Nervous system

Question 1

Components

Answer 1

Brain, spinal cord, peripheral nerves, sensory nerves

Question 2

Functions

Answer 2

• Directs immediate response to stimuli
• Coordinates activity of other organ systems
• Provides and interprets sensory information
• Controls thoughts and emotions

Question 3

CNS vs PNS

Answer 3

PNS
- Somatic (voluntary) and autonomic (involuntary)
- Autonomic > Parasympathetic and sympathetic branch
- Para - rest and digest
- Sympathetic - fight or flight

Question 4

What do neurons do in the CNS?

Answer 4

• Measures environment
• Make decisions and sends orders

Question 5

CNS nervous tissues

Answer 5

• Neuroglia
• Microglia
• Ependymal cells
• Astrocytes

Question 6

Peripheral nervous system nervous tissues

Answer 6

• Oligodendrocytes
• Schwann and satellite cells

Question 7

Structure of a neuron

Answer 7

Nucleus, dendrite, soma (cell body), acetylcholine, myelin sheath, axon, nodes of ranvier, axon terminal, synapse

Question 8

Depolarisation

Answer 8

Inside of the cell becomes less negative relative to outside

Question 9

Hyperpolarisation

Answer 9

Inside of cell become more negative relative to outside

Question 10

Graded potentials

Answer 10

Localised changes in membranes potential (depolarisation or hyperpolarisation)

Question 11

Action potentials

Answer 11

Rapid, substantial depolarisation of the membrane

Question 12

Potassium in

Answer 12

Sodium out

Question 13

Protective mechanisms - Muscle spindles structure

Answer 13

Specialised muscle fibre
- Lie between + connected to regular skeletal muscle fibres
- Middle of the spindle can only stretch not contract

Question 14

Protective mechanisms - Muscle spindle function

Answer 14

Reflexive muscle contraction triggered to resist further stretching
- Muscles attached to the spindle are stretched
- Neurons on spindle transmit information to the CNS about the muscle length

Question 15

Protective mechanisms - Golgi tendon organs overview

Answer 15

• Encapsulated sensory organ through which tendon fibres pass
• Located close to tendons attachment to the muscle
  INJURY PREVENTION AGAINST LIFTING TOO HEAVY

Question 16

Protective mechanisms - Golgi tendon organs function

Answer 16

INJURY PREVENTION AGAINST LIFTING TOO HEAVY
- Sense small change in tension
- Inhibit agonist and excite antagonist

Question 17

Force gradation

Answer 17

Ability for muscles to produce varying levels of force/contraction depending on the demands of the task
AKA more force for a heavier object, less force for a lighter object

Question 17

Motor unit recruitment with force gradation

Answer 17

More muscle fibres activated
More motor units = more force

Question 18

Rate coding with force gradation

Answer 18

Firing faster
The motor units fire more frequently to increase force (low firing rate = small, weak, twitch like contractions)

Question 18

Motor unit recruitment small vs large

Answer 18

Small motor units (slow twitch) are activated first, however as more force is needed, larger motor units (fast twitch) are recruited too
Adding more cells to provide more force

Question 19

Rate coding

Answer 19

If the rate increases, the twitches overlap so that the contraction is smooth and strong

Question 20

Difference between rate coding and recruitment

Answer 20

Recruitment - How many muscle fibres are activated
Coding - How often they fire
Both are a mechanism
Both work together to produce smooth, controlled movement

Question 21

What part of the brain causes movement

Answer 21

Pre motor cortex
Left side of brain controls right side of body
Right side of brain controls left side of body

Question 22

Phases of movement - 1. Motor cortex

Answer 22

Decision and initiation in the brain
- Premotor cortex - Plans movement
- Basal ganglia - Starts motion
- Cerebellum - Smooth coordinated movement

Question 23

Phases of movement - 2. Signal travels down the CNS

Answer 23

Upper motor neuron carries movement command from brain to spinal cord - Primary motor cortex sends signal - It moves through internal capsule down the brainstem - At the medulla oblongata, the signal crosses over at the pyramids

Question 24

Phases of movement - 3. Reaching the spinal cord

Answer 24

Travels down corresponding nerve and exits either at the lumbar, thoracic or cervical region

Question 25

Phases of movement - 4. Lower motor neuron activation

Answer 25

- Lower motor neuron exits the spinal cord - Travels through a nerve network - The musculocutaneous nerve carries the signal directly to the muscle

Question 26

Phases of movement - 5. Neuromuscular junction: Signal reaches the muscle

Answer 26

(connection between a motor nerve and muscle fibre) - At the NM junction, the motor neuron releases acetylcholine - ACh binds to receptors on muscle fibre - Sodium enters (generates action potential) - Action potential spreads via T-tubules, triggering calcium release from sarcoplasmic reticulum

Question 27

Phases of action potential 1. Resting potential

Answer 27

The neuron at rest with negative internal charge (-70mV) Maintain this state with 3 sodium out, 2 potassium in

Question 28

Phases of action potential 2. Depolarisation

Answer 28

If stimulus reaches threshold (-55mV), sodium channels open Sodium rushes into neuron, making inside more positive

Question 29

Phases of action potential 3. Repolarisation

Answer 29

Potassium gates open and flows out of the neuron (inside of neuron now negative)

Question 30

Phases of action potential 4. Hyperpolarisation

Answer 30

Potassium channels close slowly, membrane becomes slightly more negative than resting potential

Question 31

Phases of action potential 5. Returning to resting potential

Answer 31

Sodium-potassium pumps restore the original balance, bringing neuron back to resting state