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Biology A2 Unit 1 - Physiology, Coordination And Control, And Ecosytems > Topic 4 - Coordination And Control In Animals > Flashcards

Topic 4 - Coordination And Control In Animals Flashcards

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1
Q

What are the two mammalian nervous systems

A

Central nervous system
Peripheral nervous system

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2
Q

What nerves are involved in the PNS

A

Cranial nerves attached to the brain, and spinal nerves that are attached to the spinal cord

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3
Q

What is a neurone

A

The functional unit of the nervous system

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4
Q

What is the structure of a neurone

A

A cell body (centron) which contains the nucleus and other organelles and has a number of cytoplasmic extensions
Dendrons which transmit impulses to the cell body
Axons which transmit impulses away from the cell body and terminate in synaptic bulbs

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5
Q

Why are axons and dendrons myelinated

A

To insulate the axon, preventing ion movement between the axon and the tissue fluid around it

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6
Q

What are axons and dendrons myelinated in

A

Many layers of Schwann cells

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7
Q

What are nodes of Ranvier

A

Small spaces between Schwann cells giving rise to gaps in the myelin sheath

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8
Q

Why do neurone have a particularly large potential difference

A

A large excess of positively charged Sodium ions on the outside

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9
Q

What is the resting potential of the neurone

A

When the potential difference occurs when the neurone is at ‘rest’

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10
Q

Can the potential difference of a neurone be reversed

A

Yes

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11
Q

What makes a potential difference across the neurone membrane make the inside more negative

A

When a neurone is stimulated, the cell-surface membrane allows sodium ions to diffuse in

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12
Q

What is the threshold value

A

If a critical potential difference is reached

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13
Q

When does depolarisation of a neurone occur

A

When a threshold value is reached, then ions surge in and quickly depolarise the neurone

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14
Q

What is the action potential

A

The reversal of the potential difference

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15
Q

What is the all-or-nothing phenomenon

A

As an action potential does not vary in size, it either occurs or it doesnr

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16
Q

What is the refractory period

A

The period following the action potential when the membrane depolarises and recovers it resting potential

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17
Q

What are the 5 steps of changes in the potential difference, action potential and resting potential

A
  1. Axon membrane is at resting potential
  2. Depolarisation to threshold value needed for further depolarisation to occur
  3. Further depolarisation leads to action potential
  4. Magnitude of action potential
  5. Repolarisation of axon membrane during the refractory period when the membrane cannot be depolarised
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18
Q

How do local circuits occur

A

As positive ions are attracted by neighbouring negative regions and flows in both directions

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19
Q

How do the two sides of the membrane differ in impulse propagation

A

On one side, the membrane is still recovering its resting potential, it is in its refractory period during which it cannot be stimulated
On the other excitable side, the local circuit triggers depolarisation and the formation of an action potential

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20
Q

What is saltatory conduction

A

When an action potential jumps from one node of Ranvier to the next, which greatly increases the speed at which it is propagated along the axon

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21
Q

Where is the neurotransmitter chemical located

A

At the synaptic vesicles at the synaptic bulbs

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22
Q

What is the synaptic cleft

A

The gap between the synaptic bulbs

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23
Q

What is the difference between the pre-synaptic membrane and post-synaptic membrane

A

The membrane of the neurone just before the cleft is called the pre-synaptic membrane and the one on the other side is the post-synaptic membrane

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24
Q

What is the first step of synaptic transmission

A

When an impulse arrives at the synaptic bulb, the membrane becomes permeable to calcium ions which diffuse into the bulb

25
Q

What step of synaptic transmission occurs after ‘When an impulse arrives at the synaptic bulb, the membrane becomes permeable to calcium ions which diffuse into the bulb’ and before ‘Vesicles fuse with the presynaptic membrane and releases the neurotransmitter molecules by Exocytosis into the synaptic cleft’

A

Calcium ions stimulate movement of synaptic vesicles towards the pre-synaptic membrane

26
Q

What step of synaptic transmission occurs before ‘Neurotransmitter molecules diffuse across the synaptic cleft to the post-synaptic membrane’ and after ‘Calcium ions stimulate movement of synaptic vesicles towards the pre-synaptic membrane’

A

Vesicles fuse with the presynaptic membrane and releases the neurotransmitter molecules by Exocytosis into the synaptic cleft

27
Q

What step of synaptic transmission occurs before ‘On the post-synaptic membrane, neurotransmitter molecules attach to specific receptors’ and after ‘Vesicles fuse with the presynaptic membrane and relates the neurotransmitter molecules by Exocytosis into the synaptic cleft‘

A

Neurotransmitter molecules diffuse across the synaptic cleft to the spot-synaptic membrane

28
Q

What step of synaptic transmission occurs before ‘This causes ion channels to open so that the potential difference in the post-synaptic membrane is altered. The magnitude of this change is dependent on the amount of transmitter released and so the number of receptors filled’ and after ‘Neurotransmitter molecules diffuse across the synaptic cleft to the spot-synaptic membrane’

A

On the post-synaptic membrane, neurotransmitter molecules attach to specific receptors

29
Q

What step of synaptic transmission occurs before ‘When a molecule of ACh attaches to its receptor site, a sodium ion channel opens and the post-synaptic membrane becomes depolarised’ and after ‘On the post-synaptic membrane, neurotransmitter molecules attach to specific receptors’

