L5 Nervous System Structure and Function

Question 1

what are the 6 main regions of the brain?

Answer 1

Medulla Oblongata 
Pons
Midbrain
Cerebellum
Diencephalon
Telencephalon

Question 2

How does the medulla oblongata contribute to voluntary control of movement?

Answer 2

control of automatic function relaying signals between the brain and spinal cord

coordination of body movement

Question 3

How does the Pons contribute to voluntary control of movement?

Answer 3

• Sleep and control of autonomic

- Relays sensory info between cerebellum and cerebrum

Question 4

How does the Midbrain contribute to voluntary control of movement?

Answer 4

connects pons and cerebral hemispheres.

Controls responses to sight, eye movement, body movement and hearing

Question 5

How does the Cerebellum contribute to voluntary control of movement?

Answer 5

Comparing, evaluating and integrating centre for postural adjustments and reflex-related movement

Question 6

How does the Diencephalon contribute to voluntary control of movement?

Answer 6

thalamus, hypothalamus, epithalamus and subthalamus

Hypothalamus - regulates body temperature and metabolic rate

Question 7

How does the Telencephalon contribute to voluntary control of movement?

Answer 7

Has 2 hemispheres of cerebral cortex including the corpus striatum and medulla

Question 8

what is the hierarchy of motor control

Answer 8

1. Motor cortex - direct motor control. major output pathway to spinal motor neurons
2. Cerebellum - Modulates movement accuracy
3. Basal Ganglia - strategic aspects of movement

Question 9

what is the spinal cord protected by? What does it attach to ?

Answer 9

protects by the vertebral column

attaches to the brainstem

Question 10

what are the 3 types of neurons the spinal cord contains?

Answer 10

motor neurons
sensory neurons
interneurons

Question 11

what are the 2 main tracts in the spinal cord?

Answer 11

Pyramidal (lateral) tract

Extrapyramidal (ventromedial) tract

Question 12

what are the 4 things that a motor neuron consists of

Answer 12

1. cell body - contains nucleus
2. Dendrites - conduct impulses toward cell body
3. Axon - carries impulse AWAY from the cell body
   - Can be covered in Schwann cells - that form the myelin sheath
4. Synapse - contact points between axon and dendrite of another neuron

Question 13

Resting membrane potential of a nerve cell:

Negative charge inside cells at rest (polarised) -40 to -75

What is this determined by?

What is this maintained by?

Answer 13

Determined:

• permeability of plasma membrane to ions
• Difference in ion concentrations across membrane - Na+ K+ Cl- and Ca+2

Maintained:

• Potassium tends to diffuse out of the cell
• Na+/K+ pump moves 2K+ in and 3Na+ out

Question 14

Action potentials occur when….

What does this then cause?

Answer 14

occurs when a stimulus of sufficient strength depolarises the cell.

this causes the opening of Sodium channels and the sodium floods into the cell. The inside therefore becomes more positive

Question 15

What is repolarization and what happens here?

Answer 15

the return to resting membrane potential

Potassium leaves the cell and the sodium channels close

Question 16

what is the neuromuscular junction?

Answer 16

interface between the end of a myelinated motor neuron and a muscle fibre; transmits nerve impulse to initiate muscle action

Question 17

what do excitatory postsynaptic potentials do? what 2 summations can these be?

Answer 17

cause depolarization

Temporal summation - sum of several different EPSPs from one presynaptic neuron
Spatial Summation - sum of several different presynaptic neurons

Question 18

What is the structure, function and action of the muscle spindles

Answer 18

Structure –> Intrafusal fibres that are parallel to normal muscle fibres. Gamma motor neurons that stimulate the Intrafusal fibres to contract with the extrafusal fibres

Function = responds to changes in length of the muscle

Action = Stretch reflex = stretch of muscle causes reflex contraction eg knee-jerk reflex

Question 19

What is the structure, function and action of the Golgi Tendon Organ

Answer 19

Function = monitors tension developed in the muscle to ensure the muscle isn't damaged during excessive force
Action = stimulation results in reflex relaxation of muscle. Ability to voluntarily oppose GTO inhibition may be related to gains in strength 

Structure - capsule of extrafusal fibres within the musculotendinous junction. One end connects to the muscle fibres. The other connects to the tendon

Question 20

what are the muscle chemoreceptors and the mechanoreceptors sensitive to?

Answer 20

Chemo = sensitive to changes in the chemical environment around the muscle
Mechano = sensitive to muscle contraction and stretch

Question 21

Describe the Structure and function of the autonomic nervous system

Answer 21

Function = maintains internal environment, organs not under voluntary control 
Structure = Has sympathetic and parasympathetic divisions

Question 22

What to the sympathetic and parasympathetic divisions do?

Answer 22

Sympathetic = noradrenaline. Excites effector organ . Fight or flight
Para = acetylcholine. Inhibits effector organ. Rest and digest