Adrenal Gland, Hormones of the Adrenal Gland.pptx

*Adrenal Gland
*Anatomy of the Adrenal Gland
*Hormones of the adrenal cortex (Cortisol, Aldosterone, Adrenal Androgens)
*Hormones of adrenal medulla (Epinephrine and Norepinephrine)

1. Adrenal Gland Adrenal glands, also known as suprarenal glands , are small, triangular-shaped glands located on top of both kidneys . Adrenal glands produce hormones that help regulate your metabolism, immune system, blood pressure, response to stress and other essential functions.

2. Anatomy of the Adrenal Glands An adrenal gland is made of two main parts : adrenal cortex and adrenal medulla. The  adrenal cortex  is the outer region and also the largest part of an adrenal gland. It is divided into three separate zones: zona glomerulosa , zona fasciculata and zona reticularis . Each zone is responsible for producing specific hormones. The  adrenal medulla  is located inside the adrenal cortex in the center of an adrenal gland. It produces “stress hormones”. The adrenal cortex and adrenal medulla are enveloped in an  adipose capsule  that forms a protective layer around an adrenal gland.

3. Hormones of the Adrenal Cortex Adrenal Cortex releases the following hormones: Cortisol Aldosterone Adrenal Androgens All these hormones are steroid hormones.

4. Cortisol It is produced and secreted by zona fasciculata . The hypothalamus produces adrenocorticotropic releasing factor that stimulates the pituitary gland to secrete adrenocorticotropic hormone (ACTH ). ACTH then stimulates the adrenal glands to make and release cortisol hormones into the blood. It helps in the metabolism of fats , proteins and carbohydrates; suppresses inflammation; regulates blood pressure; increases blood sugar; and can also decrease bone formation.

5. Aldosterone Produced and secreted by Zona glomerulosa . It plays a central role in regulating blood pressure and certain electrolytes (sodium and potassium). Aldosterone sends signals to the kidneys, resulting in the kidneys absorbing more sodium into the bloodstream and releasing potassium into the urine. This means that aldosterone also helps regulate the blood pH by controlling the levels of electrolytes in the blood .

6. Adrenal Androgens These are produced and released by Zona reticularis . Androgens are hormones that contribute to growth and reproduction in both men and women. Androgens are usually thought of as male hormones, but the female body naturally produces a small amount of androgens too . Adrenal androgens are male sex hormones. They have weak effects, but play a role in early   puberty i.e. early development of the male sex organs in childhood, and female body hair during puberty.

7. Hormones of Adrenal Medulla The adrenal medulla secretes two hormones, adrenaline or epinephrine and noradrenaline or norepinephrine, whose functions are very similar. T he overall effect of these hormones is to prepare the body for the ‘fight or flight’ response in times of stress. These are water-soluble hormones. These are amino-acids derived hormones, derived from the amino-acid tyrosine.

8. Epinephrine ( Adrenaline ) and Norepinephrine ( Noradrenaline ) The amount of these two hormones produced by the adrenal medulla is in the ratio of 4:1 in terms of epinephrine to norepinephrine . These two hormones are secreted in response to stimulation by sympathetic nerve, particularly during stressful situations. Chromaffin cells are the neuroendocrine cells found in the medulla; they are modified sympathetic neurons that receive sympathetic input . The adrenal medulla receives input from the sympathetic nervous system through these chromaffin cells. When stimulated, chromaffin cells secrete adrenaline and noradrenaline.

9. Key actions of adrenaline include: increasing the heart rate, expanding the air passages of the lungs, enlarging the pupil in the eye, Increase blood flow to skeletal muscles and increase concentration of glucose in the blood due to glycogen breakdown, Norepinephrine stimulates reactions similar to those produced by epinephrine. However , norepinephrine can also make your blood vessels become narrower, increasing blood pressure. The effects of these hormones provide a short term response to stress.