Question

a)You are walking through your living room when you step on a Lego.  Briefly describe the process of sensing and responding to this painful stimulus.  Be very specific about the efferent pathway that will be involved in your response. Include nervous system division, a neurotransmitter(s) that will be utilized and stimulation of effector(s).

b)You have just eaten a large Thanksgiving meal and are relaxing on the couch enjoying the holiday with your family.  Briefly describe the process of sensing and responding to these stimuli.  Be very specific about the efferent pathway that will be involved in your response.  Include nervous system division, a neurotransmitter(s) that will be utilized and stimulation of effector(s).

Answer 1

a) The pain receptors in the foot are activated because of the substances like Prostaglandins. They send an afferent impulse to the spinal cord passing through the dorsal root. the spinothalamic tract ascends from the spinal cord. This spinothalamic tract carries the impulse to the cerebral cortex passing through the thalamus. The fibres are known as A beta or C fibers. after this, the impulse travels down via the descending tract from the cerebral cortex, and reaches to the spinal cord. From here the efferent nerves travel down to the effector muscles. The Neurotransmitter nor-epinephrine, serotonin or dopamine can play the role. These carry the activity of pain pathway depending on the type of receptors. nor-epinephrine in this case.

b) The parasympathetic nervous system works when relaxing. Parasympathetic NS controls body functions like digestion, breathing, heart rate, during period of rest and relaxation.

Both biological and environmental factors affect hunger, when we feel hungry. Most commonly the regulation of hunger mechanism involves interpreting different stimulus as a need to take in food .The hormones leptin and gherlin (also called hunger hormones) increase appetite Gherlin functions as appetite stimulating signal from GI tract to brain acting through vagal afferent pathway.

Hypothalamus regulates the food intake. It is found below the thalamus and above the pituitary gland and the brain stem. Hypothalamus controls process like food and water intake, hunger and thirst including the body temperature.

Hypothalamus has various nerve cells, when activated they produce sense of hunger. They do it by producing two proteins known as neuropeptide Y (NPY) and agouti related peptide (AGRP). These proteins send signals to hypothalamus. Hormones circulate in the blood plays an important role after meals

The hypothalamus also receives signal from dopamine and serotonin. The insulin like peptide (ILP-5), Cholecystokinin, peptides, glucagon like peptides, amaylin, insulin, pancreatric polypeptide.