Histology- the study of tissue Tissues Histology- the study of tissue Groups of cells that are similar in structure and perform a common or related function.

4 primary types: Epithelial (covering) Connective (support) Muscle (movement) Nervous (control)

Epithelial- Used for covering (ex: organs) or Glands

Epithelial Function- protection, absorption, filtration, excretion, secretion, sensory reception

Characteristics of Epithelial: -Innervated -Avascular -High regenerative capacity -Polar- Apical surface= free -Basal surface= attached -Lots of cells / form sheets

2 names for epithelia: Layers: simple or stratified Shapes: Squamous Cuboidal Columnar

Simple Squamous- thin, permeable, for filtration or exchange, found in lungs, kidneys

2 types: Endothelium- inner covering, slick friction reducing lining vessels Mesothelium- middle covering lining the ventral body cavity

Simple Cuboidal- secretion and absorption, found in glands

A gland consists of one or more cells that make and secrete a product

Endocrine gland- ductless, absorb and secrete product by diffusion (thyroid, adrenals, pituitary) Exocrine gland- ducts (salivary, oil, liver, pancreas)

Simple Columnar- lines the digestive tract from stomach to rectum

Microvilli- lines intestines, absorbs nutrients Examples: Microvilli- lines intestines, absorbs nutrients Goblet Cells- secretes protective lubricating mucus

Stratified Squamous Stratified Squamous- is most widespread. Thick, protective, and is the external part of skin. Covers tongue, lines mouth, throat, esophagus, anal canal, vagina

Epidermis- the outer layer of the skin that contains a protective protein called keratin

Stratified cuboidal and stratified columnar are rarer types-found in sweat glands, salivary glands

Connective Tissue

2 Parts Fibroblast Chondroblast Osteoblast Hemocytoblast Cells (living) Matrix (non-living) Fibroblast Chondroblast Osteoblast Hemocytoblast 1) Ground Substance: Amorphous material 2) Fibers: Collagen Elastin Reticular

Mesenchyme (embryonic origin) Fibroblast Chondroblast Osteoblast Hematoblast Fibrocyte Chondrocyte Osteocyte Blood Cells Connective Tissue Cartilage Bone Blood Proper

Connective Tissue Proper Loose Connective * Areolar * Adipose * Reticular 2) Dense Connective * Regular * Irregular

Areolar (connective tissue proper) Gel like, wraps and cushions organs-found in blood vessels, muscles

Adipose (fat) connective tissue proper Matrix contains stored neutral fat oil Shock absorber and insulator

Reticular Connective tissue proper Forms a soft internal skeleton (stroma) Found in lymphoid organs-spleen, thymus, lymph nodes

Dense Regular connective tissue proper Parallel collagen fibers Tendons, Ligaments

Dense Irregular connective tissue proper Thicker bundles of collagen fibers Forms sheets in body areas where tension is exerted in different directions Fibrous joint capsules, dermis

Cartilage -Tough but flexible -Avascular -Devoid of nerves -80% water -Heals slowly

Cartilage-3 Types 1) Hyaline Cartilage 2) Fibrocartilage 3) Elastic Cartilage

1) Hyaline Cartilage embryonic skeleton ends of long bone costal cartilage (rib) Nose trachea, larynx supports, reinforces flexible

Fibrocartilage Thick collagen fibers Intervertebral Discs

Elastic Cartilage More elastin fibers Ear, Epiglottis

Bone 1) Compact bone 2) Spongy bone

Bone Hard calcified matrix Very well vascularized Gives support

Mesenchyme (embryonic origin) Fibroblast Chondroblast Osteoblast Hematoblast Fibrocyte Chondrocyte Osteocyte Blood Cells Connective Tissue Cartilage Bone Blood Proper

Blood Various Complex Cells

Blood Atypical Connective tissue Blood Cells= macrophages, wbc, rbc Matrix= plasma Fibers=soluble proteins that are visible in clotting -Carries gas, nutrients, waste, etc.

Nervous Tissue

Makes up brain, spinal cord, nerves Neurons- highly specialized nerve cells-generate and conduct nerve impulses Supporting cells- no conducting-support, insulate, and protect neurons

Muscle Tissue Highly vascular Highly cellular Function= movement

Skeletal Muscle Tissue Voluntary Attaches to bone, skin Gross body movements Long cylindrical, many nuclei Striated (banded)

Skeletal Muscle Picture

Cardiac Muscle Tissue Involuntary Walls of the heart Striated Branched Fit together by intercalated discs

Cardiac Muscle Picture

Smooth Muscle Tissue -Involuntary -Function= to propel (squeeze) -Found in walls of hollow organs (uterus), digestive system, urinary system and blood vessels -Spindle shape -Central nucleus -NO STRIATIONS

Smooth Muscle Picture

Functions of Tissue Protection Mechanical protection= (barrier) skin, mucosa Ciliary protection= epithelial (trachea) Chemical protection= glands

Inflammatory response Occurs when tissues are injured Non-specific

Immune Response Specific Takes longer to come to action Involves antibodies

Tissue Repair Three steps: Inflammation Organization Regeneration

Inflammation Histamine  macrophage, mast cell Capillaries dilate Leak clotting proteins Clot  scab

Organization Clot  Granulation tissue New blood vessels  collagen fibers  scar

Regeneration Epithelial cells migrate across granulation tissue and thickens

The ability to regenerate: Good: Epithelial (skin, epidermis, mucosa) Limited: Smooth muscle, dense regular connective (ligaments, tendons) Poor: Skeletal muscle, Cartilage