http://meded.ucsd.edu/histimgbank/chapter_1/Slide_2_kid
ney/index.htm
Histo- Greek for ‘web’
 Tissue-groups of similar cells ‘webbed’
together

http://www.tutorvista.com/content/science/s
cience-i/tissues/animal-tissues.php
Protects outer body and lines inner organs
 Sheets/tubes of tightly-packed cells
 Polarity- has a top (apical) and a bottom
(basal)

› Apical- surface that can be exposed to air or
fluid
 Sometimes has cilia (hair-like growth)
 Moves material over cell surface
 Or microvilli (finger-like projections)
 Increases surface area for absorption
› Basal attaches to a connective tissue
Classification by layers


Single-layered: simple
Multi-layered: stratified
Pseudostratified epithelium- appear multilayered
because of differing cell lengths but it is only
simple epithelium
Thickly cornified stratified
squamous epithelium. The
cells in the bright red layer
and in the pale layers
above it are completely
flattened and dead, and
have lost their nuclei.
http://www.meddean.luc.edu/L
UMEN/MedEd/Histo/frames/h
_frame1.html
Simple columnar epithelium with very regular line-up of
nuclei
http://www.meddean.luc.edu/LUMEN/Med
Ed/Histo/frames/h_frame1.html
Key functions
 Protection
› Protects more vunerable structures in the body

Barrier
› Prevents foreign objects from entering the body

Sensation
› Sensory nerve endings in epithelial tissue connect
with outside stimuli

Secretion
› Can be specialized to secrete enzymes,
hormones, and fluids
It is the frame-work and
support for organs, stores fat,
transports substances, protects
against disease, repairs tissue
damage.
Classified by the extracellular
matrix- what they lay in.
Collagen- fibrous protein



›

Gives the tissue the strength it
needs
Connective tissue is made up
of a mix of collagen, elastic,
and reticular fibers
Primary types of connective tissue
Dense regular connective tissue: in tendons used as
bundles of collagenous fibers to attach muscle to bone. In
ligaments as elastic fibers from bone to bone, surrounding a
joint, and anchoring organs.
Dense irregular connective tissue: fibers twist and weave to
form thick tissue that withstands stress from any direction.
Makes up inner skin layer called the dermis and the outer
capsule of organs like the kidney and the spleen.
Reticular tissue: thin, branching fibers made of collagenous
fibers. It is a filter found in the spleen, lymph nodes, and
bone marrow.
• Areolar (loose) tissue: almost
everywhere in the body, it binds
structures together and fills
space. Made of collagenous
protein fibers (wavy ribbons),
elastic fibers (cylindrical
threads), and amorphous
ground substance (semisolid
gel). http://www.lab.anhb.uwa.edu.au/mb140/Co
http://meded.ucsd.edu/hist-imgbank/chapter_1/Slide_9_omentum/inde
x.htm
rePages/Connective/Connect.htm#loose
• Adipose tissue: made from
fat cells. Forms padding for
internal organs, reduces
heat loss, and stores energy
in fat molecules
(triglycerides). Have a ringlike structure bc fat
molecules fill cells forcing
the nuclei against the cell
membranes. Has an
intracellular matrix, not
Bone (osseous) tissue: repeating patterns
called Haversian systems. The Haversian
canal (center of each system) contains
blood vessels, lymph vessels, and nerves.
It is surrounded by thin membranes
called lamellae.
 Blood: extracellular matrix is plasma.
Erythrocytes (red blood cells), leukocytes
(white blood cells), and thrombocytes
(platelets) are suspended in it.

http://training.seer.cancer.gov/module_anatomy/unit2_2_b
ody_tissues2_connective.html

Cartilage: firm, flexible tissue made of collagen and
elastic fibers with no blood vessels or nerve cells. Contains
openings called lacunae that enclose mature cells
(chondrocytes). There are 3 types:
› Hyaline- foundation for embryonic skeleton, forms the rib
cartilages, makes nose cartilage, and covers articulating surfaces
of bones
› Fibrocartilage- thick, compact collagen fibers. Its sponge-like
structure makes it a good shock-absorber. Found in intervertebral
discs and symphysis pubis (front of pelvis).
› Elastic cartilage- more tightly packed lacunae and chondrocytes
beween parallel elastic fibers than hyaline. Makes the ear lobe
and other structures with specific form. It tends to ‘bounce back’
into its original

Made of fibers called myocytes
› Cytoplasm in the fiber is called sarcoplasm
 In the cytoplasm is myofibrils
 They contain the protein filaments actin and myosin
 These filaments slide past each other during muscle
contractions to shorten the fiber.

