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Hubs progress test 2 (lectures 16 - 31) > Lecture 16-26 > Flashcards

Lecture 16-26 Flashcards

1
Q

2 parts which the nervous system is divided into:

A

Central nervous system (CNS) & Peripheral nervous system (PNS)

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2
Q

What does the CNS consist of?

A

The brain and spinal cord (made of neurons & glia)

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3
Q

What does the PNS consist of?

A

Peripheral nerves (made of neurons & glia)

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4
Q

In the CNS, a nucleus is..?

A

A group of cell bodies

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5
Q

In the CNS, a tract is…?

A

bundle of axons

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6
Q

What is grey matter?

A

Cell body groups, in the CNS

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7
Q

What is white matter..?

A

A bundle of axons, in the CNS.

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8
Q

In the PNS, what is the name for a group of cell bodies?

A

Ganglion

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9
Q

In the PNS, what is the name from axon bundles?

A

Nerve

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10
Q

What structures make up a neuron?

A

Dendrites, cell body, axon hillock, axon and axon terminals.

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11
Q

What sections of a neuron are found in the input zone? And what are their functions?

A
  1. Dendrites - receive a signal & sends the input to the cell body.
  2. Cell body - Receives & sums chemical signals, contains nucleus & organelles
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12
Q

What sections of a neuron are found in the summation zone? And what are their functions?

A

Axon hillock - This is where signals are integrated and a decision is made on wether to pass the signal or not.

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13
Q

What structures of a neuron are found in the conduction zone? and what are their functions?

A

Axon (can either be myelinated or un-myelinated) - This structure carries electrical signals between brain areas, to and from the spinal cord. From peripheral sensory receptors and to effector cells.

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14
Q

What structure(s) of a neuron are found int eh output zone? and what are their functions?

A

Axon terminals - they contact other neurons/effectors releasing neurotransmitter.

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15
Q

What are the 4 key types of neurons?

A
  1. Multipolar - multiple processes from the cell body
  2. Bipolar - 2 process from the cell body
  3. Unipolar - 1 process from the cell body
  4. Anaxonic - no distinct axon, all processes look the same.
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16
Q

What are the 5 types of glia (support) cells?

A
  1. Astrocytes
  2. Micro-glia
  3. Ependymal cells
  4. Oligodendrocytes
  5. Schwann cells
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17
Q

What is the functions of astrocytes?

A

To supply nutrients to neurons, ensheath blood capillaries & transmits information for injury response.

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18
Q

Function of micro-glia?

A

Immune cells that engulf micro-organisms and debris

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19
Q

Function of ependymal cells?

A

Line the fluid filled spaces un the brain & spinal cord to circulate cerebrospinal fluid (CSF) with their cilia.

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20
Q

Function of oligodendrocytes?

A

Support & myelinated neurons in the CNS

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21
Q

Function of Schwann cells

A

Supports & myelinated neurons in the PNS - similar to oligodendrocytes but are found in the PNS NOT the CNS

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22
Q

What is a synapse?

A

A connection between 2 neurons.

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23
Q

What does the synapse involve?

A

It involves the pre-synaptic neurons’ axon terminals and the post-synaptic neurons’ dendrites.
The nerve impulse is passed from neuron to neuron. And the signal goes;
Electrical —> Chemical —> Electrical

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24
Q

What is afferent information flow

A

Information that goes INTO the brain. Also known as ascending info
- Sensory information (incoming) which moves from;
the body -> peripheral nervous system (PNS) -> central nervous system (CNS)

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25
Q

What is efferent information flow

A

Information that goes OUT OF the brain. Also known as descending.
- Motor ‘instructions’ (outgoing) moving from;
central nervous system (CNS) -> spinal nerves -> effectors

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26
Q

What is the afferent/ascending process?

A
  1. Information enters the body through receptors
  2. Relay information to spinal nerves
  3. Relay to the CNS (spinal cord/brain)
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27
Q

What is the efferent/descending process?

A
  1. Motor output through motor neurons

2. Effectors respond to a motor command and produce and action.

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28
Q

What is somatic?

A

Voluntary or controlled.

