Tissues, Integumentary System, and Skeletal System: Structured Study Notes

Chapter 4: Tissues

Four Primary Tissue Types

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

• Epithelial Tissue: Covers body surfaces, lines cavities, and forms glands. Characterized by tightly packed cells with minimal extracellular matrix.

• Connective Tissue: Supports, protects, and binds other tissues. Contains abundant extracellular matrix.

• Muscle Tissue: Responsible for movement. Composed of cells that can contract.

• Nervous Tissue: Enables communication and control by conducting electrical impulses.

Epithelial Tissue

Epithelial tissue forms protective barriers and is specialized for absorption, secretion, and sensation.

• Structural Characteristics:

  • Cells are tightly packed with little extracellular matrix.

  • Exhibits polarity: an apical surface (exposed to open space) and a basal surface (attached to basement membrane).

  • Avascular (lacks blood vessels) but usually innervated (supplied by nerves).

  • High rate of regeneration due to rapid cell division.

• Naming: Based on number of layers (simple = one layer, stratified = multiple layers) and cell shape (squamous, cuboidal, columnar).

Type	Function	Location
Simple Squamous	Diffusion	Alveoli, capillaries
Simple Cuboidal	Secretion & absorption	Kidneys, glands
Simple Columnar	Absorption	Digestive tract
Pseudostratified	Secretion & movement	Trachea
Stratified Squamous	Protection	Skin
Transitional	Stretching	Urinary bladder

Glandular Epithelium

Glands are specialized epithelial cells that produce and secrete substances.

• Exocrine Glands: Secrete products through ducts onto surfaces (e.g., sweat glands).

• Endocrine Glands: Release hormones directly into the bloodstream (e.g., thyroid gland).

Only endocrine glands produce hormones.

Connective Tissue

Connective tissue provides structural and metabolic support for other tissues and organs.

• Common Characteristics:

  • Cells are separated by an abundant extracellular matrix (composed of fibers and ground substance).

  • Varying degrees of vascularity (blood supply).

  • Derived from embryonic mesenchyme.

• Structural Components: Cells, fibers (collagen, elastic, reticular), and ground substance (gel-like material).

• Cell Terminology:

  • blast: immature, matrix-producing cell (e.g., osteoblast).

  • cyte: mature cell (e.g., chondrocyte).

  • clast: cell that breaks down tissue (e.g., osteoclast).

Type	Function	Location
Bone	Support	Skeleton
Cartilage	Flexible support	Nose, joints
Blood	Transport	Blood vessels
Adipose	Fat storage	Under skin
Dense connective	Strength	Tendons

Body Membranes

Body membranes are sheets of tissue that cover or line body surfaces.

Type	Composition	Location	Wet/Dry
Cutaneous	Epidermis + dermis	Skin	Dry
Serous	Simple squamous	Organs	Wet
Mucous	Epithelium + CT	Body cavities	Wet

Muscle Tissue Types

Muscle tissue is specialized for contraction and movement.

Type	Location	Function
Skeletal	Attached to bones	Movement
Cardiac	Heart	Pumps blood
Smooth	Organs	Moves substances

Tissue	Voluntary	Striated	Nuclei
Skeletal	Yes	Yes	Multi
Cardiac	No	Yes	1–2
Smooth	No	No	1

Nervous Tissue

Nervous tissue is responsible for rapid communication and control of body functions.

• Characteristics: Excitable, conducts electrical signals.

• Cells: Neurons (transmit signals) and glial cells (support neurons).

• Locations: Brain, spinal cord, peripheral nerves.

Cell	Tissue
Chondroblast	Cartilage
Fibroblast	Connective tissue
Osteoblast	Bone
Neuron	Nervous
Glia	Nervous

Chapter 5: The Integumentary System (Skin)

Skin Layers

The skin is composed of three main layers, each with specific functions.

Layer	Function
Epidermis	Protection
Dermis	Strength, blood supply
Hypodermis	Fat storage

• Thick skin: Found on palms and soles.

