the structure and function of the heart 2.6

Question 1

hearts function

Answer 1

a muscle that pumps blood around the body via a complex network of blood vessels

Question 2

what is the heart made up of

Answer 2

four chambers, right and left atrium and right and left ventricle

Question 3

direction of blood through the heart

Answer 3

-deoxygenated blood enters the right atrium through the vena cava, the right atrium contracts and blood is forced into the right ventricle
-at the same time, oxygenated blood enters the left atrium through the pulmonary vein, the left atrium contracts and blood is forced into the left ventricle
-the right ventricle contracts and deoxygenated blood is pumped through the pulmonary artery which travels to the lungs to pick up oxygen
-the left ventricle contracts and oxygenated blood is pumped through the aorta to the rest of the body

Question 4

what are the walls of the heart made up of

Answer 4

cardiac muscle

Question 5

why is the wall of the left ventricle thicker than the right ventricle

Answer 5

because it has to pump blood all around the body whereas the right ventricle only has to pump blood to the lungs

Question 6

where are valves present in the heart

Answer 6

between the atria and ventricles and between the ventricles and pulmonary artery and aorta

Question 7

valves function

Answer 7

prevent the back flow of blood and ensure blood travels in the one direction

Question 8

what is cardiac output

Answer 8

the volume of blood pumped through each ventricle per minute

Question 9

how to calculate cardiac output

Answer 9

CO = HR x SV

HR (heart rate)
SV (stroke volume)

Question 10

heart rate

Answer 10

the number of beats per minute (bpm)

Question 11

stroke volume

Answer 11

the volume of blood (in litres) pumped by the left ventricle during one contraction

Question 12

cardiac cycle

Answer 12

the pattern of contraction (systole) and relaxation (diastole) in one complete heartbeat

Question 13

average cardiac cycle

Answer 13

0.8 seconds based on a heart rate of 75 bpm

Question 14

atrial systole

Answer 14

atria contract together pushing remaining blood into the ventricles through OPEN AV valves

Question 15

ventricular systole

Answer 15

-ventricles contract CLOSING AV valves
-SL valves OPEN and blood is pumped out of the heart and into the aorta and pulmonary artery

Question 16

atrial and ventricular diastole

Answer 16

-blood returns to atria through vena cava and pulmonary veins
-increased volume of blood in atria causes AV valves to OPEN
-blood flows down into ventricles
-higher pressure in the arteries closes the SL valves

Question 17

what causes the heart sounds

Answer 17

the opening and closing of AV and SL valves

Question 18

what valve causes the lubb sound

Answer 18

the closing of the AV valves

Question 19

what valve causes the dupp sound

Answer 19

the closing of the SL valves

Question 20

where does the heart beat originate

Answer 20

the heart itself

Question 21

what regulates the heart

Answer 21

the nervous and hormonal control

Question 22

where is the SAN located

Answer 22

the wall of the right atrium

Question 23

SAN

Answer 23

(sino atrial node) sets the rate at which the heart contracts

Question 24

what controls the timing of the cardiac muscle

Answer 24

impulses from the san spreading through the atria causing atrial systole

Question 25

where is the AVN located

Answer 25

centre of the heart

Question 26

AVN

Answer 26

(atrio ventricular node) impulses travel down fibres in the central wall of the heart and then up through the walls of the ventricles causing ventricular systole

Question 27

calculating heart rate using an ECG

Answer 27

60/time for 1 heart beat

Question 28

what indicates every heart beat

Answer 28

SAN

Question 29

what can alter heart rate

Answer 29

nervous and hormonal activity

Question 30

what regulates the rate of the SAN

Answer 30

the medulla through the antagonistic action of the automatic nervous system

Question 31

what happens when there’s an increase in the number of impulses from the sympathetic nerves

Answer 31

heart rate increases because they release noradrenaline, these fibres are activated by stress and fear

Question 32

what happens when there’s an increase in the number of impulses from the parasympathetic nerves

Answer 32

heart rate decreases because they release acetylcholine, these fibres are activated during periods of rest

Question 33

why are the sympathetic and parasympathetic neves said to be antagonist

Answer 33

they have opposite effects on heart rate

Question 34

blood pressure

Answer 34

the force exerted by blood against the walls of blood vessels

Question 35

how is blood pressure measured

Answer 35

millimetres of mercury (mmHg)

Question 36

how is blood pressure generated

Answer 36

by the contraction of the ventricles

Question 37

where is blood pressure the highest

Answer 37

aorta and pulmonary artery

Question 38

when does blood pressure change in the aorta

Answer 38

during the cardiac cycle

Question 39

when does blood pressure increase in the aorta

Answer 39

ventricular systole

Question 40

when does blood pressure decrease in the aorta

Answer 40

diastole

Question 41

how do you measure blood pressure

Answer 41

using a sphygmomanometer

Question 42

hypertension

Answer 42

prolonged high blood pressure when resting

Question 43

what can hypertension lead to

Answer 43

strokes and coronary heart disease (CDH)

Question 44

what causes hypertension

Answer 44

obesity, no exercise, high fat or salt diet, excessive drinking, continuous stress