Chapter 3: Tissue level

Histology

(microscopic anatomy) study of tissues and how they are arranged into organs

Tissue

aggregation of similar cells and cell products that forms a region on an organ

What are the 4 primary tisses

Epithelial, Connective, Nervous, Muscular

• with atleast 23 subtypes of these four

matrix

extracellular material

Matrix is composed of

• fibrous proteins

• ground substance, aka extracellular fluid, interstitial fluid aka tissue fluid

Epithelial Tissue

• protection, secretion, and absorption

• epidermis, inner lining of digestive tract; liver and other glands

Connective Tissue

• support, bind, and protect organs

• tendons & ligaments; cartilage and bone; blood and lymph

Nervous Tissue

• Tissue containing excitable cells

• rapid transmission of info to other cells

• brain spinal cord; nerves

Muscular tissue

• elongated excitable cells specialized for contraction. movement, and maintaining tension

  • skeletal muscles; heart (cardiac muscle); walls of viscera (smooth muscle)

Epithelium

sheet of tissue composed of one or more layers of closely adhering cells

Epithelium locations

• internal lining of hollow organ or body cavity

• external surface of an organ

• secretory tissue of a gland

• epidermis of skin

Epithelium general features

• cells close together

• avascular (no blood vessels)

• regenerative; high rate of mitosis

• basement membrane between epithelium and underlying CT

• Epithelial cell surfaces: basal, apical, and lateral surface

Stratified epithelium

• two or more layers of cells, some rest directly on others and only deepest layer rests on basement membrane.

• 4 types: Stratified squamous, stratified cuboidal, Stratified columnar, Urothelium

Stratified squamous Epithelium

• provides abrasion resistance

• surface cells dead (exfoliate/desquamation)

• can be keratinized or nonkeratinized

Stratified Cuboidal Epithelium

located in sweat gland ducts

Stratified Columnar Epithelium

Relatively rare in the body

Urothelium (Transitional Epithelium)

• urinary tract

• surface umbrella cells

• can stretch and resist damage from urine (acid)

Connective Tissue

• highly vascular tissue, typically occupy less space than extracellular material

• most abundant and widely distributed tissue type

Connective tissue functions

• Binds organs - fibrouse tissue

• support - bones and cartilage

• physical protection - bones (cranium, ribs, sternum)

• immune protection - immune cells

• movement - bones

• storage - white fat

• heat production - metabolism of brown fat

• transport - blood transport gases, nutrients, wastes

What are the 4 broad categories of connective tissues and 2 matrix?

Categories: Fibrous, adipose (fat), supportive (cartilage and bone), fluid (blood)

Matrix: fibers and ground substance

Connective Tissue- What are the three kinds of fibers?

Collagenous fibers, Reticular Fibers, Elastic fibers

Connective tissue- fibers- collagenous fibers

• made of collagen

• tough and flexible and resist stretching

• most abundant protein

Connective tissue- Fibers- Reticular fibers

• thin collagen fibers coated w glycoprotein

• internal framework of some organs (spleen, lymph nodes) and part of basement membranes

Connective tissue- Fibers- Elastic fibers

• thin, coiled,

• made of elastin protein coated w glycoprotein

• stretch and recoil like rubber band

Cells of fibrous connective tissues:

fibroblasts, macrophages, leukocytes, plasma cells, mast cells, adipocytes (fat cells)

Fibroblasts

• produce fibers, ground substance of matrix

Macrophages

• phagocytic immune cells

Leukocytes (WBCs)

• multiple types of immune cells; ex: neutrophils, and lymphocytes

Plasma cells

• secrete antibodies (defensive proteins)

Mast cells

• found near blood vessels; secrete heparin (inhibits blood clotting) and histamine (increase blood flow by dilating blood vessels. inflammatory rxn)

Adipocytes (fat cells)

• small clusters, abundant in adipose tissue, energy storage and regulation of body temp

Connective tissue (Supportive):

Cartilage and bone

Cartilage

• stiff tissue w rubbery matrix

• shapes and supports nose and ears

• partially encloses larynx, tranches, and thoracic cavity

• no blood vessels (avascular)

• produced by chondroblasts (secrete matrix, trapped in cavities (lacunae); once enclosed; now called chondrocytes)

• matrix is rich in glycosaminoglycans and collagen fibers

Cartilage three types:

• Hyaline cartilage: clear matrix; forms articular cartilage, trachea

• Elastic cartilage: elastic fibers; external ear, epiglottis

• fibrocartilage: collagen bundles; in invertebral discs, knee and pubic synthesis

Perichondrium

surrounds elastic and most hyaline

supportive connective tissue - cartilage

Compact Bone

Microscopic appearance: calcified matrix arranged in concentric lamellae around central canals; osteocytes occupy lacunae between adjacent lamellae, lacunae interconnected by delicate canaliculi

Rep location: Skeleton

Functions: physical support of body; leverage for muscle action; protective enclosure of viscera; reservior of calcium and phosphorus.

Hyaline Cartilage in a Bronchus

Mic App: stained light blue, violet or pink

Rep Locations: articular cartilage, trachea and bronchi, larynx, costal cartilage

Functions: Eases joint movements

Muscular Tissue

specialized to contract when stimulated

Muscular tissue: Skeletal muscle

• long threadlike cells (muscle fibers)

• attached to bones

• Striated and voluntary; many nuclei per cell

Muscular tissue: Cardiac muscle

• found in heart

• striated and involuntary

• cells (cardiomyocytes) are short and branching. one nucleus cells joined by intercalated discs w gap junctions

Muscular tissue: Smooth muscle

• found in walls of hollow organs (visceral muscle)

• no strations, involuntary

Glands

• cell or organ that secretes substances; for use in body (secretion) or elimination of waste (excretion)

• Exocrine glands (secretion pass to surface via duct) or Endocrine glands (no ducts, high density of blood capillaries; secrete hormones)

Membranes

thin sheet of tissue covering organ surface, lining a space, separating tissues and spaces

Mucous membrane (mucosa)

• lines passages open to the exterior (digestive, respiratory, urinary, reproductive tracts)

• 2-3 layers: epithelium, lamina propria (areolar CT), and sometimes muscularis mucosae (smooth muscle)

• absorptive, secrete, and protect

• Contain goblet cells (mucus), multicellular mucous glands, or both

Serous membrane (serosa)

• lines pleural, pericardial, and peritoneal cavities

• simple squamous epithelium rests on a thin layer of areolar connective tissue

• produce serous fluid

tunica interna of blood vessels and endocardium of the heart

• Membrane composed of endothelium (simple squamous

epithelium) resting on a thin layer of areolar tissue, which

sometimes rests on an elastic sheet

Synovial membrane

• fibrous connective tissue membrane that spans the gap from one bone to next in some joints; secretes synovial fluid

Atrophy

• shrinkage of tissue through loss of cell size/number

• results from normal aging, lack organ use

• Ex: disuse atrophy (when you dont excersize muscle get smaller)

Necrosis

premature, pathological death of tissue due to trauma, toxin, infection

Infarction

• sudden tissue death

• cardiac muscle (myocardial infarction) or brain tissue (cerebral infarction)

• blood supply’s cut off

Gangrene

necrosis from infection or obstructed blood supply (dry gangrene in diabetics; decubitus ulcers (bed sores,pressure sores)

Apoptosis

programmed cell death

• normal death of cells that have completed function.