pulmonary artery

atrial fibrillation

when atria start to contract out of time, contractions rapid and unsynchronised

atrial kick

topping up of the ventricles by contraction of muscle in walls of atria at end of diastole (ventricle receives 85% of blood from diastole and 15% from atrial systole but this increases with age)

elderly people

age where topping up of ventricles increases to closer to 35%

cardiac muscle

contains many mitochondria to produce ATP for contraction

myogenic

property of cardiac muscle where it doesn’t require nerve impulses from neurone to initiate contraction

control rate of contraction

by frequency of nerve impulses in accelerator and vagus nerves and by hormones like adrenaline

2, 5, 6, 1, 3, 7, 4, 8

order statements for coordination of heart action:


1. atrioventricular node (AVN) in septum between the atria, detects the electrical impulse
2. sinoatrial node (SAN) or pacemaker, in the wall of the right atrium, initiates the heart-beat
3. After a short delay (to allow atria to contract), the electrical / nerve impulse travels down the bundle of His (through Purkyne tissue) in the septum to the base of the ventricles
4. Both ventricle walls contract together from the bottom upwards so blood is pushed upwards and out of the heart
5. SAN initiates an electrical / nerve impulse that spreads across the walls of both atria causing them to contract together
6. A band of non-conducting collagen fibres prevents the random conduction of the electrical / nerve impulse to the ventricles
7. The Purkyne fibres branch from the bundle of His and transmit the electrical / nerve impulse to the muscle in the walls of the ventricles
8. Purkyne fibres also carry electrical / nerve impulse to the papillary muscles, which contract to keep the chordae tendinae taut and prevent the atrioventricular valves inverting

Coronary heart disease

when arteries carrying blood to the heart muscle become narrowed or blocked

low density lipoproteins

responsible for narrowing of artery lumen, contain cholesterol, deposited in artery wall underneath endothelium

atherosclerosis

process when low density lipoproteins (LDLs) are engulfed by macrophages, accumulating forming a fatty plaque called atheroma which narrows the artery

angina

sever chest pain from coronary heart disease

blood clot

formed from the atheroma breaking through endothelium, exposing collagen fires

heart attack

otherwise called a myocardial infraction, where a blood clot block the coronary artery, causes part of the tissue to be deprived of oxygen and dies, can cause death to individual

streptokinase

given intravenously to dissolve blood clots, it hydrolyses plasminogen to plasmin which breaks down fibrin and dissolves blood clots

stent

inserted to artery to widen lumen to treat coronary heart disease, inflated by a balloon when in place

diet

increase chance of CHD as high salt intake increase blood pressure, increased saturated fat/cholesterol intake increases its deposition in artery wall

hypertension

increases chance of CHD as it increases damage to endothelium in arteries and therefore increases chances of atheroma developing

exercise

decreases chance of CHD by lowering blood pressure, blood cholesterol and chance of developing obesity

smoking

increases chance of CHD by raising blood pressure, increasing atheroma formation and chance of blood clots

genetics

some ethnic gropes are at higher risk of CHD eg afro-caribbeans

male

one is more at risk of CHD until menopause when there the same

heart rate

number of beats per minute (bpm)

stroke volume

volume of blood pumped out of the left ventricle each cardiac cycle (typically 60-80cm3)

calculated by = volume at end of ventricular diastole - volume at end of ventricular systole

cardiac output

volume of blood pumped out left ventricle each minute (4-8dm3min-1)

calculated by stroke volume x heart rate

ultrasound

able to measure volume of blood in left ventricle at 2 points in cardiac cycle, the end of ventricular diastole (most blood) and end of ventricular systole (least blood)

pulse rate

due to expansion of artery wall during ventricular systole and elastic recoil of artery wall as blood pressure drops during diastole

radial or carotid

artery in wrist and neck where pulse rate can be measured done for 15 seconds then multiplied

thumb

not used to measure heart rate as contains own pulse

age

effects heart rate as children have a faster heart rate

genetics

some people inherit a tendency to have a lower or higher heart rate or inherited diseases like cystic fibrosis

physical activity

heart rate increases in excursive and recovery, sustained her long term it can reduce heart rate as it becomes stronger

