Histology Tissues A&P chapter.5

Tissue

a group of similar cells & cell products working
together to perform a specific role in an organ

Epithlial tissue defenition

tissues composed of closely spaced cells that cover organ surfaces, form glands, and serve for protection, secretion, and absorption

Connective tissue defenition

tissue with usually more matrix than cell volume, often specializes to support, bind , and protect organs

Nervous tissue defenition

tissue containing EXCIT cells specalized for rapid transmission of coded information to other cells

COMMUNICATION

Muscular tissue

tissue composed of elongated EXCITABEL muscle cells specialized for contraction

helps remain body temperature, help generate force

high degree of cellularity: cells are packed closely together

Locations of Epithelial tissue

Epidermis

inner lining of digestive tract

liver and other organs

Location of connective tissues

tendons

ligaments

cartalige and bones

blood

location of nervous tissue

brain

spinal cord

nerves

location of muscular tissue

skeletal muscles

heart cardiac muscles

walls of viscera

Resting membrane potential

RMPC usually -70m

more potassium inside the cell while more sodium outside of cell

neuroglia

housekeepers of nervous system

protect and assist neurons

amitotic

Does not undergo cellular division

Cardiac muscle

limited to the heart

No striated and involuntary- not under consious control

cells are shorter and widerd and more branched then skeletal cells

skeletal muscle

Cells are very long and thin, cilinder

Made of muscle fibers

cells contain multiple nuclei next to plasma membrane

Voluntary and *striation* - under consious control

multi nucleus

smooth muscle

involuntary actions/movements- don’t control it

no striations

uni nucliet

Vascularized (muscle tissue)

Direct blood supply by blood vessels

Innervated (muscle tissue)

Direct nerve supply

Limited regenerative capability (muscle tissue)

Some ability to divide but does not divide often

Striations (skeletal muscle)

Alternating dark and light bands

Myocytes (cardiac muscle)

shorter , wider, and branch

only one nucleolus

Intercalated discs

join cardiocytes end to end

provide electrical and mechanical connection

spindle-shaped (smooth muscle)

Nucelous + cytoplasm in middle.

Epithelia tissue function

• excretes waste (sweat)

• protect deeper tissues from injury

• Absorbs chemicals including nutrients

• sense stimuli

• Selectively filter substances

• produce and release chemical secretions

• mitosis

Apical surface (epithelia tissue)

Facing an external enviorment or upper surface

know as the FREE SURFACE

Basal surface (epithelia tissue)

surface of epithelium next to basement membrane

Basement membrane

anchoring layer between an epithelium and underlying connective tissue

lumen (epithelia tissue)

, hollow space of blood vessel, digestive organs, respiratory passages

High degree of

cells pack closely together without a lot of stuff in-between them

Avascular (epithelia tissue)

no blood vessels, usually nourished by underlying connective tissue

Squamous cell

fried egg looking

cuboidal cells

the height and width of cells are about equal

columnar cells

simple cells (epithelium cells)

One layer of cells

stratified cells (epithelium cells)

stratified squamous

transitional epithelium

pseudostratifed columnar (epithelium cells)

falsely appear stratified because some cells are taller than others

every cell reaches the basement membrane

goblet cells produce mucus in it

goblet cells (epithelium cells)

(UNICELLULAR MAKE MUCUS)

wineglass shaped mucus secreting cells in simple columnar and pseudostratifed epithelia

unicellular glands that make mucus in certain areas of epithelium

clear bubble like appearance

simple squamous (epithelium cells) structure/function/and location

single rows of thin, scaly cells, with flattened disc shaped nuclei

func- secretes serous fluid

loca- *alveoli lungs*,lining of blood vessels, serous membranes

Simple cuboidal (epithelium cells) function/location/structure

single layer of cells,square to round cells with spherical nuclei

func- absorption, secretion, mucus production, movement

loca- **kidney tubules**

Simple columnar (epithelium cells) structure/function,location

single rows of tall, narrow cells with oval shaped nuclei

func- absorption and secretion of nutrient and mucus, helps move move along in large intestines

loca-**lining of GI track**, uterus , kidney, uterine tubes

pseudostratifed epithelium cells Function/location/structure

one layer of cells, has cilia and goblet cells

Func- secrets and propels mucus

Location- respiratory tract

stratified squamous keratinized (epithelium cells)

Multiple layers of dead cells

found on skin surface, abrasion resistant

transitional epithelium (epithelium cells) function, location, strucuture

also called UROTHELIUM therum

dome shape cells, form from round to flat when stretched

func- allow for stretching and filling in urinary tract

location- linging of bladder and ureter

stratified squamous nonkeratinized (epithelium cells)

lacks surface layer of dead cells

Connective tissues properties

• diverse and abundant

• cells usually occupy less space than the matrix

• cells are usually not in direct contact with each other

• highly variable vascularity

Primary Germ tissue

layers that give rise to all of the body’s mature tissues

endoderm

The inner layer of the primary germ layers

gives rise to muscous membranes of the digestive tract and respiratory tracts.

histological section

a thin slice of tissue prepared for microscopic observation

ectoderm

an outter layer which gives rise to the epidermis and nervous system

mesoderm

inbetween ectoderm and endoderm

layer of loosly organized cells, gives rise to cardiac muscles, composed of protein fibers

A tissue cut along its long axis is called

longitudinal section

urothelium is unique to the ——— track

urinary

stratified ———- epithelium is the most widespread epithelium of the body

squamous

Fibroblasts and macrophages are found in

fibrous connective tissues

Fibroblasts produce

fibers, collagen fibers

which epithelium is best suited for resisting abrasion and preventing pathogen entery into deeper tissues?

