Four basic types of tissue:
Epithelial, Connective, Muscle and Neural
Epithelial tissue:
protective covering of surfaces; consists almost entirely of cells with very little extracellular matrix epithelial cells joined by cell junctions
Histology:
microscopic study of tissues
4 types of cell junctions:
tight junctions, adherens junctions or desmosomes, gap junctions
Occluding or Tight Junction:
lipid portions of the two p;lasma membranes are tightly bound together by interlocking membrane proteins
Function of Occluding junctions:
isolate the contents of the lumen (passageway) from basolateral surfaces of the cell
Gap Juncctions:
two cells are held together by interlocking channel proteins (connexons) that form narrow passageways for ions and small molecules
Macula Adherens or Demosome:
dens area of cell is connected to the cytoskeleton which gives the cell its strength.
Two types of Macula Adherens:
1) Spot Demosomes - small discs connected to filaments which stabilize cell shape. 2) Hemidesmosomes - half of a spot demosome, attaches cell to extracelular filaments in the basal lamina, anchors cell.
Major functions of Epithelial tissue:
Physicla protection, control permeability, sensation, absorption, specialized secretions
Major characteristics of Epithelial tissue:
cellularity, avascularity, attachement, regeneration
Cellularity is:
epithelia are almost entirely of cells bound closely together by interconnections know as cell junctions
Avascularity is:
lacking blood vessels. Epithelial cells obtain nutrients by diffusion or absorption.
Attachement is:
the base of an epithelium is bound to a thin basal lamina or basement membrane.
Regeneration is:
epithelia cells that are damaged or lost are continuously replaced through the divisions of stem cells in the epithelium.
4 functions of Epithelial Tissue:
1) Provide Physical Protection 2) Control permeability 3) Provide Sensation 4) Produce specialized Secretions
3 Types of Epithelium:
Covering and Lining Epithelium; Glandlular Epithleium
7 types of covering and lining epithelium:
1) simple squamous 2) simple cuboidal 3) simple columnar 4) stratified squamous 5) stratified columnar 6) transitional 7) pseudostratified columnar
Simple Squamous Shape:
Single layer, Flat, scalelike
Where are simple squamous cells found:
lines air sacs of lungs, inner lining of heart and blood vessels, serous membranes, inner ear drum
Simple Cuboidal shape:
Single layer, Cube Shaped
Where are simple cuboidal cells found:
lines surface of ovary, kidney tubules, kidney, thyroid, mammmary glands, salivary glands
Simple Columnar shape:
Single layer, Rectangular
Where are simple columnar cells found:
lines gastrointestinal tract from stomach to anus, uterus, uterine tubes
Stratified Squamous shape:
Several layers, flat scalelike
Where are stratified squamous cells found:
Epidermus of skin (keratinized), lining of mouth, tongue, throat, larynx, esophagus, canal vagina (nonkeratinized)
Stratified Columnar shape:
Several layers, cube shaped
Where are stratified columnar cells found:
male urethra, mammary gland duct
Transitional cell shape:
stratified cells with variable appearance
Transitional cells are found:
lines urinary bladder, ureters
Pseudostratified Columnar Shape:
Attached to basement membrane, but not all reach the surface. Cells are almost always cilated and associated with goblet cells
Where are pseudostratified columnar cells found:
Lining upper respiratory tract, portions of male urethra
Function of Glandular Epithelium:
Produces specialized secretions
2 Types of Glandular Epithelium:
Exocrine glands and Endocrine glands
Function of Exocrine glands:
Discharge secretions onto body surface or into ducts, may be multicellular (simple or compound) or unicellular (globlet cells)
Types of Glandular Secretions:
Serous glands, mucous glands, mixed glands, cytogenic glands
Functino of Serous glands:
Secrete thin fluids: perspiration, tears, milk, digestive juices
Function of Mucous glands:
secrete mucin (glycoprotein); tongue, roof of mouth, goblet cells
Function of mixed glands:
secrete serous fluid and mucous; salivary glands
Function of Cytogenic glands:
release whole cells: testes and ovaries
