Anatomy & Physiology Study Guide: Skeletal, Muscular, Integumentary, and Respiratory Systems

Skeletal System

Functions of the Skeletal System

The skeletal system provides structural support, protection for internal organs, facilitates movement, stores minerals, and produces blood cells.

• Support: Framework for the body, maintaining shape.

• Protection: Shields vital organs (e.g., skull protects brain).

• Movement: Muscles attach to bones, enabling motion.

• Mineral Storage: Stores calcium and phosphorus.

• Blood Cell Production: Hematopoiesis occurs in bone marrow.

Skeletal Bones and Identification

Human bones are classified and located within the axial and appendicular skeleton. Students should be able to label a skeleton diagram and identify major bones.

• Axial Skeleton: Skull, vertebral column, rib cage.

• Appendicular Skeleton: Limbs, pelvic and pectoral girdles.

Bone Classification

Bones are categorized by shape and function.

• Long Bones: Femur, humerus.

• Short Bones: Carpals, tarsals.

• Flat Bones: Sternum, skull.

• Irregular Bones: Vertebrae.

• Sesamoid Bones: Patella.

Anatomy of a Long Bone

Long bones have distinct structural regions, each with specific functions.

• Diaphysis: Shaft, provides strength.

• Epiphysis: Ends, site of joint articulation.

• Articular Cartilage: Reduces friction at joints.

• Epiphyseal Plate: Growth area in children.

• Medullary Cavity: Contains bone marrow.

• Periosteum: Membrane covering bone.

• Myeloid Tissue: Hematopoietic tissue.

Bone Growth

Bones grow in length at the epiphyseal plate and in width by appositional growth.

• Length: Endochondral ossification.

• Width: Periosteal activity.

Bone Histology

Bone tissue is classified as compact (dense) or cancellous (spongy).

• Compact Bone: Organized in osteons, provides strength.

• Cancellous Bone: Trabecular structure, supports marrow.

Chemical Composition of Bone

Bones are composed of organic (collagen) and inorganic (hydroxyapatite) materials.

• Organic: Collagen fibers for flexibility.

• Inorganic: Calcium phosphate for hardness.

Joints: Function and Classification

Joints connect bones and allow movement. They are classified by structure and function.

• Fibrous Joints: Suture, syndesmosis (immovable or slightly movable).

• Cartilaginous Joints: Synchondrosis, symphysis (slightly movable).

• Synovial Joints: Hinge, ball and socket (freely movable).

Structure of Synovial Joints

Synovial joints have specialized structures for movement and stability.

• Articular Capsule: Encloses joint.

• Synovial Fluid: Lubricates joint.

• Ligaments: Stabilize joint.

• Articular Discs: Absorb shock.

• Bone Shape, Muscles, Tendons: Influence joint function.

Muscular System

Functions of the Muscular System

Muscles enable movement, maintain posture, generate heat, and stabilize joints.

• Movement: Skeletal muscles contract to move bones.

• Posture: Continuous muscle activity maintains position.

• Heat Production: Muscle contraction generates heat.

• Joint Stabilization: Muscles reinforce joints.

Types of Muscle Tissue

There are three types of muscle tissue, each with unique characteristics.

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

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

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

Anatomy of a Skeletal Muscle

Skeletal muscles are composed of muscle fibers, connective tissue, and attachments.

• Tendons: Connect muscle to bone.

• Aponeuroses: Flat sheets connecting muscles.

• Epimysium, Perimysium, Endomysium: Layers of connective tissue.

Muscle Histology

Muscle fibers contain myofibrils, sarcoplasmic reticulum, transverse tubules, and myofilaments.

• Myofibrils: Contractile units.

• Sarcoplasmic Reticulum: Stores calcium.

• Transverse Tubules: Conduct impulses.

• Myofilaments: Actin and myosin.

• Sarcomere: Functional unit of contraction.

Sliding Filament Theory

Muscle contraction occurs when actin and myosin filaments slide past each other.

• Actin: Thin filament.

• Myosin: Thick filament.