stratified squamous

Adipocytes

fat cells

Most abundant tissue type

Connective

what are the three fiber types found in the fibrous connective tissues

collagenous fibers, reticular fibers, and elastic fibers

which cell types are found in fiberous connective tissue

fibroblast , macrophages, white blood cells, and adipocytes

What connective tissue is composed of loosly arranged reticular fibers and lymphocytes

recticular connective tissue

Matrix

nonliving organic material that is between living cells

ground supstance, organic fillers, fibers

3 types of fibers

collogen, elastic

Collagenous fibers

thick, tough, flexible , stretch resistant

Found in tendons, ligaments,deep layer of the skin

Elastic fibers

provide stretch, recoil, thinner

Reticular fiber

form stromas (spongy network), thin, branched collagen fibers

form spongy framework of sleep and lymph nodes

Connective tissues functions

binding organs, , support, transport, protection

Fibroblasts

produce fibers & ground substance of
matrix

(builder cell)

Macrophages

phagocytize foreign material &
activate immune system when they sense antigens

Adipocytes

store triglycerides (fat molecules)

Mast cells

often found alongside blood vessels & aid
in the inflammatory response

3 types of loose connective tissue

Areolar
• Reticular
• Adipose*

Mostly gel-like ground
substance between cells

Dense connective tissue 2 types

fibers fill spaces between cells

Dense regular connective tissue &

dense irregular connective tissue

Recticular loose connective tissue

Mesh of reticular fibers & fibroblasts
• Forms supportive stroma (framework) for lymphatic organs
• Found in lymph nodes, spleen, thymus, bone marrow

Adipose tissue

• Empty-looking cells with thin margins, nucleus pressed
  against cell membrane
  • Energy storage, insulation, cushioning
  • Subcutaneous (under skin) fat & organ packing

Insulation = *thermoregulation *

Dense Fibrous Connective Tissue:
Dense Regular Connective

Densely packed, parallel collagen fibers
• Compressed fibroblast nuclei
• Tendons attach muscles to bones & ligaments hold
bones together

offers protection from directional forces

Dense Fibrous Connective Tissue:
Dense Irregular Connective

• Densely packed & randomly arranged collagen fibers + few
  visible cells

• Withstands unpredictable stresses

• Locations: *deeper layer of skin (dermis)*

• 
  

Protect you from multi-directional forces

loose Fibrous Connective Tissue: Areolar

loosely organized fibers, abundant blood vessels
• Underlies & nourishes epithelia
• In serous membranes, between muscles, passageways for nerves &
blood vessels

Connective tissue cartilage 3 types

hyaline cartilage

fibrocartilage

elastic cartilage

Chondroblasts

cartilage cells that produce the matrix
that will trap them

Chondrocytes

cartilage cells that are trapped in
lacunae (cavities)

hyaline cartilage

Clear, glassy appearance because of fineness of collagen fibers
• Eases joint movement, holds airway open, moves vocal cords,
growth of juvenile long bones
• Locations: articular (joint) cartilage, costal (rib) cartilage, trachea,
larynx, fetal skeleton

most abundant type of cartilage’

removal able joints

Fibrocartilage

Cartilage containing large, coarse bundles of collagen
fibers
• Resists compression & absorbs shock
• Locations: pubic symphysis, menisci of knees,
intervertebral discs

Connective tissue Bone (osseous) tissue

is a calcified connective tissue
– Bones of the skeleton are organs made of bone tissue,
cartilage, marrow, and other tissues
– Functions: movement, mineral storage, blood cell
production

2 types of osseous (Bone connective tissue)

Spongy bone

compact bone

spongy bone tissue (for chapt 7 )

• Porous appearance
• Covered by compact bone
• Found in ends of long bones & in middle of flat bones (such
as the sternum)

compact bone tissue (Chapt 7)

Denser, calcified tissue with no visible spaces
• More complex microscopic arrangement
• Smooth bone on external surface of all bones in body

Osteocytes

(bone cells) reside in the lacunae

how is Compact bone is arranged (Chapt 7)

in layered cylinders of matrix
(lamellae) that surround central (haversian) canals,
which run longitudinally through shafts of long bones

Elastic cartilage

• cartilage containing abundance of elastic fibers

• provides flexible, elastic support

• locations: external ear and epiglottis

Blood tissue

Fluid connective tissue
• Transports cells, gases,
nutrients, wastes, and
dissolved matter to/from the
body’s cells
• Living cells = red blood
cells, white blood cells,
platelets

fluid matrix (blood plasma

Fibers- soluble clotting proteins (Fibrinogen —→ fibrin)

Fluid matrix

Blood (blood plasma)

Gland

cell/tissue/organ that secretes substances for use
elsewhere in the body, or releases them for elimination
from the body

Two types of glands

exocrine glands

endocrine glands

Secretion

product useful to the body

Excretion

sweat glands

wasste product

Exocrine glands

have ducts through which their products
are released onto an internal surface or external surface

Endocrine glands

have no ducts & secrete hormones
directly into blood

Hormones

chemical messengers that stimulate cells
elsewhere in the body

Modes of secretion

Merocrine
– Apocrine
– Holocrine

Merocrine secretion

Merocrine secretion (used by eccrine glands) uses vesicles that release their
secretion by exocytosis
• Examples: lacrimal (tear)
glands, pancreas, gastric
glands