3 methods of secretion:
Merocrine Glands, Apocrine Glands; Holocrine Glands
Function of Merocrine Glands:
Product released through exocytosis; most common secretion mode (mucous, sweat glands, salivary glands)
Funciton of Apocrine Glands:
Product released through the loss of both the secretory product and cytoplasm (mammary glands)
Function of Holocrine Glands:
Product released through destruction of cell (lysis); oil (sebum), underarm perspiration
Functin of Endocrine Glands:
Discharge secretions (hormones) into surrounding interstitial fluid; lack ducts
Connective Tissue:
Most abundant, makes up part of every organ, cells separated by extracellular matrix
Major Functions of Connective Tissue:
Structural support, transportation, protection of delicate organs, energy storage, immune protection
Major Characteristics of Connective Tissue:
Never exposed to outside environment; vascularity; contain sensory receptors; Extensive extracellular matrix
2 Major components of connective tissue:
Cells, Extracellular Matrix
Connective Cells are:
specialized, produce extracellular matrix
3 types of connective tissue cells:
1) Fibroblasts 2) Chondrocytes 3) Macrophage
Fibroblasts (fib):
Secrete fibers; mast cells - release histimine and heparin
Chondrocytes (cho):
cartilage cells; adipocytes (adp); osteocytes (ost); macrophage (mac)
Adipocytes:
Fat cells
Osteocytes:
Bone cells
Macrophage:
Phagocytes
Extracellular Matrix is made up of:
Fibers and Ground Substance
3 types of extracellular fibers:
1) collage (col) fibers, 2) reticular (ret) fibers, 3) elastic (els) fibers
Collagen Fibers:
Strong and flexible - resist stretching
Reticular Fibers:
Thin collagen fibers, covered with glycoprotein: fill space between tissue and organ
Elastic Fibers:
Resist forces applied in many directions; allow tissue to spring back after they've been stretched
Ground Substance:
Clear viscous fluid that fills space between cells; gelatinous to rubbery consistency
3 Types of Ground Substances:
Glycosaminoglycan (GAG), Proteoglycan, Adhesive Glycoproteins
Glycosaminoglycan (GAG):
Negatively charged polysaccharides that absorb and hold water. (Ex: chondroitan sulfate - found in blood vessels and bones; hyaluronic acid - slippery quality, good lubricant for joint cavities, vitreous humor)
Proteoglycan:
Polysaccharaide and protein; trap large quantities of water
Adhesive Glycoproteins:
Composed of protein and carbohydrate; bind plasma membrane to collagen and proteoglycans outside cell; bind all components of a tissue together.
2 Classifications of Connective Tissue:
Embryonic Connective Tissue; Adult Connectiive Tissue
Embryonic Connective Tissue:
Mesenchyme - made of fiber in semifluid matrix with delicate collagenous fibers; all adult connective tissue develop from mesenchyme
5 Types of Adult Connective tissue:
1) Loose 2) Dense 3) Cartilage 4) Bone 5) Blood
Function of Loose tissue:
much of the space occupied by ground substance, fill spaces between organs, cushion, support epithelia
3 Types of loose tissue:
Areolar, Adipose, Reticular
Areolar loose tissue:
(fib, mst, mac) (col, els, ret) - skin (subcutaneous layer, dermis); forms lamina propria of mucous membranes
Adipose loose tissue:
(adp) (ret) - skin (subcutaneous layer); around heart and kidneys
Reticular loose tissue:
(fib) (ret) - liver; spleen; lymph nodes; thymus
2 Types of Dense tissue:
Regular and Irregular
Regular Dense tissue:
(fib) (col) - fibers oriented in one direction; white appearance; tendons (muscle to bone); ligaments (bone to bone)
Irregular Dense tissue:
: (fib) (col, els) - fibers arranged randomly; skin (dermis), around liver, kidney, spleen; fibrous sheath around cartilages and bones
Function of Cartilage Tissue:
supporting connective tissue; support; flexibility
Composition of Cartilage:
Cartilage cells in a matrix rich in chondroitin sulfate
3 Types of Cartilage:
1) Hyaline, 2) Fibrocartilage, 3) Elastic
Hyaline Cartilage:
(chondrocyte) col-fine fibers - ends of long bone, nose
Fibrocartilage:
(Chondrocyte) (Colagen) intervertebral discs, pubic symphasis (junction of hip bones)
Elastic Cartilage:
(Chondrocyte) (Elastic) External ear, epiglottis of larynx
