Tag: control and coordination in living organisms

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.

Removal of the thymus gland in the adult has little effect, but when the thymus is removed in the newborn, T cells in the blood and lymphoid tissue are depleted and failure of the immune system causes a gradual, fatal wasting disease. 

T cells or T lymphocytes are a type of lymphocyte, that plays a central role in cell-mediated immunity. They are called as T-cells because they mature in the thymus gland.

The thymus gland is an organ in the upper chest cavity, that processes lymphocytes, a type of white blood cell, that fights infections in the body.