The nervous system and brain Flashcards

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1
Q

What does the CNS consist of?

A

Brain
Brain stem
Cerebellum
Spinal cord

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2
Q

What does the PNS consist of?

A

Cranial nerves and their branches, spinal nerves and their branches, ganglia, enteric plexuses and sensory receptors

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3
Q

How many pairs of cranial nerves are there?

A

12

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4
Q

How many pairs of spinal nerves are there?

A

31

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5
Q

What are the three main functions of the nervous system?

A

Sensory
Integrative
Motor

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6
Q

What are the subdivisions of the PNS?

A

Somatic nervous system (SNS)
Autonomic nervous system (ANS)
Enteric nervous system (ENS)

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7
Q

What are some effects of the parasympathetic nervous system?

A

‘Rest and digest’
-Decreased heart contractility
-Increased salivation and gastric/pancreatic juice secretion
-Contraction of smooth muscles of viscera
-Bronchospasm
-Pupil constriction

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8
Q

What are some effects of the sympathetic nervous system?

A

‘Fight or flight’
-Pupil dilation
-Increased sweating
-Vasoconstriction of some blood vessels
-Vasodilation of skeletal muscle and liver blood vessels
-Increased heart rate
-Increased cardiac contractility
-Relaxation of the smooth muscles of the viscera
-Bronchodilation
-Skeletal muscle contraction
-Glycogenolysis
-Thermogenesis

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9
Q

What is the function of neuroglia (glial cells)?

A

Supporting, nourishing and protecting neurons and maintaining their interstitial fluid

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10
Q

What subdivision of the PNS can function with or without input from the CNS?

A

The enteric nervous system

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11
Q

Where are cell bodies of the the grey matter found?

A

Periphery of the brain and centre of the spinal cord

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12
Q

What are ganglia?

A

Collections of neuronal bodies found in the PNS. Act as synaptic relay stations between neurons

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13
Q

What does grey matter mainly consist of?

A

Neuronal cell bodies (soma)

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14
Q

What does white matter mainly consist of?

A

Myelinated axons

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15
Q

What membrane surrounds axons?

A

Axolemma (the plasma membrane of the axon)

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16
Q

Is transmission speed faster in myelinated or unmyelinated neurones?

A

Myelinated

(Unmyelinated neurones range from 0.5-10m/s in speed compared to up to 150m/s in myelinated neurones)

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17
Q

What is the structure of myelin sheaths?

A

Several Schwann cells along the length of the axon. Each Schwann cell curled around the axon (like thin dough wrapped around a rolling pin) to create several layers of Schwann cell cytoplasm.

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18
Q

Where is white matter located?

A

The centre of the brain and periphery of the spinal cord

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19
Q

What is resting membrane potential?

A

-70mV

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20
Q

What happens during the initial phase of depolarisation of neurone action potential?

A

Voltage gated Na+ channel activation gates are opened

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21
Q

When is the depolarisation phase of action potential started?

A

When a stimulus alters the potential above the threshold (-55mV)

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22
Q

What happens during the depolarisation phase of action potential?

A

Na+ are opened initially, followed by voltage gated K+ channels being opened, towards the end Na+ channels are inactivating.

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23
Q

What happens during the repolarisation and after-hyperpolarisation phase of action potential?

A

Voltage gated K+ channels are still open and Na+ channels are still inactivating. Then Na+ channels fully return to the resting state whilst Voltage gated K+ channels remain open.

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24
Q

During neuron resting state what ions are in a higher concentration outside the cell?

A

Na+, Ca++ and Cl-

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25
Q

During neuron resting state what ions are in a higher concentration inside the cell?

A

K+, organic phosphates (-ve) and amino acids (-ve)

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26
Q

Are voltage-gated channels active or passive?

A

Active

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27
Q

What is threshold membrane potential?

A

-55mV

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28
Q

What initial ion movement occurs to depolarise the cell?

A

Sodium channels open and flood the cell with sodium

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29
Q

What ion movement occurs once peak membrane potential is reached?

A

Potassium channels open causing K+ to flood outside of the cell, sodium channels close stopping Na+ inflow.

(Repolarisation)

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30
Q

When does a hyperpolarising phase occur?

A

When, while potassium channels are still open, outflow of K+ is high enough to cause the membrane potential to dip below the normal resting level (to about -90mV)

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31
Q

How does the neuron return to resting potential after hyperpolarising?

A

Potassium channels close, extra movement of ions through leakage channels allows a return to the resting state

32
Q

What is the relative refractory period?

A

A period where a larger than normal stimulus is needed to produce another action potential

33
Q

What is the absolute refractory period?

A

A state of sodium channel inactivity after an action potential, another action potential cannot occur within this period.

34
Q

What is a synapse?

A

The region where communication occurs between two neurones or between a neurone and an effector cell

35
Q

What is the synaptic cleft?

A

The small gap between the axon of the presynaptic neurone and the membrane of the post-synaptic membrane

36
Q

What happens when the action potential reaches the axon terminal?

A

Ca++ channels are opened and Ca++ floods in triggering synaptic vestibules to release their neurotransmitters and allow them to diffuse across the cleft and bind to the receptor proteins on the postsynaptic cell

37
Q

Which two paired arteries supply the brain with blood?

