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physiology 215 > The central nervous system > Flashcards

The central nervous system Flashcards

1
Q

what are the functions of the CNS ?

A
  • subconscious neural regulation of your internal environment
  • emotions
  • voluntary control of movement
  • perception
  • higher learning such as memory
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2
Q

Afferent division of PNS

A

carry info from the periphery to the brain

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3
Q

efferent division

A

CNS sends info back to the periphery through this division

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4
Q

Afferent Neuron

A

majority of the neurones that make up the PNS , peripheral ending contains a sensory receptor

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5
Q

inter neuron

A

comprised of about 99% of neurons ad lie completely within the CNS and are connector neurons that lie between afferent and efferent neurons - play important role in integrating responses ( higher learning

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6
Q

Efferent Neurons

A

Cell bodies lie within the CNS where they receive converging pre synaptic inputs

  • when they initiate an action potential it travels down the efferent fibre to the effector organ
  • efferent fibre lies mainly outside the CNS
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7
Q

Glial cells

A

in both the CNS and PNS , they use chemical signals to communicate in between other glial cells and neurons

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8
Q

what sort of tissue does glial cells form ?

A

they form connective tissue in the brain and their primary role is to support and maintain homeostatic control of extracellular environment around the neurons
90% of the CNS

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9
Q

Oligodendrocytes

A

form the myelin sheath that surround some neuronal axons in the CNS allows for faster signalling

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10
Q

Schwann cells

A

found in the PNS , can only myelinated one segment of an axon of a single neuron

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11
Q

Ependymal cells

A

line the areas of the brain and spinal cord in the fluid filled areas ( ventricles ) and contain cilia to produce a current in fluid –> production of cerebrospinal fluid (CSF)

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12
Q

Astrocytes

A

most numerous class of glial cells,

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13
Q

what are the functions of glial cells ? theres 6

A

1) form the primary connective tissue to hold the neurons in their proper spatial relationship 2) induce the blood vessels of the brain to undergo changes necessary to establish the blood brain barrier
3) help in the repair of brain and spinal cord injuries
4) Help to halt neurotransmitter activity
5) enhance synapse formation and modify synaptic transmission
6) take up excess K+ to maintain the proper extracellular environment for neurons ( raising K+ will increase likely hood of going to threshold and make neurons more excitable

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14
Q

Micro glia

A

non neuronal cells that are a type of immune cell found within the CNS

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15
Q

inactive micro glia

A

typically not active and have many dendrite like branches - secret nerve growth factor to support other neurons andglial cells

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16
Q

activated microglia

A

become activated when they sense any kind of pathological change ( cytokines, plaques, cell death , they become activated and phagocytose foreign particles , reduce inflammation and release cytotoxic chemicals ( they have the ability to destroy normal cells i.e. cause disease

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17
Q

what protects the brain and spinal cord ?

A

cranium / skull and the vertebrae surround the spinal cord

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18
Q

What are the protective membranes of the CNS

A 
dura mater
arachnoid mater 
pia mater 
cerebro spinal fluid 
blood brain barrier
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19
Q

dura mater

A

the outermost layer, tough, double membrane that lies next to the bon. certain regions create the dural sinuses which are blood filled spaces

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20
Q

Arachnoid mater

A

the middle meninges , delicate and highly vascularized

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21
Q

transfer of cerebrospinal fluid from the sub arachnoid space is done through ?

A

arachnoid granulation villi penetrate through the dura and extend into the sinuses

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22
Q

Pia Mater

A

inner most membrane, is highly vascularized and tightly adheres to the surface of the brain and the spinal cord

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23
Q

Cerebrospinal fluid

A

protect the brain by acting as a shock absorber , has similar density to tissue , fluid is located in the sub arachnoid space between the arachnoid mater and pia mater

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24
Q

Cerebrospinal fluid is essential for what ?

A

transfer of materials between blood and neural tissue , brains interstitial fluid supplies the neurons and glial cells while the CSF has strong influence on the blood stream

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25
Q

blood brain barrier

A

endothelial cells of the brain capillaries are joined together by tight junctions to prevent materials from passing between the cells . therefore exchange of materials between the brine must pass thought the endothelial cells

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26
Q

why is the blood brain barrier regulated by variety of cell types

A

must protect the brain cells from toxins but are able to respond to the dynamic metabolism of neurons , glial cells and the extracellular matrix , the permeability of the cells need to be highly regulated

27
Q

Choroid plexus

A

Highly vascularized masses of Pia mater that dip into pockets of the ependymal cells and create the CSF. One can be found in each ventricle

28
Q

What is the spinal cord ?

