Investigate the various mechanisms used by organisms
Investigate the various mechanisms used by organisms to maintain their internal environment within tolerance limits, including:
- Trends and patterns in behavioural, structural and physiological adaptations in endotherms that assist in maintaining homeostasis (ACSBL099, ACSBL114)
- Internal coordination systems that allow homeostasis to be maintained, including hormones and neural pathways (ACSBL112, ACSBL113, ACSBL114)
- Mechanisms in plants that allow water balance to be maintained (ACSBL115)
Behavioural, Structural and Physiological Adaptations in Endotherms for Maintaining Homeostasis:
Behavioural Adaptation for Temperature Homeostasis:
- When temperature rises, organisms capable of locomotion tend to move near areas having water bodies.
- Human behavioural changes include swimming, drinking cold water, sitting in a shade etc.
- Non-human endotherms too have certain behaviours in response to temperature rise. For example, Elephants spray themselves with water to cool down.
Structural Adaptation for Temperature Homeostasis:
- To replenish excess heat from the body, animals’ breath rapidly and shallowly with their mouth open which is known as panting. This process of breathing allows evaporation through the mouth thus cools down body temperature.
- In humans, sweat glands help in cooling down excessive body temperature.
- In case of cold weather, by the method of insulation, heat is trapped in the body. Marine mammals like whales use this method to keep them warm during winter.
- Birds use feathers, and most mammals use hair or fur, to trap a layer of air next to the skin and reduce heat transfer to the environment. In case of humans, their body hair is not enough to trap heat because of which, humans wear warm clothes during winter.
Physiological Adaptation for Temperature Homeostasis:
- In case of cold weather to avoid the body from losing heat to the environment, shrinking the diameter of blood vessels in a process known as vasoconstriction, reduces blood flow and helps retain heat.
- In case of warm weather to expel heat from the body, these blood vessels get wider, or dilate. This process is called vasodilation. Vasodilation increases blood flow to the skin and help the animal lose some of its extra heat to the environment.
Internal Coordination for maintaining Homeostasis:
- The endocrine system guides different changes in the body by regulating functions such as metabolism and growth rate by secreting hormones into the bloodstream and sending them to other organs.
- The nervous system provides quick responses to threats to the body’s stability.
- The hypothalamus acts as the bridge between endocrine and nervous system and relays instructions from the brain to a structure called the pituitary gland, which influences the activity of the endocrine glands in controlling factors like body temperature, hunger and thirst.
Mechanism of maintaining water balance in plants – Transpiration:
- Transpiration is process by which water is removed from plant bodies in the form of vapour through aerial parts.
- Water enters the roots of the plant by osmosis and is transported up through the xylem until it reaches the leaves.
- Water enters the leaf by the process of osmosis (movement of water particles from an area of higher concentration to an area of lower concentration down water potential gradient) to the spongy mesophyll via apoplast pathway and plasmodesmata.
- Water evaporates in the spongy mesophyll to form water vapour.
- Water vapour leaves out of the leaf through stomata by diffusion.
Extract from HSC Biology Stage 6 Syllabus. © 2017 Board of Studies NSW.
EasyBio > Non-infectious Disease and Disorders > Homeostasis > Investigate the various mechanisms used by organisms
Investigate the various mechanisms used by organisms to maintain their internal environment within tolerance limits, including:
- trends and patterns in behavioural, structural and physiological adaptations in endotherms that assist in maintaining homeostasis (ACSBL099, ACSBL114)
- internal coordination systems that allow homeostasis to be maintained, including hormones and neural pathways (ACSBL112, ACSBL113, ACSBL114)
- mechanisms in plants that allow water balance to be maintained (ACSBL115)
Behavioural, Structural and Physiological Adaptations in Endotherms for Maintaining Homeostasis:
Behavioural Adaptation for Temperature Homeostasis:
- When temperature rises, organisms capable of locomotion tend to move near areas having water bodies.
- Human behavioural changes include swimming, drinking cold water, sitting in a shade etc.
- Non-human endotherms too have certain behaviours in response to temperature rise. For example, Elephants spray themselves with water to cool down.
Structural Adaptation for Temperature Homeostasis:
- To replenish excess heat from the body, animals’ breath rapidly and shallowly with their mouth open which is known as panting. This process of breathing allows evaporation through the mouth thus cools down body temperature.
- In humans, sweat glands help in cooling down excessive body temperature.
- In case of cold weather, by the method of insulation, heat is trapped in the body. Marine mammals like whales use this method to keep them warm during winter.
- Birds use feathers, and most mammals use hair or fur, to trap a layer of air next to the skin and reduce heat transfer to the environment. In case of humans, their body hair is not enough to trap heat because of which, humans wear warm clothes during winter.
Physiological Adaptation for Temperature Homeostasis:
- In case of cold weather to avoid the body from losing heat to the environment, shrinking the diameter of blood vessels in a process known as vasoconstriction, reduces blood flow and helps retain heat.
- In case of warm weather to expel heat from the body, these blood vessels get wider, or dilate. This process is called vasodilation. Vasodilation increases blood flow to the skin and help the animal lose some of its extra heat to the environment.
Internal Coordination for maintaining Homeostasis:
- The endocrine system guides different changes in the body by regulating functions such as metabolism and growth rate by secreting hormones into the bloodstream and sending them to other organs.
- The nervous system provides quick responses to threats to the body's stability.
- The hypothalamus acts as the bridge between endocrine and nervous system and relays instructions from the brain to a structure called the pituitary gland, which influences the activity of the endocrine glands in controlling factors like body temperature, hunger and thirst.
Mechanism of maintaining water balance in plants – Transpiration:
- Transpiration is process by which water is removed from plant bodies in the form of vapour through aerial parts.
- Water enters the roots of the plant by osmosis and is transported up through the xylem until it reaches the leaves.
- Water enters the leaf by the process of osmosis (movement of water particles from an area of higher concentration to an area of lower concentration down water potential gradient) to the spongy mesophyll via apoplast pathway and plasmodesmata.
- Water evaporates in the spongy mesophyll to form water vapour.
- Water vapour leaves out of the leaf through stomata by diffusion.
Extract from HSC Biology Stage 6 Syllabus. © 2017 Board of Studies NSW.