  • somatic efferent = (voluntary, outgoing info) -> e.g. running
  • somatic afferent = (voluntary, incoming info) -> e.g. sight
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29
Q

What is autonomic?

A

Things you are unaware of, involuntary.

  • Autonomic efferent = (involuntary, outgoing info) -> e.g. contraction of heart
  • Autonomic afferent = (involuntary, incoming info) -> e.g. blood pressure.
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30
Q

What is the somatic efferent division?

A

This is the pathway in the body which allows for voluntary movement of our muscles, containing ONLY 2 NEURONS!

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31
Q

Neuron 1 is…?

A

The upper motor neuron:

  • cell body in the brain and axon in the spinal cord.
  • –> contained in the central nervous system (CNS) & myelinated.
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32
Q

Neuron 2 is…?

A

The lower motor neuron:

  • cell body in the spinal cord and axon in spinal nerve to the effector (skeletal muscle at NMJ)
  • —-> In the peripheral nervous system (PNS) & myelinated.
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33
Q

What is the neurotransmitter of the somatic efferent division?

A

Acetylcholine (ACh)

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34
Q

What is the Autonomic efferent nervous system?

A

This system allows for involuntary, outgoing information to get to the effector.

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35
Q

What are the two sub-divisions of the autonomic efferent nervous system?

A

Sympathetic & parasympathetic nervous systems

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36
Q

Neuron 1 - autonomic efferent nervous system

A

cell body in brain & axon in brain/spinal cord

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37
Q

Neuron 2 - autonomic efferent nervous sytem?

A

Cell body in the brain or spinal cord, with axons in the peripheral nervous system (PNS) synapsing in the autonomic ganglion.
NEUROTRANSMITTER = ACETYLCHOLINE (ACh)

38
Q

Neuron 3 - autonomic efferent nervous system:

A

Cell body & axon in the peripheral nervous system (PNS) synapsing on the effector, unmyelinated.
NEUROTRANSMITTER = ACh or NOREPINEPHRONE

39
Q

What is the sympathetic stress response?

A

‘fight or flight’ stress response.
- The neurotransmitter is noradrenaline
Results in an increased; heart rate, pupil size & sweating
And a decreased; gastric motility & salivation.

40
Q

What is a parasympathetic stress response?

A

‘rest and digest’ stress response.
- The neurotransmitter is acetylcholine (ACH)
Is the opposite of the sympathetic response.

41
Q

Where can the differences between the sympathetic and parasympathetic nervous system she found?

A

In the 2nd and 3rd neurons ONLY

42
Q

Pre-ganglionic neuron - In the sympathetic nervous system…?

A

Cell body in thoracolumbar levels of the spinal cord.

Axons is short with the terminals in the sympathetic ganglion

43
Q

Post-ganglionic neuron - In the sympathetic nervous system…?

A

Cell body in the sympathetic ganglion. \

Axon is long & unmyelinated

44
Q

Pre-ganglionic neuron - In the parasympathetic nervous system…?

A

A.K.A - Neuron 2.

  • Cell bodies are in the cranial & sacral levels
  • Axon is long and terminates at the parasympathetic ganglia near the effector
45
Q

Post-ganglionic nero - In the parasympathetic nervous system:

A

A.K.A - Neuron 3.
- Cell body in parasympathetic ganglia in/near the effector organs.
Axon is short.

46
Q

What is resting membrane potential?

A

A difference in charge on the outside of the membrane compared to the inside
- The two ions important for the resting membrane potential (RMP) are NA+ and K+ & it is determined by their concentrations inside & outside the cells.
RMP = -70mV

47
Q

What is a voltage-gated channel?

A

A type of channel that will ‘open’ when there is a change in voltage
- Will only occur when the local potentials are greater than the THRESHOLD POTENTIALS.

48
Q

What is threshold potential?

A

The minimum potential needed ignorer for voltage-gated channels to open.

49
Q

What are the 3 key channels that cause the propagation of Action potentials.

A
  1. Chemically gated channel (ligand-gated)

2. Mechanically gated channels.

50
Q

Mechanically-gated channel…?

