Tissue Histology

histology

study of tissues and how they are arranged into organs

four primary tissues

epithelial, connective, nervous, muscular

epithelial tissue

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

connective tissue

tissue with more matrix than cell volume, often specialized to support, bind together, and protect organs

nervous tissue

tissue containing excitable cells specialized for rapid transmission of coded information to other cells

muscular tissue

tisse composed of elongated, excitable cells specialized for contraction

tissues

group of similar cells derived from a common embryonic origin that are arranged in a way that allows them to carry out a particular structural or physiological function

epithelial tissues are often connected to

connective tissue

classification of epithelial tissue

squamous, cuboidal, columnar
simple, stratified, pseudo-stratified columnar, transitional

squamous epithelium

thin, flat, good for exchange of gases, nutrients, waste products

cuboidal epithelium

square or round, lining ducts of glands

columnar epithelium

tall, narrow, lining intestines, have microvilli

simple epithelium

single layer of cells

stratified epithelium

several layers of cells

pseudo stratified columnar epithelium

single layer of cells varying in height and the position of their nuclei

transitional epithelium

specialized to change in response to increased tension/stretching

simple squamous epithelium

one layer of thin, flat cells

simple cuboidal epithelium

one layer of cubed/round cells

simple columnar epithelium

one layer of tall, narrow cells

goblet cells

produce mucus

stratified squamous epithelium

multiple layers of thin, flat cells

keratinized stratified squamous epithelium

cannot see nuclei

non-keratinized stratified squamous epithelium

can see nuclei

components of connective tissue

cells, fibers, ground substance

major functions of connective tissue

connection, support, protection, movement, storage and heat production, transport

types of connective tissue

Fibrous, Cartilage, Blood, Bone

fibrous connective tissue

ligaments and tendons

cartilage

rubbery connective tissue that supports nose and ears, found between bones

bone/osseous tissue

rigid connective tissue that protects organs, supports weight, produces movement

blood tissue

fluid connective tissue, transports materials throughout the body

cells in fibrous connective tissue

fibroblasts, macrophages, leukocytes, mast cells, adipocytes

fibroblasts

large cells that produce the fibers and ground substance

macrophages

phagocytic cells that look for, engulf, and destroy bacteria and viruses

leukocytes

white blood cells, monitor body for invasion, coordinates immune response

mast cells

found neat blood vessels, product factors that promote blood flow in inflamed tissues

adipocytes

store large vacuoles of lipid

fibers in fibrous connective tissue

collagenous, reticular, elastic

collagenous

very common, strong and flexible

reticular fibers

not common, found inside several organs for structural support, coated with glycoproteins

elastic fibers

common, coiled to allow fibers to stretch and return to normal shape

types of fibrous tissue

loose and dense

loose fibrous connective tissue

more ground substance

Types of loose fibrous connective tissue

areolar, reticular, adipose

areolar connective tissue

randomly oriented collagen and elastin fibers, few fibers

reticular connective tissue

randomly oriented reticular fibers, possesses many lymphocytes

adipose connective tissue

few fibers and many adipose cells filled with lipid

dense fibrous connective tissue

more collagen fibers

types of dense fibrous connective tissue

regular and irregular

dense regular connective tissue

collagen fibers densely packed and parallel to each other, very strong

dense irregular connective tissue

collagen fibers densely pack, but run in random directions

types of cartilage

hyaline, elastic, fibrocartilage

hyaline cartilage

most common, clear, glassy appearance, many thin collagen fibers, individual fibers cannot be seen

elastic cartilage

many elastin fibers

Firbrocartilage

many course, collagen bundles, visible collagen fibers

types of bone tissue

spongy and compact

spongy bone tissue

found in the heads of long bones, vertebral bones

compact bone tissue

dense osseous tissue that surrounds spongy bone, most common

Osteocytes

bone cells that live in lacunae

Formed elements of blood

erythrocytes, leukocytes, platelets

Erythrocytes

red blood cells, don't have nucleus, carry oxygen/carbon dioxide

Leukocytes

white blood cells, immune protection

Platelets

blood clotting, direct new blood vessel growth

action potential

generated when there is a change in electrical charge across the cell membrane

central nervous system

brain and spinal cord

peripheral nervous system

all the nerves outside the brain and spinal cord

cells of nervous tissue

neurons and glial cells

glial cells

support cells

Neuron Anatomy

soma, dendrite, axon

soma

cell body of a neuron

Dendrites

short processes that receive signals from other neurons

axon

large nerve fiber that sends signals to other neurons

types of muscular tissue

skeletal, cardiac, smooth

skeletal muscle

long, cylindrical, multinucleate cells, striated

cardiac muscle

shorter, more tightly connected than skeletal muscle; involuntary, striated

smooth muscle

long cells that are tapered at ends, no striations, involuntary

cell junctions

allow cells to communicate

types of cell junctions

tight junctions, desmosomes, gap junctions

tight junctions

form grooves and ridges that help adjacent cells attach, completely circles the cell, not very strong

desmosomes

form a patch using intermediate filaments, strong

gap junctions

form a pore (connexon), very common

glands

organs/cells that produce that is used by another tissue, or eliminated from the body

two types of glands

exocrine and endocrine

endocrine glands

produce substances that will be used by other cells/tissues within the body

exocrine glands

produce substances that will leave the body or be deposited into the cavity of another organ

simple gland structure

ducts do not branch, single coiled tube

compound gland structure

ducts have numerous branches

types of gland secretion

serous, mucous, mixed, cytogenic

serous secretion

thin watery fluid

mucous secretion

thick, stringy fluid

mixed secretion

Both serous and mucus secretion

cytogenic secretion

secrete whole cells

modes of gland secretion

merocrine, holocrine

merocrine secretion

release a substance into the duct via exocytosis

holocrine secretion

release a substance through the cell disintegrating

basement membrane

contains collagen, glycoproteins, protein-carbohydrate complexes

white adipose tissue

most abundant, found in adults, provides insulation, cushions organs

brown adipose tissue

found in fetuses, infants, children, generates heat

hyperplasia

tissue growth through cell multiplication, how embryonic and childhood growth occurs

hypertrophy

enlargement of preexisting cells, how skeletal muscle and adipose tissue growth occurs

neoplasia

development of a tumor