TISSUE AND MEMBRANES

ST110CONCORDE CAREER COLLEGE

INTRODUCTION 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

FOUR MAJOR TYPES OF HUMAN TISSUE

Epithelial

Connective

Muscle Nervous

EPITHELIAL TISSUE Types

Epithelium is divided into two types: Membranous (covering or lining) epithelium Glandular epithelium

EPITHELIAL TISSUELocations

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.

EPITHELIAL TISSUES 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

EPITHELIAL TISSUE (CONT.) Generalizations about epithelial tissue

Limited amount of matrix materialMembranous type attached to a basement

membraneAvascularCells are in closely packed together, with

many desmosomes and tight junctionsCapable of reproduction

EPITHELIAL TISSUE: MEMBRANOUS Classification of epithelial tissue

Membranous (covering or lining) epithelium Classification based on cell shape

SquamousCuboidalColumnarTransitional Pseudostratified columnar

EPITHELIAL TISSUE: MEMBRANOUS Epithelial and Connective tissue are

bound together by basement membrane

EPITHELIAL TISSUE Classification based on layers of cells: Simple epithelium

Simple squamous epithelium One-cell layer of flat cellsPermeable to many substancesExamples: 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)

SIMPLE SQUAMOUS Found in the lining of the heart, blood

and lymphatic vessels, body cavities, and alveoli of the lungs.

SIMPLE CUBOIDAL

EPITHELIAL TISSUE (CONT.)

• Classifications based on layers of cells (cont.) Simple columnar epithelium

Single layer of tall, column-shaped cellsCells 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 heightsAll cells rest on basement membrane but

may not reach the free surface aboveCell nuclei at odd and irregular levelsFound lining air passages and segments of

male reproductive systemMotile cilia and mucus are important

modifications

SIMPLE COLUMNAR

PSEUDOSTRATIFIED COLUMNAR

CILIA Hair-like extensions of cells in the

respiratory tract and female reproductive system.

EPITHELIAL TISSUE (CONT.)Classifications based on layers of cells

(cont.) Stratified epithelium

Keratinized stratified squamous epithelium Multiple layers of flat, squamous cells Cells filled with keratin Covering outer skin on body surface

Nonkeratinized stratified squamous epithelium 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

KERATINIZED STRATIFIED SQUAMOUS Found in covering outer skin on body

surface.

NONKERATINIZED STRATIFIED SQUAMOUS Found in lining of vagina, mouth and esophagus.

STRATIFIED CUBOIDAL

EPITHELIAL TISSUE (CONT.)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)

EPITHELIAL TISSUE: GLANDULAR EPITHELIUM

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

EPITHELIAL TISSUE: GLANDULAR EPITHELIUM (CONT.)

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 alveolarSimple exocrine glands: only one duct

leads to the surfaceCompound exocrine glands: have two

or more ducts

EPITHELIAL TISSUE: GLANDULAR EPITHELIUM (CONT.)

Functional classification of exocrine glands (Figure 5-12)Apocrine 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 examplesHolocrine glands

Secretion products, when released, cause rupture and death of the cell

Sebaceous glands are holocrineMerocrine glands

Secrete directly through cell membrane Secretion proceeds with no damage to cell wall and

no loss of cytoplasm Most numerous gland typeMast= cell that produces heparin and histamine

CONNECTIVE TISSUE 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

CONNECTIVE TISSUE Types

Three subgroups: Loose connective Tissue Dense Connective Tissue Specialized Connective Tissue

CONNECTIVE TISSUE (CONT.)

Loose Connective Tissue Areolar Adipose Reticular

• Dense Connective Tissue • Fibrous • Elastic

• Specialized Connective Tissue • Bone

Compact bone Cancellous bone

• Cartilage Hyaline Fibrocartilage Elastic

• Blood

LOOSE AREOLAR CONNECTIVE TISSUE

CONNECTION TISSUE CONT.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

AREOLAR CONNECTIVE TISSUE

CONNECTION TISSUE (CONT.)

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

ADIPOSE TISSUE

RETICULAR TISSUE

DENSE CONNECTIVE TISSUE

Dense Connective Tissue Matrix consists mainly of densely packed

fibers and relatively few fibroblast cellsIrregular: 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

DENSE CONNECTIVE TISSUE

DENSE FIBROUS CONNECTIVE TISSUE

FIBROUS ELASTIC DENSE CONNECTIVE TISSUE

DENSE CONNECTIVE TISSUE (CONT.)

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

DAY 2 Membranes and Wound Healing

SPECIALIZED CONNECTIVE TISSUE: BONE TISSUE Bone tissue

Uniquely hard and strong connective tissue type 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

SPECIALIZED CONNECTIVE TISSUE:BONE TISSUE (CONT.)

