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Year 1 Animal Physiology > 3. Neurophysiology > Flashcards

3. Neurophysiology Flashcards

Types of Neuron and Basis of Action Potential Synapses, Plasticity and Homeostasis

1
Q

Why do cells communicate with each other?

A

To control rapid responses of the body and contribute to homeostasis.

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2
Q

What is a neuron?

A

Neurons are excitable cells which have specialized projections called dendrites and axons which transmit information, in the form of electrochemical impulses, around the body by electrochemical transmission

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3
Q

What is the function of Dendrites?

A

Bring information to the cell body

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4
Q

What is the function of the Axon?

A

Takes information away from the cell body.

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5
Q

How many synapses are there estimated to be in the human brain?

A

1 Quadrillion Synapses (10^15)

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6
Q

Define Neurotransmission.

A

The fundamental process that drives information transfer between neurons and their targets

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7
Q

List the parts of a Neuron.

A

Axon Terminals, Schwann’s Cells, Axon, Node of Ranvier, Myelin Sheath, Dendrites, Cells Body (with Nucleus)

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8
Q

Describe Axon Transport of ‘Cargo’.

A

Steady transport of materials (vesicles, mitochondria) from the cell body along axon. Flow driven by kinesins, which are specialist motor proteins, moving along the many microtubules in the cytoplasm within the axon.

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9
Q

What is the Myelin Sheath?

A

Expanded plasma membrane of an accessory cell, Schwann Cell. Schwann cells are spaced at regular intervals along the axon. Their plasma membrane is wrapped around and around the axon, forming sheath.

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10
Q

What is the Node of Ranvier?

A

Where the sheath of one schwann cell meets the next, which is an unprotected axon. It plays an important part in the propagation of the nerve impulse.

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11
Q

Name the three major classes of neurons.

A

Interneurons (relay neurons), Sensory neurons and Motor neurons.

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12
Q

Where are Interneurons located?

A

Exclusively in the spinal cord and brain.

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13
Q

Describe the function of Sensory Neurons.

A

Run impulses from the stimulus receptors to the CNS.

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14
Q

List 3 stimuli that can be detected.

A

Touch, odor, taste, sound, vision, pressure, pain, temperature etc…

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15
Q

Describe the function of motor neurons.

A

Transmit impulses from the CNS to the effectors to carry out the response.

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16
Q

Name the 2 effectors.

A

Muscles and Glands

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17
Q

What are ganglia?

A

Clusters of cell bodies of the sensory neurons that lead to the spinal cord.

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18
Q

How many pairs of spinal nerves are there along the spinal cord?

A

31 pairs

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19
Q

How do sensory axons join to the spinal cord?

A

Sensory axons pass into the dorsal root ganglion where their cell bodies are located and then on into the spinal cord itself.

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20
Q

How do Motor axons join to the spinal cord?

A

Motor axons pass into ventral roots before uniting with the sensory axons to form the mixed nerves.

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21
Q

Name the 4 regions of the spinal cord.

A

Cervical, Thoracic, Lumbar and Sacral.

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22
Q

What is the function of Support Cells?

A

Surround and provide support for and insulation between them.

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23
Q

What are the most abundant cell types in the CNS?

A

Glial Cells

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24
Q

Name the 6 types of Glial Cells.

A

Oligodendrocytes, astrocytes, ependymal cells, Schwann Cells, Microglia and satellite cells.

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25
Q

Name the 4 cortexs of the brain.

A

Motor, Somatosensory, Visual and Auditory cortex.

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26
Q

List 3 things the brain can control and process.

A

Control movement, senses environment, processes what you hear, see, smell, feel. Encodes memories, regulates sleep, feeding and autonomic physiology. Controls characteristics and behaviour.

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27
Q

What is the resting membrane potential of neuron cells?

A

-70mV

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28
Q

Is it the inside or outside the cell that is negative at resting potentials?

A

Inside

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29
Q

What is the function of Na+/K+ ATPase at a resting potential?

A

Pump pushes 2 K+ into cell for every 3 Na+ it pumps out so its activity results in a net loss of positive charges within cell, hence negative potential.

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30
Q

What is the function of leaky K+ channels?

A

Allow slow facilitated diffusion of K+ out of the cell in order to reduce build up of K+ inside cell which would cause potential to increase.

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31
Q

What effect does external stimuli have on the membrane potential?

A

Increases the potential by activating mechanically-gates or ligand gated sodium channels.

32
Q

What is the threshold voltage of a neuron?

A

-50mV

33
Q

What happens when the membrane potential surpasses the threshold potential?

A

An Action Potential is generated.

34
Q

What causes the increase in potential during depolarisation?

A

Movement of Na+ ions into the cell via voltage-gated Na+ channels

35
Q

What restores to potential to -70mV during repolarisation?

A

Movement of K+ out of cell and closure of Na+ channels.

36
Q

How does a myelinated neuron speed up transmission?

A

Inrush of Na+ ions at one node creates enough depolarisation to reach the threshold for the next. Impulses jump from node to node rather than along the entire axon like in nonmyelinated neurons.

37
Q

What is the Central Nervous System?

A

The part of the nervous system which consists of the spinal cord and brain.

38
Q

What is the peripheral nervous system?

A

The PNS consists of the nerves and ganglia outside the brain and spinal cord

39
Q

How do electrical synapses work?

A

Connexins link the two neurons together by forming a pore than connects the two cytoplasms of each neuron. These pores facilitate transport of ions and small molecules across the cell gap in gap junctions.

40
Q

Advantages of Electrical Synapses.

A

Fast and can go in either direction.

41
Q

Where do electrical synapses appear?

