When core body temperature falls, skin receptors send signals to the ________________________ (Control Center). The brain commands peripheral blood vessels to ________________________ (constrict/shrink) to prevent heat loss, and commands skeletal muscles (Effectors) to ________________________ (shiver). This metabolic muscle activity generates ________________________, bringing temperature back up to baseline.
During intense exercise, core body temperature spikes. The control center signals blood vessels in the skin to ________________________ (dilate/widen) to release heat through radiation, and activates ________________________ glands to secrete moisture. As sweat liquid ________________________ off the skin, it cools the body.
Refer to Slide 5. Fill in the blanks mapping how two antagonistic hormones control sugar balance:
If blood glucose is high (e.g. after a sweet snack):
1. The ________________________ (organ) detects high sugar.
2. It secretes the hormone ________________________ into blood.
3. Body cells take in glucose, and liver cells absorb excess sugar to store it as a giant carbohydrate chain called ________________________.
4. Blood glucose levels drop.
If blood glucose is low (e.g. skipped breakfast):
1. The same organ detects low sugar.
2. It secretes the hormone ________________________ into blood.
3. This hormone tells the liver to break down stored glycogen into active ________________________ molecules and release them.
4. Blood glucose levels rise.
Unit 1: Biological Homeostasis Study Guide Page 2 of 3
Section 5: Amplification Loops Internal Balance Dossier
Positive Feedback Loop: A mechanism where the output/response ________________________ or accelerates the initial stimulus, pushing the system further away from safety or baseline ranges.
Note: This continues until a final ________________________ event ends the cycle.
During labor, the baby's head presses against the cervix. Sensory nerves send signals to the brain, which triggers the pituitary gland to release the hormone ________________________. This hormone causes the uterus to contract ________________________ (stronger/weaker), causing more pressure, causing more hormone release. The loop stops only when the baby is ________________________.
When a blood vessel breaks, cells release chemical cues. These cues attract specialized cell fragments called ________________________ to clump at the damage. Once they stick, they release MORE chemical signals, which attract ________________________ platelets to the pile. This spiral of growth continues until the wound is sealed by a secure ________________________.
Refer to Slide 7. Answer the following questions in complete sentences.
1. Core Contrast: In your own words, outline the structural difference between negative and positive feedback.
2. Pathway Mapping: If a person has high blood pressure, and their brain commands their blood vessels to expand, are the blood vessels the receptor, control center, or effector? Explain.
3. Real World Fault: What chronic human disease is caused by a complete breakdown or failure of the blood glucose negative feedback loop?
Unit 1: Biological Homeostasis Study Guide Page 3 of 3
During intense exercise, core body temperature spikes. The control center signals blood vessels in the skin to dilate / widen to release heat through radiation, and activates sweat glands to secrete moisture. As sweat liquid evaporates off the skin, it cools the body.
Hormonal responses maintaining glucose baseline levels:
If blood glucose is high (after eating):
1. The pancreas detects high sugar.
2. It secretes the hormone insulin into blood.
3. Body cells take in glucose, and liver cells absorb excess sugar to store it as a giant carbohydrate chain called glycogen.
4. Blood glucose levels drop back down.
If blood glucose is low (during fasting):
1. The same organ detects low sugar.
2. It secretes the hormone glucagon into blood.
3. This hormone tells the liver to break down stored glycogen into active glucose molecules and release them.
4. Blood glucose levels rise back up.
Unit 1: Biological Homeostasis Teacher Key Page 2 of 3
Section 5: Amplification Loops Key Internal Balance Dossier Key
Positive Feedback Loop: A mechanism where the output/response amplifies / reinforces or accelerates the initial stimulus, pushing the system further away from safety or baseline ranges.
Note: This continues until a final climax / terminal event ends the cycle.
During labor, the baby's head presses against the cervix. Sensory nerves send signals to the brain, which triggers the pituitary gland to release the hormone oxytocin. This hormone causes the uterus to contract stronger, causing more pressure, causing more hormone release. The loop stops only when the baby is born.
When a blood vessel breaks, cells release chemical cues. These cues attract specialized cell fragments called platelets to clump at the damage. Once they stick, they release MORE chemical signals, which attract more / additional platelets to the pile. This spiral of growth continues until the wound is sealed by a secure blood clot.
1. Core Contrast: In your own words, outline the structural difference between negative and positive feedback.
Negative feedback acts to decrease or reverse a stimulus to restore the body to a stable set-point (corrective). Positive feedback amplifies the stimulus, moving the system further from baseline until a culminating event resolves it (escalating).
2. Pathway Mapping: If a person has high blood pressure, and their brain commands their blood vessels to expand, are the blood vessels the receptor, control center, or effector? Explain.
Effector. The blood vessels are the structures (organs) that physically carry out the brain's directive to dilate/widen to drop the overall blood pressure back into range.
3. Real World Fault: What chronic human disease is caused by a complete breakdown or failure of the blood glucose negative feedback loop?
Diabetes Mellitus (Accept Type 1 or Type 2 Diabetes, where insulin signaling fails).
Unit 1: Biological Homeostasis Teacher Key Page 3 of 3
