 Tissue:
group of similar cells that perform a
common function
 Matrix:
nonliving intercellular material
 Histology:
The study of the structure,
composition and functions of tissues
 Epithelial
 Connective
 Muscle
 Nervous
 Types

Epithelium is divided into two types:


Membranous (covering or lining) epithelium
Glandular epithelium

Locations



Membranous epithelium: covers the body and some of
its parts and lines the serous cavities; blood and
lymphatic vessels; and respiratory, digestive, and
genitourinary tracts
Glandular epithelium: secretory units of endocrine and
exocrine glands
Along with connective are bound together by a
basement membrane.
 Functions
include:
Protection
 Skin
 Excretion and Secretion
 endocrine glands
 Mucous glands
 Kidneys
 Sweat glands
 Diffusion
 Alveolar wall

Cleaning
 Intestinal tract
(Ciliated)
 Absorption
 Intestinal tract
 Kidneys
 Sensation
 Skin
 Tongue

 Generalizations





about epithelial tissue
Limited amount of matrix material
Membranous type attached to a basement
membrane
Avascular
Cells are in closely packed together, with many
desmosomes and tight junctions
Capable of reproduction
 Classification of epithelial tissue
 Membranous (covering or lining) epithelium

Classification based on cell shape
 Squamous
 Cuboidal
 Columnar
 Transitional
 Pseudostratified columnar
 Epithelial
and Connective tissue are bound
together by basement membrane
Classification based on layers of cells:
Simple epithelium


Simple squamous epithelium
 One-cell layer of flat cells
 Permeable to many substances
 Examples: Alveoli of the lungs and lining of blood
vessels
Simple cuboidal epithelium
 One-cell layer of cells that are as tall as they are
wide
 Found in many glands and ducts (secretion &
absorption)
 Found
in the lining of the heart, blood and
lymphatic vessels, body cavities, and alveoli
of the lungs.
•
Classifications based on layers of cells (cont.)
 Simple columnar epithelium
 Single layer of tall, column-shaped cells
 Cells often modified for certain functions such
as goblet cells (secretion), cilia (movement),
microvilli (absorption)
 Often lines hollow visceral structures
 Pseudostratified columnar epithelium
 Columnar cells of differing heights
 All cells rest on basement membrane but may
not reach the free surface above
 Cell nuclei at odd and irregular levels
 Found lining air passages and segments of male
reproductive system
 Motile cilia and mucus are important
modifications
 Hair-like
extensions of cells in the respiratory
tract and female reproductive system.
Classifications based on layers of cells
(cont.)

Stratified epithelium
 Keratinized stratified squamous epithelium




Nonkeratinized stratified squamous
epithelium




Multiple layers of flat, squamous cells
Cells filled with keratin
Covering outer skin on body surface
Lining vagina, mouth, and esophagus
Free surface is moist
Primary function is protection
Stratified cuboidal epithelium



Two or more rows of cells are typical
Basement membrane is indistinct
Located in sweat gland ducts and pharynx
 Found
in covering outer skin on body surface.

Found in lining of vagina, mouth and esophagus.
Classifications based on layers of cells (cont.)
 Stratified columnar epithelium
 Multiple layers of columnar cells
 Only most superficial cells are typical in shape
 Rare
 Located in segments of male urethra and near anus

Transitional epithelium
 Located in lining of hollow viscera subjected to
stress (e.g., urinary bladder)
 Often 10 or more layers thick
 Protects organ walls from tearing
 Has varying shapes and is capable of stretching
(found in urinary bladder)

Glandular epithelium





Glands are usually composed of simple cuboidal cells
Specialized for secretory activity
Exocrine glands: discharge secretions into ducts
 Simple exocrine glands- only has one duct leading to
the surface
 Compound exocrine glands- only has two or more
ducts leading to the surface
Endocrine glands: “ductless” glands; discharge
secretions directly into blood or interstitial fluid
Goblet cells- glandular epithelial cells that secrete
mucous to lubricate the intestinal wall

