histology - sharpschool
TRANSCRIPT
BIO 201
Tissues 1
HistologyHistology
Study of TissuesStudy of Tissues
Epithelial TissueEpithelial Tissue Intercellular Junctions and Intercellular Junctions and
GlandsGlands
Connective TissueConnective Tissue
MembranesMembranes
11
Muscular Tissue Muscular Tissue
Nervous TissueNervous Tissue
The Study of TissuesThe Study of Tissues
Histology (microscopic anatomy)Histology (microscopic anatomy) study of tissues and how they form organsstudy of tissues and how they form organs
TissueTissue Tissue Tissue group of similar cells and cell products (i.e., ECM)group of similar cells and cell products (i.e., ECM)
Organ Organ composed of 2 or more tissue types (almost always connective composed of 2 or more tissue types (almost always connective
and epithelial; usually includes muscle and nervous)and epithelial; usually includes muscle and nervous)
Four primary tissue classesFour primary tissue classesith li l tiith li l ti
22
epithelial tissueepithelial tissue
connective tissueconnective tissue
muscular tissuemuscular tissue
nervous tissuenervous tissue
BIO 201
Tissues 2
Features of TissuesFeatures of Tissues
Differences between tissuesDifferences between tissues type and function of cellstype and function of cells characteristics of the characteristics of the
surrounding matrix (surrounding matrix (extracellular extracellular matrix; ECMmatrix; ECM)) ground substance made from ground substance made from
proteins, sugars, and sometimes proteins, sugars, and sometimes mineralsminerals called many different names (ECF, called many different names (ECF,
ECM, tissue fluid, interstitial fluid, ECM, tissue fluid, interstitial fluid, basement membrane)basement membrane)
amount of space occupied by amount of space occupied by
33
cells versus matrixcells versus matrix very little ECM exists between very little ECM exists between
epithelial and muscle cellsepithelial and muscle cells connective tissue cells are widely connective tissue cells are widely
separated by ECMseparated by ECM
Epithelial TissueEpithelial Tissue
One or more layers of closely adhering cellsOne or more layers of closely adhering cells
Forms a flat sheet with the upper surface exposed to the Forms a flat sheet with the upper surface exposed to the environment or an internal body cavityenvironment or an internal body cavity one side of tissue exposed to “outside”one side of tissue exposed to “outside”
Sits on Sits on basement membranebasement membrane (at the (at the basalbasal surface of cells)surface of cells) thin layer of thin layer of collagencollagen and adhesive proteinsand adhesive proteins
anchors epithelium to underlying connective tissue; provides anchors epithelium to underlying connective tissue; provides supportsupport
44
BIO 201
Tissues 3
LayersLayers
Simple epitheliumSimple epithelium contains one layer of cellscontains one layer of cells
named by shape of cellsnamed by shape of cells
Stratified epitheliumStratified epithelium contains more than one layercontains more than one layer
named by shape of named by shape of apicalapical (surface) (surface) cellscells
d t ll (d t ll (b l llb l ll ) it) it
55
deepest cells (deepest cells (basal cellsbasal cells) sit on ) sit on basement membranebasement membrane
ShapeShape
•• Squamous (squashed)Squamous (squashed)•• Allows rapid diffusion of Allows rapid diffusion of
substances; secretes serous substances; secretes serous fluidfluidfluidfluid
•• Cuboidal (square)Cuboidal (square)•• Absorption & secretion; Absorption & secretion;
produces mucusproduces mucus
66
•• Columnar (rectangular)Columnar (rectangular)•• Absorption & secretion; Absorption & secretion;
produces mucusproduces mucus•• Often ciliatedOften ciliated
BIO 201
Tissues 4
Epithelial FunctionsEpithelial Functions
77
Intercellular JunctionsIntercellular Junctions
88
All cells except blood cells are anchored to each other (or to the All cells except blood cells are anchored to each other (or to the matrix surrounding them) by matrix surrounding them) by intercellular junctions intercellular junctions formed by formed by adhesion proteinsadhesion proteins
