Tissues Histology the study of tissue Groups of

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 Functionprotection, absorption, filtration, excretion, 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

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

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

Connective Tissue Proper 1) 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 Connective Tissue Cartilage Proper Bone Blood Cells Blood

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 conductingsupport, 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