Study Guide: Tissues, Integumentary System, and Bones (Anatomy & Physiology)

Chapter 4: Tissues

Overview of Tissues

Tissues are groups of similar cells that perform a common function. The human body contains four primary tissue types: epithelial, connective, muscle, and nervous tissue. Each type has distinct structures and functions essential for maintaining homeostasis.

• Epithelial Tissue

• Connective Tissue

• Muscle Tissue

• Nervous Tissue

Epithelial Tissue

• Functions: Protection, absorption, filtration, excretion, secretion, and sensory reception.

• General Characteristics: Closely packed cells, little extracellular material, avascular (no blood vessels), high regenerative capacity, polarity (apical and basal surfaces).

• Classification: Based on the number of cell layers (simple or stratified) and cell shape (squamous, cuboidal, columnar).

Types of Epithelia:

• Simple squamous epithelium: Single layer of flat cells; found in areas of diffusion (e.g., alveoli of lungs, lining of blood vessels).

• Simple cuboidal epithelium: Single layer of cube-shaped cells; found in glands and kidney tubules.

• Simple columnar epithelium: Single layer of tall, column-like cells; lines digestive tract.

• Pseudostratified epithelium: Appears layered but all cells touch the basement membrane; found in respiratory tract.

• Stratified squamous epithelium: Multiple layers of flat cells; protects against abrasion (e.g., skin, mouth).

Connective Tissue

• Functions: Support, protection, insulation, storage, and transport.

• General Characteristics: Most abundant tissue type, cells separated by extracellular matrix (ECM), varying degrees of vascularity.

• Extracellular Matrix (ECM): Non-living material between cells, composed of ground substance and fibers.

• Ground Substance: Unstructured material that fills the space between cells; contains water, proteins, and polysaccharides.

• Fibers:

  • Collagen: Strong, provides tensile strength.

  • Elastic: Stretchy, allows recoil.

  • Reticular: Fine, forms supportive networks.

• Cell Types: -blast cells are immature, actively secreting matrix; -cyte cells are mature, maintaining the matrix.

Types of Connective Tissue:

• Connective Tissue Proper

  • Loose: Areolar, adipose, reticular

  • Dense: Dense regular, dense irregular, elastic

• Cartilage: Hyaline, fibrocartilage, elastic

• Bone

• Blood

Muscle Tissue

Muscle tissue is specialized for contraction and 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.

Nervous Tissue

• Location: Brain, spinal cord, nerves.

• Function: Transmits electrical impulses for communication and control.

• Neurons: Specialized cells that generate and conduct nerve impulses.

Chapter 5: The Integumentary System

Overview

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

Skin Structure

• Two Major Regions: Epidermis (superficial) and dermis (deep).

Epidermis

• Five Layers (from superficial to deep):

  • Stratum corneum

  • Stratum lucidum (only in thick skin)

  • Stratum granulosum

  • Stratum spinosum

  • Stratum basale

• Keratin: A protein that provides strength and waterproofing.

• Cell Types:

  • Keratinoctyes: Produce keratin.

  • Melanocytes: Produce melanin pigment.

  • Dendritic (Langerhans) cells: Immune defense.

  • Tactile (Merkel) cells: Sensory receptors for touch.

Dermis

• Two Layers: Papillary (superficial, forms fingerprints) and reticular (deep, dense connective tissue).

• Dermal Papillae: Projections that create fingerprints.

• Glands:

  • Sweat (sudoriferous) glands: Eccrine (produce watery sweat, secrete to skin surface) and apocrine (secrete into hair follicles).

  • Sebaceous glands: Produce sebum (oil), secrete into hair follicles.

• Vascularization: Papillary layer is vascularized; epidermis is avascular.

• Pigments: Melanin, carotene, hemoglobin.

Skin Types and Burns

• Thick vs. Thin Skin: Thick skin has all five epidermal layers and is found on palms and soles; thin skin lacks stratum lucidum.

• Burns:

  • 1st degree: Epidermis only

  • 2nd degree: Epidermis and part of dermis

  • 3rd degree: Full thickness (epidermis, dermis, possibly deeper tissues)

Chapter 6: Bones and Skeletal Tissue

Cartilage

• Types:

  • Hyaline cartilage: Most abundant, provides support and flexibility; found in nose, trachea, articular surfaces.

  • Elastic cartilage: Flexible, found in ear and epiglottis.

  • Fibrocartilage: Strong, resists compression; found in intervertebral discs, pubic symphysis.

Bone Structure and Classification

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

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

• Compact vs. Spongy Bone: Compact bone is dense and forms outer layer; spongy bone is porous and found inside bones.

• Long Bone Anatomy:

  • Diaphysis: Shaft

  • Epiphysis: Ends

  • Epiphyseal line/plate: Growth area in children; becomes line in adults

  • Articular cartilage: Covers joint surfaces

  • Periosteum: Outer membrane; dense irregular connective tissue

  • Endosteum: Lines internal bone surfaces

  • Medullary cavity: Contains bone marrow

Microscopic Anatomy of Bone

• Osteon (Haversian system): Structural unit of compact bone

• Central canal: Contains blood vessels and nerves

• Lacunae: Small spaces housing osteocytes

• Canaliculi: Tiny canals connecting lacunae

Bone Formation (Ossification)

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

• Endochondral ossification: Bone replaces hyaline cartilage (most bones)

• Primary ossification center: First area of bone formation in the diaphysis

Hormonal Control of Bone

• Parathyroid hormone (PTH): Secreted by parathyroid glands in response to low blood calcium; increases blood calcium by stimulating osteoclasts.

• Calcitonin: Secreted by thyroid gland in response to high blood calcium; lowers blood calcium by inhibiting osteoclasts.

Summary Table: Types of Connective Tissue

Type	Main Features	Location
Areolar	Loose, supports and binds tissues	Under epithelia
Adipose	Stores fat, insulates	Subcutaneous tissue
Dense Regular	Parallel collagen fibers, strong	Tendons, ligaments
Dense Irregular	Irregular collagen fibers, resists tension	Dermis of skin
Elastic	Elastic fibers, allows stretch	Walls of large arteries
Hyaline Cartilage	Firm, glassy matrix	Nose, trachea, articular surfaces
Fibrocartilage	Thick collagen fibers, strong	Intervertebral discs
Elastic Cartilage	Elastic fibers, flexible	Ear, epiglottis

Key Equations

• Calcium Homeostasis:

$\text{PTH} \uparrow \Rightarrow \text{Blood Ca}^{2+} \uparrow$ $\text{Calcitonin} \uparrow \Rightarrow \text{Blood Ca}^{2+} \downarrow$

Additional info: Some explanations and examples have been expanded for clarity and completeness based on standard Anatomy & Physiology curriculum.