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2. TISSUE - a group of similar cells that function
together to perform a specialized activity
There are four kinds of tissues:
1. Epithelial tissue = covers body surfaces; lines body cavities,
hollow organs (protection), and ducts; and forms glands
(secretion).
2. Connective tissue = supports the body and binds its organs;
binds organs together, stores energy reserves as fat, and
provides immunity.
3. Muscular tissue = for contraction (movement)
4. Nervous tissue = initiates and transmits nerve impulses that
coordinate body activities.

3. EPITHELIAL TISSUE
General Features:
• consists largely or entirely of closely packed cells
with little extracellular material (extracellular
matrix) between adjacent cells.
• cells are arranged in continuous sheets, in either
single or multiple layer
• cells have a free surface (apical surface)
exposed to a body cavity of an internal organ, or
the exterior of the body, and a basal surface
which is attached to the basement membrane.

4. • are avascular
• with nerve supply
• lies on a connective tissue layer - the basal
lamina / basement membrane
• has a high capacity for renewal (high mitotic
rate)
• Functions: protection (skin), filtration (kidneys),
diffusion (lungs), secretion (glands), absorption
(large intestines)

5. Kinds of Epithelial Tissue:
 Based on the shape of the cells.
Squamous – cells are flat; hexagonal; for
diffusion
Cuboidal – cube-shaped. Important in
secretion and in also in absorption
Columnar – cells are tall and cylindrical
Transitional – cells can readily change
shape esp. when stretch

6.  Based on the number of layers of cells.
Simple epithelium – single layer of cells;
found in areas where diffusion, osmosis,
filtration, secretion and absorption occur.
Stratified epithelium – contains two or more
layers of cells; protects underlying tissues;
found where there is wear and tear.
Pseudostratified epithelium – contains a single
layer of a mixture of cell types. Has a stratified
appearance, but is a single layer.

8. These cells are large, but quite thin, and have a prominent, protruding
nucleus. Found in linings of the peritoneal, pleural and pericardial
cavities. As well as in the glomerulus of the kidney, the walls of
capillaries, and the alveoli of the lungs.
SIMPLE SQUAMOUS EPITHELIUM

10. These are collecting ducts in the medulla of a mammalian kidney.
Each duct is lined by simple cuboidal epithelium, whose nuclei are
quite prominent. This type of epithelium is thicker than simple
squamous epithelium
SIMPLE CUBOIDAL EPITHELIUM

12. A cross section of the small intestine. The tall, vertical cells seen at
the top of the tissue are columnar cells (one is shown - red arrow),
which make up simple columnar epithelium (the cells at the bottom of
the image are connective tissue). Since columnar cells are quite thick,
they do not readily allow passive diffusion. They have numerous
microvilli (seen as a darker pink staining border at their lumenal
edge). The black arrow is indicating a goblet cell.
SIMPLE COLUMNAR EPITHELIUM

24. Glandular Epithelium-Exocrine

25. Glandular Epithelium-Exocrine

26. Glandular Epithelium-Endocrine

27. Glandular Epithelium-Endocrine

28. CONNECTIVE TISSUE
General Features:
• do not usually occur on free surfaces
• has a nerve supply (except for cartilage)
• usually is highly vascular (except cartilage & tendons)
• has three basic elements:
– cells
– ground substance
– fiber
The ground substance and the fibers, which are
outside the cells, make up the extracellular
matrix.

29. The matrix may be solid (as in bone), soft (as in
loose connective tissue), or liquid (as in blood)
• the most widespread and abundant type of tissue in
the human body
• Function: support, anchor and bind various parts of
the body
• also serves for: protection, blood formation, fat
storage, filling space

30. Kinds of Connective Tissue
1) Loose connective tissue
Has fibers which are far apart from each other, and
there are many cells.
• Areolar Connective Tissue
found in the lower layers of the skin, mucous
membranes, blood vessels, nerves, and around
body organs. Its function is to provide strength,
• Adipose Tissue
designed to store fat (triglycerides). The cells are
called adipocytes.

31. • Reticular Connective Tissue
contains a network of interlacing reticular fibers.
Its purpose is to form the framework of many
organs and bind together smooth muscle tissue
cells such as the lymph nodes, spleen and bone
marrow
2) Dense Connective Tissue
Also called dense fibrous tissue
Has collagen fibers as its main matrix element
They form strong, rope-like structures such as the
tendons – attach skeletal muscles to bones
ligaments – connect bones to bones at joints
also found in the dermis of the skin

32. 3) Specialized CT:
A. Bone (osseus) tissue
Composed of bone cells (osteocytes) embedded in
small spaces called lacunae
Surrounded by concentric rings that consist of mineral
salts (calcium)
Small canals (canaliculi) project out of the lacunae
and provide a pathway for nutrients and wastes
Has rock-like hardness

34. B. Cartilage
Composed of cartilage cells chondrocytes
found in spaces called lacunae.
Surrounded by a membrane (perichondrium)
No blood vessels or nerves
Cartilage repairs very slowly after it has been
injured
Types of cartilage
1) Hyaline cartilage has abundant collagen fibers hidden
by a rubbery matrix with a glassy blue-white appearance
ex: ends of long bones, nose, anterior portion of
the ribs, and parts of the larynx, trachea,
bronchi, fetal skeleton

35. 2) Fibrocartilage
highly compressible
serves as cushion
strongest type
ex: pubic symphysis,
intervertebral discs, and meniscus of the knee.
3) Elastic cartilage
highly elastic
ex: epiglottis of the larynx, tip of nose, external ear, and
auditory (Eustachian) tubes.

37. C. Vascular Tissue (Blood)
Plasma
liquid portion of the blood
consists mostly of water along with suspended
proteins, and dissolved substances, ions, food
molecules, and hormones
Formed Elements
solid portions of the blood
of three kinds:

38. 1) erythrocytes - oxygen transporter
2) leukocytes – soldiers of the body, has
2 kinds
a. Granulocytes
neutrophils - most abundant of the
WBCs; squeeze through the capillary
walls and into infected tissue where they
kill the invaders and then engulf the
remnants by phagocytosis
eosinophils - numbers increase
sharply in certain diseases, especially
infections by parasitic worms; are
cytotoxic, releasing the contents of their
granules on the invader

39. basophils - increases during infection; play an
important part in some allergic responses
b. Agranulocytes
lymphocytes – 2 kinds: B and T lymphocytes
monocytes - functions in the ingestion of
bacteria (macrophage)
3) thrombocytes – important in blood clotting