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

Integumentary System

Overview and Functions

The integumentary system is the body's first line of defense and includes the skin, hair, nails, and associated glands. It serves multiple protective, sensory, and regulatory functions.

• Components: Skin (epidermis, dermis, subcutaneous layer), hair, nails, glands.

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

• Subcutaneous Layer: Also known as the hypodermis, it anchors the skin to underlying tissues and stores fat.

Structure of the Epidermis

The epidermis is the outermost layer of the skin, composed primarily of epithelial tissue.

• Five Layers of the Epidermis:

  1. Stratum basale

  2. Stratum spinosum

  3. Stratum granulosum

  4. Stratum lucidum (only in thick skin)

  5. Stratum corneum

• Cell Types: Keratinocytes, melanocytes, Langerhans cells, Merkel cells.

• Functions: Barrier against pathogens, water loss prevention, sensory reception.

• Growth and Keratinization: Cells migrate from the stratum basale to the surface, accumulating keratin and eventually dying.

Structure of the Dermis

The dermis lies beneath the epidermis and provides structural support and nourishment to the skin.

• Layers: Papillary layer (loose connective tissue), reticular layer (dense irregular connective tissue).

• Functions: Houses blood vessels, nerves, hair follicles, and glands; provides strength and elasticity.

Accessory Structures

Accessory structures include hair, nails, and glands, each with specialized functions.

• Hair: Protection, sensory input, thermoregulation.

• Nails: Protect distal phalanges, aid in grasping.

• Glands: Sebaceous (oil), sweat (eccrine and apocrine).

Homeostasis and Physiological Importance

• Homeostasis: The integumentary system helps maintain body temperature and water balance.

• Examples: Sweating for cooling, vasoconstriction for heat retention.

Layer	Main Cell Type	Function
Epidermis	Keratinocytes	Protection, water resistance
Dermis	Fibroblasts	Strength, elasticity
Subcutaneous	Adipocytes	Insulation, energy storage

Skeletal System and Articulations

Overview and Functions

The skeletal system provides structural support, protection, movement, and mineral storage. It consists of bones, cartilage, and joints.

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

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

• Appendicular Skeleton: Limbs and girdles.

Bone Structure and Classification

• Long Bone Structure: Diaphysis, epiphyses, metaphysis, medullary cavity, periosteum, endosteum.

• Bone Markings: Foramina, processes, condyles, etc.

• Classification by Shape: Long, short, flat, irregular, sesamoid.

Bone Growth and Formation

• Ossification: Intramembranous and endochondral processes.

• Bone Cells: Osteoblasts (build bone), osteoclasts (break down bone), osteocytes (maintain bone).

• Hormonal Regulation: Parathyroid hormone, calcitonin, vitamin D.

• Calcium Homeostasis: Regulation of plasma calcium via bone remodeling.

Joints and Articulations

• Classification: Fibrous, cartilaginous, synovial joints.

• Synovial Joint Structure: Articular cartilage, joint cavity, synovial membrane, ligaments.

• Movements: Flexion, extension, abduction, adduction, rotation, circumduction.

Joint Type	Structure	Movement Allowed
Fibrous	Dense connective tissue	Little/no movement
Cartilaginous	Cartilage	Slight movement
Synovial	Joint cavity, synovial fluid	Free movement

Muscular System

Overview and Functions

The muscular system enables movement, maintains posture, and produces heat. Skeletal muscle is under voluntary control and is attached to bones.

• General Functions: Movement, posture, heat production.

• Organization: Muscle fibers, fascicles, connective tissue coverings (endomysium, perimysium, epimysium).

Muscle Structure and Contraction

• Myofibril Organization: Sarcomeres, actin, myosin, troponin, tropomyosin.

• Sliding Filament Theory: Muscle contraction occurs as actin and myosin filaments slide past each other.

• Contraction Sequence: Excitation, coupling, contraction, relaxation.

• Neuromuscular Junction: Site where motor neuron stimulates muscle fiber.

Muscle Energy and Fatigue

• ATP Sources: Creatine phosphate, glycolysis, aerobic respiration.

• Muscle Fatigue: Caused by depletion of energy sources, accumulation of metabolic byproducts.

Muscle Response and Types of Contraction

• Myogram: Graphical recording of muscle contraction.

• Types of Contraction: Isometric (no length change), isotonic (length changes).

• Length-Tension Relationship: Optimal sarcomere length for maximal force production.

Muscle Groups and Actions

• Major Skeletal Muscles: Identified by origin, insertion, and action.

• Muscle Roles: Prime movers, antagonists, synergists, fixators.

Muscle Role	Function
Prime mover	Main muscle responsible for movement
Antagonist	Opposes prime mover
Synergist	Assists prime mover
Fixator	Stabilizes origin

Predicting Changes in the Muscular System

• Adaptations: Muscular system responds to exercise, injury, and disease by hypertrophy, atrophy, or altered function.

Additional info: Learning outcomes and cognitive levels are based on Bloom's taxonomy, guiding the depth of understanding required for each topic.