1. TISSUE LEVEL OF ORGANIZATION

2. 4 BASIC TISSUE TYPES
Epithelial
Connective
Muscle
Nervous

3. Tight Junctions Adherens Desmosomes Hemidesmosomes Gap Junctions
Cell Connections
Tight Junctions
Adherens
Desmosomes
Hemidesmosomes
Gap Junctions

4. Tight Junctions most apical part of cell
fuse 2 adjacent membranes with fibrous connections
prevents passage of molecules & ions between cells
if epithelium forms tube  space in tube is-lumen
presence of tight junctions ensures that contents of lumen are isolated from basolateral cell surfaces

5. Adherens dense layers of proteins on inside of membrane
attach membrane proteins to microfilaments of cell’s cytoskeleton

6. Desmosomes localized patches holding cells together
allow tissues to resist twisting & stretching
stabilize cell shapes
most abundant in superficial skin layers
links so strong that dead skin cells are shed in thick sheets-not individually

7. Hemidesmosomes
made of proteins
anchor cells to basement membrane

8. Gap Junctions intercellular channels
permit passage of ions & small molecules
comprised of pore-like transmembrane proteins-connexons
help coordinate functions such as cilia beating
most abundant in cardiac & smooth muscle
coordinate muscle cell contraction

9. Epithelial Tissue flat sheets of contiguous cells
line body surfaces & cavities
cover every exposed surface
skin & all passageways that communicate with the outside world
Digestive
Reproductive
Urinary
Respiratory

10. EPITHELIA TISSUE CHARACTERISTICS
Cellularity
made almost entirely of cells
packed together tightly with little extracellular space
Polarity
cytoplasmic components of cells not evenly distributed
cells have one exposed face either to external world or to a lumen- apical surface and basal surface which faces underlying connective tissue
Attachment
bottom row of cells bound to basement membrane
Avascularity
no direct contact of epithelial cells with blood vessels
nutrition comes via diffusion or absorption from underlying tissues
Regeneration
able to repair and renew themselves
stem or germinative cells are found in deepest layer of epithelium near basement membrane

11. FUNCTIONS physical protection
protect underlying cells from abrasion, dehydration and destruction
control permeability
anything entering or leaving the body must cross an epithelium
provide sensation
some detect environmental changes & relay information to nervous system
produce special secretions
primary function of glandular epithelium

12. Specializations of Apical Surface
Microvilli
finger-like projections
increases surface area 20X
specialized for absorption & secretion
Cilia
longer with larger diameter
beat in coordinated fashion
movement of fluids across & through epithelia

13. Classification of Epithelia
cell shape
arrangement of cell layers

14. Arrangement of Layers Simple one layer of cells Pseudostratified
one layer that looks like several layers
all cells attach to basement membrane
Stratified
several layers of cells stacked on top of each other

15. Function & Classification of Epithelia
Simple
each cell rests on basement membrane
one surface faces either lumen or outside world
cells are thin
same polarity
typically fragile
do not provide much protection against mechanical damage
found only internally
absorption or secretion
Stratified
basal layer of cells rests on basement membrane
subsequent layers do not
stacked on top of basal layer
cells of only most superficial layer have free surface
found in areas subjected to mechanical or chemical stresses
skin & lining of mouth

16. Cell Shapes Squamous Cuboidal Columnar cells Transitional cells
flat & irregularly shaped
often so thin that flattened nucleus bulges at cell surface
Cuboidal
about as tall as wide
look like cubes or hexagonal boxes
Nucleus-usually round & not flattened
Columnar cells
taller than wide
look like columns
Nucleus-usually elongated & found in long axis of cell
Transitional cells
go from squamouscuboidal & back again
all organs to change shape

17. TYPES OF EPITHELIA

18. Simple Squamous one layer of squamous cells delicate
found in protected regions
filtration or diffusion
slick, slippery surfaces are needed to reduce friction
substances can move quickly through

19. Simple Cuboidal one layer of cuboidal cells
specialized for secretion & absorption
found in secretory portion of glands
some cells may have a dense border of microvilli
found in kidney tubules, pancreas & salivary glands

20. Simple Columnar one layer of columnar cells
found where absorption & secretion take place
small intestine
in small intestine epithelium has goblet cells which secrete mucus to protect and lubricate
found with cilia in oviducts & respiratory tract

21. Stratified Squamous several layers of squamous cells
surface cells look squamous
lower ones appear more cuboidal or columnar
found where body experiences severe mechanical stresses
cells are worn away quickly
replaced rapidly by mitosis in lower layers
outer layer of the skin- epidermis
here mechanical stress and dehydration of the superficial layers is aided with keratin
skin is said to be keratinized
Non-keratinized stratified squamous epithelium
found in mouth, pharynx & esophagus

