The following question regards action potentials and neurons: 1.) A.) How is the physiology different for...

The following question regards action potentials and neurons:

1.) A.) How is the physiology different for an excitatory synapse vs. an inhibitory synapse? Consider neurotransmitter differences, ion channel differences, and how they affect the potential of the post synaptic cell

B.) (3 points) How is an electrical gradient produced across a gradient? How is this related to having a membrane potential?

C.) (4 points) A) Describe negative feedback in physiology. B) How is negative feedback important for maintaining homeostasis?

D.) (4 points) Under what circumstances would cells produce lactate? If a cell produces and can’t use lactate, what happens to it?

E.) (3 points) Can an action potential be initiated when the membrane is experiencing the relative refractory period? Explain the physiology of why or why not.

Solutions

Expert Solution

A	Characteristics	Excitatory	Inhibitory
1.	Neurotransmitter	Acetylcholine, Dopamine, Glutamate, Nor-epinephrine	GABA, serotonin
2.	Ion channel	Positive ion channel, e.g. Na+, Ca2+	Negative ion channel e.g.Cl-
3.	Effect on post synaptic membrane potential	Increase from -70 to -50, i.e. Excitatory post synaptic potential	decreses, -70 to -80 i.e. Inhibitory post synaptic potential.

B. Elecrical gradient is due to differences in the charge across the two sides.

A membranec of cell have both positive and negative charge ion inside and outside. The difference of the charge of sum of these ions create elecric gradient across membrane.

Membrane potential is combination of electrical and chemical gradient (conncentration of ions) across the membrane.

Negative feedback mechanism :

Negative feedback is negative stimulus to a proces by product of the a process to controle excess synthesis of the product.

Eg. Hypothalamus secrete TRH which stimulate pituitary to secrete TSH which stimulate thyroid gland to release T3 & T4 hormones. In turn when T3, T4 level rise in blood it gives negative signal to both hypothalamus and pituitary to decrease synthesis of TRH and TSH.

Hence, this negative feedback mechanism is very important for the maintaining body basal metabolic rate to normal level.

D. Under anarobic condition cells produce lactate.

E. Yes, a membrane in relative refractory period can be excited by a higher stimulus.

Sydney Mullin answered 11 months ago

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