There are 3 types
http://training.seer.cancer.gov/module_anatomy/unit2_2_body_tissues3_muscle.html
1.
2.
3.
Smooth muscle tissue- contracts without
conscious control. Made of spindle-shaped
fibers with large, central nuclei. Found in
internal organ walls. It is not striated.
Cardiac muscle tissue- known as
myocardium. Branching fibers with a
central nucleus and alternating light and
dark striations make it. Intercalated discs
are the dark structures between fibers.
Controlled by the autonomic nervous
system.
Skeletal, striated, muscle tissue- it attaches
to the skeleton and is used throughout the
central nervous system for movement.
Fibers are cylindrical with several nuclei in
each cell.
Neurons are the only
type of nerve tissue
 It generates and
conducts electrical
signals throughout the
body
 Sense receptors
receive a stimulus
which then sends
electrical impulses
through finger-like
cytoplasmic
projections called
dendrites.
 It moves through the
body through axons.

http://training.seer.cancer.gov/module_anat
omy/unit2_2_body_tissues4_nervous.html
http://academic.kellogg.cc.mi.us/herbrands
onc/bio201_McKinley/f51_layers_of_the_inte_c.jpg
Integere (Latin)- “to cover”
 Dermato and cutis (Greek and Latin)“skin”
 Epi- (Greek)- “upon” or “above”




Largest organ
Retains moisture
Sensory receptors
for:
› pain,
› Heat
› Touch




Excretes salts
Excretes small
amounts of waste
Stores blood
Regulates body
temp.

2 main parts
› Epidermis and dermis

Under the dermis is the hypodermis
(supericial fascia- subcutaneous tissue)
› It acts a foundation not truly part of the skin
http://images.google.com/imgres?imgurl=http://www.yvcc.edu
/academics/biology/seveyka/Histology%20Zoomer/Integume
ntTutor

Surface skin
› 1st line of defense against infection
› Contains no blood vessels
› Layers and layers of epithelial cells
http://biology.clc.uc.edu/Fankhauser/La
bs/Anatomy_&_Physiology/A&P203/Re
productive_Tract_Histology/epidermis_
nerve_400x_P5170459lbd.jpg

Melanocytes
› ¼ of stratum basale is made of these
› Synthesize a pale yellow to black pigment
called melanin
› Cytocrine secretion- melanin is secreted into
keratinocytes
Melanin- skin color and protection
against uv rays
 Keratinocytes

› majority of stratum basale
› Primary epithelial cell of skin
•
Carotene- in stratum
corneum and fatty
layers beneath the skin
– Produces yellowish
hue common with
Asian ancestry
•
Hemoglobin- cause for
pinkish color of
Caucasian skin
– Less melanin, more
hemoglobin
•
Albinos- no melanin in
skin at all

Ridges and groovesincrease friction to
grasp other objects
› Ex. Loops and whorls
(fingerprints, palm
prints, footprints)




Also known as the
corium
Thicker and more
fibrous than the
dermis
2 layers
Fibrolastsconnective tissue
develops





Macrophagesengulf wastes and
foreign
microorganisms
Adipose tissue
Thinnest over eyelids
and male sex organs
Thicker on back than
stomach
Thickest on palms of
hands and soles of
feet
•
•
•
Top (outer) layer
Soft
Elastic, reticular fibers that enter the
epidermis
– Brings blood and nerve endings closer
•
Papillae are finger-like projections- loops of
capillaries to increase the surface area of
dermis and anchor epidermis
nerve endings
sensitive to soft touch.
– In some papillae
Rete- net (Latin)
 Dense, irregular connective tissue

› Interlacing bundles of collagenous and
elastic fibers
 Strong resistant layer
 Gives skin strength, extensibility, ad elasticity

Oil glands (seaceous glands), sweat
glands, fat cells, and larger blood vessels
are in this layer
Follicles embedded in the epidermis and
extend to the dermis angle hair growth
(curly or straight).
• Follicle bases are expanded (called bulbs)
reach nerve endings
• Epithelial cells in the bulb divide to create
the hair shaft
• Hair pigment: melanin

– Gives hair its color
– Gray and white hair grow when melanin levels
decrease and air pockets form
•
sebaceous gland- sebum is produced
(cholesterol, fats, and other substances)
– Keeps hair soft, pliable, and waterproof
•
Hair has 3 layers
– Medulla
• Central core
• Cells contain eleidin separated by air spaces
• Fine hair- minimal/ nonexistent
– Cortex
• Major part of hair shaft
– Several layers
– Flattened cells
http://www.inhousedrugstore.com/images/follicle.jpg
• Elongated pigment-bearing cells in dark hair
• Air pockets in white hair
– Cuticle
• Single layer, overlapping cells with free end pointing up
• Strengthens and compacts the inner layers
• Split ends
– Abrasion wears away the end of the shaft, exposes the medulla
and cortex to create the horrid split end
•
2 types of sweat glands
(sudoriferous)
– Coiled tubules in the dermis
– Eccrine glands-all over body
• Watery (99%), salty secretion
known as sweat
• Passes through the epidermis to
skin’s surface and opens to a
sweat pore
• Controlled by the sympathetic
nervous system
– Apocrine sweat glands
• Under the armpits and groin area,
associated with hair follicles
• Same components as eccrine
and is odorless
– Bacteria breaks down apocrine
sweat’s fatty acids and proteins
» Creates the odor accompanying
post exercise
http://www.riversideonline.com/sour
ce/images/image_popup/skin_type.
jpg