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Biology A2 > Responding To The Enviroment 5.1 > Flashcards

Responding To The Enviroment 5.1 Flashcards

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1
Q

What do effectors produce?

A

A response

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2
Q

What do sensory neurones do?

A

They transmit electrical impulses from receptors to the CNS

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3
Q

What do motor neurones do?

A

Transmit electrical impulses from the CNS to the effectors

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4
Q

What do relay neurones do?

A

Transmit electrical impulses between sensory and motor neurones.

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5
Q

What is a gland?

A

A group of cells that are specialised to secrete a useful substance such as a hormone.

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6
Q

How are glands stimulated?

A

By a change in concentration of a specific substance, they can also be stimulated by electrical impulses

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7
Q

Difference between hormonal response and nervous system communication.

A

Hormonal system: Neural system:
Slower Faster
Longer lasting effect Shorter lived effect
Widespread Localised

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8
Q

What is the generator potential?

A

When a stimulus is detected the cell membrane becomes excited and more permeable, so ions move across altering the potential difference. This change is called the generator potential.

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9
Q

How is an action potential produced?

A

If the generator potential is big enough it’ll trigger an action potential. An action potential is only triggered if the generator potential reaches the threshold level.

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10
Q

What do receptors detect?

A

Stimuli

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11
Q

What are Pacinian corpuscles?

A

They are machanoreceptors (detect mechanical stimuli) Pressure receptors in your skin

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12
Q

Explain how a generator potential is created when a Pacinian Corpuscle is stimulated?

A

Pacinian corpuscles contain a sensory neurone called a sensory nerve ending which is wrapped in lamellae. When a Pacinian corpuscle is stimulated (by a tap the arm) the lamellae are deformed and press the sensory nerve ending. This causes deformation of stretch-mediated sodium channels in the sensory neurones cell membrane. The sodium ions open open, and sodium ions diffuse through creating a generator potential.

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13
Q

What is the Forea?

A

An area of the retina where there are lots of photoreceptors.

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14
Q

Where is the blind spot?

A

Where the optic nerve leaves the eye

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15
Q

What are Pacinian corpuscles?

A

They are machanoreceptors (detect mechanical stimuli) Pressure receptors in your skin

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16
Q

Explain how a generator potential is created when a Pacinian Corpuscle is stimulated?

A

Pacinian corpuscles contain a sensory neurone called a sensory nerve ending which is wrapped in lamellae. When a Pacinian corpuscle is stimulated (by a tap the arm) the lamellae are deformed and press the sensory nerve ending. This causes deformation of stretch-mediated sodium channels in the sensory neurones cell membrane. The sodium ions open open, and sodium ions diffuse through creating a generator potential.

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17
Q

What is the Forea?

A

An area of the retina where there are lots of photoreceptors.

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18
Q

Where is the blind spot?

A

Where the optic nerve leaves the eye

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19
Q

Name the two types of photoreceptor the human eye has…

A

Rods and cones

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20
Q

Where are rods and cones found?

A

Rods are found mainly in the perineal parts of the retina

Cones are found packed together in the Forea

21
Q

Name the three types of cones…

A

Red sensitive
Green sensitive
Blue sensitive

22
Q

Why are rods more sensitive than cones?

A

Rods are very sensitive to light (give information in black and white), they can fire an action potential in dim light. This is because many rods join to one neurone. So many weak generator potentials combine to reach the threshold and trigger an action potential.

23
Q

What is visual ability?

A

The ability to tell apart points that are close together

24
Q

Why do rods give low visual activity, but cones give high?

A

Rods give low visual activity because many rods join to the same neurone, which means light from two objects can’t be told apart. With cones, only one cone attaches to one neurone.

25
Q

Why is a neurone membrane polarised at rest?

A

Because it’s not being stimulated, the outside is positively charged and the inside is negatively charged

26
Q

How is a resting potential created and maintained?

A

Sodium potassium pumps: pump 3Na+ out of the cell for every 2K+. The Na+ ions can’t diffuse back in so this creates a sodium ion electrochemical gradient. Although the pump moves K+ ions in they are able to diffuse straight out the through the potassium ion channels.

27
Q

Explain the changes in potential difference…

A
  1. Stimulus
  2. Depolarisation
  3. Repolarisation
  4. Hyper polarisation
  5. Resting potential
28
Q

Why does an action potential move along the neurone in waves?

A

Because when an action potential happens, some sodium ions diffuse sideways which causes a wave of depolarisation to move along the neurone.

29
Q

A bigger stimulus won’t create a bigger action potential, but will…….

