CNS, brain structure, AP, synaptic transmission

What is the nervous system?

A network of cells that form the basis for our psychological experiences.

What is the CNS made up of?

Brain and spinal cord

What is the function of the CNS?

To control behaviour and regulate the body’s physiological processes like breathing.

What is the brain?

The centre of all consciousness and it deals with higher order thinking like memory.

What is the spinal cord?

A collection of nerve cells attached to the brain and run the length of the spinal column.

What is the function of the peripheral nervous system?

To transmit millions of neurons to and from the CNS.

What is the peripheral nervous system made up of?

Everything except the brain and spinal cord.

What are the 2 sub-divisions of the peripheral nervous system?

Autonomic nervous system

Somatic nervous system

What is the autonomic nervous system responsible for?

Automatic responses like fight or flight.

What is the somatic nervous system responsible for?

Voluntary actions

What structures is the neuron made up of?

Dendrite

Nucleus

Cell body

Axon

Myelin Sheath

Nodes of Ranvier

Axon terminal

What is the function of the dendrite?

To collect signals from other surrounding neurons

What is the function of the cell body?

To collect signals into one stronger signal

What is the function of the axon?

To carry the electrical nerve impulse down the length of the cell

What is the function of the myelin sheath?

Acts as insulation to speed up the conduction of the impulse and keep it travelling in one direction

What is the function of the nodes of Ranvier?

Gaps between the myelin sheath to speed up the impulse

What is the function of the axon terminal?

To pass on the impulse to the next neuron

What are the 4 lobes of the brain?

• Frontal lobe

• Temporal lobe

• Parietal lobe

• Occipital lobe

• Cerebellum

What is the function of the frontal lobe?

• Higher order thinking

• Emotional control

• Decision making

What is the function of the temporal lobe?

• Auditory info

• Memory

What is the function of the parietal lobe?

• Sensory info

• Physical sensation e.g skin contact and movement

What is the function of the occipital lobe?

Visual info

What is the function of the cerebellum?

Co-ordinating motor movement e.g balance

What are action potentials?

Electrochemical impulses that travel along axons in one direction only, carrying information.

What is the resting membrane potential of a neuron?

\-70mV

What does the neurons negative resting membrane potential mean?

It is negatively charged compared to outside of the cell.

At what voltage is an action potential triggered?

\-55mV

What does the All-or-None principle state?

If a neuron doesn’t reach -55mV the action potential will not occur.

What happens after the neuron reaches -55mV?

The action potential sends an impulse along the axon towards the axon terminal where it carries on to the next neuron.

What does depolarisation mean?

Ions move in and out of the membrane causing it to become less negative.

What does repolarisation mean?

The membrane gets more negative.

What happens after repolarisation?

A refractory period of hyperpolarisation.

Describe the process of synaptic transmission.

• AP comes down the axon to the axon terminal

• A vesicle full of neurotransmitters releases them into the synaptic cleft

• Neurotransmitters drift across the gap and bind to a receptor

• AP is passed onto the next neuron

• Some of the neurotransmitters are degraded by enzymes, others are carried back to the pre-synaptic neuron by transporter proteins- called reuptake

What are the 3 things that can happen to neurotransmitters in the synaptic cleft?

• Bind to a receptor

• Degraded by enzymes

• Carried back to the pre-synaptic neuron by transporter proteins (reuptake)

What are neurotransmitters?

Chemical messengers that act between the neurons in the brain. This allows the brain to process thoughts and memories.

What are synapses?

Gap between neurons

What mechanism do receptors work on?

Lock and key