Adrenal gland - class-XII

Aldosterone secretion is primarily regulated by the renin-angiotensin-aldosterone system (RAAS) and directly by plasma potassium (K+) concentration. An increase in plasma K+ directly stimulates the adrenal cortex to release aldosterone.

The endoderm gives rise to the epithelium of the pharynx, including the eustachian tube, the tonsils, the thyroid gland, parathyroid glands, and thymus gland; the larynx, trachea, and lungs; the gastrointestinal tract (except mouth and anus), the urinary bladder, the vagina (in females) and the urethra. The adrenal glands develop from two separate embryological tissues; the neural crest ectoderm and the intermediate mesoderm.

The adrenal cortex is located on the outer layer of the adrenal gland and makes different hormones, that help control the heart, kidneys, GI tract, bones, genitalia and immune system. 

Aldosterone is a steroid hormone (mineralocorticoid) produced by the outer section (zona glomerulosa) of the adrenal cortex in the adrenal gland. Aldosterone promotes sodium ($Na^+$) and water retention and lowers plasma potassium ($K^+$) concentration.

Conn's syndrome is a condition associated with the development of high blood pressure and low potassium levels in the blood. In the majority of patients a small tumour is found in the adrenal cortex. Excess production of aldosterone by the tumour leads to the development of Conn's syndrome with high blood pressure and low potassium levels. In a small group of patients abnormal function of the adrenal cortex from a condition called as adrenal hyperplasia, may give rise to the Conn's syndrome.

Cortisol or glucocorticoid hormone is a steroid hormone produced by the adrenal cortex. It is released in response to stress and a low level of blood glucose. Its functions are to increase blood sugar through gluconeogenesis and to aid the metabolism of fat, protein, and carbohydrate. 

Renal reabsorption of sodium ($Na^+$) uses Na-H antiport, sodium-glucose symport, sodium ion channels (minor). It is stimulated by angiotensin II and aldosterone, and inhibited by atrial natriuretic peptide.

It does not secrets hormones which maintain the correct salt balance in the blood. It secretes hormones which helps to maintain the body's salt and water level, regulates blood pressure.

• Body fluid volume disturbances involve an imbalance of intake and loss.
• Aldosterone plays a central role in the homeostatic regulation of blood pressure, plasma sodium (Na+), and potassium (K+) levels.
•  It does so primarily by acting on the mineralocorticoid receptors in the distal tubules and collecting ducts of the nephron.
•  It influences the reabsorption of sodium and excretion of potassium of the kidney, thereby indirectly influencing water retention or loss, blood pressure and blood volume.
•  When dysregulated, aldosterone is pathogenic and contributes to the development and progression of cardiovascular and renal disease. Aldosterone has exactly the opposite function of the atrial natriuretic hormone secreted by the heart. Hence, Our body retains NaCl, during the periods of excessive heat and aldosterone triggers this action.

In urinary, system, aldosterone takes part in retention of sodium ions. The ADH released by posterior pituitary triggers the release of aldosterone which increases the concentration of sodium ions in the blood. The increased salt concentration in the blood increases the blood osmotic potential which further increases reabsorption of water and incraeses the blood volume and blood pressure.

• Outer layer ectoderm
• Middle layer mesoderm
• Inner layer endoderm

The adrenal medulla secretes two hormones called adrenaline or epinephrine and noradrenaline or norepinephrine. These are commonly called as catecholamines. Adrenaline and noradrenaline are rapidly secreted in response to the stress of any kind and during emergency situations and are called emergency hormones or hormones of Fight or Flight.

Our body had one pair of adrenal glands, one at the anterior part of each kidney. The gland is composed of two types of tissues. The centrally located tissue is called the adrenal medulla and outside this lies the adrenal cortex.

Aldosterone is a major mineralocorticoid, secreted by adrenal cortex. It regulates mineral metabolism and controls the sodium and potassium ratio in the extracellular and intracellular fluid. Therefore, it is called salt-retaining hormone.

