Anatomy & Physiology: Tissue Types, Integumentary System, and Skeletal System Study Guide

Tissues of the Human Body

1. Epithelial Tissue

Epithelial tissue covers body surfaces, lines internal cavities, and forms glands. It is classified based on cell shape and the number of layers.

• Special Characteristics: Epithelial cells are tightly packed, have polarity (apical and basal surfaces), and are avascular but innervated.

• Classification:

  • By cell shape: Squamous (flat), Cuboidal (cube-shaped), Columnar (tall).

  • By layers: Simple (one layer), Stratified (multiple layers).

• Locations and Functions: Different types of epithelium are found in the skin, lining of the gut, respiratory tract, and glands, serving functions such as protection, absorption, secretion, and filtration.

• Glandular Epithelium:

  • Endocrine Glands: Ductless glands that secrete hormones directly into the bloodstream. Can be unicellular or multicellular.

  • Exocrine Glands: Secrete products into ducts (e.g., sweat, saliva).

2. Connective Tissue

Connective tissue supports, binds, and protects other tissues and organs. It is characterized by cells embedded in an extracellular matrix.

• Common Origin: All connective tissues arise from mesenchyme (embryonic tissue).

• Structural Components:

  • Ground Substance: Unstructured material filling the space between cells.

  • Fibers: Collagen (strength), elastic (flexibility), reticular (support).

  • Cells: Fibroblasts, chondrocytes, osteocytes, adipocytes, etc.

• Types of Connective Tissue Proper: Loose (areolar, adipose, reticular) and dense (regular, irregular, elastic).

• Specialized Connective Tissues: Cartilage, bone, blood.

3. Muscle Tissue

Muscle tissue is responsible for movement. There are three types:

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

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

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

4. Nervous Tissue

Nervous tissue is specialized for communication via electrical and chemical signals. It consists of neurons and supporting glial cells.

5. Covering and Lining Membranes

• Cutaneous Membrane: The skin.

• Mucous Membranes: Line body cavities open to the exterior (e.g., digestive, respiratory tracts).

• Serous Membranes: Line closed body cavities (e.g., peritoneum, pleura).

6. Aging Tissue

Tissues change with age, often losing elasticity and regenerative capacity.

Integumentary System

Skin Structure and Function

The integumentary system includes the skin and its derivatives (hair, nails, glands). It serves as a barrier, regulates temperature, and provides sensory information.

• Skin Layers:

  • Epidermis: Outermost layer, composed of keratinized stratified squamous epithelium.

  • Dermis: Deeper layer, contains connective tissue, blood vessels, nerves, and appendages.

• Cells of the Skin: Keratinocytes (produce keratin), melanocytes (produce melanin), dendritic cells (immune function), Merkel cells (sensory).

• Dermal Papillae: Projections that increase surface area for exchange between dermis and epidermis.

• Skin Markings: Include fingerprints, lines, and flexure lines.

• Skin Color: Determined by melanin, carotene, and hemoglobin.

• Hair and Nails: Accessory structures derived from the epidermis.

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

• Functions: Protection, sensation, thermoregulation, excretion, vitamin D synthesis.

• Burns: Classified by depth (first, second, third degree).

• Developmental Aspects: Skin changes with age, including thinning and decreased elasticity.

Bone

Part 1: Cartilage and Bone Overview

Bones and cartilage form the framework of the body, providing support, protection, and enabling movement.

• Cartilage: Flexible connective tissue found in joints, ear, nose, and respiratory tract.

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

• Classification of Bone: Long, short, flat, irregular, and sesamoid bones.

• Gross Anatomy: Compact (dense) bone and spongy (cancellous) bone.

• Microscopic Anatomy: Osteons (Haversian systems) in compact bone; trabeculae in spongy bone.

Part 2: Bone Formation and Growth

• Bone Formation (Ossification):

  • Intramembranous Ossification: Bone develops from fibrous membrane (e.g., flat bones of skull).

  • Endochondral Ossification: Bone forms by replacing hyaline cartilage (e.g., long bones).

• Interstitial Growth: Growth in length at the epiphyseal plate.

• Appositional Growth: Growth in thickness.

The Skeleton

Axial Skeleton

The axial skeleton includes the skull, vertebral column, and thoracic cage. These bones protect vital organs and support the body’s axis.

• Skull: Protects the brain and forms the structure of the face.

• Vertebral Column: Supports the body and protects the spinal cord.

• Thoracic Cage: Protects the heart and lungs.

Additional info: The appendicular skeleton (not detailed in the provided notes) includes the limbs and girdles, which facilitate movement.