Tissue,Anatomy and Physiology.Structure of Tissue,types,functions of tissues and Tissue Repair.

1. TISSUES:
By Mr Ebenezer Aboagye Akuffo

2. Learning outcomes
 describe the structure and functions of
these tissues: epithelial, connective,
muscle, nervous
 explain the capacity of different types of
tissue to regenerate
 outline the structure and functions of
membranes
 compare and contrast the structure and
functions of exocrine and endocrine
glands.

3. Tissues
 Definition: a group of closely associated
cells that perform related functions and are
similar in structure
 Between cells: nonliving extracellular
material
 Four basic types of tissue…function
Epithelium…covering
Connective tissue…support
Muscle tissue…movement
Nervous tissue…control

4. Epithelia (plural)
 Epithelium: sheet of cells that covers a body
surface or lines a body cavity; also form most of
the body’s glands
 Roles: as interfaces and as boundaries
 Functions:
Protection Absorption
Sensory reception Ion transport
Secretion Filtration
Formation of slippery surfaces for movement

5. Special characteristics of epithelia
 Cellularity(mostly composed of cells)
 Covers body surfaces
 Polarity(distinct cell surface)
 Free upper (apical) surface
 Lower (basal) surface contributing basal lamina to
basement membrane
 Cell and matrix connections
 Avascular but innervated
 Without vessels
 With nerve endings
 capable of Regeneration

6. Classification of epithelia
 According to thickness
“simple” - one cell layer
“stratified” – more than one layer of cells
(which are named according to the shape of
the cells in the apical layer)
Pseudostratified -false
 According to shape
“squamous” – wider than tall
“cuboidal” – as tall as wide
“columnar” - taller than wide

7. to protect

8. where diffusion is important
where tissues are involved
in secretion and absorption:
larger cells because of the
machinery of production,
packaging, and energy
requirements

11. “ciliated” literally =
eyelashes
(see next page)

13. STRATIFIED EPITHELIA
 several layers of cells of various shapes
 Basement membrane is usually absent
 function is to protect against wear and tear
 two types –stratified squamous epithelium
-transitional epithelium

14. stratified squamous epithelium
 Non-keratinised Stratified Epithelium- found
on wet surface subjected to wear & tear but are
protected from drying. eg Conjunctiva, lining of
the mouth, the pharynx, the oesophagus and the
vagina.
 Keratinised Stratified Epithelium- found in dry
surface subjected to wear and tear, contain the
protein keratin. Eg skin, hair and nails


15. Stratified: regenerate from below

16. Rare…

17. Rare…

18. TRANSITIONAL EPITHELIUM
 cells rounded and can spread out when
the organ expands
 found lining organs which must expand
and must be water proof eg. The bladder

20. Endothelium
A simple squamous
epithelium that lines
the interior of the
circulatory vessels
and heart
Mesothelium
Simple squamous epithelium that lines the
peritoneal, pleural and pericardial cavities and
covers the viscera

21. Glands
 Glands are cells or organs that secrete
something; that is, they produce a substance
that has a function either at that site or at a
more distant site.
 Production & secretion of needed
substances
 Are aqueous (water-based) products
 The protein product is made in rough ER,
packed into secretory granules by Golgi
apparatus, released from the cell by
exocytosis

22. Classification of glands
 By where they release their product
Exocrine: external secretion onto body
surfaces (skin) or into body cavities
Endocrine: secrete messenger molecules
(hormones) which are carried by blood to
target organs; “ductless” glands
 By whether they are unicellular or
multicellular

23. Exocrine glands
unicellular or multicellular
Unicellular: goblet cell
scattered within epithelial
lining of intestines and
respiratory tubes
Product: mucin
mucus is mucin & water

24. Multicellular exocrine glands

25. Examples of exocrine gland products
 Many types of mucus secreting glands
 Sweat glands of skin
 Oil glands of skin
 Salivary glands of mouth
 Liver (bile)
 Pancreas (digestive enzymes) The exocrine
portions secrete digestive enzymes that are
carried by ducts to the duodenum of the small
intestine, their site of action
 Mammary glands (milk)

