histology 2
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Introduction to Histology Vertebrate Organization:molecules
organelles
cells
tissues
organs
organ systemsorganism
All the different cells in the body originate from a single cell.
cartilage neurons muscle
gut lining
TISSUES
groups of related cells with
similar function
Histology = study of tissues
Related cells (tissues) have similar biochemical make-up.
3 steps:
(1) Fixation
(2) Sectioning(3) Staining
H&E stainingnuclei = purple
cytoplasm, matrix proteins = pinkish
Tissue stained to
indicate insulin
BIO223: Human Anatomy L02: Epithelium UNC-Asheville, f2011
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Slides give you a 2D look at a 3D structure.Structures look different depending on how/where they are sliced.
Longitudinal
(LS)
Cross-section
Sections:
(XS)
Oblique section
EPITHELIUM
CONNECTIVE TISSUE
MUSCLE
NERVOUS TISSUE
4 basic kinds of tissues make up all structures in body:
EPITHELIUM
CONNECTIVE TISSUE
MUSCLE
NERVOUS TISSUE
4 basic kinds of tissues make up all structures in body: Covers surfaces
Apical Surface (free edge)
Basal lamina (= Basement Membrane) attaches epithelium to the
underlying tissues
Cells have polarity
Cells packed closely together
Characteristics of Epithelium:
o en speca ze unc ons e ween ce s
little ECF = Extra-Cellular Fluid [aka interstitial fluid(ISF)]
High rate ofmitosis and regeneration
Avascular contains no blood vessels
all nutrients and oxygen must diffuse from the underlying tissue
[blood vessels themselves are a special case endothelium]
BIO223: Human Anatomy L02: Epithelium UNC-Asheville, f2011
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Vertebrates have tube-within-a-tube body plan
Different tissue types arise from different layers of the embryo
Epithelium covers all surfaces that open to the outside of body
mouthEarly embryo
Lancet
anus
free space filled with air or fluid
nucleus
single cell
Apical Surface
EpitheliumEpitheliumEpitheliumEpithelium
Basal
Lamina
Connective TissueConnective Tissue
Polarity
Organelles are notdistributed
evenly throughout cytoplasm
there is a top (apical) and
bottom (basal)
Apicalsurface (top)
Basallamina (bottom)
Cell-1 Cell-2
Apical surface(microvilli)
Specialized junctions
connect tightly-packed cells, and
regulate communication among
neighboring cells
Basal lamina
attaches epithelium to underlying
Basal lamina
connective tissue.
Functions of epithelium:
All contact w/ external world mediated by epithelium
Protection
Control permeability, absorption & secretion
Sensation (neuroepithelium)
(e.g. sweat, synovial fluid, hormones, milk, digestive enzymes)
2. Cuboidal
3. Columnar
SHAPE:(as seen in cross-section)
Classification of epithelial tissues:
1. SquamousBasal lamina
StratifiedSimple Pseudostratified
BIO223: Human Anatomy L02: Epithelium UNC-Asheville, f2011
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Classification is based on # of layers and
shape of cells at apical surfaceExamples
Simple
epithelium
lines body cavity (coelom)
inside blood vessels/heart
alveoli of lungs
Simple squamous epithelium
~3D cartoonLung alveoli
capillaryEndothelial cell
lumen
Endothelial cell
(simple squamous)
RBCs in
lumen of capillary
Examples
stratified
s uamousepithelium
Examples
Simple
cuboidal
epithelium
BIO223: Human Anatomy L02: Epithelium UNC-Asheville, f2011
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LOCATION: lining of stomach, intestine, gall-
bladder, uterine tubes, collecting ducts of kidneyFUNCTION: protection, secretion, absorption
Examples
Simple
columnar
epithelium
Examples
Stratified
columnar
epithelium
Salivary gland duct
Stratified squamous epithelium (cornea)Stratified squamous epithelium
(wall of vagina)
Simple cuboidal epithelium
(kidney duct, LS)
Simple cuboidal epithelium
(kidney ducts, XS)
BIO223: Human Anatomy L02: Epithelium UNC-Asheville, f2011
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Simple Columnar
epithelium
Stratified cuboidal epithelium
(lactiferous duct of breast)
Pseudo-stratified (columnar) epithelium [special case]
nuclei are at different positions, so it appears layered, but
all the cells contact the basement membrane
Mucosa of trachea
True stratified columnar epithelium
distinct rows of nuclei
Tongue,Mucousgland duct
Pesudostratified epithelium
more irregular arrangement of nuclei
Trachea
Epithelium always has a free surface,
and is named by number of layers
and shape of cells at apical surface.
Epithelium, review
Tissue that covers surfaces
Classified based on cell
shape and number
most epithelial tissues are in
membranes and/or glands
BIO223: Human Anatomy L02: Epithelium UNC-Asheville, f2011
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Epithelium in the body is commonly part of
membranes and glands
Epithelial Membranes
Cutaneous membrane
skin; outer covering of body
Mucous membranes (mucosa)
epithelial lining of wet internal surfaces that connect
to outside of body
Serous membranes (serosa)
epithelial linings inside the body cavity, does notopen
to outside of body
Endothelium
inner lining of blood vessels
Cutaneous membranecovers outside of body
Serous membrane
Does not open to outside
lines body cavity & covers outer
Mucous membrane
Surfaces ultimately connect
to outside of body
sur ace o a omna organs
Glandular Epithelium (secretion)
ENDOCRINE glands
secrete products directly into interstitial fluid (ISF)
and/or bloodstream (e.g. Hormones)
EXOCRINE glands
secrete products through ducts to surface of body
(ex. sweat, digestive enzymes, milk)
Endocrine glands
empty into blood or ECF
Products are called
hormones.
Exocrine glands
empty onto surfaces through ducts
surfaces may be external (skin) or internal (lumen of stomach)
BIO223: Human Anatomy L02: Epithelium UNC-Asheville, f2011
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REVIEW:
Identify the epithelium
shown on each of the
following slides
Indicate the apical surface
and the basal lamina.
BIO223: Human Anatomy L02: Epithelium UNC-Asheville, f2011