histology
TRANSCRIPT
TISSUES
Janice V. Ng, MSc
Department of Biology
CAS, UP Manila
Tissues
“weave”
group of cells with a common structure
and function
held together by intracellular substances
Types
Epithelial Tissues
Connective Tissues
Muscular Tissues
Nervous Tissues
Epithelial Tissues
composed of closely packed cells with very little intercellular substance
surface epithelia – exposed to air or fluid; continuous with one or more layer of cells
base of epithelia usually resting on a basement membrane
◦ Basement membrane – separates epithelia from underlying tissues; never penetrated by blood vessels
cover the outside of the body and line organs and cavities within the body
wide range of activities:
◦ protective covering and lining surfaces (skin), absorption (intestine), secretion (epithelial cells of glands), sensory (neuroepithelium) and contractility (myoepithelial cells).
Cell joined together by cellular junctions
Epithelial Tissues
Shape
squamous cuboidal columnar
Number
simple stratified
Stratified squamous
Pseudostratified
columnar
Name: Number of layers + shape
Example…
Simple epithelium
◦ ___ layer of cell
◦ Involved in selective diffusion, absorption,
secretion
◦ Protection?
Only minimal
Simple Squamous
Epithelium
• air sacs of lungs, glomeruli,
linings of heart, lymphatic and
blood vessels
• diffusion and filtration
Simple Cuboidal
Epithelium
• kidney tubules, ducts and
small glands and surface of
ovary
• secretion and absorption
Simple Columnar
Epithelium
• linings of digestive tract, gall
bladder, and excretory ducts
of some glands
• villi, microvilli, goblet cells
• absorption and enzyme
secretion
Stratified epithelium
◦ ____ layer of cells
◦ Mainly for protection
◦ Degree of stratification related to the kind of
physical stresses to which the surface is
exposed
◦ Name is based on the structure of the ____
cells
Stratified Squamous
Epithelium
• keratinized: surface of the
skin
• nonkeratinized:
linings of the esophagus,
mouth and vagina
• protect underlying tissues in
areas subject to abrasion
Pseudostratified
Ciliated Columnar
Epithelium•True simple epithelium
• All cells rest at the basement
membrane
• Nuclei disposed at different
levels
• Cilia
• Linings of bronchi, uterine
tubes, and some regions of the
uterus.
• propel mucus or reproductive
cells by ciliary action.
Connective Tissues
Provide structural and metabolic support
for other tissues and organs
Usually contain blood vessels
Mediate exchange of nutrients,
metabolites, waste products between
tissues and circulatory system
Connective Tissues
Basic Components
◦ Cells – scattered through extracellular matrix
Fibroblast/fibrocyte, Adipocytes, Mast cells, macrophages, Blood cells
◦ Extracellular Matrix
Fibers
Collagen, Elastin, Reticulin (Type III collagen)
Ground Substance - mixture of polysaccharide chains, glycosaminoglycans (GAGs), proteoglycans
Structural glycoproteins – mediates interaction of cells with other constituents
Connective Tissue
Connective Tissue Proper
Loose/Areolar
Dense Modified Loose
Specialized Connective
Cartilage
BoneBlood
Connective Tissue Proper - jelly-like extracellular matrix
Specialized Connective Tissue - liquid/ semi-solid/ hard solid matrix
Loose/ Areolar
Connective Tissue
• with numerous fibroblast
that produce collagenous and
elastic fibers
• subcutaneous layer
• wrap and cushions organs
Dense Regular Connective
Tissue
• contains densely packed
parallel collagen fibers
• tendon, ligaments
Dense Irregular
Connective Tissue
• contains densely packed
randomly arranged collagen
fibers
• Frog skin
Modified Loose Connective Tissue
Adipose Tissue
• subcutaneous layer
• cushions, storage of fats
Reticular Tissue
• supports hemopoietic organs
Cartilage Cell component – chondrocytes
Ground substance – chondroitin sulfate and hyaluronate
Fibers: collagen, elastic
Hyaline Cartilage
• collagen fibers
• cartilage of nose, trachea, larynx
• support and reinforcement
Elastic Cartilage
• collagen fibers and many elastic
fibers
• cartilage of external ear and
epiglottis
• maintains shape and allows
flexibility
Fibrocartilage
• dense collagen fibers
• cartilage of intervertebral disc,
pubic symphysis and disk of knee
joints
• absorbs compression shock
Bone
Cell Components – osteoblasts,
osteocytes, osteoclasts
Ground Substance – calcium
phosphate, chondroitin-sulfate
and keratan sulfate (hard and
mineralized matrix)
Fibers: collagen (Type I)
Blood
Granulocytes Agranulocytes
Neutrophil Eosinophil
Basophil
Lymphocyte
Monocyte
Erythrocytes Leukocytes
Muscle Tissue
Striated Voluntary Muscle (Skeletal
Muscle)
Striated Involuntary
Muscle (Cardiac Muscle)
Non-striated Involuntary Muscle (Smooth/Visceral
Muscle)
*Striations – arrangement of the contractile proteins (actin and myosin)
Skeletal Muscle Tissue
• striated muscle fibers
• cylindrical
• many peripheral nuclei
• skeletal muscles attached to
bones
• useful for voluntary
movement
• sarcolemma
• sarcoplasm
Cardiac Muscle Tissue
• striated muscle fibers
• branched, with intercalated
disc
• uninucleated
• involuntary heart movement
Smooth Muscle Tissue
• Spindle-shaped cells
• uninucleated
• lacks striations
• involuntary movement of
visceral organs and blood
vessels
• epimysium, perimysium,
endomysium
Nervous Tissues
Sense stimuli and transmit signals from one
part of the animal to another
Functional unit neuron/nerve cell
Smear, Cross section, Longitudinal section
Nervous Tissue (smear)
• cell body
• nucleus
• dendrites and axon
• glial cells
Axons are bundled together in structures
called nerves.
Longitudinal section
• Neurilemma- membrane covering the fiber
• Axis cylinder- the central region of the nerve
fiber
• Medullary sheath - thick sheath covering the
fiber between the neurilemma and the axis
cylinder
• Nodes of Ranvier- constrictions in the
medullary sheath
Cross section (not available)
• Epineurium - the membrane covering a
bundle of fascicule of nerve fiber
• Perineurium - the membrane covering a
fasciculus of nerve fiber
• Endoneurium - the membrane covering a
nerve fiber
END