Nervous System 1

Question 1

What is the only muscle that you can control?

Answer 1

Skeletal muscle

Question 2

Types of motor neurones and location ?

Answer 2

1. Upper motornuerones - found entirely within the CNS

2. Lower motorneurones - communicate with the muscle tissue, cause to contract

Question 3

Where does the intention to move come from ?

Answer 3

1. Cortex / premotor area - involved with planning of movement, in front of primary motor area
2. Primary motor area - converts plan to actual muscle contractions , in front of central sulcus

Question 4

What are is the direct descending pathways ?

Answer 4

1- Direct pathway - axon travels straight down spinal cord and comes from precentral gyrus, 3 types;

1. lateral corticospinal tract - axon travels down side of spine and cross in medulla oblangata, complex movements in limbs
2. anterior corticospinal tract - axon travels down front of spine and cross in spinal cord, neck and muscles in torso
3. corticobullar tract - axon travels to brainstem will sometimes cross in brainstem, facial muscles

Question 5

What is the indirect pathway? Cortex of brain - ? - spinal cord

Answer 5

2- indirect pathway - axons take a different path, provide stability and posture, and autonomous processes like walking
- involves a variety of subcortical nuclei (cluster of nerve cells) in the brain a.k.a basal ganglion
3 parts of basal ganglia ;
1. Caudate nucleus + 2. Putamen = neostratium
3. Globus pallidus

4. Extra part = substantia niagra = separate structure but interacts with basal ganglia

Question 6

What are the excitatory and inhibitory neurotransmitters and where are they released in the indirect pathway ?

Answer 6

1. Glutamate - excitatory = neostriatum
2. GABA - inhibitory = substantia nigra
3. Dopamine - inhibitory = neostriatum
4. ACh - excitatory = neostriatum

Question 7

What are the 2 neural conditions affected by the pathway ?

Answer 7

Huntington’s disease and Parkinson’s disease

Question 8

Huntington’s disease ?

Answer 8

Inherited
motor and intellectual impairment
falls in level of ACh and GABBA so rise in Dopamine because nothing to inhibit substantia nigra
anti-dopaminergic drug

Question 9

Parkinson’s disease?

Answer 9

Age related
Motor and dementia and shaking
Brain has reduced levels of dopamine, less inhibition, too much ACh
Given L-dopa
Condition progressive so have to be careful because dosage too high will cause huntingtons (to little ACh)