Higher Biology | Key Area 2.4: Conformers and Regulators

An organism’s ability to maintain its metabolic rate is affected by:

External abiotic factors, eg. pH, salinity, temperature, ie. when conditions deviate from the optimum, they affect an organism’s ability to carry out metabolic functions.

Conformer

An organism whose internal environment is dependent upon its external environment, eg. most reptiles, amphibians, fish, insects (cold-blooded organisms).

Conformers and responses

- Conformers use behavioural responses to maintain optimum metabolic rates, and allow them to tolerate variation in their external environment to maintain these metabolic rates.

- Low metabolic costs since they rely on external environments, and have a narrower range of ecological niches.

Give examples of conformers and behavioural responses:

- Snakes will bask in the sun to warm up and maintain body temperature.

- Lizards will bury themselves in mud or dip into water to cool down.

Regulator

An organism whose internal environment can be maintained regardless of external environments, (ie. internal environment remains unaffected) eg. mammals.

Regulators and responses

- Regulators use their metabolism to control their internal environment and maintain an optimum temperature (which can be at levels difference from their external environment).

- Higher metabolic costs as the regulation of metabolism requires energy to achieve homeostasis.

- Increases range of possible ecological niches as they can overcome external challenges.

Give examples of regulators and responses:

- Salmon increase the activity of ion pumps in their gills as they enter saltwater to withstand high salinity, and decrease when they enter freshwater.

- Polar bears are versatile and can withstand cold temperatures via negative feedback.

Homeostasis

Any self-regulating process by which biological systems and to maintain stability, while adjusting to conditions optimal for survival, ie. the maintenance of a constant internal environment.

Negative feedback control

The mechanism by which regulators maintain homeostasis (a constant internal environment). Feedback tends to stabilise a process by reducing its rate or output when its effects are too great, eg. body temperature, control of blood glucose and heart rate.

Hypothalamus

- The temperature monitoring centre in the brain that carries out thermoregulation by negative feedback control.

- Sensitive to nerve impulses that come from receptors in the skin.

- Information is communicated by electrical impulses through nerves to effectors (eg. sweat gland, blood vessel, muscle), which bring about corrective responses to return temperature to normal.

- Nerve impulses are sent by the hypothalamus to effectors to make response measures.

Thermoregulation

The control of internal body temperature within tolerable limits.

Why is thermoregulation important?

- Essential for high diffusion rates to maintain metabolism by providing enough energy for molecules to diffuse at sufficient rates.

- Essential for optimal enzyme activity by maintaining optimum temperatures.

Corrective responses taken by the body in response to an increase in temperature:

- Sweating, where body heat evaporates water in sweat, cooling the skin.

- Vasodilation, where the dilation of blood vessels increases blood flow to the skin, and increases heat loss through the surface via radiation.

- Decreased metabolic rate, where less heat is produced.

Corrective responses taken by the body in response to a decrease in temperature:

- Shivering, where involuntary muscle contractions generate heat.

- Vasoconstriction, where the constriction of blood vessels decreases blood flow to the skin, and decreases heat loss through the surface by radiation.

- Contraction of hair erector muscles, where hairs rise to trap a layer of insulating air.

- Increased metabolic rate, where more heat is produced.