2. — Humans are vertebrates and therefore the human body has
four levels of organization.
— These levels are:- cells
- tissues
- organs
-organ systems
3.
4. Cells
— The human body has different cell type
— Humans have 210 different cell types.
— The cells are differentiated and have specific structure and
function.
— Group of cells that are similar in structure and function are
organized into tisssues.
5. Tissues
— In early development the cells of the embryo differentiate
into three embryonic tissues namely:
Endoderm, mesoderm and ectoderm.
— The embryonic tissues are also called germ layers.
— The germ layers differentiate into different cell types and
tissues that make up the body.
— There are four kinds of tissues or primary tissues which
are :epithelial, connective , muscle and nerve tissue.
6. EPITHELIAL TISSUE
— Epithelial tissue also called epithelium covers the entire
body surface and most of the body’s inner cavities.
— It forms a continuous layer or sheet over the body surface.
— The epithelium can come from any of the three germ
layers.
— For example the epidermis derived from ectoderm forms
outer part of skin. Epithelium from endoderm form the
inner lining of the digestive system while inner surfaces of
blood vessels are from mesoderm.
7. — The epithelium has strong regenerative powers i.e they
constantly replace themselves throughout the life of the
organism.
— For example the epidermis renews every two weeks while
the epidermis in the stomach is renewed every two to three
days.
— The ability to regenerate is useful in a surface tissue
because it constantly renews the surface and also allows
quick replacement of the protective layer should damage
or injury occur.
8. Classes of epithelial tissues
— Simple (single layer of cells)
— Stratified (multiple layers of cells)
— These are further subdivided into squamous , cuboidal and
columnar based on the shapes of the cells.
— The squamous are composed of flat cells and found in lining
of stomach and blood vessels.
— Cuboidal contains cube-shaped cells and are found in lining the
kidney tubules.
9. — Columnar resemble pillars or columns and have nuclei
located near the bottom of each cell found in lining of
digestive tract
— An epithelium can have microvilli or cilia as appropriate
for its function
10. Epithelial tissues: simple epithelium
Squamous
Typical Location
Lining of lungs, capillary
walls, and blood vessels
Function
Cells form thin layer across
which diff usion can
readily occur
Characteristic Cell Types
Epithelial cells Simple
squamous
epithelial
cell
nucleus
11. Cuboidal
Typical Location
Lining of some glands and kidney
tubules; covering
of ovaries
Function
Cells rich in specific transport
channels; functions in
secretion and absorption
Characteristic Cell Types
Gland cells
Cuboidal epithelial
cells
nucleus
12. Columnar
Typical Location
Surface lining of stomach, intestines,
and parts of
respiratory tract
Function
Thicker cell layer; provides
protection and functions in
secretion and absorption
Characteristic Cell Types
Epithelial cells
Columnar
epithelial cells
Goblet cell
nucleus
13. Pseudostratified Columnar
Typical Location
Lining of parts of the respiratory tract
Function
Secretes mucus; dense with cilia that
aid in movement
of mucus; provides protection
Characteristic Cell Types
Gland cells; ciliated epithelial cells
cilia
Goblet
cell
Pseudostratified
columnar cell
15. Summary of epithelial tissues
Number of Cell
Layers
Cell Form Examples of
Distribution
Main Function
Simple (one layer) Squamous Lining of vessels
(endothelium).
Serous lining of
cavities;
pericardium,
pleura, peritoneum
(mesothelium).
Facilitates the
movement of the
viscera
(mesothelium),
active transport by
pinocytosis
(mesothelium and
endothelium),
secretion of
biologically active
molecules
(mesothelium).
Cuboidal Covering the ovary,
thyroid
Covering, secretion
16. Number of Cell
Layers
Cell Form Examples of
Distribution
. Main Function
Columnar Lining of
intestine,
gallbladder.
Protection,
lubrication,
absorption,
secretion
Pseudostratified
(layers of cells with
nuclei at different
levels; not all cells
reach surface but
all adhere to basal
lamina)
Lining of trachea,
bronchi, nasal
cavity.
Protection,
secretion; cilia-
mediated
transport of
particles trapped
in mucus out of
the air passages.
