Chemical Coordination and Integration Test - 5

Thyroid stimulating hormone (TSH) and adrenocorticotropic hormone (ACTH) are secreted by an anterior pituitary gland that targets thyroid gland and adrenal cortex respectively to produce their hormones. Interstitial cell-stimulating hormone (ICSH) promotes secretion of androgens from testes. Secretory activity of adrenal medulla is under control of sympathetic nerve fibers of the nervous system.

At puberty, the hypothalamus begins to secrete gonadotropin-releasing hormone (GnRH). GnRH stimulates the anterior pituitary to secrete the gonadotropic hormones follicle-stimulating hormone (FSH) and luteinizing hormone (LH). Both FSH and LH are glycoproteins that use cyclic AMP as a second messenger. FSH stimulates Sertoli cells to secrete androgen-binding protein (ABP) and other signaling molecules that are necessary for spermatogenesis. LH stimulates the interstitial cells to secrete testosterone. FSH, LH, and testosterone all directly or indirectly stimulate testosterone secretion and spermatogenesis. A high concentration of testosterone in the testes is required for spermatogenesis. Testosterone and FSH stimulate Sertoli cells to produce ABP, which binds to testosterone and concentrates it in the tubules. Testosterone also maintains the male secondary sex characteristics. Reproductive hormone concentrations are regulated by negative feedback mechanisms. Testosterone acts on the hypothalamus, decreasing its secretion of GnRH, which decreases FSH and LH secretion by the pituitary. Testosterone also directly inhibits the anterior lobe of the pituitary by blocking the normal actions of GnRH on LH synthesis and release.

The pituitary gland is sometimes called the "master" gland of the endocrine system because it controls the functions of many of the other endocrine glands. The pituitary gland is no larger than a pea, and is located at the base of the brain.

The thymus gland is located in the chest, behind the sternum. T-cells are produced in the bone marrow. These cells migrate to the thymus. The thymus gland is responsible for the differentiation and maturity of the T-cells. These mature T-cells are released in the bloodstream to fight against infections. The T-cells work in coordination with the B-cells to destroy the bacteria, viruses and other foreign antigens. If any damage is caused to the thymus during childhood may cause lack or less number of mature T-cells. This will cause the child to become more prone to infections. Thus, there will be lack or loss of cell-mediated immunity provided by the T-cells. 

So, the correct answer is option A.

The neurohypophysis is the structural foundation of a neuro-humoral system coordinating fluid balance and reproductive function through the action of two peptide hormones: vasopressin and oxytocin. Clinically, deficits in the production or action of vasopressin manifest as diabetes insipidus.

The pituitary gland is a small gland that sits in the sella turcica (‘Turkish saddle’), a bony hollow in the base of the skull, underneath the brain and behind the bridge of the nose. The pituitary gland has two main parts, the anterior pituitary gland and the posterior pituitary gland. The gland is attached to a part of the brain (the hypothalamus) that controls its activity. The anterior pituitary gland is connected to the brain by short blood vessels. The posterior pituitary gland is actually part of the brain and it secretes hormones directly into the bloodstream under the command of the brain. 

Antidiuretic hormone (ADH) is secreted by the posterior pituitary gland and targets nephrons to increase water reabsorption and thereby decreasing water content in urine. The man-made form of ADH hormones is named as vasopressin which is administered to the patient with diabetes insipidus. Thu, the correct answer is C.

Growth hormone (GH), also called somatotropin or human growth hormone, peptide hormone secreted by the anterior lobe of the pituitary gland. It stimulates the growth of essentially all tissues of the body, including bone.

Gonadotropins are the trophic glycoprotein hormones synthesized in and secreted from gonadotropes, the least abundant cell type of all the anterior pituitary gland.

The hormones FSH and LH are together called as gonadotropin hormones. They are called the gonadotropins as they stimulate gonadal activity. The anterior pituitary (pars distalis) releases following gonadotrophic hormones:
Follicle stimulating hormone (FSH): In males, FSH regulates spermatogenesis (formation of sperms) and in females, FSH stimulates growth and development of ovarian follicles and secretion of estrogen hormone.
Luteinizing hormone (LH): In males, LH is also called ICSH (interstitial cell-stimulating hormone) which stimulates testes to synthesize and secrete androgens (testosterone). It activates Leydig cells of the testes to secrete testosterone. In females, LH stimulates the ovulation of the fully matured Graafian follicles and also maintains the corpus luteum, formed from the remnants of Graafian follicles after ovulation. The corpus luteum secretes progesterone and some estrogen under the action of LH.
So, the correct answer is 'Gonadotropic hormone'.

Gigantism and acromegaly occur when the pituitary gland makes too much growth hormone (hyperpituitarism) due to a tumor on the gland. The difference between acromegaly and gigantism is that acromegaly occurs in adults, typically between the ages of 30 and 50. Hence, option A is correct.

Over secretion of growth harmone (somatotripin) is causes acromagale due to this deasese gorilla like appearance occurs.due to low secretion of growth harmone causes gigantism also called as pituitary dwarf.

