Tag: parts of the brain

Intravenous injection of insulin is the injection of insulin directly into the blood. It is used to control blood sugar in people, where the body does not make insulin and therefore cannot control the amount of sugar in the blood. Insulin cannot be taken orally because the oral dose of insulin degenerates in the stomach by digestive enzymes. Thus, the correct answer is option C.

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.

In males, luteinizing hormone (LH) is also called as an interstitial cell-stimulating hormone (ICSH). It stimulates the production of testosterone by the Leydig cells. It acts synergistically with FSH.

Antidiuretic hormone (ADH) is secreted by posterior pituitary gland and targets nephrons to increase water reabsorption and thereby decreasing water content in urine. Oxytocin facilitates uterine contractions to push the foetus downward which in turn stretches cervix and leads to childbirth. MSH stimulates melanin production from melanocytes. Adrenocorticotropic hormone (ACTH) is secreted by the anterior pituitary gland and targets adrenal cortex to produce its hormones. Thus, the correct answer is option B.

The pharynx of amphioxus is perforated by over 100-150 pharyngeal gill slits or stigmata, which are used to strain food particles out of the water. In cephalochordates, a vestibule lies in front of the pharynx that is guarded by the oral cirri. The vestibule contains ciliated tracts of wheeler organ or muller's organs, an excretory organ (Hatschek's nephridium), and a shallow groove (Hatschek's pit) that is probably homologous to the adenohypophysis in vertebrates. In ascidian or 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. 

Oxytocin is released by posterior pituitary during parturition in response to foetus ejection reflex. It stimulates strong uterine muscle contraction forcing the fetus downwards during parturition. Oxytocin helps to initiate release of milk by mammary gland after child birth. The more a baby suckles, the more oxytocin is released leading to milk let down. Thus, the correct answer is D.

MSH stimulates secretion of melanin from pigment cells in the skin and thereby causes skin darkening as required for camouflage in some lower vertebrates. Depending on the amount of melanin and carotene, the colour of skin is determined from pale yellow to dark. Thus, the correct answer is option A.

Rickets is a disorder caused by a lack of vitamin D, calcium, or phosphate. It leads to softening and weakening of the bones. Vitamin D helps the body control calcium and phosphate levels. If the blood levels of these minerals become too low, the body may produce hormones that cause calcium and phosphate to be released from the bones. This leads to weak and soft bones.

A fall in the concentration of calcium in the bloodstream is detected by the parathyroid glands, which then produce parathyroid hormone. 

Hormones of the adrenal cortex and pineal body are under control of tropic hormones of the anterior pituitary gland. The hormonal secretion of anterior pituitary is under control of regulatory hormones of the hypothalamus. The hormones of posterior pituitary are stored in axon ending and are secreted under nervous control. Thus, the correct answer is C.