Key Area 4 : Conformers and Regulators Unit 2: Metabolism and Survival

Environment If there are changes in an external ABIOTIC factor in an organism’s environment, this can cause problems in its ability to maintain its metabolic rate. The distribution of animals and plants can be affected by ABIOTIC and OTHER factors. Metabolism and Survival CfE Higher Biology Metabolism and Survival

Environment What is an abiotic factor? Non-living condition affecting where organism lives. E.g. pH, salinity, light intensity, moisture What other types of factors can affect an organisms environment? BIOTIC factors – relate to other living things in environment e.g. amount of available food, number of predators, disease, competition for light, water, food, space) Metabolism and Survival CfE Higher Biology Metabolism and Survival

Conformers and Regulators When environmental conditions vary, an organism can respond in 2 ways: Regulation Conformity Organisms that are able to alter and regulate their normal metabolic rate and maintain a steady internal state using physiological means are called REGULATORS. Organisms that are unable to do this are called CONFORMERS. Metabolism and Survival CfE Higher Biology Metabolism and Survival

Conformers The internal environment of a conformer is directly dependant on its external environment and the abiotic factors that affect this environment. The internal environment of the organism fluctuates directly with the external environment. Most conformers live in the ocean and so this doesn’t pose a problem as this is a relatively stable environment. Metabolism and Survival CfE Higher Biology Metabolism and Survival

Conformers The advantage of living this way is the low metabolic cost to the organism as they do not employ physiological mechanisms to alter their metabolic rate. These mechanisms are energy consuming. A disadvantage to living as a conformer is that there is only a narrow range of ecological niches that the organism can live in. This means they are less adaptable to environmental change. Metabolism and Survival CfE Higher Biology Metabolism and Survival

Conformers Conformers utilise behavioural adaptions to maintain their body temperature. e.g. lizards bask on rocks in order to increase their body temperature. Metabolism and Survival CfE Higher Biology Metabolism and Survival

Regulators A regulator’s internal environment is not directly dependant upon the abiotic factors that affect their external environment. They employ physiological means to maintain a stable internal environment called HOMEOSTASIS. An advantage of living this way is that a wide range of ecological niches can be exploited by these organisms. Metabolism and Survival CfE Higher Biology Metabolism and Survival

Regulators A disadvantage is that they have to expend energy on these physiological mechanisms in order to maintain homeostasis. e.g. Atlantic salmon live in fresh water as well as salty water. It must be able to regulate and maintain the concentration of salts in its blood at a steady state by osmoregulation. Metabolism and Survival CfE Higher Biology Metabolism and Survival

Homeostasis Homeostasis describes the functions of an organisms body which all work together to keep the organism’s internal environment constant and within a narrow range. The body can do this despite changes in the external environment of the organism. This regulation is brought about by Negative Feedback Control. Energy is required for this to occur. Metabolism and Survival CfE Higher Biology Metabolism and Survival

Negative Feedback Control A negative feedback control system responds when conditions change from the ideal or set point and returns conditions to this set point. There is a continuous cycle of events in negative feedback. These systems have monitoring centres that are made up of receptor cells. These receptor cells monitor the internal environment and detect any changes that may occur. Metabolism and Survival CfE Higher Biology Metabolism and Survival

Negative Feedback Control What are the internal functions that an organism needs to control to maintain a stable environment? Water balance, temperature regulation, glucose concentration. Metabolism and Survival CfE Higher Biology Metabolism and Survival

Negative Feedback Control A negative feedback control system responds when conditions change from the ideal or set point and returns conditions to this set point. There is a continuous cycle of events in negative feedback. These systems have monitoring centres that are made up of receptor cells. These receptor cells monitor the internal environment and detect any changes that may occur. Metabolism and Survival CfE Higher Biology Metabolism and Survival

Negative Feedback Control If and when a change occurs the receptors send out nerve or hormonal messages in order to correct this change. These messages are sent to and received by effectors. Effectors, which can be parts of the body such as glands or muscles, bring about certain responses. These responses counteract the original change from the norm and bring the system back to its optimum condition. Metabolism and Survival CfE Higher Biology Metabolism and Survival

Negative feedback control messages (nerves/hormones) effectors receptor cells corrective mechanism bringing about negative feedback control + factor affecting internal environment at its norm/optimum factor affecting internal environment at its norm/optimum no change in condition - corrective mechanism bringing about negative feedback control receptor cells messages (nerves/hormones) effectors

Thermoregulation Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries even when the surrounding temperature is very different. An Ectotherm is an animal that is unable to regulate its body temperature by physiological means. They therefore obtain most of their heat from their surroundings. Examples of endotherms are: fish, amphibians and reptiles. Metabolism and Survival CfE Higher Biology Metabolism and Survival

Thermoregulation An Endotherm is an animal which is able to maintain its body temperature at a relatively constant rate despite changes in the external temperature. They generate their body heat by their high metabolic rate. Examples of endotherms are birds and mammals. Metabolism and Survival CfE Higher Biology Metabolism and Survival

Thermoregulation . Effect of external temperature on conformers and regulators Metabolism and Survival CfE Higher Biology Metabolism and Survival

Role of the Hypothalamus The hypothalamus is the body’s temperature monitoring centre. It acts as a THERMOSTAT. It receives impulses from heat and cold receptors present in the skin. Thermoreceptors are also present in the hypothalamus. It detects changes in the temperature of the blood as it passes through the brain, which reflect changes in the body core temperature. Metabolism and Survival CfE Higher Biology Metabolism and Survival

Role of the Hypothalamus Metabolism and Survival CfE Higher Biology Metabolism and Survival

Role of the Hypothalamus This thermoregulatory centre sends impulses to several different effectors which trigger corrective feedback mechanisms that adjust body temperature to its normal level. What effectors adjust body temperature? Voluntary control – putting on/taking off clothes, moving into shade, turning up heat. Involuntary control - Sweat glands, skin hairs, blood vessels, skeletal muscles. Metabolism and Survival CfE Higher Biology Metabolism and Survival

The Skin The skin plays a leading role in regulation and acts as an effector. It promotes heat loss by utilising the following mechanisms: Metabolism and Survival CfE Higher Biology Metabolism and Survival

Correction of Temperature Increase In the event of a temperature increase, dilation of arterioles occurs. This allows a large volume of blood to flow to the surface of the skin via capillaries. Heat is lost from the blood by radiation. An increase in sweating occurs which produces water. As this water evaporates from the skin it brings about a lowering of the body temperature. Hair erector muscles relax and this prevents heat being trapped in a layer of air next to the skin. Metabolism and Survival CfE Higher Biology Metabolism and Survival

Correction of Temperature Increase Metabolism and Survival CfE Higher Biology Metabolism and Survival

Correction of Temperature Decrease In the event of a temperature decrease, constriction of arterioles occurs. This allows a small volume of blood to flow to the surface of the skin via capillaries. Little heat is lost from the blood by radiation. An decrease in sweating occurs which thus preventing heat loss by evaporation. Hair erector muscles are stimulated by shivering. This causes hairs to be raised from the surface of the skin trapping air between the body and the external environment. Air is a poor conductor and provides a layer of insulation which reduces heat loss. Metabolism and Survival CfE Higher Biology Metabolism and Survival

Correction of Temperature Decrease Metabolism and Survival CfE Higher Biology Metabolism and Survival

Negative Feedback Control Metabolism and Survival CfE Higher Biology Metabolism and Survival