nervous tissue structure and function - why we need a nervous system

Question 1

what is grey matter and where is it located

Answer 1

grey matter contains dendrites, cell bodies, axon terminals, non myelinated axons and all support cells. located in centre of spinal chord and on edge of brain

Question 2

what is white matter and where is it located

Answer 2

contains axons and myelinated material. is located on the outside of the spinal chord and in the centre of the brain. it is white because the myelinated material contains lots of lipids

Question 3

what produces the myelin sheath

Answer 3

in CNS= produced by oligodendriytes and in PNS= by shcwann cells

Question 4

structure of neurone

Answer 4

draw with dendrites, cell body, axon and end plate labelled. cell body and dendrites are located in the CNS

Question 5

variations of neurone structure in the CNS

Answer 5

pyramiding and purkinje neurones both have very extensive dendrite network. their function is to collate information and they the sub type of neurone called integrative

Question 6

types of neurone in the PNS (variations)

Answer 6

multipolar- 1 axon and multiple dendrites (cell body at the end)
unipolar- look at pic but cell body then dendrites and axon
bipolar- 1 axon and 1 dendrite with cell body in the middle
psuedounipolar - cell body coming off in the middle

Question 7

what are nissil bodies

Answer 7

A Nissl body, also known as Nissl substance and Nissl material, is a large granular body found in neurons. These granules are of rough endoplasmic reticulum (RER) with rosettes of free ribosomes, and are the site of protein synthesis

Question 8

how is information passed so quickly along neurone

Answer 8

atugrade and retrograde use microtubules to shuttle from the soma (cell body) to the synapse

Question 9

how is neurotransmitter synthesised

Answer 9

vesicles are transported using microtubules. each vesicle contains just 1 enzyme and as it travels the length of the axon it starts to synthesis its neurotransmitter. vesicles without neurotransmitter will be transported back to the cell body or lost to the neurolemma

Question 10

structure of a nerve

Answer 10

epineurium- covers outside holding the fascicles together
perineurium - on the outside of a fascicle (paraneurium)
endoneurium covers the outside of a nerve fibre
within each fascicle there are the same type of nerve e.g myelinated or non myelinated

Question 11

how to recognise nerves with myelin on a microscope slide

Answer 11

toluidine blue stains fat and if there is a large blue ring around the nerve = myelin

Question 12

difference between myelinated and unmyelinated structure

Answer 12

in unmyelinated multiple nerve fibres are surrounded by a Schwann cell. here the impulse will travel along the outer edge. whereas in myelinated each nerve fibre is surrounded by a myelin sheath, here the impulse will travel down the centre. look at pics

Question 13

how does myelination occur

Answer 13

axon is sitting in grove surrounded by Schwann cell. the mesaxon membrane surrounds axon and wraps itself around it forming multiple layer. the cytoplasm is extorted from between the layers and it becomes compact to form myelin

Question 14

what is an oligodendrocyte

Answer 14

does the same thing as a Schwann cell but in the CNS however it wraps more the 1 axon simultaneously

Question 15

what is an astrocyte

Answer 15

star like structure. Have perineural diet which contain gap junctions. regulate nerve impulses by releasing glutamate and contribute to blood brain barrier

Question 16

what is a microglial cell

Answer 16

large cell with elongated nucleus acting as a resident macrophage removing damaged nerve cells and acting as an immune cell

Question 17

what is an ependymal cell

Answer 17

they line the spinal chord and ventricles of brain producing cerebral fluid which is moved with their villi. microvilli absorb the cerebral fluid for the removal of pathogens. look at pic of them

Question 18

what is multiple sclerosis

Answer 18

autoimmune degradation of myelin = loss of conduction velocity and therefore symptoms such as fatigue, vision problems, slurred speech, numbness/tingling and mobility issues

Question 19

name the support cells of the CNS

Answer 19

oligodendrocytes, astrocytes, microglial cell and ependymal cell

Question 20

what is myelin and what does it do

Answer 20

many layers of plasma membrane without the cytoplasm. acts as an insulating material preventing action potentials from being generated. speed up rate of conduction by saltatory conduction

Question 21

what are satellite/glial cells and where are they found

Answer 21

Found in the PNS they cover the cell bodies in the ganglia

Question 22

glial cells?

Answer 22

cell present in the CNS

Question 23

nerves that carry impulses towards CNS and away from CNS

Answer 23

towards= sensory or afferent 
away = motor or efferent

Question 24

what is a ganglion

Answer 24

an accumulation of neurone cell bodies outside the CNS

Question 25

why do we need a nervous system

Answer 25

can’t rely on diffusion alone for communication

Question 26

how can the motor output of nervous system be divided

Answer 26

somatic (voluntary) and autonomic (involuntary). And then autonomic is divided into sympathetic (fight or flight, affects whole body) or parasympathetic (rest and digest, selectively targets cells/organs)

Question 27

where are the parasympathetic spinal chord segments found and the sympathetic spinal chord segments found

Answer 27

para- top and bottom

sympa- in the middle

Question 28

draw myosynaptic reflex arc

Answer 28

draw?

Question 29

difference between structure of para and sympathetic

Answer 29

both have 2 chains of neurones and a synapse between them at the autonomic ganglion. sympathetic has short axon and long dendron whereas para has a long axon and a ganglia found in the wall of target organ with therefore a short axon

Question 30

how spinal chord communicates with autonomic NS

Answer 30

draw it

Question 31

how does the sympathetic nervous system supply the skin - 1 spinal chord doesn’t add up to 1 dermatome?

Answer 31

from the entry level segment it will ascend and descend the chain and the impulse will be sent out from the spinal chord

Question 32

how are the viscera supplied by the sympathetic nervous system because this dermatome lines up to the parasympathetic spinal chord segment

Answer 32

go straight through chain and the no the aorta where there are specialised ganglion called splachic nerves. This is the example with the heart as a part of the viscera. can also be for other organs in viscera

Question 33

targets of the parasympathetic nervous system

Answer 33

supplies visera via vagus nerve and the head also has 4 specialised ganglia found in the target organs - cilary to eye, pterygopalatine to facial nerves and lacrimal gland in eye, submandibular to salivary gland and otic to parotid gland