Anatomy & Physiology: Tissues, Skin, Bone, and Joints Study Guide

Chapter 4: Tissues

Basic Tissue Types

The human body is composed of four basic tissue types, each with distinct structures and functions.

• Epithelial Tissue: Covers body surfaces, lines cavities, and forms glands. Functions include protection, absorption, secretion, and sensation. Most abundant: Connective tissue.

• Connective Tissue: Supports, binds, and protects other tissues and organs. Includes bone, blood, cartilage, and adipose tissue.

• Muscle Tissue: Responsible for movement. Types include skeletal (voluntary), cardiac, and smooth (involuntary).

• Nervous Tissue: Initiates and transmits electrical impulses for communication.

Epithelial Tissue

• Distinguishing Characteristics: Closely packed cells, avascular, high regenerative capacity, polarity (apicual and basal surfaces), supported by connective tissue.

• Naming System: Based on cell layers (simple, stratified, pseudostratified) and cell shape (squamous, cuboidal, columnar).

• Pseudostratified Ciliated Columnar Epithelium: Found in the respiratory tract, functions in secretion and movement of mucus.

• Glands: Structures that secrete substances. Endocrine glands release hormones into the bloodstream; exocrine glands secrete onto surfaces via ducts.

• Goblet Cells: Unicellular glands that secrete mucus, found in the respiratory and digestive tracts.

Connective Tissue

• Main Elements: Cells, fibers (collagen, elastic, reticular), and ground substance (matrix).

• Subtypes: Loose (areolar, adipose, reticular) and dense (regular, irregular, elastic) connective tissue; cartilage, bone, blood.

• Immature Cell Types: End in -blast (e.g., fibroblast, chondroblast, osteoblast).

• Major Fiber Types: Collagen (strength), elastic (flexibility), reticular (support).

Muscle Tissue

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

Membranes

• Definition: Thin layers of tissue covering surfaces or lining cavities.

• Types: Mucous, serous, cutaneous (skin).

• Fibrosis vs. Regeneration: Regeneration restores normal function; fibrosis replaces tissue with scar tissue.

• Poor Regenerative Capacity: Cardiac muscle, nervous tissue in the brain and spinal cord.

Chapter 5: Skin (Integumentary System)

Layers and Cell Types

The skin consists of two main regions: the epidermis and dermis, each with specialized cells and functions.

• Regions: Epidermis (superficial, avascular, stratified squamous epithelium) and dermis (deeper, connective tissue, vascular).

• Major Cell Types: Keratinocytes (produce keratin), melanocytes (produce melanin), dendritic (Langerhans) cells (immune defense), Merkel cells (sensory).

• Five Layers of Epidermis (superficial to deep):

  1. Stratum corneum (protection, dead cells)

  2. Stratum lucidum (only in thick skin, palms/soles)

  3. Stratum granulosum (keratinization begins)

  4. Stratum spinosum (strength, flexibility)

  5. Stratum basale (mitotically active, melanocytes)

• Most Actively Mitotic Layer: Stratum basale.

• Water Loss Prevention: Stratum corneum.

• Thick Skin: Stratum lucidum present; found on palms and soles.

Skin Features and Functions

• Fingerprints: Formed by dermal papillae; unique to each individual.

• Cleavage (Tension) Lines: Natural orientation of collagen fibers; important for surgical incisions.

• Pigments: Melanin, carotene, hemoglobin.

• Pathologies: Cyanosis (blue), erythema (red), jaundice (yellow), pallor (pale).

• Hair: Functions in protection, sensation, and thermoregulation; arrector pili muscle causes hair to stand.

• Sweat Glands: Eccrine (most common, thermoregulation), apocrine (axillary/genital, odor).

• Other Glands: Sebaceous (oil), ceruminous (earwax), mammary (milk).

• Skin Cancer: Basal cell carcinoma (most common, least dangerous), squamous cell carcinoma, melanoma (most dangerous).

• Burns: 1st degree (epidermis), 2nd degree (epidermis + dermis), 3rd degree (full thickness).