26. Endocrine glands
 Ductless glands
 Release hormones into extracellular space
Hormones are messenger molecules
 Hormones enter blood and travel to
specific target organs

27. Examples of endocrine glands
 thyroid gland, adrenal glands, and pituitary
gland.
 The pancreas is an organ that is both an
exocrine and an endocrine gland
 The endocrine portions of the pancreas,
called pancreatic islets or islets of
Langerhans, secrete the hormones insulin
and glucagon directly into the blood.

28. Epithelial surface features
 Lateral surface
Adhesion proteins
Cell junctions: see next slide
 Basal surface
Basal lamina: noncellular sheet of protein
together with reticular fibers form basement
membrane
 Apical surface

29. Cell Junctions
 Tight junctions
 So close that are
sometimes impermeable
 Adherens junctions
 Transmembrane linker
proteins
 Desmosomes
 Anchoring junctions
 Filaments anchor to the
opposite side
 Gap junctions
 Allow small molecules to
move between cells

30. Apical surface features
 Microvilli – maximize surface area
Fingerlike extensions of the plasma
membrane of apical epithelial cells
On moist and mucus secreting epithelium
Longest on epithelia that absorb nutrients
(small intestine) or transport ions (kidneys)
(continued)

31.  Cilia
Whiplike motile
extentions of the
apical surface
membranes
 Flagellum
Long isolated
cilium
Only found as
sperm in human

33.  Four basic types of tissue
Epithelium
Connective tissue
 Connective tissue proper (examples: fat
tissue, fibrous tissue of ligaments)
 Cartilage
 Bone
 Blood
Muscle tissue
Nervous tissue

34. Connective Tissue
 Connective tissue is distinguished by its
extracellular matrix.
 Functions of Connective Tissue
Connective tissues enclose and separate
organs and tissue; connect tissues to one
another; play a role in support for
movement; store high-energy molecules;
cushion; insulate; transport; and protect.

35. Cells of Connective Tissue
 The extracellular matrix results from the activity
of specialized connective tissue cells; in general,
blast cells form the matrix, cyte cells maintain it,
and clast cells break it down. Fibroblasts form
protein fibers of many connective tissues,
osteoblasts form bone, and chondroblasts form
cartilage.
Adipose (fat) cells, mast cells, white blood cells,
macrophages, and mesenchymal cells (stem cells)
are commonly found in connective tissue.

36. Connective Tissue
 Originate from embryonic tissue called
mesenchyme
 Most diverse and abundant type of tissue
 Many subclasses
 Function: to protect, support and bind together
other tissues
 Bones, ligaments, tendons
 Areolar cushions; adipose insulates and is food
source
 Blood cells replenished; body tissues repaired
 Cells separated from one another by large
amount of nonliving extracellular matrix

37. Extracellular Matrix explained
 Nonliving material between cells
 Produced by the cells and then extruded
 Responsible for the strength
 Two components
1. Ground substance
 Of fluid, adhesion proteins, proteoglycans
 Liquid, semisolid, gel-like or very hard
2. Fibers: collagen, elastic or reticular

38. Basic functions of connective tissue
reviewed
 Support and binding of other tissues
 Connecting tissues to one another
 Defending the body against infection
macrophages, plasma cells, mast cells, WBCs
 Storing nutrients as fat
 Cushioning and insulating

39. MAJOR CELLS OF THE CONNECTIVE
TISSUE
 Fibroblast- star-shape, produce fibres (collagen)
by secreting protein into the matrix of the
connective tissue.
 Macrophages- specialized to carry on
phagocytosis, defend against infections agents
-monocytes in blood
- Phagocytes in the alveoli of the lungs
-kupffer cells in liver
-fibroblasts in lymph nodes and spleen
-microglial cells in the brain