Structural classification of exocrine glands
 Multicellular exocrine glands are classified
by the shape of their ducts and the
complexity of their duct system
 Shapes include tubular and alveolar
 Simple exocrine glands: only one duct leads
to the surface
 Compound exocrine glands: have two or
more ducts

Functional classification of exocrine glands (Figure 5-12)

Apocrine glands




Holocrine glands



Secretory products collect near apex of cell and are
secreted by pinching off the distended end
Secretion process results in some damage to cell wall
and some loss of cytoplasm
Mammary glands are good examples
Secretion products, when released, cause rupture and
death of the cell
Sebaceous glands are holocrine
Merocrine glands
Secrete directly through cell membrane
 Secretion proceeds with no damage to cell wall and no
loss of cytoplasm
 Most numerous gland type
Mast= cell that produces heparin and histamine

 Has
large amounts of intracellular matrix
 Most varied and abundant tissue in the body
 Functions, characteristics, and types

General function:




Support – holds organ together
Bind together tissues
Mechanical framework (skeleton)
General characteristics


ECM predominates in most connective tissues and
determines its physical characteristics
Consists of fluid, gel, or solid matrix, with or without
extracellular fibers (collagenous, reticular, and elastic)
and proteoglycans or other compounds that thicken
and hold together the tissue

Types

Three subgroups:
 Loose connective Tissue
 Dense Connective Tissue
 Specialized Connective Tissue

Loose Connective Tissue



Areolar
Adipose
Reticular
• Dense Connective Tissue
• Fibrous
• Elastic
• Specialized Connective Tissue
• Bone
Compact bone
 Cancellous bone
• Cartilage
 Hyaline
 Fibrocartilage
 Elastic
• Blood


Areolar connective tissue




One of the most widely distributed of all tissues
Intercellular substance is prominent and consists of
collagenous and elastic fibers loosely interwoven and
embedded in soft viscous ground substance
Several kinds of cells present, notably fibroblasts and
macrophages, also mast cells, plasma cells, fat cells,
and some white blood cells
Function: stretchy, flexible connection


Adipose tissue
 Similar to loose connective tissue but contains mainly
fat cells
 Functions: protection, insulation, support, and food
reserve
Reticular tissue
 Forms framework of spleen, lymph nodes, and bone
marrow
 Consists of network of branching reticular fibers with
reticular cells overlying them
 Functions: defense against microorganisms and other
injurious substances; reticular meshwork filters out
injurious particles and reticular cells phagocytose
them

Dense Connective Tissue
 Matrix consists mainly of densely packed
fibers and relatively few fibroblast cells
 Irregular: fibers intertwine irregularly to
form a thick mat
 Regular: bundles of fibers are arranged in
regular parallel rows
 Fibrous(Collagenous): mostly collagenous
fibers in ECM
 Elastic: mostly elastic fibers in ECM
Locations: structures that need great tensile
strength, such as tendons and ligaments; also
dermis and the outer capsule of the kidney
and spleen
 Function: furnishes flexible connections that
are strong or stretchy

Membranes and Wound Healing
 Bone

Uniquely hard and strong connective tissue type



tissue
Cells (osteocytes) embedded in a calcified matrix
Inorganic component of matrix accounts for 65% of total
bone tissue
Functions






Support
Protection
Point of attachment for muscles
Reservoir for minerals
Supports blood-forming tissue
Provide movement

Compact bone


Osteon (Haversian system)
 Structural unity of bone
 Spaces for osteocytes called lacunae
 Matrix present in concentric rings called lamellae
 Canaliculi are canals that join lacunae with the
central Haversian canal (communication
passageway)
Cell types
 Osteocyte: mature, inactive bone cell
 Osteoblast: active bone-forming cell
 Osteoclast: bone-destroying cell

Cancellous bone made up of trabeculae


Trabeculae: thin beams of bone
Supports red bone marrow





Myeloid tissue: a type of reticular tissue
Produces blood cells
Called spongy bone because of its spongelike appearance
Endochondrial ossification- the conversion of cartilage to
bone
Periosteum- membrane that surrounds bone
 Cartilage
 Chondrocyte is the only cell type present
 Lacunae house cells as in bone
 Avascular: nutrition of cells depends on diffusion



of nutrients through matrix
Heals slowly after injury because of slow nutrient
transfer to cells
Perichondrium is membrane that surrounds
cartilage
Endochondrial ossification- the conversion of
cartilage to bone

