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

The ways in which a mammal maintains constant conditions inside its body.

Extracts from this document...

Introduction

The ways in which a mammal maintains constant conditions inside its body. Maintaining constant internal conditions is vital to the survival of a mammal. Cells in any living mammal will only function properly in the correct conditions. The environment of a mammal is variable and this variation could be a key problem if cells were susceptible to the changes in the external environment. An approximately constant cellular environment must be maintained for efficient functions of cells and to give independence from the environment; homeostasis allows this to be achieved. Homeostatic mechanisms use negative feedback to maintain the constant levels within the mammal. Changes in the internal environment trigger a response, which a receptor detects, that counteracts the change, by use of effectors; the corrective mechanism is triggered by the very substance that is being regulated. Having separate mechanisms for the regulation of certain conditions allow for a greater degree of control. In a mechanism controlled by negative feedback the level is never maintained perfectly, but constantly oscillates about the set point. An effective and efficient homeostatic system minimises the size of these oscillations. This only works within certain limits - if the environment changes too much, then the effector may not be able to counteract it. Mammals often use several different responses to keep a system in homeostasis. ...read more.

Middle

The thermoregulatory centre sends impulses to several different effectors to adjust body temperature. Temperature control is achieved by negative feedback. The thermoregulatory centre is part of the autonomic nervous system, so the various responses are all involuntary. When a mammal is cold there are four main physiological responses. Firstly shivering; muscles contract and relax repeatedly, generating heat by friction and from metabolic reactions. Vasoconstriction; the arterioles leading to capillaries on the surface layers of the skin constrict to reduce blood flow through the capillaries, this means less heat is carried from the core to the surface of the body, maintaining core temperature. It also means the amount of heat lost through the skin by radiation and conduction is reduced. Hair rising; muscles contract, raising skin hairs and trapping an insulating layer of still, warm air next to the skin. Increased metabolic rate; glands secrete adrenaline and thyroxine respectively, which increase the metabolic rate in different tissues, especially the liver, so generating heat. When a mammal is cold there are two main physiological responses. Firstly vasodilation; arterioles leading to the capillaries dilate, also the shunt vessels are closed off. This results in increased blood flowing closer to the surface of the skin and so more heat is lost to the environment by radiation and conduction. ...read more.

Conclusion

This then passes to the kidney which is excreted as urine. The liver is also responsible for the regulation of lipids. The lipids are removed from the blood by either the break down of them or modification and transportation to fat depots. Bile compounds, minerals and cholesterol are also regulated. Another form of excretion arises in the lungs. This organ excretes waste carbon dioxide as well as water. Carbon dioxide is a waste product of respiration and is released from the lungs during expiration along with water vapour. The lungs are specialized organs which contain millions of microscopic air sacs called alveoli. The large numbers of alveoli means a large surface area to volume ratio for gas exchange. The alveoli consist of a single celled epithelium so the thickness of the membrane is reduced and the diffusion pathway is small. A steep concentration gradient between the alveoli and the capillary surrounding it is maintained. This all enables Fick's law to be at its optimum so diffusion is at its maximum. Maintaining constant internal conditions is vital to the survival of any organism especially a mammal. Mammals have evolved through time to consist of many mechanisms that can counteract any change that arises. This has allowed mammals to become more complex and able to survive regardless of their external environment unlike other members of the animal kingdom. ?? ?? ?? ?? 1 ...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

    Investigate the water potential of celeriac.

    5 star(s)

    There were 5 celeriac discs per test tube and 6 test tubes all together. Therefore, when I placed the celeriac discs into one test tube I started the stopwatch. This meant that I had to quickly fill the remaining 5 test tubes with the celeriac discs.

  2. Marked by a teacher

    Human Reproductive System

    4 star(s)

    LH maintains luteal function for the first two weeks during the menstrual cycle. LH causes the graaafian follicle to rupture and release the egg. It supports thecal cells in the ovary that provide androgens and hormonal precursors for estradiol, a type of oestrogen, production.

  1. Marked by a teacher

    Effect of temperature on membranes

    3 star(s)

    adenosine diphosphate and a phosphate group.5 Beetroot Image 2: A bunch of fresh beetroots6 Beetroot is commonly known as table beet, garden beet, red beet and botanically-known as Beta vulgaris (a cultivated variety of beetroot). The wild seabeet7 which it origins from is a native of coastlines from India to

  2. Rate of Respiration

    hence the syringe is unable to show the amount of C02 gas that has entered the syringe. Thus I will change my method and apparatus by using the invested burette water displacement method, which inaccurate to 0.1 cm3 (which is more accurate that the gas syringe).

  1. The mechanism of Negative feedback.

    Ventilation of respiratory system is controlled by the breathing centre in a region of the hindbrain called medulla oblongata. The ventral portion of this centre controls inspiratory movements and is called the inspiratory centre. The remainder controls breathing out and is called the expiratory centre.

  2. The Endocrine System

    been shown that oxytocin has a role in mother-child bonding as well as in more general social relationships. Anti-diuretic Hormone (ADH) also known as Vasopressin, is produced by the hypothalamus, stored and then secreted by the posterior pituitary. ADH causes the kidneys to retain water.

  1. Regulation and Control Homeostasis.

    the organic residue from deamination of amino acids) to glucose. Excretion: Excretion: This is the removal of potentially toxic products which are produced as a result of metabolism. Excreted Substances: * Urea, Ammonia, Uric acid (nitrogenous compounds) * Bile * Salts * Carbon Dioxide Importance of Excretion: * The removal of metabolic waste substances which are by-products of

  2. Urinary system

    If the alkali reserve is reduced, the blood becomes acidic and this condition is known as acidosis. The normal level in blood is 135 to 147mmol/l. By excreting acid salts and other acidic substances, the kidneys spare the use of the alkali reserve, which would otherwise have been used to neutralise them (Smith, T.

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