What is Homeostasis?Homeostasis is a function that uccurs in the body that allows for the body to maintain relative stability even through drastic changes in the environment or changes in the body. The endocrine system is made up of ductless glands called endocrine glands that secrete chemical messengers called hormones into the bloodstream or in the extracellular fluid. A hormone is a chemical substance made and secreted by one cell that travels through the circulatory system or the extracellular fluid to affect the activities of cells in another part of the body or another nearby cell. The nervous system modifies the stimulation of endocrine glands and their negative feedback mechanisms. These hormones consist of chains of amino acids that vary in size from 3 amino acids (TRH) to 191 amino acids (GH). Thyroid hormones that go to the mitochondria increase the rate of ATP production in the cell. Ex: Preganglionic sympathetic nervous system (SNS) fibers stimulate the adrenal medulla to secrete catecholamines. This hormone signals the collecting ducts of the kidneys to reabsorb more water and constrict blood vessels, which leads to higher blood pressure and thus counters the blood pressure drop caused by dehydration. Stimulates the myoepithelial cells of the breasts to contract which releases milk from breasts when nursing.
The releasing and inhibiting hormones made by the hypothalamus reach the anterior lobe of the pituitary gland DIRECTLY by a special set of blood vessels called the hypophyseal portal system. The hypothalamus makes antidiuretic hormone (ADH) and oxytocin in the cell bodies of neurons and then the hormones are transported down the axons which extend into the posterior pituitary gland.
Click here for an animation on the relationship of the hypothalamus to the anterior and posterior pituitary glands and on the relationship of the hormones made in the hypothalamus (ADH, oxytocin, releasing hormones, and inhibiting hormones) to the anterior and posterior pituitary glands. Neurohypophysis – posterior lobe (neural tissue) receives, stores, and releases hormones (oxytocin and antidiuretic hormone) made in the hypothalamus and transported to the posterior pituitary via axons.
IGF-I stimulates proliferation of chondrocytes (cartilage cells), resulting in bone growth. Travels to the adrenal gland (target cells) where it stimulates the release of corticosteroids (such as cortisol) in the adrenal cortex. Click here for an animation that will help you to understand how GnRH, FSH, and LH are involved in the female reproductive cycle.
Travels to the mammary glands (target cells) and stimulates the development of mammary glands to produce milk. Click here for an animation that describes how the hypothalamus releases antidiuretic hormone (ADH or vasopressin) which then acts on other organs to have its effects. In males it stimulates muscle contractions in the prostate gland to release semen during sexual activity.


Click here for an animation that provides an example of positive and negative feedback control of the reproductive hormones. Calcitonin decreases the concentration of calcium in the blood where most of it is stored in the bones; it stimulates osteoblast activity and inhibits osteoclast activity, resulting in new bone matrix formation. Click here for an animation that describes the structure of the thyroid gland, how thyroid hormones are made, the functions of calcitonin and thyroid hormones, and the effects of hypo- and hyperthyroidism. Click here for an animation that describes the structure of the parathyroid glands, the function of parathyroid hormones, and the effects of hypo- and hyperparathyroidism. Norepinpehrine is similar to epinephrine, but it is less effective in the conversion of glycogen to glucose. Up-regulation (receptors) occurs with insulin after 4 weeks of exercise to increase its sensitivity (diabetic importance). Reduced plasma volume leads to release of aldosterone which increases Na+ and H2O reabsorption by the kidneys and renal tubes. Antidiuretic Hormone (ADH) is released from the posterior pituitary when dehydration is sensed by osmoreceptors, and water is then reabsorbed by the kidneys. Organisms use feedback mechanisms to maintain their internal environments and respond to external environmental changes. Without feedback mechanisms organisms would have hard time maintaining homeostasis and would not survive. Homeostasis is the maintainance of a constant internal environment in response to a changing external environment. Negative feedback is the mechanism by which the body maintains conditions within particular limits.
Note, that the opposite change takes the level too far below the normal, therefore a negative response back up will occur, and the process repeats itself, so that over time the temperature oscillates about the normal, within small limits.
It is important to maintain a constant temperature so that living organisms can maintain metabolism. Temperature in mammals is detected by thermoreceptors in the skin and hypothalymus which is in the brain.
After you have eaten a meal, the blood glucose levels will begin to rise because because the carbohydrates in the food are digested and absorbed.
If however, you have been doing alot of exercise, and glucose is being used up, then alpha cells will produce glucagon, this causes the release of an enzyme that breaks glycogen to glucose (glycogenolysis [gli-ko-jen-oh-li-sis]).
The human body is made up of austomatic sysrtems that are able to work throughout the body and maintain a range of bodily functiuon that are required for cells to function properlly. The hormone binds to a G protein-linked receptor on the cell membrane; t he hormone acts as a first messenger.


The binding of the hormone to the G protein-linked receptor activates a second messenger such as cAMP. Steroid hormones and thyroid hormones pass directly through the cell membrane of target cells. If they bind to receptors in the cytoplasm, the hormone-receptor complex then enters the nucleus. If this level falls below normal, a hormone called glucagon is released into the blood by an endocrine organ called the ______ . When blood glucose level rise, beta cells in our pancreas releases a hormone called insulin.
There are several mechanisms of homeostasis that the body goes through in order to keep the required equality for an efficient functioning. Positive feedback increases the stimuli and negative feedback decreases the stimuli from the external or internal environment.
Normally diabetes patients wouldn’t survive but as scientific technology progressed insulin can be produced in labs. If we can’t regulate our body temperature it’s inevitable that we die if our temperature drops because our metabolism will slow down. Now, patients of diabetes maintain their feedback system through injecting insulin in their bodies. If our metabolism slows down then our nervous system won’t work because our body temperature has dropped.
Temperature, salinity, acidity and high to low concentrations of nutrient or wastes in the body are considered as factors that affect the ability for the body to work efficiently. If the blood sugar level gets too high, the endocrine organ secretes another hormone called __________ into the blood. When blood glucose level rise, alpha cells in our pancreas releases another hormone called glucagon to release the glucose stored as glycogen in our liver. This could lead to death because our brain heavily depends on ATP and when our metabolism rate drops cellular respiration slows down.



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Comments

  1. 05.07.2014 at 11:10:23


    In adrenal fatigue, the enough glucose.

    Author: SEMIMI_OQLAN
  2. 05.07.2014 at 23:46:37


    Breastfeeding within 30 to 60 minutes of birth test measures.

    Author: vefa
  3. 05.07.2014 at 20:25:38


    Hour of starting IV glucose of 10 per discussing.

    Author: 4356