16.1 - Principles Of Homeostasis Flashcards
What is homeostasis?
- Homeostasis is the maintenance of an internal environment within restricted limits in organisms.
- It involves keeping the chemical make-up, volume, and other features of blood and tissue fluid within restricted limits to meet the needs of cells and allow them to function normally despite external changes.
Does homeostasis mean there are no changes to the internal environment?
- No, there are continuous fluctuations caused by internal and external conditions (e.g., temperature, pH, water potential).
- These changes occur around an optimum point, and homeostasis enables the return to this optimum point to maintain a balanced equilibrium.
Why is maintaining a constant internal environment essential for enzymes?
- Enzymes are sensitive to changes in pH and temperature.
- Fluctuations in these factors can reduce enzyme activity or denature them, impairing their ability to function effectively.
How does homeostasis prevent issues related to water potential?
- Changes in blood and tissue fluid water potential can cause cells to shrink or burst due to osmosis, disrupting normal function.
- A constant blood glucose concentration is crucial to maintaining stable water potential.
How does homeostasis contribute to an organism’s independence?
- Organisms capable of homeostasis are more independent of external environmental changes.
- This allows them to inhabit a wider range of environments, increasing their chances of finding food, shelter, and other resources.
What are the components of a biological control mechanism?
Optimum point: The ideal system operating level.
Receptor: Detects deviations from the optimum (stimuli).
Coordinator: Processes receptor information and sends instructions to the effector.
Effector: Brings about changes to return the system to the optimum point.
Feedback mechanism: Ensures the receptor responds to the system’s changes and adjusts accordingly.
What is negative feedback?
- Negative feedback occurs when a change produced by the control system reduces the original stimulus, turning the system off.
- Example: Regulation of blood glucose.
What is positive feedback?
- Positive feedback amplifies a deviation from the optimum, increasing the stimulus effect.
- Example: Sodium ion influx in neurons increases membrane permeability, leading to more sodium entry.
Why is coordination of receptors and effectors important in control systems?
- It ensures accurate responses.
- For example, the hypothalamus can prioritize blood temperature information over skin temperature during exercise to prevent overheating.
How do ectotherms regulate body temperature?
1) Exposing to sunlight: Maximizes surface area exposed to heat.
2) Taking shelter: Avoids overheating during peak sunlight and reduces heat loss at night.
3) Gaining warmth from the ground: Pressing their body against hot surfaces increases heat absorption
What differentiates endotherms from ectotherms in temperature regulation?
Endotherms maintain constant body temperature through internal metabolic activities and use both behavioral and physiological mechanisms for thermoregulation.
How do mammals conserve heat in cold environments?
1) Vasoconstriction: Reduces blood flow near the skin surface.
2) Shivering: Produces metabolic heat through muscle contractions.
3) Raising hair: Traps insulating air next to the skin.
4) Increased metabolic rate: Hormones boost metabolic activity and heat generation.
5) Decreased sweating: Minimizes heat loss through evaporation.
6) Behavioral mechanisms: Shelter, basking, and huddling reduce heat loss.
What mechanisms enable mammals to lose heat in warm conditions?
1) Vasodilation: Increases blood flow near the skin surface to radiate heat.
2) Increased sweating: Evaporation of sweat efficiently cools the body.
3) Lowering body hair: Reduces the insulating layer to allow more heat loss.
4) Behavioral mechanisms: Seeking shade, avoiding heat, and burrowing reduce heat absorption.
How does fur affect heat loss in mammals?
In fur-covered mammals, cooling occurs through evaporation from the mouth and tongue during panting.
What adaptations do mammals and birds have for cold climates?
1) Small surface area-to-volume ratio.
2) Smaller extremities (e.g., ears).
3) Insulation through thick fur, feathers, or fat layers.
What adaptations are seen in animals from warm climates?
1) Large surface area-to-volume ratio.
2) Light-colored fur to reflect heat