A

The vertebral and internal carotid arteries

38
Q

How do neuroglia nourish and protect neurones?

A

Forming myelin
Providing nutrients
Destroying pathogens
Providing a support structure

39
Q

How does myelin increase action potential velocity?

A

By acting as an electrical insulator, allowing the action potentials to be generated and passed on only at nodes of ranvier rather than along the entire axon length

40
Q

What are the four major parts of the adult brain?

A

Brain stem
Cerebellum
Diencephalon
Cerebrum

41
Q

What are the 3 main parts of the brain stem?

A

Midbrain, pons and medulla oblongata

42
Q

What part of the brain provides the main motor and sensory innovation to the face and neck?

A

The brainstem

43
Q

How many pairs of cranial nerves come from the brainstem?

A

10

44
Q

What is the medullary respiratory centre?

A

The respiratory group in the pons that helps control breathing

45
Q

What are the main functions of the cerebellum?

A

Posture
Balance
Skeletal muscle contractions, smoothing and coordinating

46
Q

What are the three main components of the diencephalon?

A

Thalamus, hypothalamus and epithalamus

47
Q

What part of the diencephalon acts as the major relay station for most sensory impulses that reach the primary sensory areas of the cerebral cortex from the spinal cord and brain stem?

A

The thalamus

48
Q

What are some of the main functions of the hypothalamus?

A

BATHED

Behaviours and emotions
Autonomic nervous system control
Temperature control
Hormone production
Eating and
Drinking regulation

49
Q

What is the function of the pineal gland?

A

Receiving information on state of the light-dark cycle of the environment and produce and secrete melatonin

50
Q

What separates the left and right cerebral hemispheres?

A

Longitudinal cerebral fissure

51
Q

What are the four lobes of the cerebral cortex?

A

Frontal lobe
Parietal lobe
Occipital lobe
Temporal lobe

52
Q

What functions is the frontal lobe associated with?

A

Reasoning, emotions, problem solving, planning, parts of speech, movement

53
Q

What functions is the parietal lobe associated with?

A

Movement, orientation, recognition, perception of stimuli

54
Q

What functions is the occipital lobe associated with?

A

Visual processing

55
Q

What functions is the temporal lobe associated with?

A

Perception and recognition of auditory stimuli, memory and speech

56
Q

What part of the brain controls body temperature?

A

The hypothalamus

57
Q

What higher brain centres input into the cardiovascular centre?

A

Cerebral cortex, limbic system and hypothalamus

58
Q

What sensory receptors input into the cardiovascular centre?

A

Proprioceptors
Chemoreceptors
Baroreceptors

59
Q

What are the three layers of the meninges?

A

Dura mater
Arachnoid mater
Pia mater

60
Q

What type of tissue is the dura mater?

A

A tough fibrous outer membrane

61
Q

What type of tissue is the arachnoid mater and sub arachnoid space?

A

A web like connective tissue which contains cerebral arteries and veins

62
Q

What type of tissue is the pia mater?

A

A thin inner membrane tightly adhered to the surface of the brain & spinal cord, it contains smaller blood vessels.

63
Q

What is cerebral spinal fluid (CSF) and how much does the average adult contain?

A

Cerebrospinal fluid (CSF) is an ultrafiltrate of plasma contained within the ventricles of the brain and the subarachnoid spaces of the cranium and spine.
Adult CSF volume is estimated to be 150 ml, with a distribution of 125 ml within the subarachnoid spaces and 25 ml within the ventricles

64
Q

What is the function of CSF?

A

It performs vital functions, including providing nourishment, waste removal, and protection to the brain.

It acts as a shock absorber and monitors for changes in the cerebral environment helping to keep concentrations of electrolytes, glucose and proteins constant

65
Q

Where is CSF secreted from and how much is secreted each day?

A

CSF is predominantly secreted by the choroid plexus with other sources playing a more poorly defined role. In the adult population, its secretion varies between individuals, usually ranging from 400 to 600 ml per day.

66
Q

What colour is healthy CSF?

A

Clear

67
Q

How many white blood cells are usually present per 1cm^3 of CSF?

A

<5

68
Q

What are the two types of neurons and their distribution?

A

Excitory (80-90%)
Inhibatory (10-20%)

69
Q

How many ventricles does the brain have?

A

4

70
Q

What is the function of the brains ventricles?

A

They produce CSF and help keep the brain buoyant and cushioned

71
Q

What is the pathway of CSF through the brains ventricles?

A

Most produced in the first 2 ventricles
Drains into the 3rd which adds some more
Drains into the cerebral aqueduct
Drains into the 4th ventricle
Fills the subarachnoid space

72
Q

Which brain cells secrete myelin?

A

Oligodendrocytes

73
Q

What is the function of astrocytes?

A

Maintain blood brain barrier
Provide nourishment to neurons
Recycle neurotansmitters

74
Q

What is the corpus callosum?

A

The corpus callosum is the primary commissural region of the brain consisting of white matter tracts that connect the left and right cerebral hemispheres.

75
Q

Where does the spinal cord end?

A

L1 (sometimes L2 depending on anatomy)