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Another hormone responsible for maintaining electrolyte concentrations in extracellular fluids is aldosterone    , a steroid hormone that is produced by the adrenal cortex. In contrast to ADH, which promotes the reabsorption of water to maintain proper water balance, aldosterone maintains proper water balance by enhancing Na + reabsorption and K + secretion from extracellular fluid of the cells in kidney tubules. Because it is produced in the cortex of the adrenal gland and affects the concentrations of minerals Na + and K + , aldosterone is referred to as a mineralocorticoid    , a corticosteroid that affects ion and water balance. Aldosterone release is stimulated by a decrease in blood sodium levels, blood volume, or blood pressure, or an increase in blood potassium levels. It also prevents the loss of Na + from sweat, saliva, and gastric juice. The reabsorption of Na + also results in the osmotic reabsorption of water, which alters blood volume and blood pressure.

Aldosterone production can be stimulated by low blood pressure, which triggers a sequence of chemical release, as illustrated in [link] . When blood pressure drops, the renin-angiotensin-aldosterone system (RAAS) is activated. Cells in the juxtaglomerular apparatus, which regulates the functions of the nephrons of the kidney, detect this and release renin    . Renin, an enzyme, circulates in the blood and reacts with a plasma protein produced by the liver called angiotensinogen. When angiotensinogen is cleaved by renin, it produces angiotensin I, which is then converted into angiotensin II in the lungs. Angiotensin II functions as a hormone and then causes the release of the hormone aldosterone by the adrenal cortex, resulting in increased Na + reabsorption, water retention, and an increase in blood pressure. Angiotensin II in addition to being a potent vasoconstrictor also causes an increase in ADH and increased thirst, both of which help to raise blood pressure.

The Renin-angiotensin-aldosterone pathway involves four hormones: renin, which is made in the kidney, angiotensin, which is made in the liver, aldosterone, which is made in the adrenal glands, and ADH, which is made in the hypothalamus and secreted by the posterior pituitary. The adrenal glands are located on top of the kidneys, and the hypothalamus and pituitary are in the brain. The pathway begins when renin converts angiotensin into angiotensin I. Angiotensin I is the converted into angiotensin II. Angiotensin II has several direct effects. These include arterial constriction, which increases blood pressure, decreasing the glomerular filtration rate, which results in water retention, and increasing thirst. Angiotensin II also triggers the release of two other hormones, aldosterone and ADH. Aldosterone causes nephron distal tubules to reabsorb more sodium and water, which increases blood volume. ADH moderates the insertion of aquaporins into the nephridial collecting ducts. As a result, more water is reabsorbed by the blood. ADH also causes arteries to constrict.
ADH and aldosterone increase blood pressure and volume. Angiotensin II stimulates release of these hormones. Angiotensin II, in turn, is formed when renin cleaves angiotensinogen. (credit: modification of work by Mikael Häggström)

Hormonal regulation of the reproductive system

Regulation of the reproductive system is a process that requires the action of hormones from the pituitary gland, the adrenal cortex, and the gonads. During puberty in both males and females, the hypothalamus produces gonadotropin-releasing hormone (GnRH), which stimulates the production and release of follicle-stimulating hormone (FSH)    and luteinizing hormone (LH) from the anterior pituitary gland. These hormones regulate the gonads (testes in males and ovaries in females) and therefore are called gonadotropins . In both males and females, FSH stimulates gamete production and LH stimulates production of hormones by the gonads. An increase in gonad hormone levels inhibits GnRH production through a negative feedback loop.

Regulation of the male reproductive system

In males, FSH stimulates the maturation of sperm cells. FSH production is inhibited by the hormone inhibin, which is released by the testes. LH stimulates production of the sex hormones ( androgens ) by the interstitial cells of the testes and therefore is also called interstitial cell-stimulating hormone.

Questions & Answers

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The scientific study of life.
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the virus that causes mumps in humans is composed of a protein outer Shell containing a core of DNA
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Basic science and applied science question about cancer
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what are the importance of ATPs
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You go for a long walk on a hot day. Give an example of a way in which homeostasis keeps your body healthy.
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You sweat.
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sweating is your bodies way of keeping you from overheating.
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Biology is the study of Life
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is the branch of science which deals with the of living things.
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Describe the steps and results of reintroducing wolves to Yellowstone National Park.
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tag and release wolves into Yellowstone. wolves eventually reproduce and the pack grows. as wolves hunt they cull the sick and weak prey. the carcass that is left provides food for other species (scavengers and insect.. etc). this heals the circle of life and contributes to the biodiversity...
Will
before you know it species that are critical to the eco system return. having apex predators is crucial to an ecosystem... it helps run the deer and elk , etc around.
Will
example: there was a species of shrub/ plant that grows along river banks that moose love to eat.. the moose have no predator so they decimate that food source which also helps prevent erosion. when the wolves were reintroduced this changed. oddly enough this plant species started to repopulate in
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the areas where wolf feces sat and decayed
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which of the following statements about the parts of an egg are false?
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medicinal plants including microbs
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,medicinal plants including microbes
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Source:  OpenStax, Biology. OpenStax CNX. Feb 29, 2016 Download for free at http://cnx.org/content/col11448/1.10
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