Tissues are groups of cells that work together to perform a specific function. There are four main types of tissues: epithelial, connective, muscular, and nervous. Epithelial tissues cover surfaces and line organs. Connective tissues connect and support other tissues. Muscular tissues allow for movement. Nervous tissues detect stimuli and transmit signals. Each tissue contains different cell types organized to carry out their role.

1. TISSUES
JaniceV. Ng, MSc
Department of Biology
CAS, UP Manila

2. Tissues
 “weave”
 group of cells with a common structure
and function
 held together by intracellular substances

3. Types
 EpithelialTissues
 ConnectiveTissues
 MuscularTissues
 NervousTissues

4. 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

5. EpithelialTissues
Shape
squamous cuboidal columnar
Number
simple stratified
Stratified
squamous
Pseudostratified
columnar
Name: Number of layers + shape

6. Example…

7.  Simple epithelium
◦ ___ layer of cell
◦ Involved in selective diffusion, absorption,
secretion
◦ Protection?
 Only minimal

8. Simple Squamous
Epithelium
• air sacs of lungs, glomeruli,
linings of heart, lymphatic and
blood vessels
• diffusion and filtration

9. Simple Cuboidal
Epithelium
• kidney tubules, ducts and
small glands and surface of
ovary
• secretion and absorption

10. Simple Columnar
Epithelium
• linings of digestive tract, gall
bladder, and excretory ducts
of some glands
• villi, microvilli, goblet cells
• absorption and enzyme
secretion

11.  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

12. Stratified Squamous
Epithelium
• keratinized: surface of the
skin
• nonkeratinized:
linings of the esophagus,
mouth and vagina
• protect underlying tissues in
areas subject to abrasion

13. 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.

14. 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

15. 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

16. Connective
Tissue
Connective Tissue
Proper
Loose/Areolar
Dense Modified
Loose
Specialized
Connective
Cartilage
Bone
Blood
ConnectiveTissue Proper - jelly-like extracellular matrix
Specialized ConnectiveTissue - liquid/ semi-solid/ hard solid matrix

17. Loose/ Areolar
ConnectiveTissue
• with numerous fibroblast
that produce collagenous and
elastic fibers
• subcutaneous layer
• wrap and cushions organs

18. Dense Regular Connective
Tissue
• contains densely packed
parallel collagen fibers
• tendon, ligaments

19. Dense Irregular
ConnectiveTissue
• contains densely packed
randomly arranged collagen
fibers
• Frog skin

20. Modified Loose ConnectiveTissue
AdiposeTissue
• subcutaneous layer
• cushions, storage of fats
ReticularTissue
• supports hemopoietic organs

21. 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

22. 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

23. Bone
Cell Components – osteoblasts,
osteocytes, osteoclasts
Ground Substance – calcium
phosphate, chondroitin-sulfate
and keratan sulfate (hard and
mineralized matrix)
Fibers: collagen (Type I)

24. Blood
Granulocytes Agranulocytes
Neutrophil Eosinophil
Basophil
Lymphocyte
Monocyte
Erythrocytes Leukocytes

25. 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)

26. Skeletal MuscleTissue
• striated muscle fibers
• cylindrical
• many peripheral nuclei
• skeletal muscles attached to
bones
• useful for voluntary
movement
• sarcolemma
• sarcoplasm

27. Cardiac MuscleTissue
• striated muscle fibers
• branched, with intercalated
disc
• uninucleated
• involuntary heart movement

28. Smooth MuscleTissue
• Spindle-shaped cells
• uninucleated
• lacks striations
• involuntary movement of
visceral organs and blood
vessels
• epimysium, perimysium,
endomysium

29. 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

30. NervousTissue (smear)
• cell body
• nucleus
• dendrites and axon
• glial cells

31. 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

32. END