22. Stratified Cuboidal typically only 2 cell layers of cuboidal cells
not a great quantity found in
human body
large ducts of sweat & mammary glands

23. Stratified Columnar rare found where 2 other types of epithelia meet
large ducts
in pharynx, epiglottis, anus & urethra

24. Pseudostratified Epithelium
looks like stratified columnar
appears layered but is not
nuclei are at different levels but all cells rest on basement membrane
not all same height
often contains cilia & goblet cells
found lining most of respiratory tract

25. Transitional Epithelium
multi-layered
goes from cuboidal squamous and back again
thicker, multilayered epithelium
found in bladder
tolerates great deal of stretching
surface cells are more muffin-shaped
cells are rounded when organ is not filled and flattens as organ fills

26. Glanduar Epithelia Gland Endocrine Exocrine
cell or organ that secretes substances for use elsewhere in the body or releases them for elimination from body
composed primarily of epithelia tissue
Endocrine
ductless
release hormones into interstitial fluid
regulate or coordinate activity of other tissues, organs & organ systems
Exocrine
ducted
release secretions into passageways or ducts which empty onto the skin or other epithelial surfaces
produce enzymes & perspiration

27. Exocrine Gland Classification
Unicellular
Multicellular
Simple
have single, unbranched duct
Compound
have branched duct

28. Exocrine Gland Classification
if duct & secretory part are equal in diameter-gland is tubular
if secretory cells form sac-acinar
if secretory cells are found both in tubular &acinar parts-tubuloacinar

29. Exocrine Gland Structure
Unicellular
Multicellular
Secretory sheets
Tubular
Alveolar (Acinar)
Tubuloalveolar

31. Merocrine Glands
most common
sweat & mucus secreting
release products via exocytosis

32. Apocrine Glands
product accumulates in apical tip
pinched off to secrete
rest of gland repairs itself

33. Holocrine glands entire cell becomes packed with secretory product
cell bursts releasing secretion and in so doing kills the cell
further secretion depends on replacement of gland cell
sebaceous or oil glands associated with hair follicles

34. Connective Tissue widely spread throughout body
most diverse tissue type
never exposed to outside environment
highly vascularized-blood vessels are present (except cartilage & tendons)
comprised of 3 basic components:
specialized cells
extracellular matrix
protein fibers
ground substance

35. Functions structural framework
binds muscle to bone, fat holds kidneys in place & fibrous tissues bind skin to underlying muscle
supports the body
protection for delicate organs such as brain & lungs
immune protection defending body from microorganisms
transports fluids & dissolved materials through body
movement
bones provide levers for body movement
stores energy & generates heat

36. Cells
each type of connective tissue has specialized cells at different stages of maturity
Juvenile cells actively secrete matrix
have suffix blast
Mature cells have suffix-cyte
Destructive cells have suffix clasts
prefix is different for different types of connective tissues
Cartilage-chondro
Bone-osteo
Blood-hemo

37. Protein Fibers Collagen fibers
long, straight, unbranched & very strong
each fiber-bundle of fibrous protein subunits wound together like strands of rope
Elastic fibers
contain elastin
able to stretch & recoil without damage
Reticular fibers
fine collagen fibers
made of same protein subunits as collagen
arranged differently forming a tough, flexible branching framework

38. Classification Embryonic mesenchyme & mucous types
found in embryo from third gestational month to birth
tissue from which all connective tissue originates
Mature
Loose
Dense
Cartilage
Bone
Liquid

39. Loose Connective Tissue
packing material
fills spaces between organs, cushions & stabilizes cells in organs & supports epithelia
surrounds & supports blood vessels and nerves & stores lipid
areolar, adipose & reticular

40. Areolar Connective Tissue
consists of an open framework
ground substance accounts for most of its volume
forms soft-pliable-packing material around tissues
muscles, blood vessels & glands
absorbs shock
loose organization allows it to distort without damage
presence of elastic fibers makes it able to return to original shape
forms layer separating skin from deeper structures

41. Adipose Tissue composed mainly of adipocytes little matrix
cells have large vacuoles filled with fat
fat droplet compresses cytoplasm around edges of cell
organelles are squeezed to side
insulation
slows heat loss through skin
shock absorber around organs

42. Reticular Connective Tissue
consists of network of reticular fibers & cells Found-spleen, lymph nodes & liver

43. Dense Connective Tissue
Dense regular
collagen fibers regularly arranged in parallel
forms ligaments which connect bone to bone & tendons which connect muscle to bones
Dense irregular
collagen fibers found in irregular arrangements forming interwoven meshworks
provides strength & support for areas subjected to stress from many directions
found in skin where it gives strength to lower layer
forms sheath around cartilages-perichondrium & bones-periosteum
forms thick, fibrous capsule around internal organs such as liver, kidney and spleen