17. Number of Cell
Layers
Cell Form Examples of
Distribution
Main Function
Stratified (two or
more layers)
Squamous
keratinized (dry)
Epidermis. Protection;
prevents water loss.
Squamous
nonkeratinized
(moist)
Mouth, esophagus,
larynx, vagina, anal
canal
Protection,
secretion; prevents
water loss.
Cuboidal Sweat glands,
developing ovarian
follicles.
Protection,
secretion
Transitional Bladder, ureters,
renal calyces
Protection,
distensibility
Columnar Conjunctiva. Protection.
18. CONNECTIVE TISSUE
— As a rule connective tissue cells are separated widely by
a matrix,(a non cellular material found between cells)
— Connective tissue binds structures together, provides
support and protection, fills spaces, stores fat and
forms blood cells
19. CONNECTIVE TISSUE
— Connective tissues derive from embryonic mesoderm and
occur in many different forms .
— these various forms are divided into two major classes:
connective tissue proper, which further divides into loose
and dense connective tissues, and
— Special connective tissues, which include cartilage, bone,
and blood.
20. Loose connective tissue
— Cells of this tissue which are mainly fibroblasts are
located some distance from one another and are separated
by a jelly like matrix containing many white collagen
fibers and yellow elastic fibers.
— The collagen fibers occur in bundles and are strong and
flexible
— Loose connective tissue consists of cells scattered within a
matrix that contains a large amount of ground substance.
21. continuation
— This gelatinous material is strengthened by a loose
scattering of protein fibers such as collagen, which
supports the tissue by form in a meshwork elastin, which
makes the tissue elastic, and reticulin, which helps support
the network of collagen.
22. continuation
— The elastic fibers form networks that when stretched
return to their original length
— Loose connective tissues lie beneath epithelial layers.
— Adipose tissue is a type of loose connective tissue in
which the fibroblasts enlarge and store fat and in which
the intracellular matrix is reduced.
23. Picture of loose connective tissue
Loose Connective Tissue
Typical Location
Beneath skin; between
organs
Function
Provides support, insulation,
food storage, and
nourishment for
epithelium
Characteristic Cell Types
Fibroblasts, macrophages,
mast cells, fat cells
collagen
Elastin
24. Dense/fibrous connective tissue
— It contains tightly packed collagen fibers, making it
stronger than loose connective tissue. It consists of two
types: regular and irregular.
— The collagen fibers of dense regular connective tissue line
up in parallel, like the strands of a rope. This is the
structure of tendons,which bind muscle to bone, and
ligaments, which bind bone to bone.
25. continuation
— In contrast, the collagen fibers of dense irregular
connective tissue have many different orientations.
— This type of connective tissue produces the tough
coverings that package organs, such as the capsules of the
kidneys and adrenal glands. It also covers muscle, nerves,
and bones.
— This type has more specific functions than loose
connective tissue
26. Picture of dense connective tissue
Dense Connective Tissue
Typical Location
Tendons; sheath around
muscles;
kidney; liver; dermis of
skin
Function
Provides flexible, strong
connections
Characteristic Cell Types
Fibroblasts
Nuclei of
fabroblast
Collagen
fibers
28. 1. cartilage
— Cartilage cells lie in small chambers (lacunae)
separated by a matrix that is solid yet flexible.
— There are three types of cartilage and they are
distinguished by the fiber in the matrix, and these are
hyaline cartilage ,elastic cartilage and fibro cartilage
29. Cartilage continued
— Hyaline cartilage contains only very fine collagenous
fibers,Its matrix has a milk-glass appearance(found in
nose and ribs)
— Elastic cartilage has more elastic fibers than hyaline
hence it is more flexible ( found in framework of outer
ear)
— Fibro cartilage has a matrix with strong collagenous
fibers and is found in structures that withstand
tension and pressure(e.g. pads between vertebrae)
30. Picture of cartilage
Cartilage
Typical Location
Spinal disks; knees and
other joints;
ear; nose; tracheal rings
Function
Provides flexible support,
shock absorption, and
reduction of
friction on load-bearing
surfaces
Characteristic Cell Types
Chondrocytes
chondrocytes
Ground
substance
31. 2.Bone
— It’s the most rigid connective tissue and has a hard
matrix of calcium deposited around protein fibers.
