Tissues Chapter 4

2 or more cell layers

basal lamina and reticular lamina

deep to the basal lamina, part of the connective tissue

• 1. polarity
• 2. specialized contacts
• 3. supported by connective tissues
• 4. avascular but innervated
• 5. ability to regenerate

• 1. covers body surfaces
• 2. lines cavities
• 3. forms glands

Cancerous cells do not respect the boundary of basement membrane so they penetrate the tissues beneath it

• apical
• basal

tiny hair-like projections that move and propel substances along their surface

line the trachea

• 1. protection
• 2. absorption
• 3. filtration
• 4. excretion
• 5. secretion
• 6. sensory reception

simple and stratified

Apical-basal polarity:  apical and basal surfaces differ in structure and function

each epithelium has 2 names:  first indicates number of cell layers and second describes shape of its cells

sheet of cells that covers the body or lines body cavities

groups of cells similar in structure and function

• 1. epithelial tissue
• 2. muscular
• 3. connective
• 4. nervous tissue

epithelium forms boundaries between environments

Example:  boundary between bladder and urine in the bladder

histology

single layer of cells

blood vessels in underlying connective tissues

where absorption, secretion, and filtration occur

finger-like extensions of apical surface that increase surface area for absorption and secretion

high-abrasion areas where protection is important:  skin, lining of the mouth

adhesive sheet that filters what diffuses from underlying connective tissue into epithelium and acts as a scaffolding where epithelial cells can migrate to repair a wound

• flattened and scale-like

boxlike, approximately as tall as they are wide

• tall and column shaped

• Nucleus takes shape of cell:
• squamous is disc shaped
• cuboidal is spherical
• columnar is oval shaped and usually close to bottom of the cell

based on apical layer cell shape

flattened and scale-like

found where filtration or the exchange of substances by rapid diffusion is a priority because they are thin and often permeable

allows materials to pass by diffusion and filtration in sites where protection is not important

secretes lubricating substances in serosae

• 1. kidney glomeruli
• 2. air sacs of lungs
• 3. lining of heart, blood vessels, and lymphatic system
• 4. lining ov ventral body cavity (serosae)

• 1. endothelium
• 2. mesothelium

• 1. lining of lymphatic vessels
• 2. in all hollow organs of the cardiovascular system:  BV's and the heart
• 3. capillaries (exclusively made of endothelium)

its thinness encourages the efficient exchange of nutrients and wastes between the bloodstream and surrounding tissues

• 1. serous membranes
• 2. membranes lining the ventral body cavity
• 3. covering organs of the ventral body cavity

secretion and absorption

kidney tubules, ducts and secretory portions of small glands, and ovary surface

propel mucus or reproductive cells

non-ciliated:  lines most of digestive tract, gallbladder, and excretory ucts of some glands

ciliated:  lines small bronchi, uterine tubes, and some regions of the uterus

absorption and secretion:

secretion of mucus, enzymes, and others

• 1. dense microvilli on apical surface
• 2. tubular glands made primarily of cells that secrete mucus-containing intestinal juice

simple columnar

Columnar epithelium where all cells touch basement membrane but are of varying heights

nonciliated type in sperm-carrying ducts and ducts of large glands

ciliated type lines the trachea and most of the upper respiratory tract

same as columnar epithelium:  secretion and absorption

mainly secrete mucus and propel it with cilia

pseudostratified columnar epithelium with cilia  and mucus-secreting goblet cells

goblet cells make mucus that traps particles and dust and cilia sweeps it away from the lungs

contains 2 or more cell layers

protection

regenerates from below:  basal cells divide and push apically to replace the older surface cells

free surface cells are squamous and cells of deeper layers are cuboidal or columnar -

forms the external part of the skin and extends a short distance into every body opening directly continuous with the skin

because epithelium depends on nutrients from the deeper connective tissue

forms the moist linings of the esophagus, mouth, and vagina

it is keratinized - contains the protein keratin that makes it tougher

• rare- found in larger glands:  sweat glands, mammary glands

rare:  small amnts in pharynx, male urethra, lining some glandular ducts, and at transition areas or junctions between 2 other types of epithelia

only apical layer is columnar

lining of hollow urinary organs which stratch as they fill with urine

• cells of basal layer are cuboidal or columnar
• '
• apical cells vary in appearance depending on the degree they are stretched

