The Nervous System

Question 1

What does the CNS consist of and what are its functions?

Answer 1

Brain and spinal cord
Protected well against damage and injury through skull and vertebrae

Question 2

What is the CNS responsible for?

Answer 2

Interpreting sensory information and responds accordingly

Question 3

What are the functions of a brain stem?

Answer 3

Breathing
Consciousness
HR
Blood pressure
Sleep

Question 4

What are the 4 parts of brain stem?

Answer 4

The midbrain
The pons
The medulla oblongata
The diencephalon

Question 5

What is the PNS of the nervous system made up of?

Answer 5

Peripheral nervous system
Made up of the nerves that branch off from the spinal cord and extends to all parts of the body

Question 6

What is the structure and function of the midbrain?

Answer 6

Consists of nuclei and nerve fibres which connect the cerebrum with lower parts of the brain and with the spinal cord. The nuclei act as a relay stations for the ascending and descending nerve fibres and have important roles in auditory and visual reflexes

Question 7

What is the structure and function of the pons?

Answer 7

Consists of mainly nerve fibres that form a bridge between the cerebellum and fibres

The pons processes info from several cranial nerves

Relays messages from cortex to cerebellum

Question 8

What is the structure and function of the medulla oblongata?

Answer 8

The outer is composed of white matter which passes between the brain and spinal cord and grey matter lies centrally
Some medullary nerves relay info from the senses

Question 9

What is structure and function of the cerebellum?

Answer 9

It is ovoid in shape and has 2 hemispheres separated by a narrow strip called vermis
Controls and coordinates movements of skeletal muscles

Question 10

What is the function of the hypothalamus?

Answer 10

Controls the output of hormones from both anterior and posterior lobes of the pituitary gland
Controls:
Autonomic nervous system
Water balance
Emotional reactions
Circadian rhythms

Question 11

What is the function and structure of the thalamus?

Answer 11

Consists of 2 masses of grey and white matter within the cerebral hemispheres
It is the body’s information relay station and processes emotions and complex reflexes

Question 12

What are the 9 steps of action potential?

Answer 12

Resting potential = -70mv
Threshold = -50mv
Stimulus received
Stimulus changes voltage so that threshold is met
Opening of voltage gated sodium channels
Sodium moves into cell
Inside of cell becomes more positive (depolarisation)
Changes in voltage gated K+ channels
K+ leaves the cell
Inside of cell becomes more neg (repolarisation)
Return to resting membrane potential

Question 13

What are the 5 stages of synaptic transmission?

Answer 13

Arrival of action potential
Opens up voltage gates calcium channels
Ca enters cytoplasm
Triggers vesicles to move and fuse with nerve membrane
Neurotransmitters diffuse across synaptic cleft
Act on specific receptors on post synaptic neurone (on its dendrites)

Question 14

What are the 6 stages of neuromuscular transmission?

Answer 14

Action potential travels along the axon of the motor neuron.
Depolarisation of Na+ ions cause Ca+ channels to open
Ca+ diffuses into motor neuron
Choline reacts with acetylCoA from the mitochondria in the synaptic bulb releasing CoA
ACt then fuses with the synaptic vesicles leaving is exposed to the synaptic cleft
Meets motor endplate of the muscle causing the ligand gated Na+ channels to open
Na+ enters the motor end plate creating an action potential

Question 15

What is axonal conduction?

Answer 15

Process by which an action potential, or electrical signal is transmitted along the axon of a neuron
Myelin sheath present allows saltatory conduction to happen from one node of ranvier to the next as only they can be depolarised

Question 16

What is the circulation of CSF?

Answer 16

From the ventricles through the subarachnoid space around the brain and spinal cord

Question 17

Where is CSF produced?

Answer 17

In a structure called choroid plexus in the lateral, 3rd and 4th ventricles

Question 18

How do sensory receptors convey information to the nervous system?

Answer 18

Sensory receptors are stimulated by a stimulus producing an electrical signal called action potential
Action potential is conducted along the axon away from the sensory receptors towards the CNS
When action potential is at the end of the axon it triggers release of neurotransmitters into the synapse
The neurotransmitters bind to receptors on the dendrite of the next neuron causing an electrical signal to be generated in the neuron
Process is repeated as the signal is transmitted along the neural pathways to the CNS where it is interpreted and processed

Question 19

Illustrate a simple spinal reflex

Answer 19

1. Tap the patella tendon on the knee
2. Stretches muscle fibres in the quadricep
3. Stretch stimulates muscle spindles which sends signals to spinal cord
4. Intercepted by interneurons
5. Interneurons to motor neurons.
6. Motor neurons make quadricep contract
7. When they contract is causes it to extend the leg at the knee
   This equals knee jerk reflex

Question 20

What are the differences in the functions of the sympathetic and parasympathetic divisions of the autonomic nervous system?

Answer 20

Autonomic - unconscious actions, HR, digestion, respiration
Sympathetic - ‘’fight or flight’’, activated in response to stress or danger
It increases HR, BP, respiration.
Causes pupils to dilate
Parasympathetic - ‘’rest and digest’’ system as it is activated in response to relaxation or food - decreases HR, BP, promotes rest and repair functions
Pupils constrict