A

Cause them to happen more frequently

30
Q

Explain how myelination can effect the speed of conduction of action potentials…

A

The Myelin sheath is made out of a Schwann cell. Between the Schwann cells are bare patches of membrane called nodes of Ranvier. Sodium ion channels are concentrated at the nodes so depolarisation only happens at the nodes. The neurones cytoplasm conducts enough electrical change to depolarise the next node, so the impulse jumps (saltatory conduction)

31
Q

How does axon diameter affect the speed of conduction of action potentials?

A

Action potentials are conducted quicker along a one with bigger diameters because there’s less resistance to the flow of ions than in the cytoplasm of a smaller axon.

32
Q

How does temperature affect the speed of conduction of action potentials?

A

The speed of conduction increases as the temperature increases because the ions diffuse faster. (Only up to around 40 degrees)

33
Q

Explain how ACh moves from the presumptive knob to the postsynaptic membrane.

A

An action potential arrives at the synaptic knob. The action potential then stimulates voltage-gated Ca2+ ions to diffuse into the synaptic knob. This influx causes the synaptic vesicles to fuse with the presynaptic membrane and the vesicles release ACh into the synaptic cleft in exocytosis. The ACh diffuses across and binds to the specific cholinergic receptors. This causes the sodium ion channels in the postsynaptic neurone to open.

34
Q

What is a neuromuscular junction?

A

A synapse between a motor neurone and a muscle cell.

35
Q

What are the similarities and differences between a neuromuscular junction and a cholinergic synapse?

A

Similarities
Use ACh which binds to cholinergic receptors

Differences
Postsynaptic membrane has lots of folds that form clefts to store AChE.
Postsynaptic has more receptors
Always triggers a response

36
Q

What is a Excitatory neurotransmitter?

A

Neurotransmitters that depolarise the postsynaptic membrane, making it fire an action potential.

37
Q

What is an inhibitory neurotransmitter?

A

A neurotransmitter that hyperpolarises the postsynaptic membrane (making the potential difference more negative), preventing it from firing an action potential.

38
Q

What is summation?

A

Summation is where the effect of neurotransmitter released from many neurones (or one neurone that’s stimulated a lot in a short period of time) is added together

39
Q

What is spatial summation and temporal summation?

A

Spatial: many neurones to one neurone
Temporal: two or more nerve endings arrive in quick succession from the same presynaptic neurone.

40
Q

If a antagonist drug is used to inhibit receptors on the postsynaptic membrane of a synapse, what can it result in?

If a drug that inhibits enzymes in the synaptic cleft is used, what can this result in?

A

A paralysed muscle

Loss of muscle control

41
Q

What is skeletal muscle and what is it made from?

A

It is a type of muscle you use to move. It’s made up of large bundles of long cells called muscle fibres. The cell membrane of the muscle fibres is called the sarcolemma. Bits of this fold inwards and stick to the sarcoplasm. These folds are called transverse tubles and they help spread electrical impulses throughout the sarcoplasm. A network of internal membranes called the sarcoplasmic reticulum stores and releases calcium ions that are needed for muscle contraction. The muscle fibres also have lots of mitochondria and lots of long myofibrils.

42
Q

What do myofibrils contain?

A

Thick and thin myofilaments that move past each other.
Thick myofilaments are made out of myosin
Thin myofilaments are made out of the protein, actin.
Myofibrils are made up of many short units called sarcomeres

43
Q

According to the sliding filament theory what happens to the: A-band, I-bands and the H-zone?

A

A-band stays the same length

H-zone and I-bands get shorter

44
Q

In a resting muscle the actin-myosin binding site is blocked by ____________

A

Tropomyosin which is held in place by troponin

45
Q

What happens when an action potential stimulates a muscle cell?

A

It depolarises the sarcolemma. Depolarisation spreads down the T-tubules to the sarcoplasmic reticulum. This causes an influx of calcium ions into the sarcoplasm. The calcium ions bind to the troponin, causing it to change shape, this then pulls the tropomyosin out of the actin-myosin binding site on the actin filament. This allows the globular head to bind, forming a actin-myosin cross bridge. (Calcium ions also activate ATPase which helps pocked the energy needed)

46
Q

ADP + PCr —->

A

ATP + Cr

47
Q

What type of respiration do fast twitch muscles use?

A

Anearobic, because they contract very quickly, they are good for short bursts of energy. They are more whitish in colour because they don’t have much myoglobin

48
Q

What controls the SAN

A

The medulla

Biology A2 (9 decks)

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