Integrated physiological function The body's overall function is a result of coordinated
actions of numerous processes, such as digestion,
circulation, and respiration, which interact
seamlessly.
Pathophysiology The study of how normal physiological processes
are altered in disease states.
Cell division The process of one cell splitting into two identical
cells.
Differentiation The process by which unspecialized cells become
specialized with distinct functions.
Four basic cell and tissue types Epithelial, connective, muscle, and nervous tissue.
Organizational hierarchy Cells → Tissues → Organs → Organ systems →
Organism.
Epithelial tissue Covers surfaces, protects, and facilitates
absorption/secretion (e.g., skin, glands).
Connective tissue Supports and connects (e.g., bones, blood,
tendons).
Muscle tissue Enables movement (skeletal, smooth, and cardiac
muscle).
, Human Physiology Complete Study Guide 2026/2027 | Anatomy & Physiology Concepts Review
Nervous tissue Transmits signals (neurons and glial cells).
Extracellular matrix A network of proteins and polysaccharides
providing structural support and communication
between cells.
Compartmentalization Body fluids are divided into compartments
(intracellular, extracellular) with barriers to maintain
distinct compositions.
Homeostasis The body maintains stable internal conditions within
a narrow range despite external changes (e.g., body
temperature, blood glucose).
Dynamic constancy Physiological variables fluctuate over time but
remain within a predictable range (e.g., blood
pressure over 24 hours).
Steady state Energy is used to maintain a constant condition.
Equilibrium No energy is needed to maintain the balance
between two compartments.
Set point The target value for a physiological variable (e.g.,
98.6°F for body temperature).
Balance inputs and outputs Homeostasis is achieved when the body matches
inputs (e.g., food, water) with outputs (e.g., waste,
energy).
, Human Physiology Complete Study Guide 2026/2027 | Anatomy & Physiology Concepts Review
Negative feedback Reduces deviations from the set point (e.g., lowering
blood sugar after a meal).
Positive feedback Amplifies a response until a specific goal is achieved
(e.g., childbirth contractions).
Reflex (homeostatic) An automatic response to a stimulus.
Basic reflex Innate (e.g., pulling a hand from heat).
Learned reflex Acquired through experience (e.g., riding a bike).
Reflex arc components Stimulus → Receptor → Afferent pathway →
Integrating center → Efferent pathway → Effector
→ Response.
Example: Body temperature control Stimulus (cold) → Thermoreceptors → Nervous
system → Skeletal muscles → Shivering →
Increased warmth.
Four types of chemical messengers Hormones, neurotransmitters, paracrine substances,
autocrine substances.
Hormones Travel via blood to distant targets.
Neurotransmitters Act on nearby cells via synapses.
Paracrine substances Act on nearby cells.
, Human Physiology Complete Study Guide 2026/2027 | Anatomy & Physiology Concepts Review
Autocrine substances Act on the same cell that secreted them.
Adaptation Permanent genetic changes enhancing survival in an
environment (e.g., altitude adaptation in
populations).
Acclimatization Temporary physiological adjustments to a new
environment (e.g., increased red blood cells at high
altitudes).
Net gain and loss Homeostasis depends on balancing inputs (e.g.,
diet) and outputs (e.g., excretion).
Negative balance Loss exceeds gain (e.g., dehydration).
Positive balance Gain exceeds loss (e.g., obesity).
Stable balance Inputs and outputs are equal.
Atoms The smallest units of matter that retain the
properties of an element.
Elements Consist of only one type of atom.