Neurons and synpatic transmissions

Question 1

Where are most neurones located and how can signals be transmitted

Answer 1

80% of the neurones are located in the brain

Signals can be trasnmitted Chemically (across a synapse) and Electronically within a nerve cell

Question 2

How many total neurones are there in the body

Answer 2

100 billion

Question 3

What are the three types of neruones

Answer 3

Motor
Sensory
Relay

Question 4

What is the size of neurones

Answer 4

They vary in size from less than a mm to a metre long

Question 5

What is the basic structure of a neurone

Answer 5

They have a soma (body) which includes the nucleus-contains the genetic information in a cell-
And they have branch like structures called dendrites which portrude from the cell body

Question 6

What does the axon do?

Answer 6

The axon carries electrical impulses away from the cell body down the length of the neuron

Question 7

What is the neuron covered in

Answer 7

A myelin sheeth which insulates and protects the axon as well as speeds up the electrical transmission of the impulse

Question 8

What would happen if the Myelin sheeth was continuous

Answer 8

It would slow down the electrical transmission

Question 9

What are the nodes of ranvier

Answer 9

The gaps between myelin sheeth
They speed up the transmissions of the impulse as they force it to jump across the gaps along the axon
Allow ions to diffuse in and out of a neurone

Question 10

What is at the end of the axon

Answer 10

Terminal buttons- Allow communication with the next neuron across the synapse (a gap)

Question 11

What is electron transmission

Answer 11

The firing of a neuron

Question 12

Is the neuron positively charged or negatively charged when it is in its resting state compared to the outside

Answer 12

Negatively charged inside positvely outside

Question 13

What is an action potential

Answer 13

The change in electric potential that propagates along the axon during the transmission of a nerve impulse or the contraction of a muscle.

Question 14

What are the 2 steps in electrical transmission

Answer 14

1. Has to teach the action potential
2. electrical impulse travels down the axon towards the end of a neuron

Question 15

What are neural networks

Answer 15

The way neurons communicate

Question 16

What is a synapse

Answer 16

A gap that separates a neuron from another

Question 17

What does a synapse include

Answer 17

A gap between them (synaptic cleft) as well as the presynaptic terminal and post synaptic receptor site

Question 18

How are signals within neruons trasnmitted

Answer 18

Electrictronically

Question 19

How are signals between neurons trasnmitted

Answer 19

Chemically by synaptic trasnmissions

Question 20

What happens when an electrical impulse reaches the end of a neuron (presynaptic terminal)

Answer 20

Triggerers the release of a neurotransmitter from tiny sacs called synaptic vesicles

Question 21

What are neurotrasnmitters

Answer 21

Chemicals released from the synpatic vesicle that relay signals across the synapse from one neuron to another

Question 22

What happens once the neurotransmitters cross the synpase

Answer 22

It is taken up by the postsynaptic receptor sites-dendrites of the next neuron-
Here the chemical message is converted into an electrical impulse and the process of transmission happens again

Question 23

What is an example of a neurotrasnmitter having a specialist function

Answer 23

• Acetylcholine is found at each point where a motor neuron meets a muscle
• Causes the muscle to contract

Question 24

What are the two effects a neuron can have on the neighbouring neuron

Answer 24

Excitiory or inhibitory

Question 25

What does serotonin do to the recieving neuron

Answer 25

Serotonin inhibits the recieving neuron resulting in that neuron becoming more negatively charged

Question 26

What does adrenaline do to the receiving neurone

Answer 26

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

Question 27

When are action potentials of the post synpatic neuron triggered

Answer 27

When the sum of the excitory and the inhibitory signals at any one time reach the thrreshold

Question 28

What is the length of dendrites and axons in all three differnet neurons (Sensory Relay and Motor)

Answer 28

Sensory neurons have long dendrites and short axons Relay neurons have short dendrites and short axons Motor neurons have long axons (lead to muscles) and short dendrites.

Question 29

What is the location of a sensory neuron?

Answer 29

* Located in receptors such as: eyes, ears, tongue and skin * Also located in the PNS in clusters known as ganglia

Question 30

What is the function of a sensory neuron (4)

Answer 30

* Carry nerve impulses to the spinal cord and brain from the receptors * When these impulses reach the brain they are translated into ‘sensation’ for example, visual input. * However, NOT all sensory information * reaches the brain, some neurons stop at the spinal cord – allowing for quick reflexes. * Carry messages from the PNS to the CNS

Question 31

Where are relay neurons located

Answer 31

* Found only in the brain and spinal cord. * They lie somewhere between sensory input and motor output.

Question 32

What is the function of the relay neuron

Answer 32

To allow sensory and motor neurons to communicate with each other

Question 33

Where are motor neurons located

Answer 33

In the central nervous system (CNS)

Question 34

What is the function of motor neurons (2)

Answer 34

* When stimulated they release neurotransmitters that bind to the receptors on the muscle to trigger a response, leading to movement. * They form synapses with muscles to control their contractions.

Question 35

What is synaptic transmission

Answer 35

The process by which neighbouring neurons communicate with each other by sending chemical messages across the synpatic cleft which separates them