Homeostasis Water Al-Asfaar, Zohra Samantha, Hyreen, & Nicolette

What is Homeostasis? Homeostasis is the maintenance of a constant internal {immediate surrounding of cells} in response to changes in: -the changing condition in internal environment -the changing condition in external environment Homeostasis works to maintain the organism’s internal environment within tolerance limits- the narrow range of conditions where cellular process are able to function at a level consistent with the continuation of life . The failure to maintain homeostasis can cause disease and death HOMEOSTASIS= Staying the same

Why is it vital to have balance? The ph balance in the body is important to maintaining in good health. If the ph balance in the body is not right we possible to have headache, allergies or flu. The ph stands for hydrogen potential and it is measuring the concentration of the hydrogen ion. The water and ion are the next to absorbed it depends on how much we need in the body.

To what extent does the human body seek balance? The human body seeks balance because of the ability of the body and its cells to seek and maintain a condition of equilibrium or stability within its internal environment when dealing with external changes. The measures the human body will take to regulate and keep constant our body temperatures are only to harmonize the interior environment with the exterior environment, and this state of a living organism is homeostasis. Living systems are self-regulating and homeostasis happens automatically and is constant, so the body is always seeking balance. Homeostatic regulation involves three parts or mechanisms: 1)the receptor 2)the control centre 3) the effector:  The receptor receives information that something in the environment is changing (hand touching hot handle). The control centre receives and processes information from the receptor. And lastly, the effector responds to the commands of the control centre.

Evaluate what would happen if the human body became instable? Water conservation in the body is eventually connected with the maintenance of blood pressure because, as water varies, blood pressure also varies. Increased water raises blood pressure; decreased water lowers blood pressure. The process of Osmoregulation and blood pressure control interact. Osmoregulation is the regulation of water concentrations in the bloodstream, effectively controlling the amount of water available for cells to absorb.

The homeostatic control of water is: A change in water concentration leads to active via negative feedback control Osmoreceptors that are capable of detecting water concentration are situated on the hypothalamus next to the circulatory system The hypothalamus sends chemical messages to the pituitary gland next to it. The pituitary gland secretes anti-diuretic hormone (ADH), which targets the kidney responsible for maintaining water levels. When the hormone reaches its target tissue, it alters the tubules of the kidney to become more / less permeable to water If more water is required in the blood stream, high concentrations of ADH make the tubules more permeable. If less water is required in the blood stream, low concentrations of ADH make the tubules less permeable.

How do feedback loops in the endocrine and nervous system regulate the environment in the human body? A vital factor of the internal environment of cells changes such as water balance, the change is detected by either the hormonal or nervous system. Information about the direction of change is transported , by chemical or nerve message, to other parts of the body. These message lead to another change in the vital factor, backwards to the initial one so that the factor is now restored to within the normal range.

~The following diagram shows the organs that have roles in homeostasis: Pituitary gland: {growth hormone and many other} Secretes a number of hormones, a key one is ADH which is important in regulating the water content of the body. Pancreas: {insulin glucagon} Is involved in maintaining a constant amount of glucose in the body through the actions of glucagon and insulin. Hypothalamus: {many including thyrotrophic –releasing hormone} Many body activities Thyroid: {thryoxine} Metabolism growth Adrenal: {cortisol adrenalin} Metabolism response to stress Cells in gonads: {testes: testosterone} Ovaries {progesterone oestrogens} Fertility and secondary sex characteristic

Which hormones supply internal feedback mechanisms that sustain homeostasis at both cellular and organ level? Vasopressin is an antidiuretic hormone {ADH} produced by neurosecretory cells in the hypothalamus of the brain. There is a little amount of vasopressin in the blood if there are normal level of water. When blood solutes rise Osmoreceptors in the hypothalamus activate neurosecretory cells. These cells produce vasopressin which is released in the blood stream. Vasopressin travels to the kidneys and it increases permeability distal tubules and collecting ducts to water. The amount of water reabsorbed increases and the concentration in the blood declines. Negative feedback then leads to a decreased secretion of vasopressin. Increased drinking also acts as a feedback mechanism leading to a reduced secretion of vasopressin.

Neurosecretory cells in the hypothalamus in the brain produce antidiuretic hormone {ADH} or vasopressin. Vasopressin flows through axons to the posterior pituitary gland, where it is stored or secreted into the bloodstream.

Controlling the water Kidney Urinary system is have a important role in the body to maintain the water balance in to the kidney. One job that they are involved in is reabsorbing excess water so that we don’t dry out. ~ TOO LITTLE WATER The chemical messenger between the brain and the kidney is the hormone ADH, Anti- Diuretic Hormone. The important parts of the process involve: 1. The hypothalamus in the brain, which detects the lower blood water content. 2. The pituitary gland at the base of the brain, which releases the hormone ADH. 3. The kidney, which reabsorbs the water. In order to get back to the normal level of water in the blood we absorb more water from the digestive system, feel thirsty, and so drink more.

How does the kidney work? Blood enters the kidney through the renal artery. It is filtered and the ‘clean’ blood leaves via the renal vein. Any waste material leaves through the ureter, then to the bladder and the world outside. The dark red outer zone called the cortex and the lighter inner zone, the medulla.

Where there is too little water in the body the following sequence of events occur: Too little water in blood Detected by hypohalamus More ADH released into the blood by the pituitary gland Kidney reabsorbs more water Less urine is produced Blood water level not reduced further

Water content of the blood HIGH Water content of the blood LOW Too much water drunk Too much salt or sweating Brain produces More ADH Brain produces Less ADH Water content of the blood normal Low volume of water reabsorbed by kidney High volume of water reabsorbed by kidney Urine output HIGH Urine output LOW (small volume of Concentrated urine) (large volume of dilute urine)

Controlling the water TOO MUCH WATER A similar sequence of events occurs when there is too much water in the body. This time, some of the details are reversed from what they were when there was too little water. To much water in blood Detected by hypothalamus less ADH released into the body by the pituitary gland kidney reabsorbs less water more urines is produced normal blood water level is reached

BIBILIOGRAGHY ~INTERNET RESOURCES ~ Medline Plus, Medical Encyclopedia Kidney Anatomy, published 7th November 2008, retrieved on 23rd July 2009 , http://www.nlm.nih.gov/MEDLINEPLUS/ency/imagepages/1101.htm 2008 Maximillian Publishing LLC http://www.oscarriddle.com/Research.html http://www.s-cool.co.uk/gcse/biology/homeostasis/controlling-body-water.html http://www.biology-online.org/ ~TEXT BOOK RESOURCES~ Judith, Kinnear. & Marjory, Martin, {2006} Biology for the VCE Students {3rd ed.} Queensland : Wiley & Sons