basic histology - graftonps.org
TRANSCRIPT
• Very cellular
• Supported by underlying connective tissue
• Epithelial & connective tissue are separated by a basement
membrane, which is produced by both tissues.
• Packed together tightly & orderly.
Tight junctions may occur between cells.
• Avascular. Receives its nutrients
by diffusion from the underlying
connective tissue.
• Two types:
a. Covering/Lining
b. Glandular
Epithelium
• Faces a space such as the lumen
of a blood vessel or intestine.
Apical surface = adjacent
to lumen
Basal surface = adjacent
to basement membrane
• Mucous membranes - line organs and cavities
- secretion of mucous from glands
Serous membranes - cover and protect organs
Hint: These surfaces are “places”, not “things”.
Covering/Lining Epithelium
Epithelial Tissue Types
Layers : Simple - single layer – provides a selective
barrier allowing diffusion, filtration, secretion,
and absorption.
Stratified - several layers –
subject to wear and tear –
forms a protective barrier.
Pseudostratified –
appears to be several layers,
but is actually only a single layer.
Shapes
• Squamous - flattened
• Cuboidal - cube
• Columnar - cylindrical
• Transitional – change shape
They are rounder when the tissue
is relaxed and flatter when the
tissue is stretched.
NOTE: When viewed from
the apical surface, all epithelial
cells have a similar shape.
Simple SQUAMOUS Epithelium
(1) Outer layer of Bowman's capsule (yellow arrows)
(2) Inner layer of Bowman's capsule (red arrows)
(3) Capillary endothelial cells (purple arrows)
Pseudostratified Ciliated Columnar Epithelium
All of the cells are in contact with the basement membrane, but not all
of them reach the surface. The cells that do reach the surface are either
ciliated or goblet cells (mucus-secreting cells). Refer to
page 131
Respiratory Tract
• Most abundant tissue in the body.
• Supports epithelial tissue and connects it to other tissues.
Provides coverings that support and protect muscle and
nervous tissue.
• Most are not very cellular, usually containing more
matrix than cells.
• Most are vascular and regenerate easily.
Cells: Fibroblasts, Macrophage, Plasma cells,
Mast cells, Adipocytes, WBC's
Connective Tissue
EXCEPTIONS: Tendons – poorly vascularized; do NOT heal easily
Cartilage – avascular - does NOT heal easily
Connective Tissue Matrix Ground substance + Fibers
(Composition is used in classifying connective tissue)
Ground Substance = polysaccharides + proteins
Fibers:
• Collagen - most abundant protein in body
• Elastic fibers - stretchable (in skin, BV, lungs)
• Reticular fibers - support and strength
Loose Connective Tissue • Fibers are loosely arranged.
• Collagen, elastic, and reticular fibers provide strength,
elasticity, and support.
• Fibroblasts and adipocytes permanently reside here.
• Subcutaneous layer of skin.
Areolar
Reticular
Adipose
Areolar Connective Tissue
Fibroblast
nucleus
Mast cell
Elastic
fiber
Collagen
fiber
Ground
substance
Refer to page 136
Reticular Connective Tissue
Reticular
fiber
Ground
substance
Refer to page 138
Nucleus of
Reticulocyte
Dense Connective Tissue • Matrix is packed with fibers and contains very little ground
substance and few fibroblasts.
• Tendons, Ligaments, Skin dermis, Artery wall
Dense Regular
Dense Irregular
Dense Regular Elastic
Dense Regular Elastic
Connective Tissue
Wall of Artery; Ligament
Elastic fiber
Collagen
bundles
Fibroblast
nucleus
Now you try ……………. HINT: This is an ARTERY, which contains dense regular elastic CT.
• Peach outlines?
• Blue arrows?
• Green arrow?
• Grey block arrow?
• Yellow block arrow?
Cartilage Contains cells called chondrocytes housed in spaces called
"lacunae". Some lacunae contain more than one chondrocyte ...
these are daughter cells formed after division.
Hyaline - ends of bone; support rings of respiratory tubes
Elastic – elastin fibers; epiglottis; nose
Fibrocartilage - much collagen; intervertebral discs
Bone • Dense - middle portion (osteon); Spongy – ends (trabeculae)
• Bone tissue is unlike other
connective tissues in that
the extracellular matrix
becomes calcified.
• Lamellae – layers of matrix;
concentric = within osteons;
interstitial = in between osteons.
• Contains cells called
osteocytes housed in
lacunae.
• Haversian Canal - extends the length of each osteon
through its center; contains blood vessels, lymphatic
vessels, and nerves.
• Volkmann’s Canals – connect Haversian canals to each
other; communication; contain nerves and vessels that
carry blood and lymph from the exterior bone surface to
the osteons.
• Canaliculi – tiny canals radiating
in all directions from the lacunae
and connecting them to each other
as well as to the Haversian canal.
Bone
Bone Osteon
Volkmann’s
canals
Concentric
lamellae
Interstitial
lamellae
Haversian
canal
Lacunae
Refer to page 140
Blood
Refer to page 142
Platelets
White
blood cells
(Leukocytes)
Red
blood cells
(Erythrocytes)
Plasma
matrix
Muscle Tissue • Contains muscle cells and connective tissue. Thin layers of
connective tissue surround muscle cells to protect and support
them.
• Very cellular. Muscle cells = muscle fibers.
Fibers contain many microfilaments (myofilaments) - cause
muscle cells to shorten (contract) when stimulated.
Skeletal (striated; voluntary; multinucleated cells)
Cardiac (striated; involuntary; multinucleated cells;
branching cells; intercalated disks)
Smooth (non-striated; involuntary; uninucleated cells;
tapered cells)
Nervous Tissue • Forms the brain, spinal cord, and nerves.
• Two basic categories of nervous tissue cells:
a. Neurons – receive and send information; amitotic
REVIEW: axon, dendrite, cell body
b. Neuroglial cells – support the neurons; divide and
replace themselves
• Highly vascularized