44. Elastic Connective Tissue
contains great many elastin fibers
give tissue flexibility
found-vocal cords & ligaments which connect vertebrae

45. Supporting Connective Tissues-Cartilage
strong, flexible
found throughout the body
Matrix firm gel containing chondroitin sulfate which forms complexes with proteinsproteoglycans
cells are chondrocytes
found in chambers or lacunae
avascular, blood cells do not grow into it
three types : hyaline, elastic and fibrocartilage.
Hyaline
covers ends of long bones
matrix consists of closely packed collagen fibers which makes it tough & flexible
found connecting ribs to sternum, nasal cartilages, respiratory tract and as a cover in opposing bone surfaces in joints such as the knees & elbows.
Elastic cartilage
like hyaline-more elastin fibers making it flexible and resilient
epiglottis & ear pinna
Fibrocartilage
looks like dense regular connective tissue
matrix dominated by collagen fibers-densely interwoven making it durable, tough & more compressible than other cartilages
found as intervertebral discs
menisci of knees, between pubic bones, around or in joints and tendons
resists compressions, absorbs shocks
prevents bone to bone contact

46. Supporting Connective Tissues-Bone
osseous tissue
support & protection, fat storage and blood cell formation
small amount ofground substance
Matrix-like cartilage but more rigid because of calcium salt-CaPO4
remainder is collagen fibers
Ca salts make tissue hard & brittle
Collage fibers make it strong & flexible
Bone cells are called osteocytes
found in lacunae
organized around blood vessels that branch through the matrix
osteocytes communicate with each other & blood vessels by canaliculi

47. Fluid Connective Tissue
Blood
contains blood cells
formed elements
RBCs
WBCs
platelets
suspended in liquid matrix- plasma which contains protein fibers for blood clotting
Lymph

48. Membranes
physical barriers composed of epithelia & supported by connective tissue
cover & protect other tissues
4 types:
Mucous
Serous
Cutaneous
Synovial

49. Cutaneous Membranes cover body surface largest membrane in body skin
stratified squamous epithelium + layer of areolar connective tissue reinforced by underlying dense connective tissue
thick, relatively water proof & usually dry

50. Mucus Membranes line cavities in communication with outside
mucosa consists of two to three layers
an epithelium
an areolar connective tissue layer (lamina propia)
sometimes layer of smooth musclemuscularis mucosae
absorptive, secretory & protective functions
help keep epithelial surfaces moist with mucus made by goblet cells

51. Serous Membranes
line sealed internal parts such as ventral body cavities
simple squamous epithelium resting on thin layer of areolar connective tissue
produce watery serous fluid
pleura lines pleural cavity and covers lungs
pericardium lines pericardial cavity covering heart
each can be divided into parietal partlines inner surface of cavity
and visceral part-covers outer surface of organs

52. Synovial Membranes surround joint cavities
Joints-articulations for bones
allow for movement
surrounded by fibrous capsule consisting of areolar tissue with matrix of interwoven collagen fibers, proteoglycans & glycoproteins
space filled with synovial fluid

53. Muscle Tissue specialized for movement & contraction
3 types: skeletal, cardiac and smooth
all contract alike but have different internal organizations
Skeletal muscles have cells called fibers
long & thin
multinucleated often containing several hundred nuclei
striated or striped due to repeating groups of cellular proteins actin and myosin-responsible for contraction
cells contract when stimulated by nerves
under voluntary control
can be called striated voluntary muscle

54. Cardiac Muscle found only in the heart
striated like skeletal & arranged same
uninucleate-may have 1-5-centrally located nuclie
Cardiocyte-smaller than skeletal m. cell
connected to one another via darkened bands between themintercalated discs
special areas locked together by desmosomes, gap junctions & intercellular cement
Ions move through gap junctions which coordinates contractions
do not need nerve activity to contract
pacemaker cells establish regular rate of contraction
not under voluntary control
striated involuntary muscle

55. Smooth Muscle Cells-small, spindle shaped with tapering ends
contain actin & myosin-not arranged in striated fashion
cells are uninucleate
found in digestive & urinary organs, uterus & blood vessel walls
not under voluntary control
non-striated involuntary

56. Nervous Tissue consists of neurons (nerve cells) & neuralgia cells
specialized to detect stimuli, respond quickly & transmit information
each nerve cell has soma or cell body
one long process-axon-transmits messages
many smaller projections-dendrites-receive information

57. Exocrine Gland Structure Unicellular
e.g. Goblet cell