Question

Discuss the function and importance of the autonomic nervous system

Discuss one specific receptor type of the general senses; give location, type, and function

Discuss one special sense organ; you must include the area of the brain responsible to process information coming from that sense organ

Answer 1

1) Autonomic nervous system controls involuntary activities of the body such as the activities of smooth muscle, cardiac muscle and glands. It consists of two components:- Sympathetic and parasympathetic.

Organs	Sympathetic	Parasympathetic
Pupil of eye	Dilatation	constriction
Lacrimal gland	vasomotor	secretomotor
Salivary gland	vasoconstriction, produces viscous saliva	produce watery saliva
Bronchial gland	inhibition of secretions	increases secretions
Bronchioles	dilatation	constriction
GIT muscles	inhibition of gastric motility but constricts sphincters (constipation)	increases peristalsis but relaxes sphincters (diarrhoea)
Bladder muscles	relaxation of muscle of the bladder wall but constriction of the sphincter	contraction of muslces of bladder but relaxation of sphincter
Blood vessels	vasoconstriction (increase Blood pressure)	vasodilation(decrease blood pressure)
Sweat glands	sweating	no effect
Muscles of hair follicle	erection	no effect
Penile tissue	ejaculation	erection
Heart	increases heart rate	decreases heart rate

2) General senses are Touch, Pain, temperature. They are present in skin. Superficially, Meissner's corpuscles and Merkel cells are present and deeply, Pacinian corpuscles and Ruffini's nerve endings are present.

Pacinian corpuscles: onion like capsule surrounding unmyelinated nerve ending, large receptive field, very rapidly adapating receptor, encode vibration.

Meissner's corpuscles: small encapsulated, present in nonhairy skin, small receptive field, rapidly adapating, very sensitive to fine touch.

3) Special sense organs are tonge (taste), nose (olfaction), eyes (vision) , ears (hearing and balance).

Taste buds are the receptors for taste present on the tongue in papillae except for filiform papillae. 5 major taste sensations are perceived:- sweet, sour, bitter, salt, umami. Taste buds present on anterior two thirds of tongue are innervated by chorda tympani nerve (branch of facial nerve), posterior one-third is innervated by glossopharyngeal nerve and posteriormost part of palate is innervated by vagus nerve. These nerves take the sensation and send to Nucleus Tractus Solitarius (NTS) of Medulla (Taste Integration centre). From NTS, sensations are sent to Ventroposteromedial nucleus of Thalamus which sends it to Taste Cortex in the brain called Insula.