smoking

nicotine stimulates release of noradrenaline which increases heart rate

diet

eating fruit and veg is believed to be beneficial to heart rate

strenuous exercise

increase heart rate and stroke volume so therefore cardiac output

starlings law

during excursive blood Is returned to heart quicker as contracting muscle compresses veins

greater volume of blood enters ventricles during diastole stretching muscular walls of ventricles

cardiac muscle contracts more forcefully causing a greater volume of blood to be pumped out the heart

increases heart rate

due to more frequent nerve impulses along accelerator nerve to SAN

very high heart rate

decreases cardiac output as there is insufficient time for blood to enter ventricles during diastole so stroke volume decreases

training

used to achieve a lower resting heart rate as stroke volume and cardiac output increase due to stronger more efficient cardiac muscle

investigate heart rate

by measure pulse rate before and after exercise at a give intensity, evaluate data with a paired

t-test, at least 10 similar age participants, ensure no health conditions

electrocardiography

shows changes in heart during cardiac cycle, displayed as an ECG

t wave

recovery from electrical activity in ventricles, atria and ventricles relax, small hump at end of ECG

QRS complex

detection of electrical impulse by AVN, transmission of impulse down septum and through ventricle walls that then contract, 2 dips and a big peak on ECG

p wave

spread of electrical impulse from SAN through atrial walls that then contract, small hump at start of ECG

bradycardia

very slow resting heart rate (40-60bpm) gap between each peak in race is long, causing a long gap between T wave and P wave

tachycardia

high resting heart rate (above 100bpm) ECG shows little gap between one t wave and next p wave

heart attack

blood supply to part of heart muscle is blocked trough and peaks become less distinct and not as regular, S-T portion of ECG is higher (S-T elevation)

atrial fibrillation

wall of atria contract in unsynchronised manner that prevents filling of ventricles, unclear p wave

heart attack symptoms

heavy crushing pressure in chest spreading to jaw, neck and arm s

breathlessness, discomfort in stomach, profuse sweating, cold ashen looking skin, blue lips

rapid, weak irregular pulse, nausea, vomiting and unexpected collapse

4, 1, 5, 3, 2,

number statements for treatment of heart attack


1. Sit the person in **W** position (sitting up with knees bent)
2. Reassure and monitor breathing rate / pulse rate until help arrives
3. Assist patient with any personal medication for angina (tablets or spray)
4. Call 999 and tell them you suspect heart attack
5. Give them 300mg aspirin tablet if available (check allergy, must be over 16)

cardiac arrest

when the heart is no longer performing any useful function to circulate blood around the body, either ventricular fabulation (no effective movement of blood out heart) or atrial fibrillation (insufficient filling of ventricles)

treat cardiac arrest

lie down and perform CPR until emergency services arrive, a trained first aider can use a defibrillator to shock the heart out of fibrillation

6, 3, 8, 7, 9, 1, 2, 4, 8

order the process of CPR:


1. After each compression release all the pressure on the chest without losing contract between the hands and the sternum
2. Aim for a rate of about 100 compressions per minute (count out loud)
3. Check for breathing by tilting the head backwards
4. Do 30 compressions then give mouth-to-mouth resuscitation, also known as Expired Air Resuscitation (EAR), twice
5. Continue 30:2 procedure until help arrives
6. Immediately ring for help, don’t leave patient and constantly reassure them
7. Keep your elbows straight and press down vertically, bring your bodyweight over your hands to make it easier
8. Place heel of one hand in the centre of the victim’s chest and heel of the other hand on top of the first interlocking your fingers together.
9. Press down firmly and quickly to about 4 to 5 cm downwards, relax and then repeat the compression.

expired air resuscitation

process of; laying erosion on back, tilting their head back and lift their chin, gently pinch soft part of nose closed, open mount keeping chin lifted, take a deep breath and place lips around person mouth, (get a good seal), breath out and watch chest rise and fall and repeat

defibrillator use

place the two pads on chest in a diagonal line with the heart in the middle, machine reading will show if heart is fibrillating, an electric shock is applied to momentarily to stop chaotic electrical activity and heart can recover coordinated rhythm