Module 5: section 1- Communication and Homeostasis Flashcards
Why is Responding to the Environment Important?
Increases chances of survival by responding to external and internal changes.
External example: Avoid harmful environments (e.g., too hot/cold).
Internal example: Control conditions for optimal metabolism.
Plants also respond to environmental changes.
A stimulus is any change in the internal or external environment.
How Do Receptors and Effectors Work?
Receptors detect stimuli:
Receptors are specific to one stimulus type (e.g., pressure, light).
Different receptors detect different types of stimuli.
Some receptors are cells (photoreceptors) , others are proteins on cell membranes.
Effectors produce a response:
Effectors include muscles or glands (e.g., pancreas).
How Do Cells Communicate to Produce a Response?
Receptors need to communicate with effectors to produce a response.
In the nervous system, neurotransmitters are used.
In the hormonal system, chemicals (hormones) travel through the blood to distant cells.
Cell-surface receptors recognize signaling chemicals.
What is Homeostasis and Why is It Important?
Definition: Maintenance of a constant internal environment.
Maintains the internal environment despite external changes.
Ensures cells function normally and avoid damage.
Temperature control:
High temperature: enzymes denature, lowering reaction efficiency.
Low temperature: enzyme activity slows down, slowing reactions.
Optimum temperature for enzymes: 37°C in humans.
Glucose concentration also needs to be controlled for respiration.
How Do Homeostatic Systems Respond to Changes?
Homeostatic systems involve receptors, a communication system, and effectors.
Receptors detect when a level is too high or too low.
The nervous or hormonal system sends the information to effectors.
The mechanism that brings the level back to normal is called negative feedback.
What is Negative Feedback?
Negative feedback restores the level to normal.
It keeps conditions within a narrow range around the normal level (e.g., body temperature close to 37°C).
It only works within certain limits—if the change is too large, negative feedback may fail to correct it (e.g., severe exposure to cold).
What is Positive Feedback?
Positive feedback amplifies a change from the normal level.
It pushes the level away from normal (e.g., blood clot formation).
It rapidly activates processes, like clotting or triggering labor.
Positive feedback is not involved in homeostasis because it doesn’t maintain a constant internal environment.
What are Examples of Positive and Negative Feedback?
Negative feedback example: Body temperature regulation—effectors act to reduce or increase temperature when it’s too high or low.
Positive feedback example: Platelets activated to form a blood clot when there’s an injury. This amplifies the clotting process until the wound is sealed.
How Does Negative Feedback Relate to Homeostasis?
Negative feedback maintains homeostasis by bringing levels back to normal when they drift too high or low.
Homeostasis ensures the internal environment remains stable within set limits, preventing damage to cells or organ systems.
what is homeostasis?
Homeostasis is the maintenance of a stable internal environment in the body. It involves regulating factors like temperature, pH, and glucose levels to ensure optimal functioning, even when external conditions change.
How is temperature controlled differently in ectotherms and endotherms?
Ectotherms rely on external factors (like sunlight) for temperature regulation, whereas endotherms maintain their temperature internally through metabolic processes.
How What are some characteristics of ectotherms? do endotherms control body temperature?
Ectotherms cannot generate their own heat internally and are heavily dependent on external temperatures. Their activity level is influenced by environmental temperatures, and they have lower metabolic rates than endotherms.
What are some characteristics of endotherms?
Endotherms generate heat internally through metabolic activity. They have a higher metabolic rate, allowing them to maintain a stable body temperature regardless of the environment. They use mechanisms like sweating, shivering, and changing blood flow to regulate temperature.
What mechanisms help increase body temperature in mammals?
Sweating: Sweat evaporates from the skin, using heat energy from the body and cooling it down.
Hairs lying flat: Reduces the insulating layer of air, allowing more heat to be lost.
Vasodilation: Blood vessels near the skin surface widen, increasing blood flow to the skin and promoting heat loss via radiation.
What mechanisms do mammals use to increase body temperature?
Shivering: Rapid muscle contractions generate heat.
Hairs standing up: Traps a layer of insulating air close to the skin, reducing heat loss.
Vasoconstriction: Blood vessels near the skin surface narrow, reducing blood flow to the skin and minimizing heat loss.
How does the hypothalamus control body temperature in mammals?
The hypothalamus maintains a constant body temperature by processing information from thermoreceptors in the skin and the brain. It sends signals to effectors (like muscles or sweat glands) to initiate responses that either increase or decrease body temperature.
What are the roles of thermoreceptors in body temperature regulation?
Peripheral thermoreceptors: Located in the skin, they detect external temperature changes.
Central thermoreceptors: Located in the hypothalamus, they monitor the temperature of the blood.
What is the process of vasodilation and how does it aid in cooling the body?
Vasodilation involves widening the arterioles near the skin surface. This increases blood flow to the skin, allowing more heat to be lost via radiation, conduction, and convection, which helps cool the body.
What is vasoconstriction and how does it help the body conserve heat?
Vasoconstriction involves narrowing the arterioles near the skin surface. This reduces blood flow to the skin, keeping heat in the body’s core and reducing heat loss, helping to conserve warmth in cold conditions.
Why do mammals in cold climates have specific adaptations like thick fur or fat layers?
These adaptations, like thick fur and fat layers, provide insulation to reduce heat loss. Fur traps warm air close to the skin, and fat layers act as a barrier to heat loss, both helping to maintain a stable internal temperature.