Aldosterone(secreted by adrenal medulla) acts mainly on the renal tubules and stimulates the reabsorption of $Na^+$ and water and excretion of $K^+$ and phosphate ions.

(a) The adrenal medulla secretes two hormones called adrenaline and noradrenaline.

Aldosterone is a steroid hormone and has three cyclohexyl rings and one cyclopentyl ring joined into a single structure. TSH, FSH and LH are peptide hormones and have long amino acid chains. Thus, the correct answer is option B. 

Adrenal gland just lies above the kidney. It is divided into two regions outer cortex and inner medulla. Cortex region secret the steroid hormone. Inner medulla region is divided into three regions zona glomerulosa, zona fasiculata and zona reticularis. Each zone is responsible for secreting specific hormone.

So, the correct answer is ' Cortisol '

Goose flesh (piloerection) is caused by the contraction of arrector pili muscles, which is mediated by the sympathetic nervous system and the release of epinephrine (adrenaline) from the adrenal medulla.

Liver cells contain glucose stored in the form of glycogen (glucagon enzyme), which is converted to glucose and released in the blood stream to provide muscle cells and brain with the required energy to respond to the stimulus instantaneously during a fight-or -flight response.

The hormone like cortisol and aldosterone are secreted from the adrenal cortex. It is an example of steroid hormone. It regulates the salt and water balance in body.

Cortisol has a powerful anti-inflammatory action, even when secreted at normal levels. It acts quickly to remove and prevent redness and swelling of nearly all tissues. Cortisol also reduces the rate at which lymphocytes multiply and accelerates their programmed cell death to further protect the body from this overreaction. In fact, when cortisol is elevated during the alarm reaction stage, there is almost a complete disappearance of lymphocytes from the blood. That is why the immune system is suppressed when the body is under stress or taking corticosteroids. 

Adrenal virilism is a syndrome in which there is excess production of adrenal androgens. It is also called as adrenogenital syndrome. In this, there is hypersecretion of adrenocortical androgens. This is caused due to tumor of adrenal gland, called as adrenocortical carcinoma. It may also results from hyperplasia.

Mineralocorticoids: These hormones are secreted by the outer region of the adrenal cortex. They regulate mineral metabolism.

Glucocorticoids are secreted by Zona fasciculata. Mineralocorticoids are secreted by the Zona glomerulosa of the adrenal cortex.Zona glomerulosa is the outermost layer of the adrenal cortex. The hormone regulates electrolyte balance. It regulates the balance of water and Na$^{+2}$ ions. Zona reticularis secretes androgens like dehydroepiandrosterone (DHEA) and androstenedione. 

Aldosterone is the principle mineralocorticoid. It increases sodium (Na$^{+}$) and water resorption by the kidney in exchange for potassium or hydrogen. 

RAAS stands for rennin- angiotensin- aldosterone system. It is a hormone system that regulates blood pressure and fluid balance in the body. When blood pressure is low, the juxtaglomerular cells in the kidney release renin, which convert the angiotensinogen into angiotensin I after that it changes into angiotensin Ii. Angiotensin II (mineralocorticoids)is a vasoconstrictor that increases the blood pressure. Aldosterone is released by the adrenal gland. It is a mineral corticoid. It increases the absorption from distal convoluted tubule and collecting duct of kidney's nephrons.

The endocrine gland present on the kidney is the Adrenal gland. The adrenal gland produces various type of hormones like adrenaline and the steroids aldosterone and the cortisol. Each gland has an outer cortex which produces steroid hormones and an inner medulla.

Our body has one pair of adrenal glands, one at the anterior part of each kidney. The gland is composed of two types of tissues. The centrally located tissue is called the adrenal medulla, and outside this lies the adrenal cortex.
The adrenal cortex can be divided into three layers, called zona reticularis (inner layer), zona fasciculata (middle layer) and zona glomerulosa (outer layer). The adrenal cortex secretes many hormones, commonly called as corticoids. 
 The corticoids, which are involved in carbohydrate metabolism are called glucocorticoids. In our body, cortisol is the main glucocorticoid.