A

Long tube of neurons and support cells which extends from the brainstem through a hole in the skull to the lumbar region of the vertebral column . Acts as a highway for the flow of information between body and brain

29
Q

Grey matter

A

Consists of the nerve cell bodies, short inter neurons and glial cells. Contains a central canal which is filled with CSF , each half of grey matter is called a horn

30
Q

Dorsal Horn

A

cell bodies of interneurons on which afferent neurons terminate

31
Q

Lateral horn

A

cell bodies of autonomic efferent nerve fibres

32
Q

ventral horn

A

cell bodies of somatic efferent neurons

33
Q

White matter

A

consists of bundles of nerve fibres or axons , each bundle is connected to a specific region of the brain to transmit information from the brain to the periphery or from the periphery to the Brain

34
Q

Dorsal root ganglia

A

cell bodies from the afferent nerves are located here

35
Q

Ganglia

A

collection of neuron cell bodies , receive info from the periphery and relay it to the inter neurons of the dorsal horn within the spinal cord grey matter

36
Q

pathwayDorsal root

A

dorsal root —-> afferent input

37
Q

Ventral root pathway

A

ventral root —-> efferent output

38
Q

structure of a nerve

A

bundle of peripheral afferent and efferent axons, covered in connective tissues that follow the same pathway

39
Q

where are cell bodies found ?

A

in the CNS or in the ganglia in the PNS

40
Q

What is a nerve fascicle ?

A

a single nerve contains several nerve fascicles which are bundles of myelinated or unmyelinated axons in connective tissue as well as blood vessels

41
Q

Spinal cord structure

A

along the vertebral column, paired spinal nerves project from between vertebrae , these nerves are named according to the regions that they innervate ( synapse with another tissue )

42
Q

Cervical nerves

A

8 pairs emerge from neck

43
Q

thoracic nerves

A

12 pairs emerge from the chest

44
Q

lumbar nerves

A

5 pairs emerge from the abdomen

45
Q

sacral nerves

A

5 pairs emerge from the pelvis

46
Q

coccygeal nerve

A

emerges from the tailbone

47
Q

Spinal reflexes

A

certain afferent and efferent inputs that bypass the brain itself

48
Q

simple reflexes

A

unlearned reflexes such as puling your had away from something hot

49
Q

acquired reflexes

A

the result of practice, training or conditioning

50
Q

The reflex arc

A

neuronal pathways for reflexes and are comprised of 5 components

51
Q

Step 1 reflex arc

A

receptors sense a physical o chemical change in the environment and produce action potential

52
Q

step2 reflex arc

A

action potential is transmitted from the receptor to the integrating centre

53
Q

step 3 reflex arc

A

the inter neuron integrating centre is generally within the CNS. simple reflexes are integrated within brain or spinal cord or brainstem while acquired reflexes go to higher processing brain centres

54
Q

step 4 reflex arc

A

the response is transmitted away from the CNS

55
Q

step5 reflex arc

A

this is target of the efferent pathway and is usually a muscle or gland that is required to carry out direct response

56
Q

example of simple spinal reflex

A

associated with skeletal muscles which contain stretch receptors , when a muscle is stretched , this receptor is activated and the afferent fibre terminates directly on the efferent

57
Q

why is this reflex a negative feedback mechanism ?

A

resists passive change in muscle length ( patellar tendon reflex )

58
Q

step 1 withdrawal reflex

A

touching hot stove will activate thermal pain receptors in finger

59
Q

step2 withdrawl reflex

A

action potentials are generated in the afferent pathway which propagates impulses to the spinal cord

60
Q

step 3 withdrawl reflex

A

within spinal cord, afferent fibre can synapse with many other interneurons in this case , afferent neuron stimulates excitatory inter neurons to act on bicep muscle , inhibitory interneurons to act on motor neurons of tricep and inter neurons to descend from brain

61
Q

step 4 withdrawl reflex

A

one efferent pathway stimulates contraction of bicep another leads to relaxation of tricep

62
Q

step 5 withdrawl reflex

A

effectors are stimulated and allows the withdrawl of the hand

63
Q

parts of the brain oldest to newest

A

brainstem , cerebellum , forebrain , cerebrum

physiology 215 (3 decks)

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