• ATP: Provides energy for contraction.

Action of Skeletal Muscles

Muscles act by pulling on bones at origin (fixed) and insertion (moving) points.

• Origin: Fixed attachment.

• Insertion: Movable attachment.

Muscle Naming

Muscles are named based on location, direction, size, action, shape, and number of origins.

• Location: E.g., brachialis (arm).

• Direction: E.g., rectus (straight).

• Size: E.g., maximus (large).

• Action: E.g., flexor (bends).

• Shape: E.g., deltoid (triangle).

• Number of Origins: E.g., biceps (two).

Major Superficial Muscles

Students should be able to identify and name major muscle groups.

• Examples: Biceps brachii, quadriceps femoris, pectoralis major.

Integumentary System

Functions of the Integumentary System

The integumentary system protects the body, regulates temperature, and enables sensation.

• Protection: Barrier against pathogens.

• Temperature Regulation: Sweat and blood flow.

• Sensation: Receptors detect stimuli.

• Excretion: Removes waste via sweat.

Structure of the Skin

The skin consists of layers with distinct functions and structures.

• Epidermis: Outer layer, provides protection.

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

• Hypodermis: Deepest layer, stores fat.

Epidermis Anatomy

The epidermis is composed of stratified squamous epithelium, with cell replication, migration, and desquamation.

• Strata: Layers include stratum basale, spinosum, granulosum, lucidum, corneum.

• Epidermal Ridges: Increase surface area.

• Keratin: Protein for strength.

• Melanin: Pigment determining skin color.

Dermis Anatomy

The dermis is tough due to collagen and elastin fibers, and contains sensory receptors, nerves, and blood vessels.

• Dermal Papillae: Increase surface area for attachment.

• Receptors: Detect touch, pressure, pain.

Accessory Structures of Skin

Skin contains glands, hair, and nails, each with specific functions.

• Glands: Sebaceous (oil), sweat (cooling).

• Hair: Protection, sensation.

• Nails: Protection, manipulation.

Respiratory System

Functions of the Respiratory System

The respiratory system supplies oxygen, removes carbon dioxide, and regulates blood pH.

• Gas Exchange: Oxygen in, carbon dioxide out.

• pH Regulation: Maintains acid-base balance.

Organs and Structures of the Respiratory System

The respiratory tract includes several organs, each with a specific role in air flow and gas exchange.

• Nose: Filters, warms, moistens air.

• Pharynx: Passage for air and food.

• Larynx: Voice production.

• Trachea: Conducts air to lungs.

• Bronchi/Bronchioles: Branching airways.

• Alveoli: Site of gas exchange.

Air Flow Pathway

Air travels from outside the body to the alveoli through a series of structures.

• External nares → nasal cavity → pharynx → larynx → trachea → bronchi → bronchioles → alveoli

Properties of a Good Gas Exchange Surface

Effective gas exchange requires a large surface area, thin membrane, and moist environment.

• Large Surface Area: Numerous alveoli.

• Thin Membrane: Facilitates diffusion.

• Moist Surface: Aids gas dissolution.

Pleura and Lungs

The lungs are covered by parietal and visceral pleura, which reduce friction and protect lung tissue.

• Parietal Pleura: Lines thoracic cavity.

• Visceral Pleura: Covers lungs.

Pulmonary Ventilation

Ventilation involves pressure gradients and the action of respiratory muscles.

• Diaphragm: Contracts to increase thoracic volume.

• Intercostal Muscles: Elevate ribs.

• Pressure Gradient: Drives air movement.

Ventilation Rate and Lung Volumes

Lung volumes and capacities are measured to assess respiratory function.

• Tidal Volume (TV): Amount of air per breath.

• Vital Capacity (VC): Maximum air exhaled after maximum inhalation.

• Residual Volume (RV): Air remaining after exhalation.

Formula Example:

$VC = TV + IRV + ERV$

Where VC = Vital Capacity, TV = Tidal Volume, IRV = Inspiratory Reserve Volume, ERV = Expiratory Reserve Volume.