MASS TRANSPORT : HEART

Question 1

Atrioventricular valves

Answer 1

between atria and ventricles
- tricuspid = right
- bicuspid = left

Question 2

semi lunar valves

Answer 2

between aorta and left ventricle
between pulmoary artery and right ventricle

Question 3

myogenic

Answer 3

the muscles cam contract rhythmatically without any nervous stimulation

Question 4

coronary arties

Answer 4

coronary arteries supplies oxygenated blood to the cardiac muscles.

Question 5

how is a heart attack caused

Answer 5

if the coronary arteries does not supply oxygen to the cardiac muscles then the cells will not be able to respire and die resulting in heart attack.

Question 6

valves in heart

Answer 6

tricuspid in right side
bicuspid or mitral valve
semi lunar valves - aortic and pulmonic.

Question 7

systole and diastole

Answer 7

the period of contraction is called systole and the ;eriod of relaxation is called diastole.

Question 8

one cardiac cycle

Answer 8

each heartbeat is known as one cardiac cycle.

Question 9

3 main stages of cardiac cycle

Answer 9

atrial systole, ventricular systole and diastole.

Question 10

diastole

Answer 10

it is when the muscles in atria and ventricles are relaxed. blood enters into the atria through venacava and pulmonary vein. the blood entering the atria increases the pressure in the atria.
- volume is increased a sthe blood flows into

Question 11

atrial systole

Answer 11

muscular walls in atria contract which increases the pressure and decreases the volume. this causes the atrio ventricular valves to open and blood to flow into ventricles. the ventricular muscular walls are relaxed.

Question 12

ventricular systole

Answer 12

it is when the ventricles muscles contract and the pressure is higher in ventricles than in the atria . so it causes the atrio ventricular valves to shut down and open the semi lunar va;lves and blood is pushed out to arteries ( pulmonary artery and aorta)

Question 13

formula of cardiac output

Answer 13

heart rate * stroke volume.
- stroke volume = volume of blood that leaves heart in dm3

Question 14

when does the valve open

Answer 14

when the pressure is higher behind the valves.

Question 15

when does atrio ventricular valves open

Answer 15

atrioventricular valves open when the pressure is higher in atria than in the ventricles.#
it closes when the pressure is higher in ventricles than in the atria.

Question 16

when does the semi lunar valves open

Answer 16

the semi lunar valves open when the pressure is higher in ventricles than in the atria.

Question 17

san and avn

Answer 17

sino atrial node and atrio ventricular node

Question 18

where is san and avn located

Answer 18

san is located ij the right atrium also known as pacemaker and avn is located between walls of atria and ventricles.

Question 19

bundle of his and purkyne fibers

Answer 19

bundle of his runs through septum and purkyne fibres are in walls of ventricles.

Question 20

mechanism for control of heart

Answer 20

the SAN releases the first wave of depolarisation which causes the atria to contract( atrial systole). the avn also releases a second wave of depolarisation after the first wave hits it. there is a muscular layer between atria and ventricles which prevents the conductivity of wave of depolarisation. however the bundle of his running through the septum can conduct the wave of depolarisation into purkyne fibres in the wall of vemtricles . the apex and walls of ventricles contract . there is a short delay when this happens so that the atria can contract fully and pump blood to the ventricles. the avn transmits second wave of depolarisation.

Question 21

parasympathetic nervous system

Answer 21

the heart rate is controlled by the medulla oblongata in the brain via the autonomic nervous system which is of two parts paraysympathetic and sympathetic

Question 22

symathetic ns

Answer 22

increases heart rate

Question 23

parasympathetic ns

Answer 23

decreases heart rate.

Question 24

stimulus - increased pressure

Answer 24

the pressure receptors present in the cartoid artery and aorta sare stretched and they send more electrical impulses to the medulla oblongata and the impulses is sent via parasympathetic nervous system to the SAN to decrease the frequemce of electrical impulses which then lowers the heart rate.