Tag: coordination in human beings- chemical control

A fall in GFR can stimulate the JG cells to release renin which can stimulate the glomerular blood flow and thereby the GFR comes back to normal.

A) LH is Luteinising Hormone which is not involved in the concentration of urine.

Caffeine is a central nervous system stimulant of the methylxanthine class of psychoactive drugs. It is the most mildest stimulant and is most widely consumed psychoactive drug. It is present in coffee, tea and cola drinks.
Therefore, the correct answer is option D.

The water reabsorption in the distal part of the nephron is in accordance with the body's state of hydration, under the influence of ADH and is termed as 'facultative reabsorption of water'.  ADH is secreted in the hypothalamus of brain and released into blood stream from the pituitary gland. The collecting ducts become more permeable to water due to the effect of ADH, so more water is reabsorbed by osmosis and no expenditure of ATP energy is required. The release of ADH is triggered when osmoreceptors in the hypothalamus detect an increase in osmolarity of the blood above a set point of ${300 mosm L^{-1}}$. In this situation the osmoreceptors cells also promotes thirst. Drinking reduces the osmolarity of the blood, which inhibits the secretion of ADH.

Juxtaglomerular cells are specialized smooth muscle cells of glomerular arterioles. They synthesize, store and secrete the enzyme renin. It plays a critical role in the renin angiotensin system and thus in renal autoregulation of the kidney.

While the pituitary gland is known as the 'master' endocrine gland, both of its lobes are under the control of the hypothalamus; the anterior pituitary receives its signals from the parvocellular neurons and the posterior pituitary receives its signals from magnocellular neurons.

Prolactin-releasing hormone (PRH) activates the anterior pituitary to initiate production and ejection of breast milk through the production of prolactin. Oxytocin along with prolactin hormone stimulates milk production. FSH (follicle stimulating hormone) stimulates the growth of ovarian follicles in the ovary before ovulation.

In humans, pheromones are secreted onto our skin through the apocrine glands (sometimes called as human scent glands). These are similar to eccrine glands but the apocrine glands secrete a more oily substance. The apocrine glands are normally associated with hairy areas, such as armpits and the crotch area, and are also usually accompanied by eccrine glands, which help to disperse the pheromone secretions. Apocrine glands are activated at puberty, along with hair growth in the axillary (armpit) regions and crotch, which increase the surface area for pheromone dispersal. 

Most prostaglandins act locally; they are powerful as locally acting vasodilators. Vasodilation occurs when the muscles in the walls of blood vessels relax, so that the vessels dilate. This creates less resistance to blood flow and allows blood flow to increase and hence blood pressure to decrease. 

Thyrotropin-releasing hormone (TRH), also called as thyrotropin-releasing factor (TRF), is a tropic, tripeptidal hormone, produced by the hypothalamus, that stimulates the release of TSH (thyroid-stimulating hormone) and prolactin from the anterior pituitary.