Chapter 6: Bone Tissue and Skeletal System

Bone Types and Functions

• Types: Long, short, flat, irregular bones. Most abundant: Long bones.

• Functions: Support, protection, movement, mineral storage, blood cell formation (hematopoiesis), triglyceride storage.

• Axial vs. Appendicular Skeleton: Axial (skull, vertebral column, rib cage); appendicular (limbs, girdles).

• Bone Classifications by Shape: Long (femur), short (carpals), flat (sternum), irregular (vertebrae).

Bone Structure and Growth

• Diaphysis: Shaft of long bone; Epiphysis: Ends of long bone.

• Epiphyseal Line vs. Plate: Plate is growth area in children; line is remnant in adults.

• Red Blood Cell Production: Occurs in red marrow, mainly in flat bones and epiphyses of long bones in adults.

• Major Bone Cell Types: Osteoblasts (build bone), osteocytes (maintain bone), osteoclasts (break down bone).

• Compact Bone Structure: Composed of osteons (Haversian systems).

Bone Formation and Remodeling

• Intramembranous Ossification: Forms flat bones from mesenchyme.

• Endochondral Ossification: Forms most bones from cartilage templates.

• Interstitial vs. Appositional Growth: Interstitial (length), appositional (width).

• Hormones: Growth hormone, thyroid hormone, sex hormones regulate bone growth.

• Bone Remodeling: Involves bone resorption (osteoclasts) and deposition (osteoblasts).

• Parathyroid Hormone (PTH): Increases blood calcium by stimulating osteoclasts.

• Wolff's Law: Bone grows/remodels in response to mechanical stress.

Bone Disorders

• Fractures: Classified by position, completeness, orientation, and skin penetration.

• Osteoporosis: Decreased bone mass, increased fracture risk.

• Paget's Disease, Rickets, Osteomalacia: Disorders affecting bone formation/mineralization.

• Dietary Needs: Calcium, vitamin D, protein for bone health.

Chapter 8: Synovial Joints

Joint Classifications

• Main Types: Fibrous (immovable), cartilaginous (slightly movable), synovial (freely movable).

• Structure and Function: Synovial joints have a joint cavity, articular cartilage, synovial fluid, and supporting ligaments.

• Subcategories: Suture, syndesmosis, gomphosis (fibrous); synchondrosis, symphysis (cartilaginous).

Synovial Joints

• Distinguishing Features: Articular cartilage, joint cavity, synovial fluid, articular capsule, ligaments, nerves, and blood vessels.

• Major Factors for Stability: Shape of articular surfaces, ligaments, muscle tone.

• Movements Allowed: Gliding, angular (flexion, extension, abduction, adduction), rotation, special movements (supination, pronation, etc.).

• Definitions of Movements:

  • Flexion/Extension: Decrease/increase angle between bones.

  • Abduction/Adduction: Movement away/toward midline.

  • Rotation: Bone turns around its own axis.

  • Special Movements: Inversion, eversion, protraction, retraction, dorsiflexion, plantarflexion, supination, pronation, elevation, depression, opposition.

Joint Examples and Pathologies

• Examples: Shoulder (ball-and-socket), elbow (hinge), knee (modified hinge), hip (ball-and-socket).

• Cruciate Ligaments: ACL and PCL stabilize the knee joint.

• Hip vs. Shoulder: Hip is more stable, less mobile; shoulder is more mobile, less stable.

• Dislocation vs. Separation: Dislocation: bones forced out of alignment; separation: injury to ligaments (e.g., acromioclavicular joint).

• Most Easily Dislocated Joint: Shoulder.

• Arthritis Types: Osteoarthritis (degenerative), rheumatoid arthritis (autoimmune), gouty arthritis (uric acid crystals).

Joint Type	Structure	Movement	Example
Fibrous	Dense connective tissue, no cavity	Immovable	Sutures of skull
Cartilaginous	Cartilage, no cavity	Slightly movable	Intervertebral discs
Synovial	Joint cavity, synovial fluid	Freely movable	Shoulder, knee

Additional info: This study guide is based on common Anatomy & Physiology curriculum and expands on the provided exam study questions for clarity and completeness.