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AQA A Level Biology > The Heart > Flashcards

The Heart Flashcards

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1
Q

What does the Vena Cava do?

A

It carries deoxygenated blood from the lungs to the left atrium.

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2
Q

What does the Aorta do?

A

It carries oxygenated from the lungs to the left atrium

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3
Q

What does the Pulmonary Vein do?

A

It carries deoxygenated blood to the lungs from right ventricle to lungs

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4
Q

What does the Pulmonary Artery do?

A

It carries oxygenated blood from the left ventricle to the rest of the body

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5
Q

What two systems is the nervous system split into?

A

The CNS (central nervous system) and the peripheral nervous system

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6
Q

What is the CNS made up of?

A

Brain and Spinal cord

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7
Q

What is the peripheral nervous system made up of?

A

The neurones (that connect the CNS to the rest of the body)

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8
Q

What two systems is the peripheral nervous system made up of?

A

Autonomic and Somatic nervous systems

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9
Q

What does the somatic nervous system control?

A

Conscious activities e.g. running

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10
Q

What does the autonomic nervous system control?

A

Unconscious activities e.g. digestion

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11
Q

What two systems is the autonomic nervous system split into?

A

The sympathetic and the parasympathetic nervous system

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12
Q

What does the sympathetic nervous system do?

A

It is the ‘fight or flight’ system that gets the body ready for action

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13
Q

What does the parasympathetic nervous system do?

A

It is the ‘rest and digest’ system that calms the body down.

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14
Q

The cardiac muscle is ‘myogenic’ - what does this mean?

A

The heart can contract and relax without receiving signals from nerves.

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15
Q

What is the sinoatrial node (SAN)?

A

A small mass of tissue in the wall of the right atrium
It is a natural pacemaker

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16
Q

How does the SAN act as a natural pacemaker?

A

sets the rhythym of the heartbeat by sending out regular waves of electrical activity to the atrial walls.

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17
Q

Give the mechanism of a heartbeat?

A

SAN sends signal to atrial walls - they both contract at the same time
The waves of electrical activity are transferred to AVN. (slight delay)
Then passed to bundle of His –> Purkyne tissue –> walls of left and right ventricle –> contract simultaneously (from bottom up)

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18
Q

What is the AVN?

A

Atrioventricular node which is reponsible for passing the waves of electrical activity onto the Bundle of His

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19
Q

Why is there a slight delay before the AVN reacts?

A

To ensure that the atria have emptied before the ventricles contract.

20
Q

What is the bundle of His?

A

Group of muscle fibres

21
Q

What does the bundle of His do?

A

It conducts the waves of electrical activity between the ventricles to the apex (bottom of heart)

22
Q

What is the Purkyne tissue?

A

The bundle of His splits into finer muscle fibres in the left and right ventricle walls.

23
Q

What does the Pyurkyne tissue do?

A

Carries the waves of electrical activity into the muscular walls of the right and left ventricle, causes them to contract simultaneously, from bottom up.

24
Q

What prevents the wave of electrical activity from being passed directly from the atria to the ventricles?

A

A band of non-conducting collagen tissue

25
Q

EXAM TIP - REMEMBER

A

There is a delay BEFORE the AVN reacts
NOT
that there is a delay in the wave of electrical activity reaching the AVN

26
Q

Silly Ants Have Pants

A

San, Avn, bundle of His, Purkyne fibres

27
Q

What does the medulla do?

A

Unconsciously controls the rate at which the SAN fires

28
Q

Animals needs to alter their heart rate in order to…

A

respond to internal stimuli.

29
Q

Give some internal stimuli which alters heart rate:

A

pH, CO2 conc, O2 conc, blood pressure

30
Q

What are internal stimuli detected by?

A

Pressure receptors (baroreceptors)
Chemical receptors (chemoreceptors)

31
Q

Where are baroreceptors found?

A

Aorta & Carotid artery

32
Q

What stimulates baroreceptors?

A

High and low blood pressure

33
Q

Where are chemoreceptors found?

A

Aorta, carotid artery and medulla

34
Q

What do chemoreceptors do?

A

Monitor O2 levels, CO2 levels and pH levels in blood

35
Q

Response to high blood pressure:

A

Baroreceptors – Sensory neurone – Medulla – PARASYMPATHETIC NEURONE – ACETYLCHOLINE – binds to receptors on SAN = hr slows, reduced blood pressure(bp) back to normal(btn)

36
Q

Response to low blood pressue:

A

Baroreceptors – sensory neurone – medulla – sympathetic neurone – noradrenaline – binds to receptors on SAN =hr speed up, increases bp btn

37
Q

What are acetylcholine and noradrenaline?

A

Neurotransmitters

38
Q

Response to High O2, low CO2/ high pH

A

Chemoreceptors – Sensory neurone – Medulla – Parasympathetic neurone – Acetylcholine – receptors on SAN = hr slows down, O2,CO2,pH levels btn

39
Q

Response to Low O2, high CO2 / low pH

A

Chemoreceptors – sensory neurone – medulla – sympathetic neurone – noradrenaline – receptors on SAN = hr speeds up, O2,CO2,pH levels btn

40
Q

Structure the answer should follow: What happens when … high/low bp, high/low pH

A

Chemo/baroreceptors detect chemical changes/high or low bp
Sends impulses along sensory neurone to the medulla, which sends impulses along the (para)sympatheric neurones which secrete acteylcholine/noradrenaline. This binds to the receptors on the SAN which causes heart rate to inc/decrease and change to go back to normal.

41
Q

EQ - Exercise causes an increase in heart rate - describe the role of receptors and of the nervous system in this process.

A

Chemoreceptors detect the rise in CO2/fall in pH / baroreceptros high bp
Send impulses to cardiac centre/medulla
More impulses to SAN
By sympathetic nervous system

42
Q

Remember if O2 conc is high, pH is also high (which means CO2 is low) and…

A

If O2 conc is low, pH is also low (CO2 will be high)

43
Q

How do valves (atrioventricular valves) maintain a unidirectional flow of blood?

A

Pressure in atrium is higher than in the ventricle causing the valve to open
Pressure in ventricle is higher than the pressure in the atrium causing valve to close.

44
Q

When does a valve open?

A

When the pressure above the valve is higher than the pressure below the valve.

45
Q

When does a valve close?

A

When the pressure below the valve is higher than the pressure above the valve.

AQA A Level Biology (23 decks)

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