Bone (Osseous) Tissue:
Supporting connective tissue; composed of living cells in a mineralized matrix (fibers and calcium/phosphate crystals); strength & support
2 Types of Bone Tissue:
Compact; Spongy
Compact Bone is made up of:
Lamellae, Lacunae, Canaliculi, Central Canals
Lamellae:
Concentric rings on bone matrix
Lacunae:
spaces that house bone cells
Canaliculi:
microscopic channels that lead from bone cell to central canal
Central Canals:
Contains blood vessels
Spongy Bone is made up of:
bony plates and red bone marrow
Bony Plates:
Bone fragments with spaces between the plates
Red Bone Marrow:
Site of blood cell synthesis
Blood (Vascular) Tissue is:
fluid connective tissue; matrix between cells is liquid; transportation of gases, hormones, nutrients, waste products; protection from infections
2 Types of blood tissue:
1) Formed Elements, 2) Plasma
Formed Elements:
RBC (transport gases), WBC (defence agains foreign substances), Plateletes (blood clotting)
Plasma:
water, nutrients, ions, hormones, gases, plasma proteins
Function of Muscle Tissue:
contracts and shortens with force; responsible for movement, heat production; posture
Major Classifications of Muscle Tissue:
1) Skeletal, 2) Cardiac, 3) Smooth
Skeletal Muscle:
multinucleate, striated, voluntary; attached to
Cardiac Muscle:
uni- or binucleate, striated intercalated discs, involuntary; heart
Smooth Muscle:
uninucleate, nonstriated, involuntary; walls of hollow organs (stomach, intestines, urinary bladder);
Function of Nervous Tissue:
Monitors changes in internal and external environments
Neurons are:
Nerve cells; they convert stimulii into nerve impulses
Function of Neuroglia:
Support cells. They nourish, support and protect neurons
Parts of a Neuron:
Cell Body, Dendrites, Axon
Neuron Cell body function:
Contains cytoplasm, nucleus, nucleolus
Neuron Dendrite Function:
Highly branched processes, specialized for receiving stimulii
Neuron Axon Function:
Single process, specialized for conducting impulses to other cells
Function of Membranes:
(epithelia and connective tissue), thin layer of tissue that covers a structure or lines a cavity
4 Types of Membranes:
Mucous, Serous, Cutaneous, Synovial
Serous Membranes:
Internal membranes. Consist of simple squamous epithelium. Basement membrane is a thin layer of areolar connective tissue. Line cavities that do not open to the outside and secrete serous fluid.
Mucous Membranes:
Internal membranes. Consist of epithelial cells. Basement membrane is a thick layer of areolar connective tissue. Line cavities that open to the outside and secrete mucous.
Cutaneous Membranes:
External membrane. Skin - largest membrane of the body. Consists of stratified squamous epithelium, underlying areolar and dense irregular connective tissue.
Synovia Membranes:
consist of connective tissue; line freely movable joints; secrete synovial fluid
Inflammation:
occurs when tissues are damaged along with immune response. Redness, heat, swelling and pain.
Tissue Repair:
Tissues replace dead or damaged cells.
Two types of tissue repair:
Regeneration or Replacement
Regeneration:
New cells are the same as those destroyed. Normal function of tissue is restored. Involves parenchymal cells - from organs functioning part.
Replacement:
New type of tissue develops (scar tissue). Loss of some tissue function. Involves Fibroblasts through a process of fibrosis.
2 Types of Skin Repair:
Primary Union, Secondary Union
Primary Union:
Surface of clot dries; forms scab. Wound fills with blood; a blood clot forms. Fibrin binds edges together. Surface of clot dries; forms scab. Inflammatory response is occurring. Fibroblasts migrate into clot and produce collagen fibers. Capillaries grow
Secondary Union:
Similar to healing in primary union, except degree of inflammatory response is greater, more cell debris exists. risk of infection is greater. more granulation tissue forms. wound contraction occurs (leads to disfiguring scars)
Tissues and Aging:
cell division declines; collagen fibers become irregular in structure (tendons less flexible and have reduced strength); elastic fibers become fragmented and less elastic (increased skin wrinkling)