Week 2 - topic 1

Question 1

Central nervous system

Answer 1

contains the brain and spinal cord

• motor nerves allow actions to be completed, triggered by the central nervous system

Question 2

Peripheral nervous system

Answer 2

contains the nerves and most sensory organs

• sensory nerves relay sensory information towards the central nervous system

Question 3

Nerves

Answer 3

• bundles of individual neurons contained within a protective membrane.
• They act a little bit like an electrical cable sending messages to and from the CNS to the rest of the body
• sensory neurons, motor neurons and internneurons

Question 4

Parts of a neuron

Answer 4

The neurons of the nervous system are the parts that do the talking (information transmitting).
Neurons normally contain the following elements:
- Soma (Cell Body)
- Dendrites
- Axon
- Terminal Buttons

Question 5

Soma

Answer 5

• cell body
• Contains the nucleus of the cell and the machinery involved in the life process of the cell.
• Soma shape varies in different neuron types.

Question 6

Membrane

Answer 6

• Made of Double layer of lipid (fatlike) molecules
• Protein molecules embedded in membrane
• Substance detectors and Security Guards
• Transporting substances in and out of the cell

Question 7

Cytoplasm

Answer 7

• Jelly-like substance that fills the space surrounded by the membrane including the soma
• Contains organelles

Question 8

Nucleus

Answer 8

An organelle

• Contains the chromosomes
• Chromosomes consist of DNA
• Genes contain recipes for individual proteins
• Proteins important for structure and function
• > Serve as Enzymes

Question 9

Mitochondria

Answer 9

An organelle

• Extract energy from nutrients
• Produce a chemical called Adenosine Triphosphate (ATP)

Question 10

Dendrites

Answer 10

Dendrites help individual neurons talk with one another

Question 11

Neural messages

Answer 11

Neural messages are transmitted from neuron to neuron across the synapse (synaptic cleft).
*look up image
Message = action potential

Question 12

Axon

Answer 12

Long tube that carries information from the soma of a neuron to it’s terminal buttons

Question 13

Axoplasmic transport

Answer 13

• Items are moved around the cell via axoplasmic transport
• There are two types of axoplasmic transport:
• > Anterograde transport: movement from cell body to terminal buttons
• > Retrograde transport: movement from the terminal buttons to the cell body

Question 14

Internal structure of neuron

Answer 14

*look up image

Question 15

Microtubules

Answer 15

• bundles of protein filaments arranged in a hollow core
• train tracks to propel substances down axon
• to track and transport proteins for axoplasmic transport

Question 16

Myelin sheath

Answer 16

• fatty substance that works as an insulator of the action potential
• stop message information being lost

Question 17

Terminal buttons

Answer 17

Located at the end of an axon

Secrete a chemical into the synapse = neurotransmitter

Question 18

Supporting cells in the nervous system

Answer 18

• neurons are roughly half of the nervous system
• There are lots of supporting cells in the nervous system (NS).
• The NS needs supporting cells because neurons have to be constantly supplied with nutrients and oxygen by the other cells in the NS to stay alive.

Question 19

Glial cells

Answer 19

Glial Cells (means glue in Greek). (neuroglia)

• supporting cell
• Help hold neurons in place and control supply of nutrients + some chemicals used in neuronal communication
• Insulation - make sure messages don’t get scrambled
• Destroy and remove dead neurons

Question 20

Types of glia in CNS

Answer 20

Astrocytes (star cells)
Oligodendrocytes
Microglia

Question 21

Astrocytes

Answer 21

• star shaped glial cells
• Provide nutrients and other substances to neurons
• Regulates chemical composition of extracellular fluid (fluid surrounding neurons)
• take up and release substance to ensure balance is maintained in cellular fluid
• Surround synapses to ensure good communication between neurons
• Clear up debris from dead neurons = phagocytosis

Question 22

Phagocytosis

Answer 22

• process of cell engulfing and digesting dead cells and debris

Question 23

Oligodendrocytes

Answer 23

• Provide support to axons and produce the myelin sheath that surrounds axons and insulates them
• Nodes of Ranvier = naked portion of myelinated axon

Question 24

Microglia

Answer 24

• are very small glial cells involved in phagocytosis and help protect the brain from invading microorganisms.
• important for inflammatory response in response to brain damage
• form part of brains immune system

Question 25

Supporting cells in the peripheral nervous system

Answer 25

- The peripheral nervous system also contains supporting cells called Schwann Cells. - They are similar in function to the oligodendrocytes in the CNS. - Schwann cells produce myelin that cover most axons in the PNS. Just like the CNS, the myelin is segmented in the PNS. - Each segment of myelin in the PNS is a single Schwann cell, wrapped entirely around the axon many times - The chemical composition of myelin in the PNS is different to that of the CNS. Clinically, this is important for the condition multiple sclerosis (MS). It is an autoimmune disease that occurs to myelin in the CNS and not the PNS

Question 26

The blood brain barrier

Answer 26

- The Blood Brain Barrier (BBB) is a barrier exists between the blood and the fluid that surrounds the cells of the brain. - Selectively Permeable - The main function of the BBB is to help regulate the composition of the fluid surrounding cells (extracellular fluid) in the brain.

Question 27

How does the BBB keep the balance?

Answer 27

- Throughout most of the body, cells that line the smallest blood vessels are loosely packed - Gaps between cells allows substances to move between the blood and the fluid that surrounds cells of the body - In the CNS there aren’t gaps between the cells that line the smallest blood vessels - Many substances cannot leave the blood and enter the brain - > Tightly packed cells = BBB

Question 28

Structure of BBB

Answer 28

- The BBB isn’t uniform throughout the CNS. - BBB is thinner at the area postrema (initiates vomiting). - this is so neurons can easily detect toxic substances in blood and imitate vomiting if you have been poisoned - composition of extracellular fluid must be regulated otherwise communication in brain can be thrown off