Introduction to Anatomy & Physiology

Key Definitions and Concepts

Anatomy and Physiology are foundational sciences for understanding the structure and function of the human body. This section introduces essential terminology and organizational principles.

• Anatomy: The study of the structure of body parts and their relationships to one another.

• Physiology: The study of the function of body parts and how they work to carry out life-sustaining activities.

• Cytology: The study of cells.

• Histology: The study of tissues.

Organ Systems Overview

The human body is organized into organ systems, each with specific organs and functions.

• Integumentary System: Skin, hair, nails; protects body, regulates temperature.

• Skeletal System: Bones, joints; supports and protects organs, enables movement.

• Muscular System: Skeletal muscles; movement, posture, heat production.

• Nervous System: Brain, spinal cord, nerves; fast-acting control system.

• Endocrine System: Glands; hormone production, regulation of growth and metabolism.

• Cardiovascular System: Heart, blood vessels; transports nutrients and gases.

• Lymphatic System: Lymph nodes, vessels; immunity, fluid balance.

• Respiratory System: Lungs, airways; gas exchange.

• Digestive System: Stomach, intestines; breakdown and absorption of food.

• Urinary System: Kidneys, bladder; waste elimination, water balance.

• Reproductive System: Ovaries/testes; production of offspring.

Levels of Organization

The body is organized hierarchically from smallest to largest functional units.

• Chemical Level: Atoms and molecules

• Cellular Level: Cells

• Tissue Level: Groups of similar cells

• Organ Level: Two or more tissue types

• Organ System Level: Groups of organs

• Organismal Level: The whole body

Body Planes

Body planes are imaginary lines used to divide the body for anatomical study.

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

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

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

Body Cavities

Major cavities house vital organs and provide protection.

Homeostasis and Anatomical Position

Homeostasis

Homeostasis is the maintenance of a stable internal environment despite changes in external conditions.

• Example: Regulation of body temperature, blood glucose levels.

• Mechanism: Negative feedback loops are most common.

Anatomical Position

The standard reference position for describing locations and directions on the human body.

• Body standing upright, facing forward

• Arms at sides, palms facing forward

• Feet slightly apart

Basic Chemistry for Anatomy & Physiology

Atomic Structure

• Atomic Number: Number of protons in the nucleus of an atom.

• Isotopes: Atoms of the same element with different numbers of neutrons.

Bonds

• Ionic Bond: Transfer of electrons between atoms, forming charged ions.

• Covalent Bond: Sharing of electrons between atoms.

Hydrolysis

• Definition: Chemical reaction where water is used to break down a compound.

• Example: Breakdown of proteins into amino acids.

Energy in Cells

• Immediate Source: ATP (adenosine triphosphate)

Macromolecules

• Proteins: Chains of amino acids; enzymes, structural components.

• DNA: Genetic material; adenine pairs with thymine.

• Complementary Base Pairing: Adenine (A) pairs with Thymine (T); Guanine (G) pairs with Cytosine (C).

Abundant Elements in Cells

• Oxygen (O)

• Carbon (C)

• Hydrogen (H)

• Nitrogen (N)

Skeletal System

Bone Structure and Classification

The skeletal system provides support, protection, and enables movement. Bones are classified by shape and structure.

• Long Bones: Longer than wide (e.g., femur)

• Short Bones: Cube-shaped (e.g., carpals)

• Flat Bones: Thin, flattened (e.g., sternum)

• Irregular Bones: Complex shapes (e.g., vertebrae)

Parts of a Long Bone (Figure 5.1)

Osteon (Haversian System)

The osteon is the fundamental unit of compact bone.

• Central Canal (Haversian Canal): Contains blood vessels and nerves.

• Lamellae: Concentric rings of bone matrix.

• Lacunae: Small spaces housing osteocytes.

• Canaliculi: Tiny channels connecting lacunae.

Types of Joints

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

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

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

Vertebral Column Order (Superior to Inferior)

• Cervical

• Thoracic

• Lumbar

• Sacral

• Coccygeal

Muscular System

Types of Muscle Tissue

• Skeletal Muscle: Voluntary, striated, attached to bones.

• Cardiac Muscle: Involuntary, striated, found in heart.

• Smooth Muscle: Involuntary, non-striated, found in walls of organs.

Muscle Structure

Muscle Contraction

• Sliding Filament Theory: Actin and myosin filaments slide past each other to produce contraction.

• ATP: Required for muscle contraction and relaxation.

Nervous System

Neuron Structure

Reflex Arc

• Sequence: Receptor → Sensory neuron → Integration center → Motor neuron → Effector

Divisions of the Nervous System

• Central Nervous System (CNS): Brain and spinal cord

• Peripheral Nervous System (PNS): Nerves outside CNS

• Somatic: Voluntary control

• Autonomic: Involuntary control (sympathetic and parasympathetic)

Sympathetic vs. Parasympathetic

Integumentary System

Layers of the Skin

• Epidermis: Outer layer; protection

• Dermis: Middle layer; strength, flexibility

• Hypodermis (Subcutaneous): Deepest layer; fat storage

ABCDE Rule for Skin Disorders

• A: Asymmetry

• B: Border irregularity

• C: Color variation

• D: Diameter >6mm

• E: Evolving shape/size

Additional info:

• Some anatomical diagrams and tables have been inferred based on standard textbook content.

• All major systems and foundational concepts for introductory Anatomy & Physiology are covered.