The Structure and Function of the Nervous System Flashcards

1
Q

what is the CNS composed of ?

A

brain and spinal cord

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2
Q

what is the PNS composed of ?

A

composed of nerves that connect the brain or spinal cord with muscles, glands and sense organs

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3
Q

define ‘neurotransmitters’

A

neurotransmitters are the chemical transmitters released from the neurones in response to chemical signals

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4
Q

define ‘processes’

A

the long extensions that connect neurones to each other

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5
Q

define ‘cell body’

A

also called the some; contains nucleus and ribosomes(protein synthesis)

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6
Q

define ‘dendrites’

A

branched outgrowths from the cell body/some that receive signals

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7
Q

define ‘dendritic spines’

A

knob-like outgrowths that receive inputs

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8
Q

define ‘axon’

A

the ‘nerve fibre’; a long process extending from the cell body/soma that carries signals to target cells

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9
Q

what is the size of an axon ?

A

ranges form 1 um to 1 m

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10
Q

define ‘initial segment’

A

the ‘trigger zone’ on the axon

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11
Q

define ‘axon collateral’

A

axon branches which carry the signal ‘sideways’

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12
Q

define ‘axon terminals’

A

the end of the axon which establishes synaptic contact with another neurone of an effector cell

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13
Q

define ‘varicosities’

A

bulging areas along the axon at which neurotransmitters can be released from

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14
Q

Neurones are wrapped in myelin. What is myelin ?

A

20-200 layers of modified plasma membrane

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15
Q

what is Myelin made of in the CNS and in the PNS ?

A

CNS - oligodendrocytes

PNS - Schwann cells

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16
Q

define ‘axonal transport’

A

to maintain the structure and function of the nerve fibre, organelles must more more than 1 m between the soma and the axon terminals via a process called ‘axonal transport’

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17
Q

what is axonal transport dependent on ?

A

Motor proteins called Kinesins and Dyneins

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18
Q

how do the Motor proteins in axonal transport work ? (2 points)

A
  1. at one end, the motor protein binds to the cellular cargo
  2. at the other end, the motor protein uses energy derived from ATP to ‘walk’ up or down the axon
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19
Q

state 2 facts about ‘Kinesin transport’

A
  1. Kinesin transport occurs at the cell body and carries down the axon (anterograde)
  2. carries nutrients, molecules, mitochondria, neurotransmitter filled vesicles, and other organelles
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20
Q

talk about ‘Dynein transport’ (2 points)

A
  1. retrograde (opposite direction to Kinesin transport)
  2. carry recycles membrane vesicles, growth factors, and other chemical signals that effect a neurones morphology, biochemistry and connectivity
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21
Q

talk about a potential danger associated with ‘Dynein transport’

A

the route at which some harmful agents enter the CNS (eg - polio virus)

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22
Q

state the three types of neurones

A
  1. afferent - sensory - convey info to CNS (enter via dorsal)
  2. efferent - motor - convey info from CNS (exit via ventral)
  3. interneurone - convey into within CNS (reflexes between afferent and efferent neurones)
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23
Q

state 2 facts about afferent/sensory neurones

A
  1. transmit into to CNS from receptors at their peripheral endings
  2. cell body and peripheral process in the PNS; short central process and axon terminals in CNS
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24
Q

state 2 facts about efferent/motor neurones

A
  1. transmit info out of CNS to effector cells

2. cell body, dendrites and small portion of axon in CNS; most of axon in PNS

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25
Q

state 4 facts about interneurones

A
  1. integration and signal changers
  2. create a reflex circuit
  3. lie entirely within the CNS
  4. constitute for > 99% of the total neurones in the human body
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26
Q

define ‘nerves’

A

groups of afferent and efferent neurones together within a connective tissue sheath

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27
Q

define ‘synapses’

A

the anatomical specialised junction between two neurones which neurotransmitters diffuse across

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28
Q

A) what proportion of the neurones in the CNS are composed of Glial cells ?

B) what proportion of the space in the CNS is composed of Glial cells ?

A

A) 90%

B) 50% (neurones branch more extensively than Glial cells so take up more space)

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29
Q

what is the main function of Glial cells ?

A

surround the Soma, axon and dendrites and provide them with physical and metabolic support

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30
Q

state 2 functions of Astrocytes (type of glial cell)

A
  1. regulate extracellular fluid by removing potassium and neurotransmitters
  2. form tight junctions with cells forming capillaries forming a blood-brain barrier (prevents toxins and other substances entering the brain)
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31
Q

what is the function of the microglia (type of glial cell) ?

A

specialised macrophage like cells

32
Q

what is the function of ependymal cells (type of glial cell) ?

A

they line the fluid filled cavities within the CNS and regulate the production and the flow of cerebrospinal fluid

33
Q

the PNS is divided into two divisions, what are they ?

A
  1. efferent division

2. afferent divison

34
Q

what are the 3 divisions of the afferent division of the PNS ?

A
  1. somatic sensory
  2. visceral sensory
  3. special sensory
35
Q

what are the two divisions of the efferent division of the PNS ?

A
  1. somatic motor

2. autonomic motor (sympathetic, parasympathetic, enteric)

36
Q

define ‘pathway/tract’

A

a group of axons travelling together within the CNS is called a pathway/tract

37
Q

define ‘a commissure’

A

a commissure occurs when a group of axons link the left and right side of the brain together

38
Q

define ‘ganglia’

A

ganglia are the cell bodies of neurones with similar functions within the PNS

39
Q

define ‘nuclei’

A

nuclei are the cell bodies of neurones with similar functions within the CNS

40
Q

are there nerves in the CNS ?

