Anatomy Midterm Exam Review Guide
1. Homeostasis
โข Definition: Maintenance of a stable internal environment despite external
changes (temperature, pH, glucose, etc.).
โข Dynamic equilibrium โ conditions fluctuate around a set point (like a
thermostat).
โข Law of Mass Balance โ input must equal output (e.g., water intake = water
loss).
โข Regulated by the Nervous (fast, electrical) and Endocrine (slow, hormonal)
systems.
Homeostatic Control Mechanism
Receptor โ Control Center โ Effector
โข Receptor detects change (stimulus) โ sends info via afferent pathway to
control center.
โข Control Center (usually brain/hypothalamus) compares input to set point โ
sends output via efferent pathway.
โข Effector produces a response to restore balance.
Mnemonic: R-C-E โ Receive, Control, Execute.
Feedback Types
โข Negative Feedback: response reverses the change โ stabilizing (e.g.,
temperature, glucose).
โข Positive Feedback: response amplifies the change โ self-reinforcing (e.g.,
labor, blood clotting).
Positive feedback is rare and requires termination by negative feedback.โ ๏ธ๎
Examples:
โ Thermoregulation: โ temp โ shivering (muscles) โ โ heat โ restored
balance.
โ Childbirth: โ stretch โ โ oxytocin โ โ contractions โ baby born โ cycle
stops.
2. Autonomic Nervous System (ANS)