A

This causes ion channels to open so that the potential difference in the post-synaptic membrane is altered. The magnitude of this change is dependent on the amount of transmitter released and so the number of receptors filled

30
Q

What step of synaptic transmission occurs before ‘Transmitter molecules on the receptors are inactivated. This breakdown of the neurotransmitter is important as it allows the resting potential to be re-established’ and after ‘This causes ion channels to open so that the potential difference in the post-synaptic membrane is altered. The magnitude of this change is dependent on the amount of transmitter released and so the number of receptors filled’

A

When a molecule of ACh attaches to its receptor site, a sodium ion channel opens and the post-synaptic membrane becomes depolarised

31
Q

What step of synaptic transmission occurs before ‘The breakdown products diffuse across the cleft and are reabsorbed into the synaptic bulb where they are resynthesised into the neurotransmitter using energy in the form of ATP’ and after ‘When a molecule of ACh attaches to its receptor site, a sodium ion channel opens and the post-synaptic membrane becomes depolarised’

A

Transmitter molecules on the receptors are inactivated. This breakdown of the neurotransmitter is important as it allows the resting potential to be re-established

32
Q

What is the last step of synaptic transmission

A

The breakdown products diffuse across the cleft and are reabsorbed into the synaptic bulb where they are resynthesised into the neurotransmitter using energy in the form of ATP

33
Q

What is a neuromuscular junction

A

When a motor neurone synapse with a skeletal muscle fibre

34
Q

What is the main transmitter molecule in synapses

A

Acetylcholine

35
Q

What is noradrenaline

A

The neurotransmitter in the synaptic bulbs of the sympathetic nervous system

36
Q

What is an EPSP

A

Excitatory post-synaptic potential, when Sodium ion channels open, which results in depolarisation of the post-synaptic membrane

37
Q

What do EPSPs do to the membrane

A

They make it less negatively charged ad more likely to reach the threshold level to trigger an action potential, propagating an impulse in the post-synaptic cell

38
Q

What is GABA

A

Gamma-aminobutyric acid, a neurotransmitter found in the brain

39
Q

What do GABA do

A

When it attaches to its receptor sites, chloride ion channels open, causing the post-synaptic membrane to be hyperpolarised

40
Q

What is an IPSP

A

Inhibitory post-synaptic potential

41
Q

What do IPSPs do to the membrane

A

They make it more negatively charged and less likely to reach the threshold level to trigger an action potential

42
Q

What are some advantages of synapses slowing transmission

A

It ensures that transmission occurs in only one direction
It protects effectors from over-stimulation
It allows certain actions to be controlled through a combination of stimulation and inhibition
It integrates the activity of different neurone synapsing with a single post-synaptic neurone

43
Q

What are the 3 main type of muscle

A

Skeletal
Cardiac
Smooth

44
Q

What is the appearance of skeletal muscle

A

Muscle fibres are multinucleate, with distinct striations

45
Q

Where is skeletal muscle found and what is its function

A

It is attached by tendons to bones, and controls the movement of parts of the body and locomotion

46
Q

What is the cardiac muscle

A

Cells are striated and branched, forming a link network, intercalated discs between cells

47
Q

Where is the cardiac muscle found, and what does it do

A

Found in the wall of the heart, and pumps the heart to maintain blood circulation

48
Q

What is smooth muscle

A

Spindle-shaped cells with a single nucleus and no striations

49
Q

Where is the smooth muscle found, and what is its function

A

Present in the iris and ciliary body of the eye and walls of tubular organs, is responsible for movement of materials within the body

50
Q

What is the structure of the skeletal muscle

A

Skeletal muscle consist of bundle of muscle fibres. A muscle fibre is multinucleate, which lies just beneath the sarcolemma, out of the way of the packed myofibrils, each of which is surround in sarcoplasmic reticulum and joined transversely by T-tubules, and between which are numerous mitochondria.

51
Q

Why is skeletal muscle described as striated

A

Due to the different colours of the protein present, actin and myosin

52
Q

What is the Z Line

A

The sarcomere

53
Q

What is the A band

A

A thick filament of only myosin

54
Q

What is the I band

A

A thin filament of only actin

55
Q

What is the H-zone

A

The centre of the A-band

56
Q

What is the sliding filament theory

A

The theory that describes how shortening of myofibrils causes muscle contract

57
Q

What is the first step of the sliding filament theory

A

An action potential arrives via a motor neurone at the synapse with the cell-surface membrane of the muscle fibre

58
Q

What is the steps of the sliding filament theory

A
  • An action potential arrives due to a motor neurone at the synapse with the cell-surface membrane of the muscle fibre
  • Action potentials are propagated through the T-tubule and along the sarcoplasmic reticulum causing Calcium ions to be released into the cytoplasm
  • Calcium ions cause ancillary proteins to de displaced and uncover the binding sites
  • Heads of the myosin molecules next to the uncovered binding sites now attach to the actin filaments
  • The myosin heads rotate back, pulling the thin actin filaments over the thick myosin filaments
  • ATP binds with the myosin heads and the energy released causes the myosin heads to detach from the actin filaments
    The detached myosin heads regain original position and attach to another exposed bind site on the actin filament

Biology A2 Unit 1 - Physiology, Coordination And Control, And Ecosytems (9 decks)

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