unit 2 - ka4: metabolism in conformers and regulators

• The ability of an organism to maintain its metabolic rate is affected by external abiotic factors.
• Abiotic factors — temperature, salinity and pH
• Conformers’ internal environment is dependent upon external environment.
• Conformers use behavioural responses to maintain optimum metabolic rate. Conformers have low metabolic costs and a narrow range of ecological niches.
• Behavioural responses by conformers allow them to tolerate variation in their external environment to maintain optimum metabolic rate.
•  Regulators maintain their internal environment regardless of external environment.
• Regulators use metabolism to control their internal environment, which increases the range of possible ecological niches.
• This regulation requires energy to achieve homeostasis. This increases their metabolic costs.
• Thermoregulation by negative feedback — the role of the hypothalamus, nerves and effectors.
• The hypothalamus is the temperature monitoring centre.
• Information is communicated by electrical impulses through nerves to the effectors, which bring about corrective responses to return temperature to normal.
• The role of corrective responses to an increase in body temperature — sweating, vasodilation of blood vessels and decreased metabolic rate.
• Sweating — body heat used to evaporate water in the sweat, cooling the skin.
• Vasodilation — increased blood flow to the skin increases heat loss.
• Decreased metabolic rate — less heat produced.
• The corrective responses to a decrease in body temperature — shivering, vasoconstriction of blood vessels, hair erector muscles contracting and increased metabolic rate.
• Shivering — muscle contraction generates heat.
• Vasoconstriction — decreased blood flow to skin decreases heat loss.
• Hair erector muscles contract — traps layer of insulating air
• Increased metabolic rate — more heat produced.
• Importance of regulating temperature (thermoregulation) for optimal enzyme activity and high diffusion rates to maintain metabolism.