• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Control of homeostasis.

Extracts from this document...


HOMEOSTASIS According to totora .......... Homeostasis can be defined as " the condition in which the body's internal environment remains constant, within physiological limits". Homeostasis is a dynamic condition as the body's equilibrium point can change over a narrow range that is compatible with maintaining life. E.g., the level of glucose in the blood does not normally fall below 70mg of glucose per 100ml of blood. Each body structure helps to contribute to keep the internal environment within its normal limits. For example, if the level of blood glucose within the drops then the body compensates it by using fats stores as a reserve supply of glucose Body fluids An important aspect of homeostasis is maintaining the volume and composition of body fluid. The fluid within cells is called intracellular fluid (ICF). The fluid outside the body cell is called extracelluar fluid (ECF). Dissolved in the ICF and ECF are substances needed to maintain life such as O2, nutrients, proteins and electrally charged ions. ...read more.


This is done to obtain homeostasis. Feed back systems The body can regulate its internal environment through feedback systems. A feedback system is a cycle of events in which the condition of the body is monitored, changed, re-monitored and re-evaluated. Each monitored variable such as temperature, blood glucose and blood pressure etc is termed controlled condition. Any disruption that changes a controlled condition is called a stimulus. Three basic components make up the feed back system - a receptor, a control center and an effector. Receptor - is a body structure that monitors changes in a controlled condition and sends input in the form of nerve impulses or chemical signals to the control center. E.g., nerve ending in the skin sense temperature. Flow of the message Control center - a control center in the body sets the range of values within which a controlled condition should be maintained, evaluated from its input received by the receptors and generate the output commands for when they are needed. ...read more.


A change in the homeostatic condition is detected by receptors and the information is transmitted to the control center. The control center activates effectors which generate a response which increases the stimulus further reinforcing the initial change. An example of positive feedback is the action of the hormone oxytoxin on the uterus during birth. During normal conditions the uterine muscle is passive and not contracting. Dilation of the cervix triggers stretch receptors which transmit nerve impulses to the Brain (hypothalamus). Stimulation of the hypothalamus results in oxytoxin (OT) being released from the posterior pituitary. Oxytocin is carried by the blood to the uterus where it causes uterine contractions. During the birth process dilation of the cervix initiates the release of OT which causes uterine muscle contractions. The uterine contractions begin to force the fetus through the cervix. As the fetus is pushed through the cervix this further stretches the cervix which results in more oxytocin being released. This positive feedback will continue until the baby has cleared the birth canal and the cervix is no longer stretched. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Exchange, Transport & Reproduction section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Exchange, Transport & Reproduction essays

  1. Marked by a teacher

    Human Reproductive System

    4 star(s)

    Normally there are two testes present which are secured at either end by spermatic cord. Each testis contains about 250 lobules and each lobule contains 1 to 3 tightly coiled seminiferous tubules. These tubules produce sperm through spermatogenisis and consist of two types of cells: sertoli and spermatogenic cells that assist in spermatogenisis.

  2. The Endocrine System

    Examples include adrenalin and dopamine. The final sub-group of water soluble hormones are the eicosanoid hormones which are derived from arachidonic acid, examples are prostaglandins and leukotrienes. The lipid soluble hormones can also be divided into 3 groups. The first group is steroid hormones, they are derived from cholesterol.

  1. The Skeletal and Muscular System

    Regular weight-bearing exercises are particularly good for increasing bone density. b. Explain how bones are joined together to form a framework and list any common distortions. Bones are connected together by flexible connective tissues called ligaments. Ligaments are tough, elastic bands of connective tissue connecting bones or cartilage at a joint or they hold organs in position.

  2. Regulation and Control Homeostasis.

    * Iron from red blood cells is either stored in the liver or used in the formation of new blood cells by the bone marrow. Detoxification: * The liver renders harmless or removes toxic materials absorbed by the intestines. * Kupffer cells ingest foreign organisms or material, while toxic chemicals (e.g.

  1. Urinary system

    www.uh.edu The male urethra extends approximately 20cm from the bladder to its external orifice, the meatus, at the extremity of the penis. When it leaves the bladder male urethra is surrounded by sphincter muscle and prostate gland (Seeley, R. et al.

  2. Homeostasis & Control of BGL.

    -water potential (controlled by the endocrine system, kidney and ADH) -Oxygen and Co2 concentrations (controlled by the nervous system, ventilation rate etc) -blood glucose (controlled by the endocrine system, glucagon and insulin) -body temperature (controlled by the nervous and endocrine systems)

  1. The Endocrine System.

    When either of the above hormones targets the liver, the following occurs. Insulin - Insulin is released as a result of an increase in glucose levels, and therefore promotes the conversion of glucose into glycogen, where the excess glucose can be stored for a later date in the liver.

  2. Homeostasis and Feedback

    Poiseuille's law Fluid Mechanics. A law stating that the volumetric flow in a tube of circular cross section is given by the quantity pi r^4Dp/8lh, where r is the radius of the tube, Dp is the pressure difference across the ends of the tube, l is the tube length, and h is the dynamic viscosity.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work