BIO 201
Tissues 5
DesmosomesDesmosomes
Patch between 2 cells Patch between 2 cells holding them together holding them together g gg gagainst mechanical stressagainst mechanical stress CONNECTINGCONNECTING gap between cells is spanned gap between cells is spanned
by mesh of filamentsby mesh of filaments often called often called adhesion junctionadhesion junction
99
Tight JunctionsTight Junctions
Encircle the cell joining itEncircle the cell joining it Encircle the cell, joining it Encircle the cell, joining it to surrounding cellsto surrounding cells BARRIERBARRIER prevents substances and prevents substances and
bacteria from passing bacteria from passing between cellsbetween cells
1010
BIO 201
Tissues 6
Gap JunctionsGap Junctions
Transmembrane proteins form Transmembrane proteins form a watera water--filled channelfilled channel
Small solutes (metabolites and Small solutes (metabolites and ions) pass directly from cell to ions) pass directly from cell to cell cell COMMUNICATINGCOMMUNICATING
1111
aka electrical synapseaka electrical synapse
Cell to Cell JunctionsCell to Cell Junctions
1212
BIO 201
Tissues 7
Endocrine and Exocrine GlandsEndocrine and Exocrine Glands Glands secrete substances Glands secrete substances ExocrineExocrine glands connect to surface with a glands connect to surface with a ductduct (tube)(tube) EndocrineEndocrine glands secrete their products (glands secrete their products (hormoneshormones) )
directly into directly into bloodstreambloodstream Some glands are mixed Some glands are mixed
gonads release gametes and secrete hormones into bloodgonads release gametes and secrete hormones into blood pancreas secretes digestive enzymes and hormonespancreas secretes digestive enzymes and hormones
1313
Types of Exocrine SecretionsTypes of Exocrine Secretions
Serous glandsSerous glands produce thin, watery produce thin, watery
secretionssecretions sweat milk tears andsweat milk tears and sweat, milk, tears and sweat, milk, tears and
digestive juicesdigestive juices
Mucous glandsMucous glands produce a glycoprotein, produce a glycoprotein, mucinmucin, ,
that helps form a sticky that helps form a sticky secretion called secretion called mucusmucus nasal, reproductive, nasal, reproductive,
respiratory secretions respiratory secretions
Cytogenic glands release Cytogenic glands release
1414
y g gy g gwhole cells whole cells produce gametesproduce gametes
BIO 201
Tissues 8
Endocrine GlandsEndocrine Glands
Produce chemical Produce chemical signals that cause asignals that cause asignals that cause a signals that cause a responseresponse hormonehormone
Released into Released into blood!!blood!!
1515
Connective TissueConnective Tissue
Consists of widely spaced cells separated by fibers and Consists of widely spaced cells separated by fibers and ground substanceground substance
Most abundant and variable tissue typeMost abundant and variable tissue type Most abundant and variable tissue typeMost abundant and variable tissue type
FunctionsFunctions connectsconnects structures to each otherstructures to each other
gives gives supportsupport and and protectionprotection (physical & immune)(physical & immune)
stores energystores energy
movementmovement and and transporttransport of materialsof materials
1616
BIO 201
Tissues 9
Ground Ground SubstanceSubstance of Connective Tissueof Connective Tissue
Gelatinous or rubbery material found in between cellsGelatinous or rubbery material found in between cells Consists of large moleculesConsists of large molecules
proteoglycansproteoglycans embedded in plasma membranesembedded in plasma membranes embedded in plasma membranes embedded in plasma membranes create a strong bond to other cells or extracellular matrixcreate a strong bond to other cells or extracellular matrix
glycoproteinsglycoproteins proteinprotein--carbohydrate complexes that bind plasma membrane to carbohydrate complexes that bind plasma membrane to
collagen or proteoglycans outside the cellscollagen or proteoglycans outside the cells
