Simple Squamous Epithelium

1
Simple Squamous Epithelium
Description Single layer of flat cells with
disc-shaped central nuclei. Function Allows
passage of material by diffusion filtration and
reduces friction by providing a smooth surface
secreting lubricating serous fluid.
Representative locations Found in air sacs of
lungs (alveoli) where gas is exchanged, in balls
of capillaries (glomeruli) in the kidney where
blood is filtered, epithelium of serosae (called
mesothelium) and the epithelium in the inner
surface (lumen) of the heart and all blood
vessels (called endothelium).
2
Simple Cuboidal Epitheium
Description Single layer of cubelike cells with
large, spherical central nuclei. Function
Function in secretion and absorption.
Representative locations In the secretory
portions of many glands (e.g. thyroid, mammary,
and salivary). Also located in the kidney tubules
(ducts that lead away from the glomeruli). E
Epithelium
3
Simple Columnar Epithelium
Description Single layer of tall cells with oval
nuclei and often have an apical border of
microvilli. Many contain goblet cells
(mucus-secreting unicellular glands). Function
absorption of nutrients, secretion of mucus
enzymes. Representative locations lines most of
the digestive tract (from stomach to anal canal)
and most of the lining of the uterus. A ciliated
variety is found in the Fallopian tubes (uterine
tubes). EEpithelium
4
Pseudostratified Ciliated Columnar Epithelium
(P) Description single layer of cells of
differing heights, but some don't reach the free
surface. Nuclei are seen at many different
levels. They contain goblet cells and cilia (C).
Function secretion propulsion of mucus
Representative locations lines the trachea
most of the upper respiratory tract.
5
Stratified Squamous Epithelium - Nonkeratinized
Description thick sheet made of several
epithelial cell layers. Surface cells are
flattened. Basal cells (cuboidal or columnar) are
active in mitosis and produce the cells of the
more superficial layers. Function resists
abrasion and provides a barrier against
penetration by pathogenic organs. Representative
locations lining the openings of open tracts
(mouth, vagina, and anal canal) and esophagus.
6
Stratified Squamous Epithelium - Keratinized
Description multiple layers with cells becoming
increasingly flat scaly toward the surface.
Surface is covered with layers of compact dead
cells without nuclei (and full of keratin). Basal
cells (cuboidal or columnar) are active in
mitosis produce the cells of the more
superficial layers Function resists abrasion
and provides a barrier against penetration by
pathogenic organs. Retards water loss through
skin. Representative locations Epidermis of
skin (palms soles are especially highly
keratinized)
7
Stratified Squamous Epithelium
8
Transitional Epithelium (T)
Description somewhat resembles stratified
epithelium, but surface cells are rounded, not
flattened. Basal cells are cuboidal or columnar.
Surface cells are dome shaped or squamous-like,
depending on degree of organ stretch (C).
Function Stretches readily to allow filling of
urinary tract with urine. Representative
locations Lines the ureters, bladder part of
the urethra.
9
Loose (areolar) connective tissue
Description matrix is gel-like with all 3 fiber
types (collagen, elastic reticular fibers).
Contains fibroblasts (produces matrix) (FB),
macrophages (large phagocytic cells), mast cells
(release inflammatory chemicals) (MC),
neutrophils (phagocytize bacteria) plasma cells
(produces antibiotics) Function fills space
between organs, loosely binds epithelial tissue
to deeper tissue, holds extracellular fluid,
space for defense against infection
Representative locations surrounds capillaries
and organs, underlies most epithelia.
FCfibrocytes
10
Elastic Connective Tissue
Elastic connective tissue consists of fibroblasts
and densely compacted parallel bundles of fibers
- mainly elastic fibers with a minor component of
collagen fibers. It is found wherever a strong,
elastic tissue is needed, such as in the walls of
large, elastic arteries. Aorta (Media) ET
Elastic Tissue, SM Smooth Muscle,
Fenestrations
11
Reticular Connective Tissue
Description network of interlacing reticular
fibers in a typical loose ground substance.
Reticular cells lie on the network. Function
fibers form a soft internal framework (stroma)
that supports other cell types. Representative
locations stroma of liver and lymphoid organs
(lymph nodes, red bone marrow, spleen) and
reticular lamina of basement membrane. RF
reticular fibers
12
Adipose Tissue
Description matrix is similar in content to
areolar but adipose cells predominate (very
little matrix). Nucleus is pushed to the side by
stored triglycerides. Function cells are
specialized to store triglycerides (energy
reserve), insulates against heat loss supports
protects organs Representative locations under
skin (subcutaneous layer, aka superficial fascia
and hypodermis), supports protects around
kidneys eyeballs within abdomen in breasts,
yellow bone marrow
13
Hyaline Cartilage in Trachea This is a high
magnification view of hyaline cartilage in the
trachea. It contains chondrocytes (C) in lacunae
(L) within an interterritorial matrix (I) and a
territorial matrix (T). Isogenous cell nests (IN)
are present and are indicative of interstitial
growth. Hyaline cartilage may or may not have a
perichondrium (PC) present
14
Hyaline cartilage This is a low magnification
view of hyaline cartilage. Note that it contains
chondrocytes (O) in lacunae.