Types

Hyaline




Fibrocartilage





Appearance is shiny and translucent
Most prevalent type of cartilage
Located on ends of articulating bones
Strongest and most durable type of cartilage
Matrix is semirigid and filled with strong white fibers
Found in intervertebral disks and pubic symphysis
Serves as shock-absorbing material between bones
at the knee (menisci)
Elastic



Contains many fine elastic fibers
Provides strength and flexibility
Located in external ear and larynx
 Blood
 A liquid tissue
 Contains neither ground substance
 Composition of whole blood


nor fibers
Liquid fraction (plasma) is the matrix; 55% of total
blood volume
Formed elements contribute 45% of total blood volume
 Red blood cells (erythrocytes)
 White blood cells (leukocytes)
 Platelets (thrombocytes)
 Functions
Transportation
 Regulation of body temperature
 Regulation of body pH
 White blood cells destroy bacteria

 Circulating
blood tissue is formed in the
red bone marrow by a process called
hematopoiesis; the blood-forming tissue
is sometimes called hematopoietic
tissue
 Tissues

Lymphoid organs


that form RBC’s or WBC’s
WBC’s
Red bone Marrow

RBC’s
 Types



Skeletal, or striated voluntary
Smooth, also known as nonstriated involuntary or
visceral
Cardiac, or striated involuntary
 Microscopic




characteristics
Skeletal muscle: threadlike cells with many crossstriations and many nuclei per cell
Smooth muscle: elongated narrow cells, no crossstriations, one nucleus per cell
Cardiac muscle: branching cells with intercalated disks
(formed by abutment of plasma membranes of two cells)
Works with connective tissue to provide movement
 Located
in walls of hollow organs, bladder,
and uterus
 Functions:
rapid regulation and integration of
body activities
 Special characteristics


Excitability
Conductivity
 Organs
 Brain
 Spinal cord
 Nerves
 Cell types
 Neuron: conducting
unit of system. Composed of
axon, dendrites, myelin sheath, and cell body
(soma)




Cell body, or soma
Processes
 Axon (single process): transmits nerve impulse away
from the cell body
 Dendrite (one or more): transmits nerve impulse
toward the cell body and axon
Neuroglia: special connecting, supporting,
coordinating cells that surround neurons
Epineurium- the connective membrane that
surrounds entire nerve
 Thin,
“sheet like” tissue layers that cover
surfaces, line cavities, and divide spaces or
organs
 Four




major types:
Cutaneous
Serous
Mucous
Synovial (connective tissue)




Line body cavities that are not open to the outside of the
body
Secrete a thin watery fluid called Serous Fluid
 Lubricates the surface of the membrane and reduces
friction between structures
Visceral layer: covers the organs within the cavity
Parietal layer: the inner linings of those cavities


Visceral peritenium- covers the organs within the abdominal cavity
Parietal peritoneum- inner lining of the abdominal cavity
 Pleura:
serous membranes in the thoracic
cavity
 Peritoneum:
serous membranes in the
abdominal cavity
 Epithelial

membranes are most common type
Cutaneous membrane (skin)



Primary organ of integumentary system
One of the most important organs
Approximately 16% of body weight
Epithelial Tissue Membranes Cont.

Mucous membrane (mucosa)




Lines and protects organs that open outside the body
Found lining ducts and passageways of the respiratory,
digestive, and other tracts
Lamina propria: fibrous connective tissue underlying
mucous epithelium
Mucus is made of mostly of water and mucins—
proteoglycans that form a double-layer protection
against environmental microbes
 Connective

tissue membrane:
Synovial membranes line the spaces between
bone in joints (classified as connective tissue
membrane)




Do not contain epithelial components
Have smooth and slick membranes that secrete
synovial fluid
Help reduce friction between opposing surfaces in a
movable joint
Synovial membranes also line bursae
 Tissues