1717
Cells of Connective TissueCells of Connective Tissue
FibroblastsFibroblasts produce protein fibers and ground substanceproduce protein fibers and ground substance
White blood cellsWhite blood cells MacrophagesMacrophages phagocytose foreign materialphagocytose foreign materialMacrophagesMacrophages phagocytose foreign material phagocytose foreign material
NeutrophilsNeutrophils phagocytose bacteria phagocytose bacteria
Plasma cellsPlasma cells synthesize antibodiessynthesize antibodies
Mast cellsMast cells in skin secrete heparin that inhibits clotting and in skin secrete heparin that inhibits clotting and histamine that dilates blood vesselshistamine that dilates blood vessels
AdipocytesAdipocytes or fat cells store triglyceridesor fat cells store triglycerides
1818
BIO 201
Tissues 10
Fibers of Connective TissueFibers of Connective Tissue
Collagen fibersCollagen fibers tough tough
resistant to stretch, yet flexibleresistant to stretch, yet flexible
tendons, ligaments and deep layer of the skin (dermis)tendons, ligaments and deep layer of the skin (dermis)
Elastic fibersElastic fibers thin branching fibers made of thin branching fibers made of elastinelastin
stretch & recoil like rubberband (elasticity)stretch & recoil like rubberband (elasticity)
give skin, lungs and arteries ability to stretch and recoilgive skin, lungs and arteries ability to stretch and recoil
1919
Reticular fibersReticular fibers thin thin collagen fiberscollagen fibers coated with coated with glycoproteinglycoprotein
form framework for spleen and lymph nodesform framework for spleen and lymph nodes
Types of Fibrous Connective TissueTypes of Fibrous Connective Tissue
Loose connective tissueLoose connective tissue contains gelcontains gel--like groundlike ground contains gelcontains gel like ground like ground
substance between cellssubstance between cells
Dense connective tissueDense connective tissuefib fill th b tfib fill th b t
2020
fibers fill the spaces between fibers fill the spaces between cellscells
2 types varying in fiber 2 types varying in fiber orientationorientation dense regular connective dense regular connective
tissuetissue
dense irregular connective dense irregular connective tissuetissue
BIO 201
Tissues 11
Adipose TissueAdipose Tissue
2121
Large, emptyLarge, empty--looking cells with thin marginslooking cells with thin margins Nucleus pressed against cell membraneNucleus pressed against cell membrane
Energy storage, insulation, cushioningEnergy storage, insulation, cushioning Subcutaneous fat beneath skin and surrounding organsSubcutaneous fat beneath skin and surrounding organs
CartilageCartilage
Supportive connective tissue with rubbery matrixSupportive connective tissue with rubbery matrix
ChondroblastsChondroblasts produce cartilage matrix, once surrounded produce cartilage matrix, once surrounded by cartilage by cartilage chondrocyteschondrocytesy gy g yy
No blood vessels so diffusion must bring in nutrients and No blood vessels so diffusion must bring in nutrients and remove wastesremove wastes injured cartilage heals slowlyinjured cartilage heals slowly
Major types of cartilage depend upon fiber typesMajor types of cartilage depend upon fiber types hyaline, fibrocartilage and elastic cartilagehyaline, fibrocartilage and elastic cartilage
2222
BIO 201
Tissues 12
CartilageCartilage
FibrocartilageFibrocartilage Cartilage containing extensive Cartilage containing extensive
parallel collagen fibersparallel collagen fibers Resists compression andResists compression and Resists compression and Resists compression and
absorbs shock in some jointsabsorbs shock in some joints Pubic symphysis and Pubic symphysis and
intervertebral discsintervertebral discs
HyalineHyaline
2323
Clear, glassy matrix; fine Clear, glassy matrix; fine dispersed collagen fibers; dispersed collagen fibers; chondrocytes in small clusters chondrocytes in small clusters enclosed in lacunaeenclosed in lacunae
Joints; supportive material in Joints; supportive material in larynx, trachea, bronchi larynx, trachea, bronchi
