nervous system

Question 1

what is cns and what does it include

Answer 1

central nervous system
brain and spinal cord included

Question 2

what is the pns and what does it include

Answer 2

peripheral nervous system
peripheral nerves
cranial nerves 12 pairs
spinal nerves 31 pairs

Question 3

what does peripheral conatins / function?

Answer 3

it has afferent nerves which carried signals from the peripheral nerves and the external environment to the cns
effervent nerves takes signals from cns to pns

Question 4

what is the fucntion of the cns?

Answer 4

processes sensory input
generates motor output

Question 5

what are neurons ?

Answer 5

they are found in the cns and pns and are made for communication by sending signals to other cells/neurones etc
they send signals in the forms of action potential or nerve impulses.

Question 6

what are main bodies in the neuron

Answer 6

dendrites -
axon-
axin hilock-
cell body( soma)- this contains
myelin sheath-
sympatic terminal-

Question 6

function of dendrites?

Answer 6

they receive incoming signals from other neurons and those signals get converted into changes of membrane voltage.

Question 7

function of axon?

Answer 7

axon arises from the axon hillock.
axon vary in diameter which is reflected in their axon conductivity

small diameter high resistance= slow conduction

large diameter- slow resistance= fast conduction

the fucntion of axon is to carry electrical signal away from the soma to the end synaptic terminal

Question 8

soma cell body

Answer 8

centre region of the neuron which contains the neuron and other organelles

nucleus
mitochondria
golgi apparatus
microtubules

Question 9

axon hilick

Answer 9

it generate an action potential
it between an axoc and the soma

Question 10

whats the synaptic terminal/axon terminal ?

Answer 10

contains projections specialised to transmit signal to the post synaptic cleft
at the end of each synpatic terminal theres a bulb shaped structure that release neurotrasnmitter

Question 11

what are axons covered in?

Answer 11

axons are covered by myelin sheath and they are wrapped around the axon . helps with insulation and also speeding up the electrical signal

Question 12

what are the gaps between myelin sheath called

Answer 12

they are called node of ranviers causes action potential to jump from one node to another and also increases the conduction speed

Question 13

what are the 3 different types of neurons

Answer 13

1. pseudo unineurone: it contains only axon no dendrite asn example is a sensory neurone
2. bineurone: this contains one axon and one dendrite eg is retina and oflactory epithelium
3. multineurone: contains many dendrites but one axon eg motor neurone

Question 14

how is the signal processed across a neurone?

Answer 14

1.signal gets accepted by the dendrites
2. the signal reaches the membrane of the soma and then its passed to the axon hillock
3. axon hillock will generate an action potential and will only be passed down if the stimulation if high enough . action potential is the voltage different inside and out of the nerve cell
4. Then the signals gets passed down the axon as an electrical signal and the axon is covered by myelin sheath which provides insulation and conducts faster speed of the signal.
5. the signal reached the projections of the axon terminal or synaptic terminal which will release a neuro- transmitter
6. Now the pre synaptic membrane will send neurotransmitter carried in a vesicle , it will move across the synaptic cleft where they will reach a post synaptic membrane and bind the the receptors
7. this will cause changes to the membranes of post synaptic which initiates a response or signal

Question 15

what happens to a membrane whilst at rest ?

Answer 15

at rest the membrane is electrically charged , which means its being polarised.
1. at first theres is more Na+ Ions outside of the membrane whereas K+ ions are more on the inside of the membrane.
2.concentration inside the cell is 150mM for K+ AND 15Mm for Na+
3.concentration outside the cell is 150mM for Na+ and 15mM for K+
3.the membrane is more permeable to K+ ions compared to Na+ ions which means it contains many protein channels which will facilitate potassium ions taken outside of the membrane
4. this means more K+ ions are leaving the membrane along their concentration gradient so it will start being negatively charged
5. Then when it becomes more negatively charged inside the K+ Ions will start going inside the cells this reached equilibrium.
6. on the membranes theres several protein channels which are takins ions of sodium and potassium from high concentration to lower concentration. so k+ ions are leaving via one protein channel, na+ ions are coming inside the membrane via the other protein channel, and another protein channel is doing both at the same time taking k+ out and na+ inside.

Question 16

what is the ernest equation ?

Answer 16

it measures the equilibriam membrane of the ion
Eion= Rt/zf x log in ( ion outside/ion inside)
r=gas constant
t=body temp
z=ion charge
f=constant

Question 17

the ernest for k+ and na+

Answer 17

na+=61.5 mv
k+=-90.84mv

Question 18

what are gilia cells

Answer 18

gillia cells are in cns and pns and the meaning is glue
they are supporting cells and maintain the internal structure
4 in CNS:
1. Oligodendrocytes: they myelinate neurons
2.Astrocytes:support neurone environment found in blood, brain etc
3.ependyml cells:produce CSF in cerebral ventricle
4.microglia: phagocytes foreign body

2 in pns:
1. schwann cells: myelinate axon in the pns
2.satellites cell: myelinate the cell body in pns

Question 19

what is the autonomic nervous sytem

Answer 19

it basically controls the bodily functions that are not consciously detected.