40. MAJOR CELLS cont.
 Mast Cells- found in loose connective
tissue
- under the fibrous capsule of some
organs
 release heparin- that prevent blood
clotting
 Histamine- that promotes some of the
reactions associated with inflammation
and allergies

41. 41
Connective Tissue
Fiber Types Present
• Collagenous fibers
• Thick
• Composed of collagen
• Great tensile strength
• Abundant in dense CT
• Hold structures
together
• Tendons, ligaments
• Elastic fibers
• Bundles of
microfibrils embedded
in elastin
• Fibers branch
• Elastic
• Vocal cords, air
passages
• Reticular fibers
• Very thin collagenous fibers
• Highly branched
• Form supportive networks

43. Classes of Connective Tissue
*

44. 1. Loose connective tissue
■ Loose (areolar) connective tissue has many
different cell types and a random arrangement of
protein fibers with space between the fibers. This
tissue fills spaces around the organs and attaches
the skin to underlying tissues.
2.Dense connective tissue
■ Dense regular connective tissue is composed of
fibers arranged in one direction, which provides
strength in a direction parallel to the fiber
orientation. Two types of dense regular connective
tissue exist: collagenous (tendons and most
ligaments) and elastic (ligaments of vertebrae).

45.  Dense irregular connective tissue has
fibers organized in many directions, which
produces strength in different directions.
 Two types of dense irregular connective
tissue exist: collagenous (capsules of
organs and dermis of skin) and elastic
(large arteries).

46.  Connective tissue with special properties
•
Adipose tissue has fat cells (adipocytes) filled with
lipid and very little extracellular matrix (a few
reticular fibers).
Adipose tissue functions as energy storage,
insulation, and protection. Adipose tissue can be
yellow (white) or brown. Brown fat is specialized
for generating heat.
Reticular tissue is a network of reticular fibers and
forms the framework of lymphoid tissue, bone
marrow, and the liver.
Hemopoietic tissue, or red bone marrow, is the site
of blood cell formation, and yellow bone marrow is
a site of fat storage.

50. *
Classes of Connective Tissue

53. *
Classes of Connective Tissue

54. 4. Cartilage
Cartilage has a relatively rigid matrix composed of
protein fibers and proteoglycan aggregates. The
major cell type is the chondrocyte, which is located
within lacunae.
Hyaline cartilage has evenly dispersed collagen
fibers that provide rigidity with some flexibility.
Examples include the costal cartilage, the covering
over the ends of bones in joints, the growing
portion of long bones, and the embryonic skeleton.

57. Fibrocartilage has collagen fibers arranged
in thick bundles; it can withstand great
pressure, and it is found between vertebrae,
in the jaw, and in the knee.
Elastic cartilage is similar to hyaline
cartilage, but it has elastin fibers. It is more
flexible than hyaline cartilage. It is found in
the external ear.

59. Classes of Connective Tissue
*

60. Bone
Bone cells, or osteocytes, are located in
lacunae that are surrounded by a
mineralized matrix (hydroxyapatite) that
makes bone very hard. Cancellous bone has
spaces between bony trabeculae, and
compact bone is more solid.

62. Classes of Connective Tissue
*

63. Blood and hemopoietic tissue
■ Blood cells are suspended in a fluid
matrix.
■ Hemopoietic tissue forms blood cells.

65.  Four basic types of tissue
Epithelium
Connective tissue
Muscle tissue
 Skeletal
 Cardiac
 Smooth
Nervous tissue

66. 66
5.5: Muscle Tissues
• General characteristics:
• Muscle cells also called
muscle fibers
• Contractile
• Three (3) types:
• Skeletal muscle
• Smooth muscle
• Cardiac muscle
• Skeletal muscle
• Attached to bones
• Striated
• Voluntary
• Smooth muscle
• Walls of organs
• Skin
• Walls of blood vessels
• Involuntary
• Non-striated
• Cardiac muscle
• Heart wall
• Involuntary
• Striated
• Intercalated discs

67. Muscle Tissue
 1. Muscle tissue has the ability to contract, or shortens
2. Skeletal (striated(banded) voluntary) muscle attaches to
bone and is responsible for body movement. Skeletal
muscle cells are long, cylindrically shaped cells with many
peripherally located nuclei.
3. Cardiac (striated involuntary) muscle cells are cylindrical,
branching cells with a single, central nucleus. Cardiac
muscle is found in the heart and is responsible for pumping
blood through the circulatory system.
4. Smooth (nonstriated involuntary) muscle forms the walls
of hollow organs, the iris of the eye, and other structures.
Its cells are spindle shaped with a single, central nucleus.