• Thin skin: Covers the rest of the body.

Epidermal Cells

Cell	Function
Keratinocytes	Produce keratin (provides strength and waterproofing)
Melanocytes	Produce melanin pigment
Langerhans	Immune defense
Merkel	Touch receptors

Epidermis Layers (Deep to Superficial)

1. Stratum basale

2. Stratum spinosum

3. Stratum granulosum

4. Stratum lucidum (only in thick skin)

5. Stratum corneum

New epidermis is produced approximately every 4 weeks.

Skin Pigments and Color

• Melanin: Produced by melanocytes in the stratum basale; protects DNA from UV damage.

• Carotene: Obtained from diet; contributes to yellow-orange color.

• Hemoglobin: Red pigment from blood.

Condition	Cause
Cyanosis	Low oxygen
Jaundice	Liver problems
Bruising	Broken capillaries

Skin Appendages

• Hair

• Nails

• Sweat glands

• Sebaceous glands

All appendages develop from the epidermis.

Sweat Glands

Type	Function
Eccrine	Cooling
Apocrine	Scent

Hair Functions

• Protection

• Sensation

• Temperature regulation

Hair is not found on palms, soles, or lips.

Burns

Burn	Layers Involved
1st degree	Epidermis
2nd degree	Epidermis + Dermis
3rd degree	Full thickness

Rule of Nines: Used to estimate the percentage of body surface area affected by burns.

ABCDE Rule for Melanoma

Letter	Meaning
A	Asymmetry
B	Border
C	Color
D	Diameter
E	Evolving

Chapter 6: Bones and Skeletal Tissues

Skeletal Divisions

Division	Bones
Axial	Skull, ribs, vertebrae
Appendicular	Limbs

Bone Classes

Type	Example
Long	Femur
Short	Carpals
Flat	Sternum
Irregular	Vertebrae

Functions of Bone

• Support

• Protection

• Movement

• Mineral storage (especially calcium and phosphate)

• Blood cell formation (hematopoiesis)

• Fat storage

Bone Marrow

Type	Function
Red	Blood cell production
Yellow	Fat storage

In adults, red marrow is found in the pelvis, ribs, sternum, and vertebrae.

Bone Cells

Cell	Function
Osteoblast	Builds bone
Osteocyte	Maintains bone
Osteoclast	Breaks down bone
Osteogenic	Stem cells

Bone Matrix Components

• Organic (collagen): Provides flexibility.

• Inorganic (calcium salts): Provides hardness.

Compact vs Spongy Bone

Type	Structure
Compact	Osteons
Spongy	Trabeculae

Long Bone Anatomy

• Diaphysis: Shaft of the bone.

• Epiphysis: Ends of the bone.

• Medullary cavity: Central cavity containing marrow.

• Periosteum: Outer covering.

• Endosteum: Lining of the medullary cavity.

• Articular cartilage: Covers joint surfaces.

Ossification (Bone Formation)

• Intramembranous ossification: Forms flat bones (e.g., skull).

• Endochondral ossification: Forms long bones (e.g., femur).

Bone Growth

Occurs at the epiphyseal plate (growth plate) in the following zones:

1. Resting

2. Proliferation

3. Hypertrophy

4. Calcification

5. Ossification

Bone growth in width occurs by appositional growth.

Calcium Regulation

Hormone	Function
PTH (Parathyroid Hormone)	Raises blood calcium
Calcitonin	Lowers blood calcium

Bone Disorders

Condition	Cause
Osteoporosis	Bone loss
Rickets	Vitamin D deficiency
Osteomalacia	Soft bones

Fracture Types

Type	Description
Comminuted	Bone shattered
Compression	Bone crushed
Spiral	Twisting injury
Epiphyseal	Growth plate fracture

Example: A child with a fracture at the growth plate (epiphyseal fracture) may have impaired bone growth if not properly treated.

Additional info: The above notes expand on the original content by providing definitions, context, and examples to ensure a comprehensive understanding suitable for college-level anatomy and physiology students.