the neurons and synaptic transmissions

Question 1

how many nerve cells are there

Answer 1

there are 100 billion nerve cells in the human nervous system

Question 2

where are the majority of the nerves in the body

Answer 2

80% of which are located in the brain

Question 3

how do the neurones help the nervous system with its primary communication

Answer 3

by transmitting signals electrically and chemically, the neurons provide the nervous system with its primary means of communication

Question 4

what are the three types of neurons

Answer 4

1. sensory neurons
2. relay neurons
3. motor neurons

Question 5

what are neurons

Answer 5

the basic building blocks of the nervous system, neurons are nerve cells that process and transmit messages through electrical and chemical signals

Question 6

what are sensory neurons

Answer 6

these carry messages from the PNS to the CNS

they have long dendrites and short axons

Question 7

what are rely neurons

Answer 7

these connect the sensory neurons to the motor or other relay neurons

They have short dendrites and short axons

Question 8

what are motor neurons

Answer 8

these connect the CNS to effectors such as muscles and glands

They have short dendrites and long axons

Question 9

what is the structure of a neuron

Answer 9

they vary in size from less than a mm to up to a metre long

The all share the same basic structure:

• cell body/soma
• Dendrites
• the axon
• myelin sheath

T-Terminal buttons

Question 10

what is the soma/cell body

Answer 10

cell body/soma:

-includes a nucleus, which contains the genetic material of the cell

Question 11

what are the dendrites

Answer 11

Dendrites :
protrudes from the cell body
They carry nerve impulses from neighbouring neurons towards the cell body

Question 12

what is the axon

Answer 12

the axon:

carries impulses away from the cell body down the length of the neuron

Question 13

what is the myelin sheath

Answer 13

myelin sheath:
fatty layer covering the axon that protects it and speeds up electrical transmission of the impulse
If the myelin sheath was continuous this would have the reverse effect and slows down the electrical impulse

Therefore, the mylelin sheath is segmented by gaps called NODES of RAVIER
These speed up the transmission of the impulse by forcing it to “jump” across the gaps along the axon

Question 14

what are the terminal buttons

Answer 14

Terminal buttons

- at the end of the axon that communicates with the next neuron across a gap known as the synapse

Question 15

how do neurons pass electric transmissions

Answer 15

when a neuron is in a resting state the inside of the cell is negative compared to the outside

when a neuron is activated by a stimulus, the inside of the cell becomes positively charged for a split second causing an action potential to occur

This creates an electrical impulse that travels down the axon towards the end of the neuron

Question 16

how do neurons communicate with each other

Answer 16

neurons communicate with each other within groups known as neural networks

Question 17

what are each neuron separated by

Answer 17

each neuron is separated from the next by a synapse

Question 18

what is the space between the synapse called

Answer 18

The synapse includes the space between them called the (synaptic clef )as well as presynaptic terminal and postsynaptic receptor

Question 19

how are signals within neurons transmitted

Answer 19

signals within neurons are transmitted electrically

Question 20

how are signals between neurons transmitted

Answer 20

signals between neurons are transmitted chemically by synaptic transmission

Question 21

what happens when electrical impulses reaches the end of the neurons

Answer 21

when the electrical impulses reaches the end of the neuron (the presynaptic terminal) it triggers the release of neurotransmitter from tiny sacs called synaptic vesicles

Question 22

how do chemical tramsmissions pass between neurons

Answer 22

neurotransmitters are chemicals that diffuse across the synapse to the next neuron in the chain

once neurotransmitter cross the gap, it is taken up by the postsynaptic receptor sites - in other words, the dendrites of the nest neuron

Here, the chemical message is converted back into an electrical impulse and the process of transmission begins again in this other neuron

Question 23

how many neurotransmitters are there

Answer 23

several dozen types of neurotransmitters have been identified

each neurotransmitter has its own specific molecular structure that fits perfectly into a post - synaptic receptor site, similar to a lock and a key

Question 24

do all neurotransmitters have the same function

Answer 24

neurotransmitter also have specialists functions

For instance acetylchloline (Ach) is found at each point where a motor neuron meets a muscle, and upon release, it will cause it too contract

Question 25

what do neurotransmitters either do

Answer 25

1. excitatory

2. inhibitary

Question 26

what does the neurotransmitter serotonin do

Answer 26

the neurotransmitter causes inhibition in the receiving neuron, resulting in the neuron becoming more negatively charged and less likely to fire

Question 27

what does the neurotransmitter adrenaline do

Answer 27

adrenaline (an element of the stress response which is both a hormone and a neurotransmitter)

causes excitation of the postsynaptic neuron by increasing its positive charge and making it more likely to fire