Question

1. Explain the role of FSH and LH in the reproductive systems of humans. What does each hormone do, and what parts of the reproductive tract are affected?

2. Why is the action potential considered an "all or nothing" event?

3. Describe two ways in which the nervous and endocrine systems interact to help regulate body systems.

Please answer these 3 questions and please write shortly Thank you.

Answer 1

1. Gonadotropin release hormone (GnRH) released in hypothalamus, stimulates pituitary gland to release FSH and LH.

FSH and LH, both are glycoprotein hormones released by anterior pituitary.

FSH: Follicle Stimulating Hormone:

In sexually-matured Females-

• Target tissues are granulosa cells of ovary.
• FSH stimulates the production of sex steroid hormones: Estradiol (more common is E₂) and progesterone.
• Stimulates follicle and oocyte development in ovary

In sexually-matured Males-

• Target tissues are Sertoli cells in testes.
• Stimulates sperm production ad maturation.

LH: Luteinizing Hormone:

In sexually-matured Females-

• Stimulates the luteal cells and Theca interna cells of ovary.
• Increased LH in mid menstrual cycle, triggers meiosis completion of egg and ovulation.
• After ovulation, stimulates the empty follicle to form corpus luteum and secretion of progesterone.
• Stimulates release of secondary oocyte from Fallopian tube.

In sexually-matured Males-

• Act as interstitial cell stimulating hormone (ICSH).
• Stimulates the interstitial cells or Leydig’s cells of the testes.
• Stimulates secretion of testosterone.

2. “All or nothing” event:

• It also referred to as “All or None law” or “Zero-One law”.

• It is related to the action potential (AP) of nerve or muscle fibres.
• There are 4 main stages in cycle- Resting potential, depolarization, repolarization, and refractory period.
• At resting potential, each fibre maintains a minimum or a threshold potential.
• If the stimulus exerted exceeds this threshold potential, a response results, otherwise there will be no response. This is is called All or nothing event.

3. Interaction of nervous and endocrine system:

1. The hypothalamus regulating the pituitary:

• Mainly related to the connecting of hypothalamus of brain controlling the pituitary, which in turn controls the release of hormones from other glands.
• Example: Gonadotropin release hormone (GnRH) released in hypothalamus of brain, stimulates pituitary gland to release FSH and LH.

2. Autonomous nervous system controlling the flight-or-fight response:

• The sympathetic and parasympathetic nervous systems control this response by stimulation the adrenal glands to release catecholamines, epinephrine (Adrenalin) or nor-epinephrine (nor-adrenalin). These in turn stimulates other glands to generate response as per the situation, like thyroid glands or Langerhans’s cells.