Week Seven - Cells, Electrical Signaling And Synaptic Transmission

Question 1

What are the cells in the brain?

Answer 1

Nerve cells (neurons) and support cells (glial cells)

Question 2

Out of neurons and glial cells, which is present in a greater amount?

Answer 2

Glial cells

There are 100 billion neurons, but many more glia

Question 3

What makes neurons different to other cells in the body?

Answer 3

• They can communicate with other cells (neurons, muscle cells or gland cells)
• they have a cell membrane that is specialised to receive and transfer information

Question 4

What is the function of a neuron cell body?

Answer 4

• carries out the living processes of neurons

- Contains important organelles that help to carry out life processes

Question 5

What are the important organelles in the neuron cell body

Answer 5

• nucleus
• Mitochondria (which are found anywhere in the cell)
• Endoplasmic reticulum & Golgi apparatus

Question 6

What is the function of the neuron nucleus?

Answer 6

controls and regulates the activities of the cell

Question 7

What is the function of the mitochondria?

Answer 7

-provides the cell with energy that allows it to complete processes
(production of chemicals (neurotransmitter), formation of new synapses, growth of nerve fibres)

Question 8

What is the function of the endoplasmic reticulum and Golgi apparatus?

Answer 8

• produces and releases chemical substances (e.g., neurotransmitters)
• these are then packed in small vesicles (sacs) and transported to axon terminals

Question 9

What is the axon hillock?

Answer 9

• The initial segment of the axon that is never covered in a myelin sheath
• Region where nerve impulse is generated

Question 10

What happens at an axon terminal?

Answer 10

• It is the region where neurotransmitters are stored and released
• synaptic contacts with other cells (neurons, muscle cells or gland cells)

Question 11

What are the two main functions of an axon?

Answer 11

• signal transfer

- axonal transport

Question 12

What is signal transfer?

Answer 12

-one of the axon’s main functions

• transfers information from the cell body towards the axon terminal
• information in the from of an electromagnetic impulse and spreads along the cell membrane

-velocity of signal transfer depends on the axon being myelinated or not

Question 13

What is axonal transport?

Answer 13

• the carrying of important materials between the cell body and axon terminals
• vesicles, proteins, lipids, mitochondria and other organelles
• they carry these via microtubles, which are small pipes which reach from cell body to axon terminals
• substances can travel in both directions
• anterograde transport- cell body to axon terminals
• retrograde transport - axon terminals to cell body

Question 14

True/false herpes virus and other viral infections can enter the cell body via diffusion

Answer 14

False, they can enter through axonal transport

Question 15

What is the protein that hold microtubles together?

Answer 15

• Tau protein

* holds the microtubles together and keeps them parallel and straight

Question 16

What is thought to be the cause of Alzheimer’s disease

Answer 16

• tau proteins diarrange

- abnormal clusters of protein fragments (plaques) build up between neurons

Question 17

What is a dendrite?

Answer 17

• they receive signals and bring information to the cell body
• processes covered in dendritic spines that create a synapse with axon terminals of other neurons

Question 18

What is a synapse

Answer 18

-location where neurons transfer information to other cells

Question 19

True / false neurons can vary in size or shape

Answer 19

True

Question 20

What is the function of glia cells?

Answer 20

• create structural support for the brain

- serve to support and protect the neurons

Question 21

What are the main types of glia cells?

Answer 21

• astrocytes
• microglia
• oligodendrocytes and Schwann cells
• ependymal

Question 22

Astrocytes

Answer 22

• bloodbrain barrier
• allows the entry of essential nutrients while blocking harmful substances into the neuron
• responsible for transporting nutrients to neurons
• responsible for forming scar tissue

Question 23

Microglia

Answer 23

• cleans up the CNS

* can detect damaged/unhealthy neurons or foreign invaders and digest them

Question 24

Oligodendrocytes

Answer 24

• provide the myelin sheath
• can make contact with up to a dozen axons
• without myelin, signal would travel 30 times slower

Question 25

What is multiple sclerosis?

Answer 25

• a disease where the myelin degenerates (only CNS effected)
• effects signal transfer
• leads to movement disorders

Question 26

Schwann cells

Answer 26

• myelinated axons in the PNS

- make contact with only one axon and provide only a single segment of myelin

Question 27

Ependymal Cells

Answer 27

Line the

• ventricles in our brain
• central canal of the spinal cord
• choroid plexus

-barrier between the brain tissue (I.e., neurons & glial cells) and cerebrospinal fluid

Question 28

The inside of the neuron is more … than the outside when at rest

Answer 28

Negatively charged

Question 29

What are the important ions involved in electrical signalling?

Answer 29

• potassium
• sodium
• calcium
• chloride

Question 30

When a neuron is at rest a ion channel

Is…

Answer 30

Closed

Question 31

What is the ion distribution along the neuron?

Answer 31

-all have potassium and sodium

• axon terminals - calcium
• soma and dendrites - chloride

Question 32

When a neuron is not sending a signal

Answer 32

The membrane potential is about -70 millivolts

Question 33

What is the reason for the difference of potential?

Answer 33

The inside contains negative protein molecules that are too large to leave