A

Gap Junctions

42
Q

Importance of electrical synapses

A

During embryonic development of brain. and synchronisation of the activity of groups of neurons

43
Q

What does the arrival of an action potential at a presynaptic knob stimulate?

A

Depolarisation of the presynaptic membrane which leads to the opening of voltage-gated calcium channels.

44
Q

What does the influx of Ca2+ cause?

A

They attach to vesicles containing neurotransmitter and move them to the membrane where they fuse with the membrane

45
Q

What is the process that results in the release of neurotransmitter?

A

Exocytosis

46
Q

How does neurotransmitter move along the synaptic cleft?

A

By simple diffusion down its concentration gradient.

47
Q

What does the neuromuscular junction join together?

A

Motor neurone and skeletal muscle

48
Q

What neurotransmitter is released at a neuromuscular junction?

A

Acetylcholine

49
Q

What does the neurotransmitter do when it reaches the postsynaptic membrane?

A

Joins to its postsynaptic receptor, activates it and generates an action potential at the postsynaptic knob

50
Q

What are the postsynaptic receptors in the neuromuscular junction?

A

Ligand-gated ion channels which allow cations (Na+) to flow into the cell inducing partial depolarisation.

51
Q

Name the 4 types of neurotransmitter.

A

Amino Acids, Amines, Peptides and Others (ATP, Adenosine)

52
Q

Name the two types of postsynaptic receptors.

A

Ionotropic (ligand-gated - fast) and Metabotropic (G Protein-coupled receptors - slow)

53
Q

What do inhibitory neurotransmitters induce in the postsynaptic membrane?

A

Hyperpolarisation

54
Q

What do excitatory neurotransmitters induce in the postsynaptic membrane?

A

Depolarisation

55
Q

How does the binding of GABA to GABA-A postsynaptic receptors cause inhibition of impulse?

A

Binding opens ligand-gated chloride channels, hyperpolarising the postsynaptic membrane

56
Q

How does the binding of GABA to GABA-B postsynaptic receptors cause inhibition of impulse?

A

Binding activates an internal G protein and a second messenger that leads to the opening of nearby K+ channels, lowering the potential

57
Q

Are most brain synapses inhibitory or excitatory?

A

Inhibitory

58
Q

What does Summation mean?

A

Sum of the excitatory and inhibitory potentials of postsynaptic membrane and whether the threshold can be reached or not.

59
Q

How is the neurotransmitter removed after attaching to postsynaptic membrane.

A

Diffusion across cleft, enzymatic degradation and reuptake at presynaptic knob via neurotransmitter transporters

60
Q

Name a drug that activates or inhibits postsynaptic channels.

A

Alcohol, Ketamine.

61
Q

Name a drug that mimics neurotransmitters by activating receptors.

A

Morphine, Nicotine and Marijuana

62
Q

Name two neurotransmitter systems in the CNS.

A

Glutamate, GABA, Dopamine, Noradrenalin, Serotonin, Acetylcholine and Histamine.

63
Q

Where are neurotransmitters stored in the presynaptic knob?

A

Vesicles

64
Q

What does plasticity in synapses mean?

A

Ability to change in response to demands. Change in structure and function. Thought to basis of learning and memory.

65
Q

Name the 4 synaptic changes that may store memories.

A

Changes involving synaptic transmitters, changes involving interneuron modulation, formation of new synapses and rearrangement of synaptic input.

66
Q

Difference between somatic and autonomic nervous system.

A

Somatic is under conscious control (voluntary) and autonomic is not under conscious control (involuntary)

67
Q

Difference between sympathetic and parasympathetic

A

Sympathetic is fight or flight and parasympathetic is rest and digest.

68
Q

Describe the contribution of Nervous System in skeletal system to Homeostasis

A

Pain receptors in bone tissue warn of brain trauma and damage

69
Q

Describe the contribution of Nervous System in Muscular system to Homeostasis

A

Somatic motor neurons receive instructions from motor areas of brain and stimulate contraction of skeletal muscles to produce movement. Basal ganglia and reticular system set level of muscle tone and cerebellum: co-ordinates skilled movement.

70
Q

Describe the contribution of Nervous System in endocrine system to Homeostasis

A

Hypothalamus regulates secretion of hormones from pituitary gland. ANS regulates secretion of hormones from adrenal glands and pancreas

71
Q

Describe the contribution of Nervous System in Cardiovascular system to Homeostasis

A

Cardiovascular centre in the medulla oblongata provides nerve impulses to ANS that governs heart rate and forcefulness of heartbeat.
Nerve impulses from ANS regulate blood pressure and blood flow through vessels

72
Q

Describe the contribution of Nervous System in Lymphatic system to Homeostasis

A

Neurotransmitters can help regulate immune responses.

Activity in nervous system may increase or decrease immune responses

73
Q

Describe the contribution of Nervous System in Respiratory system to Homeostasis

A

Respiratory areas in brain stem control breathing rate & depth. ANS helps regulate diameter of airways

74
Q

Describe the contribution of Nervous System in Digestive system to Homeostasis

A

ANS and enteric nervous system help regulate digestion.

Parasympathetic ANS stimulates digestive processes

75
Q

Describe the contribution of Nervous System in Urinary system to Homeostasis

A

ANS help regulate blood flow in kidneys & then urine formation. Brain and spinal cord centres govern emptying of bladder

76
Q

Describe the contribution of Nervous System in Reproductive system to Homeostasis

A

Hypothalamus and limbic system control sexual behaviours.
ANS controls erection of penis & clitoris + ejaculation.
Hypothalamus regulates release of hormones that control gonads.
Nerve impulses elicited suckling infant cause release of oxytocin & milk ejection in nursing mothers.

Year 1 Animal Physiology (9 decks)

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