Heart

Question 1

Closed circulatory
system

Answer 1

Blood remains within blood vessels

Question 2

Name different types of blood vessels

Answer 2

Arteries, arterioles, capillaries, venules and veins

Question 3

Structure of arteries

Answer 3

Thick muscular layer thick elastic layer thick outer layer small luman
no valves

Question 4

Capillary endothelium

Answer 4

Extremely thin
one cell thick
contains small gaps for small molecules to pass through (e.g. glucose, oxygen)

Question 5

Capillaries

Answer 5

Form capillary beds
narrow diameter (1 cell thick) to slow blood flow
red blood cells squashed against walls shortens diffusion pathway
small gaps for liquid / small molecules to be forced out

Question 6

Arterioles

Answer 6

Branch off arteries
thickest muscle layer to restrict blood flow
thinner elastic layer and outer layer than arteries as pressure lower

Question 7

Tissue fluid

Answer 7

Liquid bathing all cells contains water, glucose, amino acids, fatty acids, ions and oxygen
enables delivery of useful molecules to cells and removal of waste

Question 8

Tissue fluid formation

Answer 8

At arteriole end, the smaller diameter results in high hydrostatic pressure
small molecules forced out (ultrafiltration)
red blood cells / large proteins too big to fit through capillary gaps so remain

Question 9

Reabsorption of tissue fluid

Answer 9

Large molecules remaining in capillary lower its water potential
towards venule end there is
lower hydrostatic pressure due to loss of liquid
water reabsorbed back into capillaries by osmosis

Question 10

Role of the lymph in tissue fluid reabsorption

Answer 10

Not all liquid will be reabsorbed by osmosis as equilibrium will be reached
excess tissue fluid (lymph) is absorbed into lymphatic system and drains back into bloodstream and deposited near heart

Question 11

Cardiac muscle

Answer 11

Walls of heart having thick muscular layer
unique because it is:
myogenic - can contract and relax without nervous or hormonal stimulation
never fatigues so long as adequate oxygen supply

Question 12

Coronary arteries

Answer 12

Blood vessels supplying cardiac muscle with oxygenated blood branch off from aorta
if blocked, cardiac muscle will not be able to respire, leading to myocardial infarction (heart attack)

Question 13

Structure of the heart

Question 14

Adaptation of left ventricle

Answer 14

Has a thick muscular wall in comparison to right ventricle enables larger contractions of muscle to create higher pressure
ensures blood reaches all body cells

Question 15

Veins connect to the heart

Answer 15

Pulmonary artery - carries deoxygenated blood from right ventricle to lungs
Aorta - carries oxygenated blood from left ventricle to rest of the body

Question 16

Valves within the heart

Answer 16

Ensure unidirectional blood flow semilunar valves are located in aorta and pulmonary artery near the ventricles
atrioventricular valves between atria and ventricles

Question 17

Opening and closing of valves

Answer 17

Valves open if the pressure is higher behind them compared to in front of them.
AV valves open when pressure in atria > pressure in ventricles SL valves open when pressure in ventricles > pressure in arteries

Question 18

The Septum

Answer 18

Muscle that runs down the middle of the heart
separates oxygenated and deoxygenated blood maintains high concentration of oxygen in oxygenated blood maintaining concentration gradient to enable diffusion to respiring cells

Question 19

Cardiac output

Answer 19

Volume of blood which leaves one ventricle in one minute.
heart rate = beats per minute
Cardiac output= heart rate x stroke volume

Question 20

Stroke volume

Answer 20

Volume of blood that leaves the heart each beat
measured in dm^3

Question 21

Cardiac cycle

Answer 21

Consists of diastole, atrial systole and ventricular systole

Question 22

Diastole

Answer 22

Atria and ventricular muscles are relaxed
when blood enters atria via vena cava and pulmonary vein increasing pressure in atria

Question 23

Atrial systole

Answer 23

Atria muscular walls contract, increasing pressure further. pressure atria > pressure ventricles
atrioventricular valves open and blood flows into ventricles ventricular muscle relaxed

Question 24

Ventricular systole

Answer 24

After a short delay (so ventricles fill), ventricular muscular walls contract
pressure ventricle > atria pressure and artery pressure atrioventricular valves close and semi-lunar valves open blood pushed into artery