Description clear, glassy matrix, collagen
fibers are small and not visible in the matrix,
making the matrix appear transparent. The
cartilage cells (chondrocytes), are located in
lacunae (spaces), within the rigid matrix.
Function Supports reinforces has resilient
cushioning properties resists compressive
stress, holds airway open during respiration,
moves vocal cords during speech and growth zones
of long bones in children Representative
locations most of fetal skeleton articular
cartilage (covering ends of long bones where they
meet in joint cavities) forms costal cartilages
(part of the ribs) and the cartilage of the nose,
trachea larynx
15
Elastic Cartilage in Epiglottis This is a low
magnification view of elastic cartilage. Note the
chondrocytes (C) lying in lacunae. This matrix
does not stain homogeneous like hyaline cartilage
because of the presence of elastic fibers (EF)
coursing through it.
16
Canaliculi - ground bone This is a section taken
through ground bone. The functional units
consists of osteons which contain a central canal
called a Haversian canal (HC) surrounded by
multiple layers of bone. These spaces contain
blood vessels, lymphatics and nerves in the
living state. In this sample, identify
circumferential lamellae (CL) which consist of
partial osteons which arise from bone remodeling.
Note also the Canaliculi (C) and osteocytes (O)
present.
17
Haversian Canals in Ground Bone This is a
section taken through ground bone. The functional
units consists of osteons (O) which contain a
central canal called a Haversian canal (HC)
surrounded by multiple layers of bone. These
spaces contain blood vessels, lymphatics and
nerves in the living state. Volkman's canals
permit communication of osteons with each other,
with the marrow space, and with the periosteum.
These canals run at right angles to the haversian
canals (HC). Identify the osteocytes present
(OS).
18
Bone continued
Description hard, calcified matrix arranged in
concentric lamellae around Haversian canals
(canals containing blood vessels nerves).
Lacunae (containing osteocytes) are
interconnected by canaliculi. Matrix contains
collagen fibers. Very well vascularized.
Function physical support of body leverage for
muscle action, protective enclosure of viscera
reservoir of calcium phosphorus. Blood cell
formation (hematopoiesis) in red bone marrow and
fat storage (in yellow bone marrow)
Representative locations skeleton
19
Description red white blood cells and
platelets in plasma (the fluid matrix). Red blood
cells are pale pink discs with no nuclei and
white blood cells are larger, few in number and
have variously shaped nuclei. Platelets are cell
fragments with no nuclei and much smaller then
RBCs. The "fibers" of blood are soluble proteins
that become visible only during blood clotting.
Function transport of respiratory gases,
nutrients, wastes, chemical signals and heat
throughout body. Involved in immune defense
(white blood cells), platelets secrete growth
factors that promote tissue maintenance repair.
Representative locations Contained within heart
blood vessels.
20
(No Transcript)
21
Dense Regular Connective Tissue Description
densely packed, parallel, wavy collagen fibers
major cell type is the fibroblast. Very few blood
vessels. Very little ground substance. Function
attaches muscles to bones or to muscles
(tendons) attaches bones to bone (ligaments)
resists tensile stress (when pulling force is in
one direction). Representative locations
Tendons, most ligaments, aponeuroses (a fibrous
sheet connecting muscle to the part it moves)
22
Dense Irregular Connective Tissue Description
densely packed collagen fibers running in random
directions. Very little ground substance. Major
cell type is fibroblast. Function provides
structural strength, withstands tension exerted
in many directions Representative locations
dermis of the skin submucosa of the digestive
tract, fibrous capsules around viscera such as
liver, kidney and spleen, fibrous sheaths around
cartilage, bone and fibrous capsules around
joints, and deep fascia (the fibrous lining of
the body wall covers muscles holds them
together subdivides muscles into functional
groups).
23
Fibrocartilage Description matrix similar but
less firm than in hyaline cartilage, thick
parallel collagen fibers similar to those of
tendons. Rows of chondrocytes in lacunae.
Function Tensile strength with the ability to
absorb compressive shock Representative
locations intervertebral discs (separate bone of
spinal column, pubic symphysis (anterior joint
between two halves of pelvic girdle), menisci
(pads in knee joint)