(Wk2) The Nervous System

Question 1

What are the 4 organs involved in the nervous system?

Answer 1

Brain, Spinal Cord, Peripheral Nerves and the Sense Organs

Question 2

Name the 2 divisions of the nervous system.

Answer 2

CNS- Central Nervous System is composed of the brain and spinal cord.

PNS- Peripheral Nervous System is composed of nerves, sense organs and receptors (eyes, ears, touch, pain..etc)

Question 3

What are the functions of the CNS?

Answer 3

To process and coordinate sensory data, motor commands and higher functions of the brain (such as intelligence and emotions).

Question 4

What are the functions of the PNS?

Answer 4

To connect the nervous system with other systems, deliver sensory information to the CNS and carry motor commands to peripheral tissues and effectors.

Question 5

Describe Neural Tissue.

Answer 5

Is made up of 2 types of cells: Neurones and Neruoglia (glial cells).
And 2 types of matter: Grey and White matter.

Question 6

What are Neurones?

Answer 6

Cells that send and receive signals.

Question 7

What are Glial Cells (Neuroglia)?

Answer 7

Cells that support and protect neurons.

Question 8

What is grey matter?

Answer 8

Cell bodies and unmyelinated neurones

Question 9

What is white matter?

Answer 9

Axons of myelinated neurones.

Question 10

Describe the structure of a Neurone.

Answer 10

Has Dendrites, Perikaryon and Nucleus (Cell Body), Axon and Telodendria.

Question 11

What are the 4 Anatomical Classifications of Neurones?

Answer 11

-Anaxonic Neuron (have more than 2 proccesses; all dendrites)

-Bipolar Neuron (have 2 processes; separated by the cell body)

-Unipolar Neuron (single, elongated process; with cell body located off to the side)

-Multipolar Neuron (have more than 2 processes; single axon and multiple dendrites).

Question 12

Describe the neuroglia of the CNS.

Answer 12

Neuroglia in the CNS includes: Ependymal Cells, Astrocytes, Oligodendrocytes and Microglia.

Question 13

Describe Astrocytes

Answer 13

Star-shaped branching glial cells. They maintain the brain blood barrier and preserve the chemical environment by recycling ions and neurotransmitters.

Question 14

Describe Ependymal Cells

Answer 14

They line ventricles (brain) and central canal (spine); are involved in the production of cerebrospinal fluid.

Question 15

Describe Oligodendrocytes

Answer 15

Myelinate axons in the CNS and provide an overall structural framework.

Question 16

Describe Microglia

Answer 16

Remove cell debris, wastes and pathogens via phagocytosis.

Question 17

Describe the neuroglia of the PNS

Answer 17

Neuroglia in the PNS includes: Schwann Cells and Satellite Cells.

Question 18

Describe Schwann Cells

Answer 18

Myelinate axons in the PNS.

Question 19

Describe Satellite Cells

Answer 19

Regulate nutrient and neurotransmitter levels around neurons in ganglia.

Question 20

What is the function of dendrites in the structure of a motor neuron?

Answer 20

Thin extensions of the cell body that carry impulses received from neighbouring neurones to the cell body.

Question 21

What does the cell body consist of in the structure of a motor neuron?

Answer 21

Nucleus, Mitochondria and many ribosomes.

Question 22

What is the function of axon in the structure of a motor neuron?

Answer 22

Long cytoplasmic extension that carries impulses away from the cell body. It is covered in Schwann Cells, that support and surround the neurones.

Question 23

What is the function of myelin sheath in the structure of a motor neuron?

Answer 23

The layer of Schwann Cells. Acts as an electrical insulator to speed up the rate of transmission.

Question 24

What is the function of nodes of ranvier in the structure of a motor neuron?

Answer 24

These are the gaps in the myelin sheath. They occur between adjacent schwann cells.

Question 25

What is the resting membrane potential?

Answer 25

Is the difference in charge across the neuronal membrane when the neurone is at rest.
It is a result of different concentrations inside and outside the cell.
The resting membrane potential of a nerve cell is about -70mV.

Question 26

By which 3 factors is the resting potential maintained through?

Answer 26

1) The membrane containing many sodium-potassium pumps.

2) Potassium ion channels making the membrane permeable to potassium ions.

3) Anion (-) concentrations are higher inside the neuron.

Question 27

How is the resting potential created?

Answer 27

By the unequal distribution of ions, such as Potassium and Sodium, across the cell membrane.

Question 28

What is the electrochemical gradient?

Answer 28

The balance of forces acting upon an ionic species.
Na+: both electrical and chemical gradients attract Na+ into the cell.
K+: the chemical (out) and electrical (in) gradients oppose one another.

Question 29

What is the equilibrium potential of K+?

Answer 29

-90mV

Question 30

What is the equilibrium potential of Na+?

Answer 30

+70mV

Question 31

Describe passive (leak) channels

Answer 31

-Always partially open
-Contribute to the resting membrane potential.

Question 32

Describe gated (active) channels

Answer 32

-Open/Close in response to specific stimuli

-Exist in 3 possible states; closed but capable of opening, open, closed and incapable of opening.

There are 3 types of gated channels: chemically regulated, voltage regulated and mechanically regulated.

Question 33

What is a graded potential?

Answer 33

A temporary, localised change in the resting potential, caused by a stimulus.

Question 34

What is an action potential?

Answer 34

Rapid sequence of changes in the voltage across a membrane.

Question 35

What is a synapse?

Answer 35

Site of transmission of electric nerve impulses between 2 neurons

Question 36

What are the main 2 types of synapses?

Answer 36

Electrical and Chemical.