A

NO, there are no nerves within the CNS

41
Q

define ‘nerve’

A

a nerve is a group of axons travelling together to and from the same general location in the PNS

42
Q

what is the largest component of the forebrain ?

A

the cerebrum - consists of the R+L hemispheres and is connected by a corpus collosum

43
Q

what is the central part of the forebrain ?

A

the diencephalon

44
Q

what is the cerebral cortex ?

A

a 2-4 mm thick membrane surrounding the cerebral hemispheres

45
Q

what are the outer and inner layers of the cerebral cortex made of ?

A

outer - grey matter (gives brain its grey appearance)

inner - white matter (mainly myelinated fibre tracts)

46
Q

what are the two cell types within the cerebrum ?

A
  1. pyramidal cells - major output cells

2. non-pyramidal cells - major input cells

47
Q

The cerebral cortex is the main integrating centre for the nervous system. State two expansionary facts to this statement

A
  1. basic afferent information is processed into meaningful perceptual images
  2. has control over the system that govern muscle movement, and can refine the movements
48
Q

state the 3 parts of the Diencephalon (part of the forebrain)

A
  1. Thalamus
  2. Hypothalamus
  3. Epithalamus
49
Q

state 4 facts about the Thalamus

A
  1. a collection of several large nuclei
  2. role in general arousal
  3. role in controlling movement and posture
  4. focusing attention
50
Q

state 2 facts about the Hypothalamus

A
  1. constitutes only 1% of total brain mass

2. has homeostatic control over the internal environment

51
Q

state a fact about the Epithalamus

A

controls biological rhythms (via the Pineal gland)

52
Q

The Hypothalamus is the master control centre for neural and endocrine co-ordination. What does it control ? (2 points)

A
  1. behaviours learning to the preservation of the individual (eg - eating and drinking)
  2. behaviours leading to the preservation of the special (eg - reproduction)
53
Q

where is the Hypothalamus situated ?

A

the Hypothalamus lies directly above, and is connected by a stake, to the pituitary gland (an important endocrine structure that the hypothalamus regulates)

54
Q

what is the main function of the Cerebellum (2 points)

A
  1. important role in the co-ordination of movements and controlling posture and balance
  2. receives sensory info from the sensory system, and information from the parts of the brain concerned with movement
55
Q

what is the Brainstem

A

The Brainstem is the ‘reticular formation’ –> the only part of the brain absolutely essential for life. It receives and integrates information from all areas of the CNS

56
Q

what are the 3 main functions of the Brainstem ?

A
  1. motor functions
  2. CV control, RS control and swallowing
  3. regulates sleep, wakefulness, attention and eye movement
57
Q

what are Meninges ?

A

Meninges line the structures in the CNS; add additional support and protection

58
Q

what are the 3 Meninges ?

A
  1. dura mater
  2. arachnoid mater
  3. pia mater
59
Q

state the 4 functions of the Meninges

A
  1. cover and protect the CNS
  2. protect blood vessels and enclose the venous sinuses
  3. contain cerebrospinal fluid (CSF)
  4. form patricians in the skull
60
Q

starting at the scalp, and moving inwards, what are the 7 structures surrounding the brain

A
  1. scalp
  2. skull bone
  3. dura mater
  4. venous blood
  5. arachnoid mater
  6. subarachnoid space of brain
  7. pia mater
61
Q

what is cerebrospinal fluid (VSF) ? (2 points)

A
  1. it protects and cushions the brain structures

2. it is made by the Choroid Plexus

62
Q

what structure produces cerebrospinal fluid (CSF) ?

A

the Choroid Plexus

63
Q

grey matter consist of what 4 things ?

A
  1. interneuroens
  2. cell bodies and dendrites of efferent neurones
  3. axons of afferent neurones
  4. glial cells
64
Q

white matter consists of what ?

A

groups of myelinated axons

65
Q

A) Afferent axons enter the CNS via what root ?

B) Efferent axons enter the CNS via what root ?

A

A) dorsal root

B) ventral root

66
Q

A) how many pairs of cranial nerves are there ?

B) how many pairs of vertebral nerves are there ?

A

A) 12 pairs

B) 31 pairs

67
Q

how many pairs of nerves are at each level of the vertebral column ?

A
  1. cervical - 8 pairs
  2. thoracic - 12 pairs
  3. lumbar - 5 pairs
  4. sarcal - 5 pairs
  5. coccygeal - 1 pair
68
Q

peripheral nerves can contain what ?

A

peripheral nerves can contain nerve fibres that are axons of afferent neurones, efferent neurones, or both

69
Q

state 3 facts about the somatic nervous system

A
  1. consist of a single neurone between the CNS and the muscle cell
  2. innervate skeletal muscle
  3. ONLY excitatory
70
Q

state 3 facts about the autonomic nervous system

A
  1. two neurone chain between the CNS and effector cell
  2. innervate smooth and cardiac muscle, glands and GI neurones
  3. excitatory OR inhibitory
71
Q

the sympathetic autonomic nervous system secretes what proportions of epinephrine and norepinephrine ?

A

80% epinephrine

20% norepinephrine

72
Q

in the autonomic division, where do sympathetic nerves leave the CNS ?

A

thoracic and lumbar regions (ganglia close to spinal cord)

73
Q

in the autonomic division, where do parasympathetic nerves leave the CNS ?

A

brainstem and sarcal regions (ganglia close to the effector cells they innervate)

74
Q

define ‘dual innervation’

A

Dual innervation is when tissues/organs can be innervated by the sympathetic and parasympathetic nervous system. They act Reciprocally (as one inc^ the other dec^)

75
Q

rest of digest = ?

A

parasympathetic

76
Q

fight or flight = ?

A

sympathetic