adrenal glands

• what are the two layers of the adrenal gland?

  Adrenal cortex- outer portion

  Adrenal Medulla- Inner portion
• what are the three layers of the adrenal cortex?

  Zona glomerulosa- outermost layer

  Zona fasciulata- middle layer

  Zona reticularis- inner most laster
• what does the zona golmerulosa of the adrenal cortex secrete?

  mineral corticoids like aldosterone
• What does the zona fasciulata of the adrenal cortex secrete?

  Gluco corticoids like cortisol
• which part of the adrenal cortex secretes mineral corticoids?

  Zona golmerulosa
• Which part of the adrenal cortex secretes gluco coritcoids?

  Zona fasciulata
• what does the zona reticularis of the adrenal cortex release?

  It is thought to secrete precursor molecules that are used to make sex hormones.
• Which part of the adrenal cortex is thought to secrete precursor molecules that are used to make sex hormones?

  Zona reticularis
• The adrenal cortex uses cholesterol to produce a range of hormones; these hormones are steroid based and are able to enter cells directly by dissolving into the cell surface membrane. Steroid hormones enter the nucleus and have a direct effect on the DNA to cause protein synthesis.
• The action of steroid hormones can be summarised as:

  1. The steroid hormone passes through the cell membrane of the target cell
  2. The steroid hormone binds with a specific receptor, that has a complementary shape to the hormone, in the cytoplasm.
  3. A receptor-steroid hormone complex enters the nucleus of the target cell and binds to another specific receptor on the chromosomal material
  4. The binding stimulates the production of mRNA which will code for the production of proteins
• what is the purpose of mineral corticoids like aldosterone?

  They help control the concentration of sodium and potassium in the blood, as such they help maintain blood pressure.
• what type of hormone, and where inside the adrenal gland is it produced, helps maintain blood pressure by altering sodium and potassium ion concentration?

  Mineral corticoids- they are produced in the zona glomerulosa of the adrenal cortex
• what is the purpose of aldosterone?

  It acts on the cells of the distal tubules and collecting ducts in the Kidney. It increases the absorption of sodium ions, decreases absorption of potassium ions, increases water retention and increases blood pressure.
• What hormone acts on the cells of the DCT, and collecting duct in the kidney- thus increasing absorption of sodium ions, decreasing absorption of potassium ions and increases water retention to increase blood pressure?

  Aldosterone
• What type of hormone helps to control metabolism of fats, proteins and carbohydrates in the liver, and what part of the adrenal gland is it made?

  Glucocorticoids from the zona fasciulata of the medulla cortex
• What do glucocorticoids do?

  They help control the metabolism of carbohydrates, fats, and proteins in the liver
• what is the purpose of Cortisol?

  Cortisol is released in response to stress or as a result of low blood glucose concentration. It stimulates the production of glucose from stored compounds, like glycogen, fats, and proteins in the liver.
• Cortisol may also be released by the zona reticularis. However, if the correct enzymes are not present for the release of cortisol then the zona reticularis releases precursor androgens into the blood. These precursor androgens are then taken up into the ovaries or testes and converted into sex hormones like testosterone in males and oestrogen in females. The sex hormones help the development of secondary sexual characteristics and regulate the production of gametes.
• The role of adrenaline is to prepare the body for activity, this includes effects like:

  Relaxing smooth muscle in the bronchioles

  Increasing stroke volume of the heart

  Increasing heart rate

  Causing general vasoconstriction to raise blood pressure

  Stimulation of glycogen conversion to glucose

  Dilating the pupils

  Increasing mental awareness

  Inhibiting gut action

  Causing body hair to stand erect
• Adrenaline is a polar molecule derived from the amino acid tyrosine. This means it cannot enter cells via the plasma membrane of the target cells. Many cells and tissues have adrenaline receptors, thus the effects of adrenaline are widespread.