Compact bone Osteon (Haversian system)

Structural unity of boneSpaces for osteocytes called lacunaeMatrix present in concentric rings called

lamellaeCanaliculi are canals that join lacunae with the

central Haversian canal (communication passageway)

Cell typesOsteocyte: mature, inactive bone cellOsteoblast: active bone-forming cellOsteoclast: bone-destroying cell

COMPACT BONE TISSUE

SPECIALIZED CONNECTIVE TISSUE: BONE TISSUE (CONT.)

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

SPECIALIZED CONNECTIVE TISSUE: CARTILAGE Cartilage

Chondrocyte is the only cell type presentLacunae house cells as in boneAvascular: nutrition of cells depends on

diffusion of nutrients through matrixHeals slowly after injury because of slow

nutrient transfer to cellsPerichondrium is membrane that surrounds

cartilageEndochondrial ossification- the conversion

of cartilage to bone

SPECIALIZED CONNECTIVE TISSUE: CARTILAGE (CONT.)

Types Hyaline

Appearance is shiny and translucentMost prevalent type of cartilageLocated on ends of articulating bones

Fibrocartilage Strongest and most durable type of cartilageMatrix is semirigid and filled with strong white

fibersFound in intervertebral disks and pubic symphysisServes as shock-absorbing material between

bones at the knee (menisci) Elastic

Contains many fine elastic fibersProvides strength and flexibilityLocated in external ear and larynx

FIBROCARTILAGE

ELASTIC CARTILAGE

SPECIALIZED CONNECTIVE TISSUE: BLOOD Blood

A liquid tissue Contains neither ground substance nor

fibersComposition of whole blood

Liquid fraction (plasma) is the matrix; 55% of total blood volume

Formed elements contribute 45% of total blood volumeRed blood cells (erythrocytes)White blood cells (leukocytes)Platelets (thrombocytes)

BLOOD

SPECIALIZED CONNECTIVE TISSUE: BLOOD (CONT.)

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

HEMATOPOIETIC TISSUES Tissues that form RBC’s or WBC’s

Lymphoid organs WBC’s

Red bone Marrow RBC’s

MUSCLE TISSUE 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 cross-

striations and many nuclei per cell Smooth muscle: elongated narrow cells, no cross-

striations, 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

SKELETAL MUSCLE

SMOOTH MUSCLE Located in walls of hollow organs,

bladder, and uterus

LOCATION OF SMOOTH MUSCLE

CARDIAC MUSCLE

NERVOUS TISSUE Functions: rapid regulation and

integration of body activities Special characteristics

ExcitabilityConductivity

OrgansBrainSpinal cordNerves

NERVOUS TISSUE (CONT.) 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

NERVOUS TISSUE

BODY MEMBRANES Thin, “sheet like” tissue layers that

cover surfaces, line cavities, and divide spaces or organs

Four major types:Cutaneous SerousMucousSynovial (connective tissue)

SEROUS MEMBRANES 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

SEROUS MEMBRANES Pleura: serous membranes in the

thoracic cavity

Peritoneum: serous membranes in the abdominal cavity

CUTANEOUS MEMBRANES 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

MUCOUS MEMBRANES 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

BODY MEMBRANES (CONT.) 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

THE BIG PICTURE: TISSUES, MEMBRANES, AND THE WHOLE BODY Tissues and membranes maintain

homeostasis Epithelial tissues

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

THE BIG PICTURE: TISSUES, MEMBRANES, AND THE WHOLE BODY (CONT.)

Muscle tissues Work with connective tissues to permit

movementNervous tissues

Work with glandular epithelial tissue to regulate body function

TISSUE REPAIR 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

CLASSIFICATION OF SURGICAL WOUNDS 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)

CLASSIFICATION OF SURGICAL WOUND(CONT.)

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

CLASSIFICATION OF SURGICAL WOUND(CONT.) Infection rate

Class I – 1%-5%Class II - 8%- 11% Class III - 15%- 20%Class IV - 27%- 40%

WOUND HEALING

First Intention– Primary Union Second Intention-- Granulation

Third Intention– Delayed primary Closure

FIRST INTENTION HEALING Primary union Ideal Wound heals side to side w/o infection Inflammatory Response aka Lag Phase: 3-5 days

InflammationSwelling Heat Redness Loss of functionScab forms

FIRST INTENTION CONTINUED Proliferation Phase: begins around

the 3rd or 4th day and lasts for 20 days Collagen fibers provide some tensile

strengthNew 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

SECOND INTENTION HEALING 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

THIRD INTENTION HEALING 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

THIRD INTENTION HEALING

COMPLICATIONS OF WOUND HEALING 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

DEHISCENCE

COMPLICATIONS OF WOUND HEALING CONT. Evisceration Hemorrhage Adhesions Herniation Fistula Keloid Scaring Sinus Tract

EVISCERATION

ADHESIONS

HERNIATION

KELOID SCARING

TISSUE TYPING 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 WBC’s and Recipient WBC’s are mixed If an immune response occurs (ex. Proliferation of

WBC’s) the tissue will likely be rejected

DNA Tissue TypingMHC: major histocompatibility complex

Particular genes unique to each individual

SURGICAL SPECIMENS 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