Anatomy & Physiology: Foundations, Organization, and Terminology

Biomolecules in Cells

Major Classes of Biomolecules

Cells contain four major classes of biomolecules, each with distinct structures and functions essential for life.

• Proteins: Composed of amino acids. Fundamental components of tissues and enzymes; responsible for metabolic functions in the cell.

• Lipids: Built from multiple building blocks. Serve as long-term energy storage, structural components of membranes, and signaling molecules.

• Carbohydrates: Made of monosaccharides. Provide short-term energy, structural support, and cell recognition.

• Nucleic Acids: Composed of nucleotides. Store hereditary information (DNA) and participate in protein synthesis (RNA).

Example: Hemoglobin (protein) transports oxygen in the blood; glucose (carbohydrate) is a primary energy source.

Structure-Function Relationship

Cellular Specialization

Cellular structures are specialized to perform specific functions, reflecting the principle that structure determines function.

• Mitochondria: Specialized for energy production; contain enzymes for cellular respiration.

• Cell Membrane: Composed of a lipid bilayer with embedded proteins; controls transport, communication, and recognition.

Example: Red blood cells have a biconcave shape to increase surface area for oxygen transport.

Characteristics of Life

Defining Features of Living Organisms

All living things share several key characteristics that distinguish them from non-living matter.

• Energy Production/Consumption: Cells produce and consume energy, primarily stored as ATP.

• Growth/Repair: Organisms grow and repair tissues over time.

• Adaptation: Ability to respond and change based on environmental conditions.

• Reproduction: Production of new individuals, either sexually or asexually.

Example: Muscle cells use ATP for contraction; skin cells divide to repair wounds.

Levels of Biological Organization

Hierarchical Structure

Biological systems are organized into hierarchical levels, each building upon the previous.

Level	Description
Cell	Basic unit of life
Tissue	Group of similar cells performing a function
Organ	Structure composed of multiple tissues
Organ System	Group of organs working together
Organism	Complete living being

Example: The heart (organ) is made of muscle, connective, and nervous tissues.

Major Tissue Types

Classification and Functions

The human body contains four primary tissue types, each with unique roles.

• Epithelial Tissue: Covers surfaces, lines cavities, forms glands; functions in protection, absorption, secretion.

• Connective Tissue: Provides support, binds tissues, stores energy; includes bone, cartilage, blood.

• Muscle Tissue: Generates movement and force; includes skeletal, cardiac, and smooth muscle.

• Nervous Tissue: Conducts electrical impulses; enables communication and control.

Example: Neurons (nervous tissue) transmit signals; adipose tissue (connective) stores fat.

Organ Systems Overview

Major Systems, Organs, and Functions

Organ systems consist of multiple organs and tissues working together to perform vital functions.

System	Organs & Tissues	Functions
Integumentary	Skin, hair, nails, sweat glands	Protection, temperature regulation
Endocrine	Glands (e.g., thyroid)	Coordination, hormone secretion
Reproductive	Ovaries, testes, uterus	Production of offspring
Nervous	Brain, spinal cord, nerves	Control, communication
Immune/Lymphatic	Lymph nodes, spleen	Defense, immune response
Cardiovascular	Heart, blood vessels	Transport of nutrients, gases
Respiratory	Lungs, trachea	Gas exchange
Urinary	Kidneys, bladder	Filtration, waste removal

Example: The respiratory system supplies oxygen and removes carbon dioxide.

Body Organization and Anatomical Terminology

Body Regions and Cavities

The body is divided into regions and cavities to facilitate study and description.

• Major Regions: Head, neck, trunk, upper limbs, lower limbs.

• Body Cavities: Cranial, thoracic, abdominal, pelvic; house specific organs.

Example: The thoracic cavity contains the heart and lungs.

Planes of Section

Sections are used to describe anatomical relationships and compartmentalization.

• Transverse Section: Divides body into upper and lower portions.

• Sagittal Section: Divides body into left and right portions.

• Coronal Section: Divides body into anterior and posterior portions.

• Mid-sagittal Section: Divides body into equal left and right halves.

Example: MRI scans often use transverse sections to view internal organs.

Directional Terms in Anatomy

Definitions and Examples

Directional terms are used to describe the locations of structures relative to one another.

Term	Definition	Example
Anterior (ventral)	Towards the front of the body	The sternum is anterior to the spine
Posterior (dorsal)	Towards the back of the body	The vertebrae are posterior to the sternum
Medial	Closer to the midline	The heart is medial to the shoulder
Lateral	Farther from the midline	The arms are lateral to the nose
Superior	Closer to the head	The shoulder is superior to the hip
Inferior	Towards the feet	The ankle is inferior to the knee
Proximal	Closer to the trunk or point of origin	The elbow is proximal to the wrist
Distal	Farther from the trunk or point of origin	The toes are distal to the knee
Superficial	Closer to the surface of the body	The epidermis is the most superficial layer of skin

Example: The nose is superior to the mouth and medial to the ears.

*Additional info: Some content and examples were inferred and expanded for clarity and completeness based on standard Anatomy & Physiology curriculum.*