Aim: Understand the difference between positive and negative feedback mechanisms.
Definition: Amplifies or increases a response to a stimulus.
Examples:
Childbirth: Hormones increase contractions.
Blood clotting: Platelets release chemicals that attract more platelets.
Fruit ripening: Ethylene production signals neighboring apples to ripen.
Definition: Slows down or stops a response, helping to maintain homeostasis.
Examples:
Regulation of body temperature: Sweat production to cool the body.
Blood sugar levels: Insulin decreases glucose levels.
Breathing rate: Increases with CO2 levels in blood.
Describe positive and/or negative feedback mechanisms.
Explain how negative feedback helps to maintain homeostasis.
Explain how positive feedback affects homeostasis.
Definition: The state of relatively stable internal conditions.
Importance: Essential for organisms to detect and respond to stimuli.
Mechanism: Maintained through feedback loops.
Definition: Values the body tries to maintain for physiological conditions.
Example of Body Temperature:
Set Point: 98.6°F
Normal Range: 97°F to 99°F
Stimulus: A variable that causes a response.
Receptor/Sensor: Organs that detect a stimulus and send information to the control center (brain).
Effector: Muscle or gland that responds to the stimulus.
Response: Change that modifies the effects of the stimulus.
Negative Feedback: Most common; reduces the effect of the stimulus.
Positive Feedback: Increases the effect of the stimulus.
Body Temperature Regulation:
Stimulus: Heat
Receptor: Skin receptors
Effector: Sweat glands
Response: Sweating to cool down.
Cold Response:
Stimulus: Cold
Receptor: Skin receptors
Effector: Muscles
Response: Shivering to warm up.
Hormones involved in regulating blood glucose levels through negative feedback.
Childbirth Process:
Stimulus: Baby pushes against cervix
Receptor: Nerve cells in cervix send signals to brain
Effector: Pituitary gland releases oxytocin
Response: Increased contractions.
Fruit Ripening Process:
Ripe apple produces ethylene
Signals neighboring apples to ripen via ethylene production.
Reasons for failure in maintaining homeostasis include:
Genetic disorders
Drug or alcohol abuse
Extreme environmental conditions (heat or cold).
Cancer: Unregulated cell growth.
Diabetes: Poor regulation of blood glucose levels.
Feedback mechanisms help maintain steady state conditions in the body.
Which statements exemplify feedback mechanisms, e.g., insulin regulation of blood sugar or guard cells in plants?