Endocrine System

A) Type of hormone is NOT A factor required for target cell activation by hormone receptor interaction.

D) Parathyroid hormone is the single most important regulator of calcium levels in the blood.

A) The neurohypophysis or posterior lobe of the pituitary gland is not a true endocrine gland because it is only a hormone storage area that receives hormones from the hypothalamus for release.

D) Thyroid hormone exerts its influences by entering some cells and binding to intracellular receptors within the nuclei.

True, the beta cells are the pacreatic islet cells that produce insulin.

D) Regulating hormones from the hypothalamus first enter into the hypophyseal portal system.

False, the hormone that raises the blood sugar levels is NOT insulin.

NOTE: Glucagon is the hormone released by the alpha cells of the pancreas and it stimulates the liver into releasing glucose thereby raising the blood glucose levels

• C) Hyperthroidism
• The thyroid gland is part of the endocrine system, which secretes regulatory hormones into the blood. The thyroid sits just below the
• Adam's apple (larynx) and has two lobes, one on either side of the windpipe. This gland controls many vital metabolic processes, such as growth and energy expenditure.

• An overactive thyroid is known as hyperthyroidism, and this condition
• tends to affect women more than men. Around two in every 100 women will
• experience some degree of hyperthyroidism. The most common cause is
• Graves' disease, which is due to an immune system abnormality. Other
• causes of an overactive thyroid include local inflammation (thyroiditis), nodules or lumps. There is no cure for hyperthyroidism,
• but it can be successfully managed with treatments such as anti-thyroid medication.

Down regulation (A) is the phenomenon caused by prolonged excessive exposure to high hormone concentrations.

D) The hypothalamic-hypophyseal tract is partly contained in the infundibulum.

Basically, the hypothalamic-hypophyseal tract is the axon connection that connects the posterior pituitary gland to the hypothalamus

A) Humoral stimulation is an example of when the pancreas releases insulin in direct response to blood glucose.

C) ADH is inhibited by alcohol.

• D) Several hormones are synthesized in the hypothalamus and transported to
• the anterior pituitary gland. The mechanism of transportation from  hypothalamus to anterior pituitary gland is through the hypophyseal portal system.

• Note: The hypophyseal portal system (or hypothalamo-hypophyseal portal system)
• is the system of blood vessels that links the hypothalamus and the anterior pituitary. It allows endocrine communication between the two structures. The anterior pituitary receives releasing and inhibitory hormones in the blood. Using these the anterior pituitary is able to fulfill its function of regulating the other endocrine glands adenohypophysis is the anterior (glandular) lobe of the pituitary gland.

B) The parathyroid glands maintain adequate levels of blood calcium. This is accomplished through targeting the bone and activating osteoclasts so that the calcium will be released.

A) Normal development of the immune response is due in part to the hormones produced by the thymus gland.

• Note: The thymus is a small gland situated in the chest cavity just behind the upper end of the sternum or breastbone. The thymus gland processes many of the white blood cells that are produced in the bone marrow and converts these cells into T-lymphocytes.These cells have a crucial role in defending the body against infection. They stimulate the production of antibodies by other
• lymphocytes and they also stimulate the growth and activity of the
• phagocytes, which are a form of scavenger cell that ingest invading viruses and bacteria. The thymus gland is at its largest size in the
• young infant and over the years it regresses in size. This reduction in size leads to reduced function in the gland.

C) Aldosterone is the adrenal hormone responsible for maintaining appropriate blood sodium levels.

D) The ability of a specific tissue or organ to respond to the presence of a hormone is dependent upon the presence of the appropriate receptors on the cells of the target tissue or organ.

D) Gonadocorticoid production by the adrenal gland is insignificant compared with sex hormone relase from the hoands during late puberty.

C) THe major targets of growth hormone are bones and skeletal muscles.

D) Common secretion of the thyroid gland are calcitonin, thyroxin and triiodothyronine.

C) All of these are cardinal signs of diabetes mellitus.

D) Glucocorticoids enable the body to deal appropriately with stress by increasing blood glucose, fatty acid and amino acid levels and enhancing blood pressure.

A) Along with the sympathetic nervous system, the adrenal medulla is the other primary mediator of acute stress.

• A) The secretion of melatonin helps regulate our circardian rhythms.
• NOTE: The signals our body clock produces are called circadian rhythms. Circadian describes the changing levels of hormones and neurochemicals that control our sleep, activity and mood. When our body clock misses critical zeitgebers (body signals) such as bright morning light or evening darkness, its rhythm may shift, and as a result, your body will produce hormones at the wrong time, or stop producing the right amounts.
• When your sleep or mood suffers, you may likely have a circadian rhythm problems.
• Melatonin is a hormone that helps regulate sleep. It also appears to influence other hormones in the body.Melatonin is made from an amino acid called tryptophan. When our
• surroundings are dark, the SCN tells the pineal gland to produce melatonin, which is thought to trigger sleep. Some melatonin is also made in the stomach and intestines.

A) Enzyme is not a category of endocrine gland stimulus.