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unit 2 bio > 2.6- structure and function of the heart > Flashcards

2.6- structure and function of the heart Flashcards

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Biology 101 flashcards
1
Q

what are the 4 chambers of the heart?

A

two atria

two ventricles

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2
Q

describe the flow of blood to and from the heart

A

body sends deoxygenated blood through the vena cava and to the right atrium

right atrium flows deoxygenated blood into the right ventricle

right ventricle sends deoxygenated blood through the pulmonary artery to the lungs

lungs send oxygenated blood through the pulmonary veins and to the left atrium

left atrium flows oxygenated blood into the left ventricle

left ventricle sends oxygenated blood through the aorta and into the body

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3
Q

where do the 2 branches in the pulmonary artery lead?

A

lungs

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4
Q

what is the largest vein in the body?

A

vena cava

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5
Q

what is the largest artery in the body?

A

aorta

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6
Q

what are the 2 different valves in the heart called?

A

atrioventricular valves

semi-lunar valves

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7
Q

where are the atrioventricular valves located and what is their purpose?

A

between the atria and ventricles

allow blood to flow from atria to ventricles and prevent backflow from ventricles to atria

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8
Q

where are the semi-lunar valves located and what is their purpose?

A

situated at the origins of the pulmonary artery and aorta

open during ventricular contraction allowing blood to flow into the arteries

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9
Q

when do semi-lunar valves close and why?

A

when arterial pressure exceeds ventricular pressure

close to prevent backflow

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10
Q

what is heart rate?

A

the number of heartbeats that occur per minute

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11
Q

what is stroke volume and what can make it greater?

A

the volume of blood expelled by each ventricle on contraction

the stronger the contraction

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12
Q

what is cardiac output?

A

the volume of blood pumped out of a ventricle per minute

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13
Q

how is cardiac output calculated?

A

cardiac output= heart rate X stroke volume

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14
Q

what is the cardiac cycle and what is its average length?

A

pattern of contraction and relaxation in the heart during one complete heartbeat

0.8 seconds

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15
Q

4 steps of the cardiac cycle stage 1

A

DIASTOLE

return of blood via the venae cavae and pulmonary veins to the atria

this causes the volume of blood in the atria to increase

eventually atrial pressure exceeds that in the ventricles

this pushed the AV valves open and blood starts to enter the ventricles

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16
Q

4 steps of the cardiac cycle stage 2

A

ATRIAL SYSTOLE
two atria contract simultaneously

they send the remainer of the blood down into the ventricles through open AV valves

ventricles are still in the relaxed state of ventricular diastole

they fill up with blood and the SL valves remain closed

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17
Q

4 steps of the cardiac cycle stage 3

A

VENTRICULAR SYSTOLE
ventricles contract and AV valves close

as the cardiac muscle contract, the pressure exerted on the blood in the ventricles soon exceeds the blood pressure in the arteries

SL valves pushed open and blood pumped out heart and into aorta and pulmonary arteries

DIASTOLE
higher pressure of blood in the arteries closes SL valves again and next cardiac cycle starts

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18
Q

what sounds can be heard with the help of a stethoscope from the heart?

A

closing of the AV and SL valves during each cardiac cycle

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19
Q

what is a pacemaker also known as?

A

sino-atrial node (SAN)

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20
Q

where is the sino-atrial node located and what does it do?

A

in the wall of the right atrium

sets the rate at which the heart contracts

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21
Q

what does the sino-atrial node do and what does this mean?

A

it exhibits spontaneous excitation

pacemaker initiates electrical impulses making cardiac muscles contract at a certain rate

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22
Q

how does the sino-atrial node work and what can it function without?

A

works automatically

function without nerve connections from the rest of the body

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23
Q

what is spread that originates from the SAN and what does this do?

A

a wave of excitation through the muscle cells in the wall of the 2 atria

makes 2 atria contract simultaneously (atrial systole)

24
Q

what picks up this wave of excitation and where is it passed to?

A

atrio-ventricular node located centrally near the base of the atria

bundle of conducting fibres which divides into left and right continuous branches

25
Q

what do each of these branches from the conducting fibres contain and where?