Micturition is the process of urination. The kidneys respond to ADH by conserving water and producing urine that is more concentrated. If there is too little ADH or the kidneys do not respond to ADH, then too much water is lost through the kidneys. Thus the micturition increases. The urine produced is more dilute than normal and the blood becomes more concentrated. This can cause excessive thirst, frequent urination, dehydration, and high blood sodium (hypernatremia).

Regulation of Urine Concentration and Volume Antidiuretic hormone (ADH) is produced by the pituitary gland to control the amount of water that is reabsorbed through the collecting of urine.

Anterior lobe of pituitary gland secrete many type of hormone some are :
FSH - follicle stimulating hormone
LH - leutinizing hormone
ACTH and GH
they are some important hormone which secreted from pituitary gland.

The Anterior Pituitary is an endocrine gland controlled by the hypothalamus in several fundamentally different fashions than is the posterior pituitary.

Sella trucia or 'Turkish saddle' is a depression in the floor of the mammalian skull in the sphenoid (Basi spenoid) bone in which the pituitary gland is lodged. It is also found in skull of chimpanzees, gorilla etc.

Vassopressin/antidiuretic hormone (ADH) is secreted by posterior pituitary gland and targets nephron tubules to increase water reabsorption and thereby decreasing water content in urine while increasing that of blood. Increased water concentration in blood raises blood volume and blood pressure. Under conditions of lower blood pressure, vasopressin secretion is inhibited. MSH stimulates melanin production from melanocytes. Follicle stimulating hormone (FSH) regulates oogenesis and spermatogenesis. Thus, the correct answer is option B.

Prolactin, also called as luteotropic hormone (LTH) or luteotropin, is a protein hormone produced by the pituitary gland of mammals, that acts with other hormones to initiate secretion of milk by the mammary glands. 

The posterior pituitary is the part of the brain that extends down from hypothalamus; the posterior pituitary and infundibulum are together termed as neurohypophysis. Pars nervosa is the posterior lobe of pituitary associated with neurohypophysis while pars distalis is anterior lobe of the adenohypophysis. Supraoptic and paraventricular nuclei of hypothalamus secrete oxytocin and vasopressin which are then stored and released into blood stream via neurohypophysis. Thus, the correct answer is option C.

The actions of interstitial cell stimulating hormone in men include:

- Stimulating testosterone production from the interstitial cells of the testes (Leydig cells);

- Interstitial cell stimulating hormone (and also follicle stimulating hormone) are essential for the maturation of spermatoza - i.e. mature male sex cells.

Pituitary gland. Located at the base of the brain, the pituitary gland is protected by a bony structure called the sella turcica of the sphenoid bone.

The term hypophysis (from the Greek for “lying under”)—another name for the pituitary—refers to the gland's position on the underside of the brain.

The pituitary is a compound organ. It is formed in the embryo by an ectodermal evagination of the stomodaeum, called Rathke's pouch which finally fuses with a ventral down growth of the infundibulum to form a pituitary gland or hypophysis cerebri.

Antidiuretic hormone (ADH) is secreted by the posterior pituitary gland in response to dehydration and targets nephrons to increase water reabsorption and thereby decreasing water content in urine. Under conditions of higher water intake and lower perspiration, ADH is not released. So, ADH regulates the water reabsorption by nephron in a facultative manner i.e., according to the hydration level of the body. The correct answer is C.

It synthesizes and secretes certain neurohormones, called releasing hormones or hypothalamic hormones, and these in turn stimulate or inhibit the secretion of hormones from the pituitary gland.

Diabetes insipidus is a pathological endocrine condition characterized by excessive thirst and excessive production of very dilute urine. The disorder is caused by a lack of antidiuretic hormone (vasopressin) or a blocking of its action. This hormone, produced by the hypothalamus, regulates the kidney's conservation of water and production of urine through its ability to stimulate reabsorption of water by the kidneys. Hence, Option A.

The gonadotropins, a family of closely related glycoprotein hormones, include follicle stimulating-hormone (FSH) and luteinizing hormone (LH) which are produced by the same pituitary cells, the gonadotrophs and chorionic gonadotropin (CG) which is of placental origin.

Herring bodies are very large swellings in the axons of the neurosecretory neurons that innervate the posterior pituitary gland.

Neurohypophysial axons often terminate as Herring bodies , but these ”end bulbs” lack the ultrastructural characteristics of release sites – in particular, they are typically engulfed by glial processes and do not directly contact the basal lamina lining the perivascular space.

The vestibule contains ciliated tracts of muller’s organs, an excretory organ and a shallow groove that is probably homologous to the pituitary gland in vertebrates. 
In ascidian (sea-squirts), the tunicate has very simple nervous systems, which could be represented as ganglion below the sub neutral gland, which was thought to produce substances similar to hypophyseal substances.

In lower vertebrates (fish, amphibians) MSH from the pars intermedia is responsible for darkening of the skin, often in response to changes in background color. This color change is due to MSH stimulating the dispersion of melanin pigment in dermal (skin) melanophore cells.