Tag: control and coordination in living organisms

Human chorionic gonadotrophin is the embryonic hormone, which ensures the corpus luteum continues to produce progesterone throughout the first trimester of pregnancy. The corpus luteum continues to produce progesterone until the placenta is established (the placenta then takes over progesterone production).

Alpha cells are endocrine cells in the islets of Langerhans of the pancreas. Thy are responsible for synthesizing and secreting the peptide hormone glucagon, which elevates the glucose levels in the blood.

Most birth control pills are combination pills containing a combination of the hormones oestrogen and progesterone to prevent ovulation. A woman cannot get pregnant if she doesn't ovulate because there is no egg to be fertilized. The pill also works by thickening the mucus around the cervix, which makes it difficult for sperm to enter the uterus and reach any eggs that may have been released. The hormones in the pill can also sometimes affect the lining of the uterus, making it difficult for an egg to attach to the wall of the uterus.

Hyperglycemia, or high blood sugar (glucose), is a serious health problem for those with diabetes. Hyperglycemia develops, when there is too much sugar in the blood.

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.