one or more cells that make and secrete a particular product

product secreted by a gland:  usually a water-based fluid containing protein

• 1. where they release their product
• 2. number of cells:  unicellular, multicellular

produce hormones that are secreted by exocytosis directly into the extracellular space where they enter blood or lymph

secrete their products onto body surfaces or into body cavities

exocytosis

duct

mucous, sweat, oil, saliva, bile in the liver, pancreatic enzymes, and many others

mucous cells and goblet cells

glycoprotein produced by unicellular exocrine glands that dissolves in water when secreted and forms mucus

unicellular exocrine glands that produce mucus and are shaped like a wine glass

2 basic parts:  a duct and a secretory unit (acinus) with supportive connective tissue that surrounds the secretory unit and divides into lobes usually

structure and type of secretion

• simple - unbranched duct
• compound - branched duct

• 1. tubular - secretory cells form tubes
• 2. alveolar - form sacs
• 3. tubuloalveolar - have tubes and sacs

merocrine glands, holocrine glands, and apocrine glands

secrete by exocytosis without altering the cell

think "merely secrete"

pancreas, most sweat glands, and salivary glands

accumulate their products within them until the rupture then are replaced by division of underlying cells

sebaceous (oil) glands of the skin

connective

• 1. connective tissue proper
• 2. cartilage
• 3. bone
• 4. blood

• 1. binding and supporting
• 2. protecting
• 3. insulating
• 4. storing reserve fuel
• 5. transporting substances within the body

• 1. common origin:  all arise from the mesenchyme (an embryonic tissue)
• 2. degrees of vascularity:  some are avascular & some are very vascular
• 3. extracellular matrix:  connective tissues are largely nonliving extracellular matrix

they are mostly composed of extracellular matrix

• 1. ground substance
• 2. fibers
• 3. cells

ground substance and fibers make up the extracellular matrix

unstructured material that fills the space between cells and contains the fibers

• 1. interstitial fluid
• 2. cell adhesion proteins
• 3. proteoglycans

glue that allows connective tissue cells to attach to matrix elements

functions as a medium through which nutrients and other dissolved substances can diffuse between blood capillaries and the cells

collagen, elastic, and reticular fibers

protein

made of collagen - provided high tensile strength (ability to resist being pulled apart) to the matrix

their fibrils are cross-linked so they hold together

elastin

allows them to stretch and recoil like a rubber band

can stretch until collagen fibers become taut then elastic fibers snap them back to normal length and shape

found where greater elasticity is needed:  skin, lungs, and blood vessel walls

collagenous fibers that are continuous with collagen fibers  but are smaller - branch out and form webs with more give than collagen fibers

surround small blood vessels, support soft tissue of organs

particularly found where connective tissue meets other tissue

each major class of connective tissue has a resident cell type

-blasts

-cytes

actively mitotic cells that secrete the ground substance and the fibers characteristic of their particular matrix

• 1. connective tissue proper:  fibroblast
• 2. cartilage:  chondroblast
• 3. bone:  osteoblast
• 4. blood:  hematopoietic stem cell is the blast cell that produces blood cells but it is not located in blood and does not produce the fluid matrix of blood

mature and less active (get old and sit around) and have the suffix (-cyte)

mature cells maintain health of the matrix

they can revert to their blast state to repair and regenerate the matrix

• 1. fat cells
• 2. white blood cells
• 3. mast cells
• 4. macrophages

store nutrients

typically cluster along blood vessels

detect foreign microorganisms and initiate local inflammatory responses against them

secretory granules with chemicals that mediate inflammation especially in severe allergies:  heparin, histamine, proteases, and other enzymes

protein-degrading enzymes

substance that makes capillaries leaky

large, irregularly shaped cells that devour a broad variety of foreign materials:  bacteria, dust, dead tissue cells

important to immune system

all connective tissues except cartilage, bone, and blood

• 1. loose connective tissue
• 2. dense connective tissue

• 1. areolar
• 2. adipose
• 3. reticular

• 1. dense regular
• 2. dense irregular
• 3. elastic

       gel-like matrix with all 3 fiber types that are loosely arranged

fibroblasts, macrophages, mast cells, fat cells, and some WBC's

fibroblasts

allows for reservoir of water and salts for surrounding body tissues, always holds approx. as much fluid as there is in the entire bloodstream

areolar

• 1. wraps and cushions organs
• 2. macrophages phagocytize bacteria
• 3. important role in inflammation
• 4. holds and conveys tissue fluid

high content of hyaluronic acid makes ground substance viscous like molasses

WBC's secrete hyaluronidase, an enzyme that liquefies ground substance - some harmful bacteria can also do this

areolar

lamina proper

• similar to areolar tissue in structure and function but has higher nutrient-storing ability and is 90% adipose cells- looks like chicken wire

it has high amount of metabolic activity

mostly found in subcutaneous tissue

also found around the kidneys behind eyeballs, genetically determined fat deposits, around high energy organs like heart and lymph nodes