A

Activated / stimulated to open with pressure

51
Q

Chemically-gated channel…?

A

Stimulated to open with chemical (ACh or norepinephrine)

52
Q

What is initial depolarisation?

A

This is when local potentials cause local depolarisation from Na+ (sodium) influx through ligand/chemical gated channels

53
Q

What is rapid depolarisation?

A

When local depolarisation threshold is reach and voltage-gated Na+ channels open, this causes rapid depolarisation to spread down the axon in a ‘Mexican wave’ like fashion.

54
Q

What is repolarisation

A

When Na+ (sodium) channels close at maximum depolarisation (+30mV), and voltage-gated K+ (potassium) channels open which let out K+, repolarising the cell.

55
Q

What is hyperpolarisation?

A

This is when K+ (potassium) channels overshoot and the membrane potential becomes more negative than the resting membrane potential (RMP)

56
Q

How is the resting membrane potential then restored?

A

The Na+ and K+ ATPase to around -70mV

57
Q

What is the absolute refectory period?

A

This is the period where is it IMPOSSIBLE to send another action potential.

  • The inactivation gates of the Na+ (sodium) channels lock shut for a time after they have opened so no Na+ (sodium) will pass through.
  • NO SODIUM = NO DEPOLARISATION = NO ACTION POTENTIAL
58
Q

What is the relative refactory period?

A

This is the period where is it REALLY HARD to send an action potential.

  • The period of time after the absolute refactory period, when the inactivation gates are open again.
  • However the cell is still hyperpolarised after sending an action potential, so it will take even more positive ions than usual to reach the threshold potential.
  • BIG GRADED POTENTIAL NEEDED FOR AP TO BE GENERATED
59
Q

What are the 3 ways to enhance the speed of an action potential?

A
  1. Size - bigger diameter = faster
  2. Sheath - myelinated = faster (insulation prevents loss of ions)
  3. Saltatory conduction - Nodes of Ranvier (between myelin) allow the action potential to ‘jump’ from node to node down the nerve = faster.
60
Q

What is chemical transmission?

A

Involves neurotransmitters and gated membrane channels.

  • ACh is the neurotransmitter involved at the neuromuscular junction (NMJ)
  • When ACh binds to the gated channels in post-synpatic membrane this allows the channel to open and for the influx of ions.
61
Q

What does neuron - neuron transmission involve?

A

Pre-synaptic and post-synaptic neurons & regulatory neurons.

  • This is the transmission of action potentials from neuron to neuron.
  • —> Also involved summation.
62
Q

What does NMJ transmission involve?

A

Pre-synaptic neuron & post-synaptic muscle fibre.

  • The transmission of action potentials in neuron to depolarise (ESPS) or hyperpolarisation (IPSP) of the muscle fibre.
  • —-> No summation, no axon hillock!! “absolute” and creates an ESPS always.
63
Q

Critical components of a chemical synapse:

A
  1. Pre-synaptic neuron
  2. Synaptic cleft
  3. Post-synaptic neuron or muscle fibre
64
Q

Grade depolarisations…?

A

Synaptic transmission doesn’t always create ESPs

  • Excitatory (ESPs) or Inhibitory (IPSP) post-synaptic potentials may be made.
  • —-> occur within milliseconds
65
Q

What are ESPs?

A

When there is an influx of positively charged Na+ (sodium) ions causing depolarisation.
- The membrane potential becomes more positive than the RMP

66
Q

What are IPSPs?

A

When there s an efflux (outflow) of positively charged K+ (potassium) ions causing hyperpolarisation
—-> The membrane potential becomes more negative than the RMP

67
Q

What is the summation of ESPs and IPSPs?

A

This is when these graded potentials are added together/cancel out.
- If the resting membrane potential is above the threshold and action potential can be generated in neuron - neuron synaptic transmission

68
Q

What is spatial summation?

A

About space.
- The closer the graded potential (EPSPs) are on the membrane the more likely it is for a large enough depolarisation to be created to reach threshold and produce an action potential.

69
Q

What is temporal summation

A

About time.

