New Jersey City University BIOL 204
Principles of Anatomy & Physiology I
2026 | Comprehensive Guide to
Anatomy & Physiology
Anatomy and Physiology
Anatomy is the scientific study of the structure of body parts and their
relationships to one another. It is subdivided into:
Gross or macroscopic anatomy: The study of large, visible structures
such as organs and tissues.
Microscopic anatomy: The study of structures too small to be seen
with the naked eye, including:
Cytology: The microscopic study of cells.
Histology: The microscopic study of tissues.
Physiology, on the other hand, focuses on the functions of body parts and
how they work to sustain life activities. It often emphasizes cellular and
molecular levels, with subdivisions based on organ systems such as renal
or cardiovascular physiology. The core principle linking structure and
function is the principle of complementarity, which states that what a
structure can do depends on its specific form.
Structural Organization of the Human Body
The human body exhibits a highly organized hierarchy from the simplest to
the most complex levels:
Chemical level: Atoms and molecules form the foundation.
Cellular level: Cells are the basic units of life.
,Tissue level: Groups of similar cells form tissues.
, Organ level: Organs consist of two or more tissue types working
together.
Organ system level: Multiple organs function closely as systems.
Organismal level: The entire human body, a sum of all systems.
This organization ensures efficient functioning and specialization of
different parts, allowing the body to perform complex tasks seamlessly.
Necessary Life Functions
Maintaining life involves several essential functions:
Maintaining boundaries: Separating internal from external
environments (e.g., skin, plasma membranes).
Movement: Of body parts via muscular system and of substances
through the body (e.g., blood, food).
Responsiveness: Ability to sense stimuli and react appropriately.
Digestion: Breakdown of food into absorbable molecules.
Metabolism: All chemical reactions in body cells, including catabolism
and anabolism.
Excretion: Removal of metabolic wastes (urea, CO₂, feces).
Reproduction: Cellular division for growth and repair, and production of
offspring.
Growth: Increase in size or number of cells.
All organ systems collaborate to support these functions, ensuring cellular
survival and overall health.
Survival Needs of Humans
Humans require specific environmental and nutritional conditions:
, Nutrients: Chemicals for energy and building body tissues
(carbohydrates, fats, proteins, minerals, vitamins).
Oxygen: Necessary for energy production (ATP synthesis).
Water: The most abundant chemical in the body, serving as a solvent
and participant in reactions.
Normal body temperature: Around 37°C; deviations impair enzyme
activity.
Atmospheric pressure: Adequate pressure is essential for proper
breathing and gas exchange.
Imbalances can lead to health issues or death, emphasizing the
importance of homeostatic regulation.
Homeostasis and Its Control Mechanisms
Homeostasis is the body's ability to maintain a stable internal
environment despite external changes. It involves:
Variables: Factors like blood sugar, temperature, and blood volume.
Components of control mechanisms:
Receptor: Detects changes.
Control center: Determines the set point and processes information.
Effector: Responds to restore balance.
The system operates via feedback loops:
Negative feedback: Most common; response reduces or halts original
stimulus, restoring equilibrium (e.g., temperature regulation, blood
glucose control).
Positive feedback: Response amplifies the original stimulus, usually for
brief, specific events (e.g., labor contractions, blood clotting).
Principles of Anatomy & Physiology I
2026 | Comprehensive Guide to
Anatomy & Physiology
Anatomy and Physiology
Anatomy is the scientific study of the structure of body parts and their
relationships to one another. It is subdivided into:
Gross or macroscopic anatomy: The study of large, visible structures
such as organs and tissues.
Microscopic anatomy: The study of structures too small to be seen
with the naked eye, including:
Cytology: The microscopic study of cells.
Histology: The microscopic study of tissues.
Physiology, on the other hand, focuses on the functions of body parts and
how they work to sustain life activities. It often emphasizes cellular and
molecular levels, with subdivisions based on organ systems such as renal
or cardiovascular physiology. The core principle linking structure and
function is the principle of complementarity, which states that what a
structure can do depends on its specific form.
Structural Organization of the Human Body
The human body exhibits a highly organized hierarchy from the simplest to
the most complex levels:
Chemical level: Atoms and molecules form the foundation.
Cellular level: Cells are the basic units of life.
,Tissue level: Groups of similar cells form tissues.
, Organ level: Organs consist of two or more tissue types working
together.
Organ system level: Multiple organs function closely as systems.
Organismal level: The entire human body, a sum of all systems.
This organization ensures efficient functioning and specialization of
different parts, allowing the body to perform complex tasks seamlessly.
Necessary Life Functions
Maintaining life involves several essential functions:
Maintaining boundaries: Separating internal from external
environments (e.g., skin, plasma membranes).
Movement: Of body parts via muscular system and of substances
through the body (e.g., blood, food).
Responsiveness: Ability to sense stimuli and react appropriately.
Digestion: Breakdown of food into absorbable molecules.
Metabolism: All chemical reactions in body cells, including catabolism
and anabolism.
Excretion: Removal of metabolic wastes (urea, CO₂, feces).
Reproduction: Cellular division for growth and repair, and production of
offspring.
Growth: Increase in size or number of cells.
All organ systems collaborate to support these functions, ensuring cellular
survival and overall health.
Survival Needs of Humans
Humans require specific environmental and nutritional conditions:
, Nutrients: Chemicals for energy and building body tissues
(carbohydrates, fats, proteins, minerals, vitamins).
Oxygen: Necessary for energy production (ATP synthesis).
Water: The most abundant chemical in the body, serving as a solvent
and participant in reactions.
Normal body temperature: Around 37°C; deviations impair enzyme
activity.
Atmospheric pressure: Adequate pressure is essential for proper
breathing and gas exchange.
Imbalances can lead to health issues or death, emphasizing the
importance of homeostatic regulation.
Homeostasis and Its Control Mechanisms
Homeostasis is the body's ability to maintain a stable internal
environment despite external changes. It involves:
Variables: Factors like blood sugar, temperature, and blood volume.
Components of control mechanisms:
Receptor: Detects changes.
Control center: Determines the set point and processes information.
Effector: Responds to restore balance.
The system operates via feedback loops:
Negative feedback: Most common; response reduces or halts original
stimulus, restoring equilibrium (e.g., temperature regulation, blood
glucose control).
Positive feedback: Response amplifies the original stimulus, usually for
brief, specific events (e.g., labor contractions, blood clotting).