• 1. shock absorption
• 2. insulation
• 3. energy storage

provide nutrient needs to active organs

does not do other functions of adipose tissue - uses stored energy to create heat in the bloodstream - mostly found in babies because they lack ability to produce body heat by shivering

resemble areolar connective tissue but only has reticular fibers in matrix with reticular cells

fibers form a soft internal skeleton (stroma) that supports other cell types:  WBC's, mast cells, and macrophages

lymphoid organs:  lymph nodes, bone marrow, and spleen

fibers are their prominent element

• closely packed bundles of collagen fibers running in same direction parallel to the direction of pull:  flexible with great resistance to tension

very few cells other than fibroblasts that continuously make collagen fibers

poor vascularized

• 1. tendons:  attach muscle to bone
• 2. aponeuroses: flat sheet-like tendons that attach muscles to other muscles or to bones
• 3. ligaments:  bind bones to joints
• 4. fascia:  wraps around muscles, blood vessels, and nerves

• similar to dense regular but collagen fibers are arranged irregularly

withstands tension exerted in many directions and provides structural strength

• 1. fibrous capsules of organs and joints:  kidneys, bones, cartilages, muscles, and nerves)
• 2. dermis of the skin
• 3. submucosa of the digestive tract

• dense regular connective tissue containing a high proportion of elastic fibers

• 1. allows tissue to recoil after stretching
• 2. maintains pulsatile flow of blood through arteries
• 3. aids passive recoil of lungs following inspiration

walls of large arteries, within certain ligaments associated with the vertebral column, within the walls of the bronchial tubes

has qualities between those of dense connective tissue and bone:  stands up to tension and compression

lacks nerve fibers and blood vessels

receives nutrients by diffusion from blood vessels located in connective tissue layer surrounding it

ground substance contains large amounts of chondroitin sulfate and hyaluronic acid,  collagen fibers, and are 80% water

high content of water in ground substance of cartilage

chondroblasts - produce new matrix until the skeleton stops growing at the end of adolescence

cavities in the cartilage that contain small groups of chondrocytes

cartilage is avascular and aging cartilage cells lose their ability to divide

• 1. hyaline cartilage
• 2. elastic cartilage
• 3. fibrocartilage

HYALINE CARTILAGE

contains large number of collagen fibers but appears glassy

forms most of the embryonic skeleton; covers the ends of long bones in joint cavities; forms costal cartilages of the ribs; cartilages of the nose, trachea, and larynx

• 1. supports and reinforces
• 2. serves as resilient cushion
• 3. resists compressive stress

hyaline cartilage the covers the ends of long bones and provides a pad to absorb compression at joints

similar to hyaline cartilage but more elastic fibers in matrix

maintains shape while allowing great flexibility

external ear (pinna), epiglottis

• intermediate between hyaline cartilage (rows of chondrocytes) and dense regular connective tissues (rows of collagen fibers)

tensile strength allow it to absorb compressive shock

intervertebral discs, pubic symphysis, discs of the knee joint

• similar to cartilage but has more collagen fibers and added matrix element:  calcium salts...has structural units called osteons formed of rings of bony matrix (lamellae) surrounding central canals that contain blood vessels and nerves serving the bone

produce the organic portion of the matrix

in lacunae within the matrix produced by osteoblasts

• 1. supports and protects (by enclosing)
• 2. provides levers for the muscles to act on
• 3. stores calcium and other minerals and fat
• 4. marrow inside bones is site for blood cell formation (hematopoiesis)

consists of blood cells surrounded by a nonliving fluid matrix called blood plasma

RBC's are most abundant, WBC's, and platelets

protein molecules that form visible fiberlike structures during blood clotting

transport respiratory gases, nutrients, wastes, and other substances

muscle

elaborate networks of actin and myosin filaments that bring about movement of contraction in all cell types

