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higher biology > 2.6 > Flashcards

2.6 Flashcards

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1
Q

what is the heart

A

a muscle that pumps blood around the body via the blood vessels

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2
Q

what are the 4 chambers of the heart

A

the left & right atrium
the left & right ventricle

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3
Q

what are the steps of blood flow through the heart

A
  • deoxygenated blood enters the right atrium through the vena cava, the right atrium contracts and 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 where it travels to the lungs to get oxygen
  • the left ventricle contracts and oxygenated blood is pumped through the aorta to the rest of the body
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4
Q

what are the walls of the heart made of

A

cardiac muscle

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5
Q

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

A

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

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6
Q

where are valves found in the heart

A

between the artiums and the ventricles and between the ventricles and pulmonary artery

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7
Q

why are valves present in the heart

A

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

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8
Q

what is the cardiac output

A

the volume of blood pumped through each ventricle per minute

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9
Q

what is the formula to calculate CO

A

CO=heart rate x stroke volume

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10
Q

what is stroke volume

A

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

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11
Q

what is the cardiac cycle

A

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

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12
Q

how long does the average cardiac cycle last

A

0.8 seconds based on a heart beat of 75bpm

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13
Q

what happens during atrial and ventricular diastole

A
  • blood returns to the atria through the vena cava and pulmonary veins
  • increased volume of blood in atria causes valves to open
  • higher pressure in the arteries closed the SL valves
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14
Q

what happens during atrial systole

A

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

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15
Q

what happens during ventricular systole

A
  • the ventricles contract causing AV valves
  • the SL valves open and blood is pumped out of the heart and into the aorta and pulmonary artery
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16
Q

what causes the heart sounds heard with a stethoscope

A

the opening and closing of the AV and SL valves

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17
Q

where does the heartbeat originate

A

in the heart itself

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18
Q

what regulates the heart rate

A

nervous and hormonal control

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19
Q

where is the SAN located

A

in the wall of the right atrium

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20
Q

what does the SAN do

A

set the rate at which the heart contracts

21
Q

what controls the timing of cardiac muscle cell contraction

A

impulses from the SAN spreading through the atria causing atrial systole

22
Q

where is the AVN located

A

in the centre of the heart

23
Q

what do impulses from the AVN do

A

they travel down fibres in the central wall of the heart and then up through the wall of the ventricles causing ventricular systole

24
Q

what does an electrocardiogram detect

A

currents generated by impulses in the heartb

25
Q

what does P, QRS and T mean in an ECG

A

P - wave of excitation across atria from SAN
QRS - wave of excitation passing through ventricles
T - recovery of ventricles after systole

26
Q

how do you calculate heart rate using and ECG

A

length of one heart beat / 60

27
Q

what initiates each heartbeat

A

the SAN

28
Q

what does the medulla regulate

A

the rate of the SAN through the antagonistic action of the automatic nervous system (ANS)

29
Q

what nerve cells is the heart supplied with

A

sympathetic and parasympathetic nerve cells

30
Q

what happens if there is an increase in the number of impulses arriving at the SAN via the sympathetic nerves

A

heart rate increases

31
Q

what do the sympathetic nerve impulses release

A

noradrenaline

32
Q

what causes impulses to be sent via the sympathetic nerves

A

stress and fear

33
Q

what does noradrenaline do

A

increases heart rate

34
Q

what happens if there is an increase in the number of impulses arriving at the SAN via the parasympathetic nerves

A

heart rate decreases

35
Q

when are nerve impulses to be sent out though the parasympathetic nerves

A

during periods of rest

36
Q

what do impulses sent out via the parasympathetic nerves release

A

acetylcholine

37
Q

what does acetylcholine do

A

decreases heart rate

38
Q

what are the parasympathetic and sympathetic pathways said to be antagonistic to each other

A

because they have opposite effects oh heart rate

39
Q

what is blood pressure

A

the force exerted by blood against the walls of blood vessels

40
Q

what is blood pressure measured in

A

millimetres of mercury (mmHg)

41
Q

what is blood pressure generated by

A

the contraction of the ventricles

42
Q

where is blood pressure highest and why

A

the aorta and pulmonary artery because they are closest to the ventricle

43
Q

what happens to blood pressure during the cardiac cycle

A

during ventricular systole, blood pressure in the aorta increased to a max
during diastole, it decreases to a min

44
Q

what machine is used to monitor blood pressure

A

a syphgmomanometer

45
Q

what are the steps of measuring blood pressure

A
  1. the cuff is inflated until blood stopes flowing through the artery in the arm
  2. the cuff deflated gradually and blood starts to flow at systolic pressure (detected by a pulse)
  3. the blood flows freely through the artery at a diastolic pressure (no pulse is detected)
46
Q

what is hypertension

A

prolonged high blood pressure when at resk

47
Q

what is high BP a risk factor for

A

many diseases such as coronary heart disease and strokes

48
Q

hypertension is commonly found in people who:

A
  • are overweight
  • don’t exercise regularly
  • have too much salt in their diet
  • drink excessive alcohol regularly
  • are under continuous stress

higher biology (24 decks)

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