— The minerals give the bone rigidity while the protein
fibers provide elasticity and strength( just as steel rods
in reinforced concrete
32. Picture of bone
Bone
Typical Location
Most of skeleton
Function
Protects internal
organs; provides
rigid support for
muscle attachment
Characteristic Cell
Types
Osteocytes
osteocyte
33. Blood
— Blood is a connective tissue in which the cells are
separated by a liquid called plasma
.
— The intracellular matrix of blood is plasma
— Others do not classify blood as a connective tissue, instead
they put it in its own category called vascular tissue.
34. Blood
Typical Location
Circulatory system
Function
Functions as highway of
immune system; carries
nutrients and waste; and is the
primary means of
communication between organs
Characteristic Cell Types
Erythrocytes, leukocytes
Red blood
cell
35. MUSCLE TISSUE
— It is also known as contractile tissue and is composed
of cells that are called muscle fibers.
— The muscle fibers contain actin and myosin filaments,
whose interaction account for movement in animals
— There are three types of muscle tissue: skeletal
smooth
cardiac
36. — Skeletal and cardiac muscles are also known as striated
muscles because their cells appear to have transverse
stripes when viewed in longitudinal section under
the microscope.
— The contraction of each skeletal muscle is under voluntary
control, whereas the contraction of cardiac and smooth
muscles is generally involuntary.
37. Skeletal muscle
— Usually attached to bones by tendons such that their
contractions result in movement of the bones at their
joints.
— The skeletal muscle cells are cylindrical and quiete
long- they run the length of the muscle.
— Their nuclei are placed at the periphery of the cell just
inside the cell membrane.
38. — Each skeletal muscle is stimulated to contract by a
motor neuron.
— Skeletal muscles are striated and they have light and
dark bands perpendicular to the length of the cell.
— The bands are due to the placement of actin and
myosin filaments in the cells.
39. Pictures of skeletal muscles
Skeletal Muscle
Typical Location
Voluntary muscles
Function
Powers walking, lifting,
talking, and all
other voluntary
movement
Characteristic Cell Types
Skeletal muscle cells
Skeletal muscle cell
nuclei
40. Smooth muscles
— It is so called because the cells lack striations
— The nuclei form an irregular pattern in the tissue.
— The spindle shaped cells form layers in which the
middle portion of one cell is opposite the thin ends of
adjacent cells.
— These muscles are involuntary
— Found in walls of viscera(stomach, small intestines
and other internal organs)
41. — Contract more slowly than the skeletal muscles but
can remain contracted for a long time.
42. Pictures of smooth muscles
Smooth Muscle
Typical Location
Walls of blood vessels,
stomach,
and intestines
Function
Powers rhythmic,
involuntary
contractions commanded
by the central
nervous system
Characteristic Cell Types
Smooth muscle cells
Smooth
muscle cell
nuclei
43. Cardiac muscle
— Found only in the heart and is responsible for heart
beat.
— It combines features of both smooth and skeletal
muscles
— It has striations like skeletal muscles but their
contraction is involuntary on the most part.
— They have a single centrally placed nucleus
44. — The cells are branched and seemingly fused to one
another
— the heart appears to be composed of one
interconnecting mass of muscle tissue
— Cardiac muscle cells are separate and individual, but
they are bound to end at areas of folded cell
membrane between the cells.
45. Cardiac Muscle
Typical Location
Walls of heart
Function
Highly interconnected
cells; promotes
rapid spread of signal
initiating
contraction
Characteristic Cell Types
Cardiac muscle cells
Intercalated
disk
Cardiac
muscle
nuclei
Pictures of Cardiac muscles
46. NERVE TISSUE
— Its cells include neurons and their supporting cells,
called neuroglia.
— Neurons are specialized to produce and conduct
electrochemical events, or impulses.
— A neuron is a specialized cell that has three parts:
- dendrites( conducts impulses to the cell body)
- cell body (contains most of the cytoplasm and
nucleus of neuron)
- axon (conducts impulses away from the cell body)
47. — When axons and dendrites are long they are called
nerve fibers.
— Outside the brain and spinal cord, nerve fibers are
bound by connective tissue to form nerves.
— Nervous tissue also contains glial cells which help
maintain the tissue by supporting and protecting
neurons, they also provide nutrients to neurons and
help to keep the tissue free from debris.
