What is the brain made of

Question 1

what are neurons?

Answer 1

electrically excitable cell and communicate with other cells via specialized connections called synapses

Question 2

what is glial cells?

Answer 2

non-neuronal cells in the nervous system that maintain homeostasis, form myelin, and support and protect for neurons

Question 2

features of neurons

Answer 2

1. neurons typically have a cell body that contains the nucleus
   2.the cell body has filaments on it called dendrites
2. a single long projection originate from the cell body – this is the axon
   4.the axon can be covered in myelin a fatty sheath that makes electrical signals pass more quickly
   5.the axon ends in axon terminal. these contact the dendrites of other neurons and so information is passed through the nervous system

Question 3

how does the electrical charge move between neurons?

Answer 3

1.information passes from the cell body to the axon terminals via an electrical signal called an action potential.

2.signals arrive at the dendrites – these signals change the electrical charge of the cell (up and down).

3.if the charge reaches a set point – threshold – an action potential occurs and travels down the axon.

4. this is a single punctate event, so information is coded by the rate of firing of action potentials

Question 3

how do neurons communicate between each other?

Answer 3

1.when an action potential reached the axon terminals it causes calcium to enter the terminal.

2. this causes synaptic vesicles containing neurotransmitters to bind to the cell membrane and release their contents into the synaptic cleft.
3. the neurotransmitter binds to specialist receptors on the dendrites of the next neurone.
4. If the neurotransmitter is inhibitory this lowers the charge in the receiving neurone, if the neurotransmitter is excitatory it increases the charge in the receiving neurone.
5. If the charge in a receiving neurone passes the threshold the neuron will fire a action potential.

Question 4

5 types of glial cells

Answer 4

1.astrocytes
2.Oligodendrocytes
3.Schwann cells
4.microglia
5.ependymal cells

Question 5

Astrocytes

Answer 5

1.regulate chemicals around neurones * regulate glucose * regulate ion concentrations * neurotransmitter uptake
2. regulate blood flow around the brain * vasomodulation
3. nervous system repair * following injury astrocytes fill spaces in the nervous system creating glial scars.
4. maintenance of the blood-brain barrier

Question 5

Oligodendrocytes

Answer 5

1.form the myelin sheath on axons in the central nervous system.
2.myelin is a fatty, protein rich sheath that wraps around axons.
3.each oligodendrocyte can myelinate up to 50 axons It is these cells that are attacked in multiple sclerosis.

Question 6

Schwann cells

Answer 6

1.form myelin in the peripheral nervous system.
2.assist in regeneration & regrowth of axons.
3.myelin allows axon potentials to propagate more quickly.
4.unmyelinated speeds - 0.5 to 10 m/s - slow. * myelinated speeds up to 150 m/s - fast.

Question 7

microglia

Answer 7

1.are the brains immune system. 2.scavenge the central nervous system for plaques, damaged cells and infectious agents

Question 8

ependymal cells

Answer 8

1.myelin is a sheath that insulates many neurones
2.it is made of fat and proteins and is white.
3.because of this parts of the brain that are many made up of axons are white (white matter)

Question 9

White matter

Answer 9

1.myelin is a sheath that insulates many neurones
2.it is made of fat and proteins and is white.
3.because of this parts of the brain that are many made up of axons are white (white matter)

Question 10

grey matter

Answer 10

1.the areas of the brain that contain mainly the cell bodies of the neurons - nuclei, ganglion, cortex - appear pink in the fresh tissue, but grey in perfused (grey matter).