The Adrenal Glands
The adrenal glands produce hormones that adjust metabolic activities at specific sites, affecting either the pattern of nutrient utilization, mineral ion balance, or the rate of energy consumption by active tissues. The hormones produced by this gland directly released into the bloodstream.
▶Adrenal Gland Anatomy
The adrenal gland lies along the superior border of each kidney. The release of hormone from adrenal gland depends upon the signal from the pituitary gland. It is surrounded by a fibrous capsule and is made of two parts-
• Adrenal cortex (outer)
• Adrenal medulla (inner)
Both parts of the medulla function differently and release different hormones. The hormone release has majorly to deal with stress and other conditions of the body.
It makes steroid hormones (corticosteroids).
- Glucocorticoids (e.g., cortisol). It is produced by zona fasciculata and is stimulated by ACTH(Adrenocorticotropic hormone secreted by the pituitary gland). It releases amino acids from skeletal muscle and lipids from adipose tissues. It has a steady role in glucose metabolism.
- Mineralocorticoids (e.g., aldosterone)- It is produced by zona glomerulosa and is stimulated by angiotensin II which restricts in loss of water, Na+ in urine, sweat, digestive tract, saliva. It increases the reabsorption of sodium ions and water by the kidneys. Also, it promotes urinary loss of potassium ions.
- Androgens (male hormone)- It is produced by zona reticularis. These are also known as weak male hormones and are precursors for female hormones.
It produces two related hormones
• Epinephrine (adrenaline)
• Norepinephrine (noradrenaline)
These hormones increase the cardiac activity, blood pressure, glycogen breakdown and blood glucose levels. It enhances the release of lipids from adipose tissue.
It is innervated by preganglionic nerve fibre. Hormone secretion is stimulated by the axons. It increases heart rate and force and releases glucose, fatty acids into the blood.