Comprehensive Study Guide: Introduction to Anatomy & Physiology

Levels of Organization

Overview of Biological Organization

The human body is organized in a hierarchical structure, from the simplest chemical level to the most complex organismal level.

• Chemical Level: Atoms and molecules essential for life (e.g., water, proteins).

• Cellular Level: Cells are the basic structural and functional units of life.

• Tissue Level: Groups of similar cells performing a common function (e.g., muscle tissue).

• Organ Level: Structures composed of two or more tissue types (e.g., heart, skin).

• Organ System Level: Groups of organs working together (e.g., digestive system).

• Organismal Level: The complete living being.

Example: Muscle cells (cellular) form muscle tissue, which is part of the muscular system (organ system).

Directional Terms, Planes, and Body Cavities

Directional Terms

Directional terms describe the positions of structures relative to other structures or locations in the body.

• Superior (Cranial): Toward the head.

• Inferior (Caudal): Toward the feet.

• Anterior (Ventral): Toward the front.

• Posterior (Dorsal): Toward the back.

• Medial: Toward the midline.

• Lateral: Away from the midline.

• Proximal: Closer to the point of attachment.

• Distal: Farther from the point of attachment.

Planes of the Body

• Sagittal Plane: Divides the body into right and left parts.

• Frontal (Coronal) Plane: Divides the body into anterior and posterior parts.

• Transverse (Horizontal) Plane: Divides the body into superior and inferior parts.

Body Cavities

• Dorsal Cavity: Includes the cranial and vertebral cavities.

• Ventral Cavity: Includes the thoracic and abdominopelvic cavities.

Feedback Mechanisms

Homeostatic Feedback

Feedback mechanisms maintain homeostasis by regulating internal conditions.

• Negative Feedback: Reverses a change to keep a variable within a normal range (e.g., body temperature regulation).

• Positive Feedback: Enhances a change (e.g., blood clotting, labor contractions).

Chemistry of the Body

Chemical Terminology

• Atom: Smallest unit of matter.

• Molecule: Two or more atoms bonded together.

• Ion: Atom or molecule with a net electric charge.

Chemical Reactions

• Synthesis Reaction: $A + B \rightarrow AB$

• Decomposition Reaction: $AB \rightarrow A + B$

• Exchange Reaction: $AB + CD \rightarrow AD + CB$

pH

• pH Scale: Measures hydrogen ion concentration; ranges from 0 (acidic) to 14 (basic).

• Neutral pH: 7 (pure water).

• Acidic: pH < 7; Basic (Alkaline): pH > 7.

Cell Structure and Function

Parts of the Cell

• Plasma Membrane: Selectively permeable barrier.

• Cytoplasm: Fluid containing organelles.

• Nucleus: Contains genetic material (DNA).

Membrane Transport

• Passive Transport: No energy required (e.g., diffusion, osmosis).

• Active Transport: Requires energy (e.g., sodium-potassium pump).

Organelles

• Mitochondria: Site of ATP production.

• Endoplasmic Reticulum (ER): Protein and lipid synthesis.

• Golgi Apparatus: Modifies and packages proteins.

• Lysosomes: Digestive enzymes.

DNA

• Deoxyribonucleic Acid (DNA): Genetic blueprint for protein synthesis.

• Double helix structure: Discovered by Watson and Crick.

Histology: Tissues and Membranes

Tissue Types and Classification

• Epithelial Tissue: Covers surfaces, lines cavities.

• Connective Tissue: Supports and binds other tissues.

• Muscle Tissue: Produces movement.

• Nervous Tissue: Transmits impulses.

Membranes

• Mucous Membranes: Line body cavities open to the exterior.

• Serous Membranes: Line closed body cavities.

• Cutaneous Membrane: The skin.

The Integumentary System

Components and Functions of Skin

• Epidermis: Outer layer; provides protection.

• Dermis: Middle layer; contains blood vessels, nerves.

• Hypodermis: Subcutaneous fat layer.

• Functions: Protection, sensation, temperature regulation, vitamin D synthesis.

Molecules of Skin

• Keratin: Protein providing strength and waterproofing.

• Melanin: Pigment protecting against UV radiation.

Burns

• First-degree: Affects epidermis only.

• Second-degree: Affects epidermis and part of dermis.

• Third-degree: Destroys entire skin thickness.

The Skeletal System

Function and Components of Bone

• Functions: Support, protection, movement, mineral storage, blood cell formation.

• Components: Compact bone, spongy bone, marrow.

Bone Growth and Types

• Ossification: Process of bone formation.

• Types of Bones: Long, short, flat, irregular, sesamoid.

Major Bones Names

• Skull, vertebrae, ribs, humerus, femur, tibia, pelvis, etc.

Articulations (Joints)

Classification and Structure of Joints

• Fibrous Joints: Immovable (e.g., sutures of skull).

• Cartilaginous Joints: Slightly movable (e.g., intervertebral discs).

• Synovial Joints: Freely movable (e.g., knee, shoulder).

Types of Synovial Joints

• Hinge, ball-and-socket, pivot, saddle, condyloid, gliding.

Levers

• Levers: Bones act as levers to produce movement with muscles.

The Muscular System

Muscle Functions and Types

• Functions: Movement, posture, heat production.

• Types: Skeletal (voluntary), cardiac (heart), smooth (walls of organs).

Muscle Groups and Structure

• Muscle Groups: Agonist, antagonist, synergist, fixator.

• Structure: Muscle fibers, myofibrils, sarcomeres.

Electrical Potentials

• Resting Membrane Potential: Difference in charge across the muscle cell membrane.

• Action Potential: Rapid change in membrane potential leading to muscle contraction.

The Nervous System

Functions and Divisions

• Functions: Sensory input, integration, motor output.

• Divisions: Central Nervous System (CNS), Peripheral Nervous System (PNS).

Synapses

• Synapse: Junction between two neurons where neurotransmitters are released.

The Brain and Sensory Systems

Brain Anatomy and Functions

• Cerebrum: Higher brain functions.

• Cerebellum: Coordination and balance.

• Brainstem: Basic life functions (breathing, heart rate).

Nerves, Sensory Receptors, and Neurons

• Nerves: Bundles of axons in the PNS.

• Sensory Receptors: Detect stimuli (e.g., touch, temperature).

• Neurons: Nerve cells transmitting electrical signals.

The Autonomic Nervous System

Divisions, Receptors, and Functions

• Divisions: Sympathetic ("fight or flight"), Parasympathetic ("rest and digest").

• Receptors: Adrenergic (respond to adrenaline), cholinergic (respond to acetylcholine).

• Functions: Regulate involuntary functions (heart rate, digestion).

The Special Senses: The Eye

Anatomy and Function of the Eye

• Cornea: Transparent front part; refracts light.

• Iris: Colored part; controls pupil size.

• Lens: Focuses light on the retina.

• Retina: Contains photoreceptors (rods and cones) for vision.

• Optic Nerve: Transmits visual information to the brain.

Example: The lens changes shape to focus on near or distant objects (accommodation).