Stayin' Alive (Homeostasis & Thermoregulation)
The part of a feedback loop that detects change in the internal environment.
What is the sensor
The process by which organisms maintain the balance of water and solutes.
What is osmoregulation
The law that explains how diffusion depends on surface area, gradient, and distance.
What is Fick’s Law
The structure that initiates each heartbeat in the human heart.
What is the sinoatrial (SA) node?
The main active transporter driving salt secretion in the shark rectal gland.
What is Na⁺/K⁺-ATPase?
When you sweat to cool off, you’re demonstrating this type of feedback.
What is negative feedback?
The nephron structure that reabsorbs most water and nutrients first.
What is the proximal tubule?
Gas exchange surfaces maximize diffusion by increasing this property.
What is surface area?
Blood pressure is highest in these vessels.
What are arteries?
This channel allows Cl⁻ to exit into the lumen of the shark’s rectal gland.
What is the CFTR chloride channel?
Animals that rely on external heat sources to regulate body temperature.
What are ectotherms?
This hormone increases water reabsorption by inserting aquaporins in the collecting duct.
What is ADH (antidiuretic hormone)?
In fish gills, oxygen transfer efficiency is increased by this flow arrangement.
What is countercurrent flow
Organisms with open circulatory systems circulate this fluid instead of blood.
What is hemolymph?
If the Na⁺/K⁺/2Cl⁻ cotransporter fails, what happens to Cl⁻ secretion?
It stops — the cell can no longer import Cl⁻ for excretion.
This mechanism conserves heat in animals with cold extremities, like bird legs.
What is countercurrent heat exchange?
Marine bony fish must do this to maintain osmotic balance in seawater.
What is drink seawater and excrete excess salts through their gills?
Pneumonia lowers gas exchange efficiency because it increases this variable in Fick’s Law
What is diffusion distance (D)
The primary advantage of a closed circulatory system compared to an open one.
What is faster, high-pressure transport of oxygen and nutrients?
The enzyme that breaks down proteins in the stomach.
pepsin
If the hypothalamus detects a body temperature drop, what two effector responses restore homeostasis?
What are shivering and vasoconstriction
If the Na⁺/K⁺-ATPase pump in the nephron stopped working, what immediate effect would occur?
What is the loss of the sodium gradient, halting secondary active transport and reabsorption?
The Bohr effect describes how this change in the blood decreases hemoglobin’s affinity for oxygen.
What is a drop in pH (or an increase in CO₂)
During intense exercise, this shift in the hemoglobin dissociation curve helps deliver more oxygen to tissues.
What is a right shift (Bohr effect)?
Two structures that increase the nutrient absorption surface area in the small intestine.
Villi and microvilli