• 1. skeletal
• 2. cardiac
• 3. smooth

skeletal muscle -within voluntary control

cardiac and smooth

composed of long, cylindrical, multinucleate cells with obvious striations

voluntary movement, locomotion, manipulation of the environment, facial expression, voluntary control

attached to bones or occasionally to skin

• cells are striated like skeletal muscle, cells have only one nucleus, contain intercalated discs:  unique junctions where branching cells fit together tightly

spindle-shaped (elongated) cells with one nucleus; no striations, cells arranged closely to form sheets

brain, spinal cord, and nerves

regulates and controls body functions

neurons and supporting cells

highly specialized nerve cells that generate and conduct nerve impulses

branching cells with cell process that may be long and extend from the nucleus-containing cell body (called axon)

support and protect neurons

glial cells or neuroglia

cutaneous, mucous, or serous

all are continuous multicellular sheets composed of at least 2 primary tissue types:  an epithelium bound to an underlying layer of connective tissue proper

skin - keratinized stratified squamous epithelium (epidermis) firmly attached to a thick layer of connective tissue (dermis)

exposed to the outside and is dry

line all body cavities that open to the outside of the body; wet/moist with secretions/urine in urinary system

most are stratified squamous or simple columnar epithelia directly over a layer of loos e connective tissue called the lamina propria

loose connective tissue that is connected to mucous membranes

hollow organs of the digestive tract, respiratory tract, and urogenital tract

absorption and secretion:  secrete mucus in digestive and respiratory tracts

moist membranes found in closed ventral body cavities

simple squamous epithelium (a mesothelium)  resting on a thin layer of loose connective (areolar) tissue

mesothelial cells add hyaluronic acid to the fluid that filters from the capillaries in the associated connective tissue:  results in serous fluid that lubricates surfaces of parietal and visceral layers

line the thoracic wall and cover the lungs

encloses the heart

encloses the abdominopelvic viscera

relatively nonspecific reaction that develops quickly wherever tissue damage occurs

extremely specific response that takes longer than inflammatory response

divide and migrate

growth factors

• 1. regeneration
• 2. fibrosis

replaces destroyed tissue with the same kind of tissue

dense connective tissue proliferates to form scar tissue

depends on the type of tissue damaged and the severity of the damage

• 1. Injured tissue cells release inflammatory
•     chemicals --> cause capillaries to dilate -->
•     capillaries are more permeable
• 2. WBC's & plasma (clotting factors,
•     antibodies, etc) seep into area
• 3. Clotting factors construct a clot:  stops
•     bleeding and walls in injured area
• 4. Blood clot is replaced by granulation
•     tissue
• 5. Surface epithelium regenerates under the
•    scab and the scab detaches
• 6. end result is fully regenerated epithelium 
•     with underlying scar tissue that may be
•     visible or invisible

removed via lymphatic vessels or by macrophages

first phase of tissue repair where clot is replaced by granulation tissue

delicate pink tissue that contains capillaries that grow in from nearby areas and lay down new capillary bed

fibroblasts:  produce growth factors and new collagen fibers

some have contractile properties that allow them to pull the margins of the ound together or pull existing blood vessels into the healing wound

macrophages digest it and collagen fiber deposits replace it

scar tissue

produces bacteria-inhibiting substances

revert to resting state or undergo apoptosis (cellular suicide)

regeneration only

epithelial tissue, bone, areolar connective tissue, dense irregular connective tissue, and blood-forming tissue

smooth muscle and dense regular connective tissue

skeletal muscle and cartilage

cardiac muscle and nervous issue in the brain and spinal cord

pale, often shiny area composed mostly of collagen fibers:  strong but less flexible than most normal tissues and cannot perform functions of tissue it replaced

Scar tissue shortens area and can cause hollow organs to become smaller on the inside, can also cause adhesions that bind 2 organs together that can prevent intestines from moving freely and obstruct flow of food

ectoderm, mesoderm, and endoderm

specialize to become the 4 primary tissue types

2nd month

most cells remain mitotic and produce rapid growth; division of nerve cells stops or nearly stops during the fetal period; all other cells continue to grow until adulthood

epithelia and blood

Epithelia thin and are easily penetrated; tissue repair is less efficient; bone, muscle, and nervous tissues atrophy (especially if not physically active)

decreased circulation is a factor in some of these changes