DP 1-5 CENTRAL NERVOUS SYSTEM

Question 1

CNS

Answer 1

The human nervous system is a complex, highly organised network of specialised cells that enables the brain to receive information from the body's internal and external environments. 
Its three main functions are to:
- Receive information (from PNS)
- Process information
- Coordinate a response to information

Question 2

Brain

Answer 2

• Regulates vital body functions - breathing, heart rate, digestion
• Receiving information from the outside world via the senses and coordinating appropriate response
• Organises, integrates and interprets information

Question 3

Spinal cord

Answer 3

• A cable like column of nerve fibres that extend from the base of the brain to the lower back
  Two direction highway
• Receives sensory information from the PNS to the brain for processing
• Receives motor information from the brain to the PNS

Question 4

PNS

Answer 4

• The complete network of neurons located outside the central nervous system comprising of muscles, organs and glands
• Carries information to the CNS from the body’s muscles, organs and glands
• Carries information from the CNS to the body’s muscles, organs and glands
  Somatic and autonomic division

Question 5

Somatic division

Answer 5

• Responsible for conscious, voluntary movement of skeletal muscles
• Carries motor information from the CNS to skeletal muscles signalling them to expand or contract.
• Carries sensory information from the sensory receptor sites to the CNS

Question 6

Autonomic division

Answer 6

• Regulates automatic/involuntary operations of non-skeletal muscles concerned with internal bodily functioning.
• is relatively self-regulating.
  Sympathetic and parasympathetic division

Question 7

Sympathetic division

Answer 7

• Activates the internal muscles, organs and glands to prepare the body for vigorous activity or to deal with a stressful or threatening situation
• The sympathetic nervous system releases adrenaline and increases responsiveness. To allow this to happen other physiological functions are suppressed
• Is the emergency or arousal system.
• Activated the fight-flight-freeze response

Question 8

Parasympathetic division

Answer 8

• Is responsible for maintaining autonomic day to day bodily functions (digestion, heart rate. breathing rate etc)
• It counterbalances the sympathetic nervous system by returning the body to a state of calm, once the cause of stress of threat is no longer present
• It maintains homeostasis in times of low stress.

Question 9

Flight - flight - freeze

Answer 9

• The fight-flight-freeze response is initiated by the sympathetic nervous system and prepares the body to confront a stressful situation to optimise the chance of survival
• Which mechanism is adopted is depends on the likelihood of survival in each situation; fight - stay and attack, flight - run, freeze - go unnoticed or detected

Question 10

Conscious response

Answer 10

• A reaction that involves awareness
• Usually a voluntary or intentional reaction
• Usually goal-directed or purposeful
  Eg. when you go outside and feel the air temp, you’ll make a conscious decision whether to put on a jacket

Question 11

Unconscious response

Answer 11

• A reaction that does not involves awareness
• It is involuntary, unintentional, automatic and we cannot ordinarily control its occurrence
  Eg. heart beating, eyes blink

Question 12

Reflex arc

Answer 12

• Is an unconscious, involuntary and automatically occurring response to certain stimuli initiated within the spinal cord without any involvement of the brain
• Whilst a spinal reflex arc is initiated, sensoy messages continue to the brain. Pain can not be felt until the messages reach the brain, although the motor response has already occurred. This ensures we learn from past experiences

Question 13

Dendrite

Answer 13

• The dendrite is a short, thin, widely branching nerve fibre that is specialised to detect and receive neural information in a chemical form from other neurons
• Each branch has a receptor site where a neuron can bind with and receive information from

Question 14

Axon (send)

Answer 14

• An axon is a single, tube-like fluid filled extension that transmits neural information to other neuron in the form of an electrical impulse
• The pathway down which the neural message travels

Question 15

Myelin Sheath

Answer 15

Is a white fatty substance that encases the axon that helps speed up transmission
→ acts as an electrical insulator
→ increase the rate at which this information travels
This protects the neural message and increases the speed at which it can travel

Question 16

Axon Terminal

Answer 16

• At the end of each axon are branches called axon terminals.
• They form a synapse with the next neuron.
• This is where neurotransmitters are released.

Question 17

Synapse

Answer 17

• Is the site where communication occurs between adjacent neurons
• Includes the terminal buttons of the presynaptic (sending) neuron and the dendrites of the postsynaptic (receiving) neuron

Question 18

Excitatory neurotransmitters

Answer 18

Stimulate or activate postsynaptic neurons to perform their function

Question 19

Glutamate

Answer 19

Essential for memory formation and learning

Question 20

Inhibitory neurotransmitters

Answer 20

Block or prevent postsynaptic neurons from firing

Question 21

GABA

Answer 21

Essential for motor control, vision and decreasing anxiety

Question 22

Lock and key process

Answer 22

• Like a key in the lock, a neurotransmitter’s shape (key) must precisely match the shape of the receptor site (lock) on the postsynaptic neuron’s dendrites in order to bind to its receptors
• The binding ‘unlocks’ the postsynaptic neuron’s response so that the neurotransmitter causes changes to the neuron, resulting in an excitatory or inhibitory effect

Question 23

Parkinson’s Disease

Answer 23

Parkinson’s disease is progressive degenerative neurological condition that affects both motor and non-motor functions. It is caused by low levels of dopamine

Question 24

Dopamine

Answer 24

• Dopamine is an excitatory neuron involved smooth motor movement.
• Neurons in the substantia nigra produce the neurotransmitter dopamine, so when the substantia nigra is diseased, the amount of dopamine available is reduced.
  Dopamine carries messages that allow smooth, coordinated function of the body’s muscles and movements, when at rest and during periods of activity.

Question 25

Symptoms

Answer 25

``` Motor symptoms - Resting tremors - Bradykinesia (slowness of voluntary movement) - Muscle rigidity - Postural instability Non-motor symptoms - Loss of sense of smell (anosmia) - Depression - Anxiety ```

Question 26

Agonist

Answer 26

A drug that binds to the receptor as it has a similar size and shape to the neurotransmitter so it can act as a neurotransmitter. Used for loss of neurotransmitter

Question 27

Antagonist

Answer 27

A drug that binds to the receptor as it has a similar size and shape but not enough to activate the neuron. Used for excess neurotransmitter