4.12 Nervous System

Question 1

What is a neuron?

Answer 1

Functional unit of the nervous system

Question 2

What are the three different types of neurons? SIM

Answer 2

Sensory, inter neuron and motorneuron

Question 3

What is the job of the sensory nervous system?

Answer 3

Communicate environmental stimuli to the central nervous system

Question 4

Where is sensory neurons found?

Answer 4

In clusters outside the spinal cord called ganglions

Question 5

What are 2 examples of sensory neurons?

Answer 5

Photoreceptors and thermoreceptors

Question 6

What is the job of interneurons?

Answer 6

Link neurons within the body

Interpret sensory information and connect it to motor neurons that initiate the correct response

Question 7

How is information received in the nervous system?

Answer 7

Dendrites from sensory neurons receive information from sensory receptors located near the surface of the skin. The information is then carried to the interneurons in the CNS that coordinate the information and relay it to the appropriate motor neuron(s). motor neurons transmit information onto the appropriate effector

Question 8

How do impulses enter all three types of neurons?

Answer 8

Impulse enters at the dendrite into the cell body

Question 9

How does an impulse leave all three types of neurons?

Answer 9

Leaves via the axon and extension of the cytoplasm

Question 10

How long or short can an axon be?

Answer 10

These axons can reach up to a metre in length while in other organisms it may be a little more than and micro meter

Question 11

How many neurons can a neuron link to?

Answer 11

One neuron may link to and affect multiple other neurons while other may come together and affect a single neuron

Question 12

What are glial cells known as in the nervous system?

Answer 12

They are the unsung hero’s of the nervous system and outnumber neurons 50:1

Question 13

What are the three functions of the glial cells? PGM

Answer 13

They provide physical support for neurons since neuron lack sufficient extra cellular matrix

They direct the growth of neurons during repair and development

They provide metabolic support to nerve cells

Question 14

How many types of glial cells are in the CNS?

Answer 14

4

Question 15

How many types of cells are in the PNS?

Answer 15

2

Question 16

What are the two most important cells in CNS and PNS and what are they responsible for?

Answer 16

Schwann and ogliodendrocytes they are responsible for the production of myelin

Question 17

What are the three functions of myelin? CDS

Answer 17

A white fatty protein that covers most axons

Insulates the axons and slow degradation of the signal (charged ions)

Along the axon there are gaps between the stealth called nodes of ranveir where nerve impulses jump from one node to the next speeding up signal propagation

Question 18

where is neurilemma found? What is the function of neurilemma?

Answer 18

All nerve fibres in the PNS contain an additional wrapping called the neurilemma

The membrane helps regenerate damaged neurons that cut axons can join

Question 19

Grey vs white matter in the brain?

Answer 19

Grey matter contains mostly cell bodies while white matter contains relatively few cell bodies and is composed chiefly of myelinated white matter. The colour difference arises mainly from the whiteness of myelin

Question 20

Why do you think damage to grey matter is usually permanent?

Answer 20

Grey matter lack neurilemma to regenerate damaged cell bodies

Question 21

nerve transmission versus electricity transmission, where they travel, their strength, charges by, substances they carry

Answer 21

current electricity travels along a wire much like impulses travel along a nerve

electrical current is diminish along a wire but nerve impulses remind strong until the end

electrical wires rely on some type of outside energy source like a battery while nerves rely on cellular energy

nerve impulses are created by the movement of ions across the nerve cell membrane rather than the movement of electrons

Question 22

what is potential difference?

Answer 22

the voltage across part of a circuit

Question 23

what is action potential?

Answer 23

the difference of voltage created when a nerve is excited

Question 24

what is resting potential?

Answer 24

the difference in voltage across the nerve membrane when a nerve is not excited

Question 25

what do neurons have on either side of their membrane?

Answer 25

neurons have a rich supply of both positive and negative ions on either side of their membrane

Question 26

what charge can not pass the neuron membrane?

Answer 26

negative ions are largely impermeable and therefore have little affect on the overall charge

Question 27

what does the generation of an electrochemical gradient result from?

Answer 27

an electrochemical gradient results from the uneven distribution of positive ions on either side of the nerve membrane

Question 28

what is the easiest way to change membrane potential of Vm?

Answer 28

transport ions across the nerve cell membrane via specific channels

Question 29

how are sensory channels opened?

Answer 29

channels are opens mechanically form in response to physical forces of pressure and light

Question 30

how are gated ion channels opened?

Answer 30

gated ion channels open in response of the secreting of neurotransmitters

Question 31

how are voltage gated channels opened?

Answer 31

open in response to electrical potential of the membrane