A

a dense network of tiny conducting fibres in the ventricular walls

26
Q

what does stimulation of the conducting fibres found in the branches cause and starting where?

A

simultaneous contraction of the 2 ventricles (ventricular systole)

starting from the heart apex and spreading upwards

27
Q

2 things ensured by this coordinated heartbeat

A

each type of systole involves the combined effect of many muscle cells contracting

ventricular systole occurs slightly later than atrial systole which allows time for ventricles to fill completely before they contract

28
Q

what is an electrocardiogram?

A

the electrical signals that when amplified and displayed on an oscilloscope screen produce a pattern

29
Q

how can electrical activity of the heart get picked up?

A

electrodes placed on the skins surface pick up the tiny currents the heart generates

30
Q

what does ECG stand for?

A

electrocardiogram

31
Q

what are the 3 distinct waves of an ECG pattern?

A

P

QRS

T

32
Q

what does the P wave do?

A

corresponds to the wave of electrical excitation spreading over the atria from the SAN that brings about atrial systole

33
Q

what does the QRS complex do?

A

represents the wave of excitation passing through the ventricles that brings about ventricular systole

34
Q

what does the T wave do?

A

corresponds to the electrical recovery of the ventricles occurring towards the end of ventricular systole

35
Q

how is each heartbeat generated?

A

by pacemaker tissue

36
Q

2 things that can alter heart rate

A

nervous activity

hormonal activity

37
Q

what is the heart supplied with branches of?

A

heart supplied with branches of opposing parts of the autonomic nervous system

38
Q

what regulates heart rate?

A

control centres located in the medulla

39
Q

what are the 2 cardio centres called?

A

cardio-accelerator centre

cardio-inhibitor centre

40
Q

what does the cardio-accelerator centre do?

A

sends its nerve impulses via the sympathetic nerve to the heart

41
Q

what does the cardio-inhibitor centre do?

A

sends its information via the parasympathetic nerve

42
Q

what are the cardio-accelerator and inhibitor centres described as and why?

A

antagonistic

they have opposite effects on heart rate

43
Q

what determines the actual rate that the heart beats?

A

whatever system has an increased relative number of nerve impulses arriving at SAN

44
Q

what can also influence the SAN?

A

neurotransmitter substances released by sympathetic and parasympathetic nerves

45
Q

what neurotransmitters do sympathetic and parasympathetic nerves release?

A

sympathetic- noradrenaline

parasympathetic- acetylcholine

46
Q

what can the sympathetic nervous system act on and what do they do?

A

adrenal glands

make them release hormone adrenaline into the blood stream

47
Q

what happens when adrenaline reaches the SAN?

A

generates cardiac impulses at a higher rate and brings about increased heart rate

48
Q

what is blood pressure?

A

the force exerted on blood against the walls of the blood vessels

49
Q

how is blood pressure measured?

A

millimetres of mercury (mmHg)

50
Q

how is blood pressure generated?

A

by the contraction of the ventricles and it is highest in the large elastic arteries

51
Q

what happens to blood pressure during ventricular systole and diastole?

A

ventricular systole- blood pressure in aorta rises to a max

ventricular diastole- blood pressure in aorta falls to a min

52
Q

how can systolic and diastolic pressures be measured?

A

using an inflatable sphygmomanometer

53
Q

3 steps of measuring blood pressure

A

cuff is inflated until the pressure it exerts stops blood flowing through arm artery

cuff allowed to deflate gradually until blood starts to flow at systolic pressure which is detected by a pulse

more air released from cuff until a pulse is no longer detected as blood flows freely through the artery at diastolic pressure

54
Q

what is the average systolic and diastolic pressure?

A

systolic- 120mmHg

diastolic- 80mmHg

120/80mmHg

55
Q

what is hypertension and how is it indicated?

A

the prolonged elevation of blood pressure when at rest

systolic pressure above 140mmHg and diastolic pressure above 90mmHg

56
Q

2 diseases hypertension is a major risk factor for

A

coronary heart disease

strokes

57
Q

6 reasons someone could be suffering from hypertension

A

being overweight

not enough exercise

eating a diet excessively rich in fatty food

consuming too much salt

drinking alcohol to excess regularly

being under continuous stress

unit 2 bio (10 decks)

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