Question

1) What are the four types of sensory receptors for the general senses? What is the nature of the stimuli that excite each type?

2) Jake steps on a piece of ice with his right foot. Outline the pathway this sensation will travel to reach his brain being specific about the structures along the way.

3) What are differences and similarities between "crude" touch and "fine" touch sensations?

4) How can an understanding of the neurotransmitters important in the function of the basal nuclei contribute to an understanding the underlying cause for Parkinson's disease?

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Answer 1

Q. 1. Receptors for general sense :

1. Mechanoreceptors:
a. Tactile receptor - touch, Pressure
b. Proprioceptor: Muscle spindle, Golgi tendon
organ, joint capsule receptors
c. Nociceptors

2. Thermoreceptor - tempratue , cold and hot

3. Chemoreceptor: smell, taste, osmoreceptors.
4. Photoreceptor - light

Q.2. Cold sensation is sensed by thermoreceptors cold receptors (Ad fibre ) --> Dorsal root ganglion --> Dorsal root -->Crosses midline --> Lateral spinothalamic tract --> In thalamus --> Venteoposterio medial nucleus --> Somatosensory cortex.

Q.3.

A. Crude Touch: Receptor is Pacinial corpuscles & it travels through anterior column, anterior spinothalamic tract.

B. Fine touch - Ruffine s end organ, travel in Posterior coulumn, posterior spinothalamic tract.

Q.4.Parkinsonism is because of imbalance berween dopamine and acetylcholine .Normally is there is harmony between acetylcholine and dopamine .In parkinsonism there is damage in Nigrostriatal fibres of Basal ganglia secreting Dopamine and which leads to increase in levels of acetylcholine .Acetylcholone causes the symotom of tremors, bradykinesia andand rigidity .