71.  Four basic types of tissue
Epithelium
Connective tissue
Muscle tissue
Nervous tissue
Neurons
Supporting cells

73.  It is found in the brain, spinal cord, and
nerves and is characterized by the ability
to conduct electric signals called action
potentials
 It consists of neurons, which are
responsible for this conductive ability, and
support cells called neuroglia.
 Neurons , or nerve cells, are the
conducting cells of nervous tissue.
 They are composed of three major parts:
cell body, dendrites, and axon.

74.  Neuron- basic
structural unit of the
nervous system
 Dendrites- carry
impulses towards the
cell
 Axon-carry impulses
away from the cell
 Myelin sheath
 Synaptic terminal
 Epinephrine
 Norepinephrine
 Acetylcholine

75.  Neurons that possess several dendrites
and one axon are called multipolar
neurons
 Neurons that possess a single dendrite
and an axon are called bipolar neurons
 unipolar neurons have only one axon
and no dendrites

76. Membranes that combine epithelial
sheets plus underlying connective tissue
proper (see next slide)
 Cutaneous membranes
 Skin: epidermis and dermis
 Mucous membranes, or mucosa
 Lines every hollow internal organ that opens to the
outside of the body
 Serous membranes, or serosa
 Slippery membranes lining the pleural, pericardial and
peritoneal cavities
 The fluid formed on the surfaces is called a transudate
 Synovial membranes
 Line joints

77. (a) Cutaneous membrane
(b) Mucous membrane
(c) Serous membrane

78. Tissue response to injury
 Immune: takes longer and is highly specific
 Inflammation
 Nonspecific, local, rapid
 Signs: heat, swelling, redness, pain
 Repair – two ways
 Regeneration
 Fibrosis and scarring
 Severe injuries
 Cardiac and nervous tissue

79. Inflammation
 The inflammatory response occurs when
tissues are damaged or associated with an
immune response
 Agents that cause injury, microorganisms,
cold, heat, radiant energy, chemicals,
electricity, and mechanical trauma
 Infla. removes foreign materials and
damaged cells so that tissue repair can
proceed

80.  After a person is injured, chemical
substances called mediators of
inflammation are released in the tissues
and the adjacent blood vessels.
 The mediators include histamine, kinins,
prostaglandins, leukotrienes, and others
 Some mediators induce dilation of blood
vessels and produce redness and heat
 some also stimulate pain receptors and
increase the permeability of blood vessels
 which leads edema

81. Tissue Repair
1. Tissue repair is the substitution of viable cells for dead ones. Tissue
repair occurs by regeneration or replacement.
■ Labile cells divide throughout life and can undergo regeneration.eg skin,
mucous membranes, and hemopoietic and lymphatic tissues,
■ Stable cells do not ordinarily divide after growth is complete but can
regenerate if necessary.eg liver, pancreas, and endocrine glands
■ Permanent cells cannot replicate. If killed, permanent tissue is repaired by
replacement. Eg. Neurons
2. Tissue repair by primary union occurs when the edges of the wound
are close together.
Secondary union occurs when the edges are far apart.

82. Tumors (neoplasms): abnormal growth
of cells
 Adenoma – neoplasm of glandular
epithelium, benign or malignant
 Carcinoma – cancer arising in an
epithelium (90% of all human cancers)
 Sarcoma – cancer arising in mesenchyme-
derived tissue (connective tissues and
muscle)

83. Thanks
Any question