Epithelial tissues




and membranes maintain homeostasis
Form membranes that contain and protect the internal fluid
environment
Absorb nutrients
Secrete products that regulate functions involved in
homeostasis
Connective tissues


Hold organs and systems together
Form structures that support the body and permit movement

Muscle tissues


Work with connective tissues to permit movement
Nervous tissues

Work with glandular epithelial tissue to regulate body
function
 Tissues
have a varying capacity to repair
themselves; damaged tissue regenerates or is
replaced by scar tissue
 Regeneration: growth of new tissue
 Scar: dense, fibrous mass; unusually thick
scar is a keloid
 Epithelial and connective tissues have the
greatest ability to regenerate
 Muscle and nervous tissues have limited
capacity to regenerate
 Two


types of surgical wounds:
Incisional : intentional cut through intact tissue
for the purpose of exposing underlying structures
Excisional : Removal of tissue
 Four
Classes of surgical wounds:
Classified by degree of microbial intrusion
 Class I (clean)
 Class II (Clean-contaminated)
 Class III (Contaminated)
 Class IV (dirty-infected)

Wound classes




Class I- Clean occurs when an incision is made
Class II- Clean-Contaminated occurs after a
primary closure- drain placed minor break in
aseptic technique
Class III- Contaminated occurs when an open
traumatic wound is encountered, aerodigestive
tract, biliary, or genitourinary tract was
entered with spillage, or major break in aseptic
technique.
Class IV- Dirty-Infected occurs in open
traumatic wounds in which microbial
contamination had previously occured
 Infection




rate
Class I – 1%-5%
Class II - 8%- 11%
Class III - 15%- 20%
Class IV - 27%- 40%
 First
Intention– Primary Union
 Second Intention-- Granulation
 Third Intention– Delayed primary Closure
 Primary
union
 Ideal
 Wound
heals side to side w/o infection
 Inflammatory Response aka Lag Phase:
3-5 days






Inflammation
Swelling
Heat
Redness
Loss of function
Scab forms
 Proliferation
Phase: begins around the 3rd or
4th day and lasts for 20 days


Collagen fibers provide some tensile strength
New capillary network is established
(day 5-6)
 Maturation
aka Differentiation Phase: Day
14 – healed



Tensile strength increases
Wound contraction complete (day 21)
Mature scar formed *Cicatrix
 Granulation
 Occurs
when a wound fails to heal by 1st
intention
 Wound left open to heal from the bottom up
 Wound closure occurs by contraction
 Weak (herniation common) and forms a large
scar
 Examples:


When wound can not be reapproximated
Infected wounds
 Delayed
primary closure
 Used for dirty wounds
 Wound is treated by debridment of dead
tissue………then left open to heal by second
intention (4-6 days)
 once the wound is infection free, it is closed
with suture or staples to finish healing by
first intention
 Dehiscence:
partial or total separation of a
layer (or layers) of tissue after closure


Most frequently between the 5th and 10th Postop
day
Causes:




Abdominal distention
Coughing or Vomiting
Improper suture
Improper suturing technique
 Dead
Space (pg. 55): can occur when
subcutaneous tissues are not approximated
with suture
 Evisceration
 Hemorrhage
 Adhesions
 Herniation
 Fistula
 Keloid
Scaring
 Sinus Tract
 We
have genetic markers on the surface of
our WBC’s

Ex. HLA: Human leukocyte antigen

An antigen is something that when introduced into the
body triggers an immune response.
 Donor

If an immune response occurs (ex. Proliferation of
WBC’s) the tissue will likely be rejected
 DNA

WBC’s and Recipient WBC’s are mixed
Tissue Typing
MHC: major histocompatibility complex

Particular genes unique to each individual

Permanent section:
10% formalin
 May remain on sterile field until the end of case


Fresh or Frozen section:
Sent immediately after removal
 Pathologist will phone OR with results


Surgical Techs Responsibilities





Must be able to Identity the specimen
Identify the origin
Must properly communicate information to circulator
Properly identify and explain markers (suture)
Specimens should be placed in/on:





Sterile specimen cup
Sterile Telfa pad
Sterile towel
Sterile basin
*a counted sterile sponge should never be used