BoneBone
Spongy bone looks Spongy bone looks spongy in appearancespongy in appearance delicate struts of bonedelicate struts of bone always covered by compact always covered by compact
bonebone
Compact bone looks solid Compact bone looks solid in appearancein appearance more complex arrangementmore complex arrangement cells and matrix vertically cells and matrix vertically
orientedoriented
2424
BIO 201
Tissues 13
BloodBlood
2525
Variety of cells and cell fragmentsVariety of cells and cell fragments white blood cells, red blood cells, and plateletswhite blood cells, red blood cells, and platelets
Found in heart and blood vesselsFound in heart and blood vessels
Mucous MembranesMucous Membranes
2626
Consists of epithelium, connective (basal lamina or lamina Consists of epithelium, connective (basal lamina or lamina propria) and underlying muscular tissuespropria) and underlying muscular tissues
Lines passageways that open to the exterior: digestive, Lines passageways that open to the exterior: digestive, respiratory, urinary and reproductiverespiratory, urinary and reproductive
Mucous coating and movement of cilia trap and remove Mucous coating and movement of cilia trap and remove foreign particles and bacteria from internal surfaces of bodyforeign particles and bacteria from internal surfaces of body
BIO 201
Tissues 14
Cutaneous, Synovial and Serous Cutaneous, Synovial and Serous MembranesMembranes
Cutaneous membrane (skin)Cutaneous membrane (skin) stratified squamous epithelium resting on layer of connective tissuestratified squamous epithelium resting on layer of connective tissue relatively dry layer serves protective functionrelatively dry layer serves protective function
S i l b li j i tS i l b li j i t Synovial membrane lines joints Synovial membrane lines joints secretes secretes synovialsynovial fluid rich in hyaluronic acid into the joint fluid rich in hyaluronic acid into the joint
Serous membrane (serosa) Serous membrane (serosa) –– internal membraneinternal membrane covers organs and walls of body cavities, produces covers organs and walls of body cavities, produces serousserous fluidfluid
2727
Muscular TissueMuscular Tissue
Elongated cells that respond to stimuli by Elongated cells that respond to stimuli by contractingcontracting Function is to exert physical force on other tissuesFunction is to exert physical force on other tissues
h dh d move handmove hand push blood through a vesselpush blood through a vessel expel urineexpel urine
Important source of body heatImportant source of body heat Three types of muscleThree types of muscle
skeletal, cardiac and smoothskeletal, cardiac and smooth
2828
BIO 201
Tissues 15
Skeletal MuscleSkeletal Muscle
2929
Long, cylindrical, unbranched cells with Long, cylindrical, unbranched cells with striationsstriations Movement, facial expression, posture, breathing, speech, Movement, facial expression, posture, breathing, speech,
swallowing and excretionswallowing and excretion
Cardiac MuscleCardiac Muscle
3030
Short branched cells with striations and Short branched cells with striations and intercalated discsintercalated discs Pumps bloodPumps blood
BIO 201
Tissues 16
Smooth MuscleSmooth Muscle
3131
Short cells; nonstriatedShort cells; nonstriated Sheets of muscle in viscera; iris; hair follicles and sphincters Sheets of muscle in viscera; iris; hair follicles and sphincters
Swallowing, GI tract functions, labor contractions, control of airflow, Swallowing, GI tract functions, labor contractions, control of airflow, erection of hairs and control of pupilerection of hairs and control of pupil
Nervous TissueNervous Tissue
3232
Large Large neuronsneurons with long cell processes surrounded by with long cell processes surrounded by much smaller much smaller glialglial cells lacking cells lacking dendritesdendrites and and axonsaxons
Found in brain, spinal cord, nerves & gangliaFound in brain, spinal cord, nerves & ganglia CommunicationCommunication and and controlcontrol of bodily functionsof bodily functions