  • The faster the graded potentials came into the axon hillock the greater the potential created and more likely that it will reach threshold and create nd action potential.
  • The time delay between 2 graded depolarisations matters. If the time delay is too long the graded potentials won’t create a large enough depolarisation to give an action potentials.
70
Q

Where can the spinal cord be found?

A

Spinal cord lies within a sack made of the meninges, located within the spinal canal of the vertebrae. This meningeal sack is filled with cerebrospinal fluid (CSF)

71
Q

What is the Conus medullaris?

A

The tapered cone like end of the spinal cord (this is non-neural tissue)

72
Q

What is film terminale?

A

Fibrous, non-neural tissue which extends from the conus medullaris to the end of the spinal cavity - anchors the spinal cord.
- Prevents movement and change.

73
Q

How many pairs of nerves does the spinal cord have?

A 
31 pairs of spinal nerves. 
8 - cervical spinal nerves
12 - thoracic spinal nerves 
5 - lumbar spinal nerves 
5 - sacral spinal nerves 
1 - coccygeal spinal nerves
74
Q

Spinal cord consists of..?

A
  1. Central canal
  2. Dorsal root (posterior)
  3. Ventral root (anterior)
  4. Inner grey matter (butterfly shaped
  5. Outer white matter
75
Q

Organisation of informational flow –> Doral (posterior)

A

Sensory, afferent information comes into the dorsal aspect of the spinal cord from the PNS.

76
Q

What happens if something in the pathway is damaged (dorsal, sensory afferent info flow)

A

There will be a loss of sensation to the region’s this pathway supplies (on the same side only)

77
Q

Informational flow - ventral (anterior)

A

Motor / efferent information goes out of the ventral aspect of the spinal cord into the PNS.

78
Q

What happens if damage occurs to the ventral horn.

A

Produces paralysis of muscles supplied by the somatic motor neurons from the spinal cord segment affected on the same side only

79
Q

What is the dorsal ramus?

A
  • Efferent (motor) output to the BACK

- Afferent (sensory) input from the BACK

80
Q

What is the ventral ramus?

A
  • Efferent (motor) output to the ventral body.

- Afferent (sensory) input from the ventral body.

81
Q

What are rami communicants?

A
  • They connect sympathetic ganglia to the spinal nerves
  • Contain nerve fibres of the sympathetic nervous system.
  • Only exist T1 - L2
82
Q

What are the 3 layers of connective tissue in the peripheral nerves?

A
  1. Axons - may be myelinated or not. All covered in endoneurium.
  2. Fasicles - Bundles of axons. Covered in perineurium
  3. Nerves - Groups of fascicles and blood vessels. Covered in epineurium.
83
Q

What is the functions of meninges? And the 3 layers of the meninges?

A

Protective covering for the brain. The three layers are;

1. Dura mater 2. Arachnoid mater 3. Pia mater

84
Q

What is the Dura mater?

A

Forms the outer layer of the meninges.

  • Is dense fibrous and tough. Composed of an outer periosteal layer and an inner meningeal layer.
  • –> Venous sinuses run between these two layers (where 2 layers of dura seperate)
85
Q

Two layers of the Dura mater?

A

Periosteal layer & inner (meningeal) layer

86
Q

What is arachnoid mater?

A

Spider like, located deep to the dura and superficial to the Pia. It doesn’t extend into the sulk unlike the Pia
—-> Contains sub-arachnoid space.

87
Q

What is the sub-arachnoid space?

A

Blood vessels
Found between the Pia mater and the arachnoid space.
Filled with cerebrospinal fluid

88
Q

What is the Pia mater?

A

Inner layer of the meninges.

  • Transparent and delicate.
  • Blood vessels in the sub-arachnoid space sit on top of the Pia
  • Pia mater adheres to the brain following the gyro (hills) and dipping down into the sulci (valleys)
89
Q

Ventricular system features?

A

A network of interconnected spaces within the brain.

—> Filled with CSF, provides support and cushioning, transports waste

90
Q

Features of the ventricles…?

A
  • Lateral ventricles
  • Third ventricle
  • Cerebral aqueduct
  • Fourth ventricle
  • Central canal

Hubs progress test 2 (lectures 16 - 31) (1 decks)

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