1. Module #2 Histology
Histology – the study of
tissues
Four tissue types:
Epithelial
Connective
Muscle
Nerve

2. Epithelial
Tissue
http://lima.osu.edu/biology/images/anatomy/Stratified%20squamous%20epithelium%20400X.jpg

3. General Features of Epithelial Tissue
•Cells are closely packed with little
extracellular material (between cells)
•Are in continuous sheets
•Single or multiple layered

4. General Features of Epithelial Tissue
•Epithelia is avascular meaning
“without blood vessels”.
•Nutrients and wastes are exchanged
by diffusion with the adjacent
connective tissue.

5. General Features of Epithelial Tissue
•have a free surface which is
exposed to a body cavity, lining of an
internal organ, or the exterior of the
body, and
• a basal surface which is
attached to the basement
membrane.

6. basal
surface

7. General Features of Epithelial Tissue
•Subject to wear, tear and injury, so
has a high capacity for renewal (high
mitotic rate).
•Functions include protection,
filtration, lubrication, secretion,
digestion, absorption, transportation,
excretion, sensory reception, and
reproduction.

8. General Features of Epithelial Tissue
•Epithelial tissue sits on a basement
membrane located between it and
the tissue underneath.
Epithelial tissue
Connective tissue
http://www.ouhsc.edu/histology/Glass%20slides/13_04.jpg

9. Epithelial Tissue con’t
There are two kinds epithelial tissue
based on function:
(1) lining
or covering epithelium –
covers the skin and outside of some
internal organs, forms the inner
lining of body cavities, blood vessels,
and internal organs.

10. Epithelial Tissue con’t
There are two kinds epithelial tissue (function):
(2) glandular epithelium -
consists of cells that secrete
substances. (ex. Thyroid/sweat/oil
glands)

11. Epithelial tissue can be divided
into categories based on……
>the shape of the cells and
> the number of layers of cells.

12. SHAPES of epithelium:
1. Squamous
-flat cells
-thin which allows substances to pass
through (diffuse) them.
-have limited cell structures due to size

13. 2. Cuboidal
cube shaped
Important in secretion and
absorption
Have more cell structures than
squamous
Uses active transport to secrete and
absorb substances

15. 3. Columnar
 cells are tall and cylindrical
 Have the most cell structures
 Most complex
 Most secretion ability

16. 4. Transitional
•cells can readily change shape
from squamous to columnar
•change shape due to stretching, of
body parts. (ex. Found in bladder)

17. Arrangement of Layers
1. Simple epithelium
a single layer of cells
found in areas where diffusion,
osmosis, filtration, secretion
and absorption occur.
Can be squamous, columnar,
or cuboidal
Ex. lungs

21. Arrangement of Layers
2. Stratified epithelium
 contains two or more layers of cells
 protects underlying tissues
 found where there is wear and tear
Ex. Skin
 Named by the free surface.

24. Arrangement of Layers
3. Pseudostratified epithelium
contains a single layer of a mixture
of cell types
has a stratified appearance
but is a single layer
All cells touch basement
membrane

26. Glandular Epithelium
Columnar epithelium that contains
special cells capable of synthesizing and
secreting certain substances such as
enzymes, hormones, milk, mucus, sweat,
wax and saliva

27. Glandular Epithelium
Goblet cells :
Special columnar cells that their
function is to secret mucin which
mixes with water to form mucous -
intestines

28. Goblet
cell

29. Glandular Epithelium
There are two types of
glands:
1. Exocrine glands
• secrete their products to the
target by ducts
• most glands in the body are
exocrine glands
(sweat/salivary)

30. Exocrine Gland

31. Exocrine glands come in many
arrangements/types:

32. Glandular Epithelium
There are two types of glands:
1. Exocrine glands
Types of exocrine glands based on how
they secrete:
a. Merocrine glands – by exocytosis
(without losing cellular material) into
the duct.
Example sweat glands.

33. Merocrine gland directly secretes
into duct.
http://www.med.umich.edu/histology/fieldTrip/sweatGland.jpg

34. Glandular Epithelium
There are two types of glands:
1. Exocrine glands
Types of exocrine glands based on how they secrete:
a. Merocrine glands
b. Apocrine glands - a portion
of the plasma membrane containing
the secretion and some cytoplasm
buds off the cell and enters the duct.
Ex. Mammary glands

35. Apocrine Gland

36. There are two types of glands:
1. Exocrine glands
Types of exocrine glands based on how they secrete:
a. Merocrine glands
b. Apocrine glands
c.holocrine gland - the entire
cell containing its secretion
disintegrates in the duct.
Ex. Oil glands

38. Glandular Epithelium
There are two types of glands:
1. Exocrine glands
2. Endocrine gland
no ducts
secrete hormones by exocytosis into
interstitial fluids that surround cells
and blood stream picks them up.
Ex. Thyroid gland

39. Endocrine Glands

40. Epithelial Tissue – Functions and locations
Handout
Type Function Location
Simple Squamous Diffusion Blood vessels, lungs
Simple Cuboidal Diffusion and secretion Kidneys
Simple Columnar Mucous producing Stomach and intestines
Stratified Squamous Protection, secreting Skin, lining mouth
Stratified Cuboidal Protection, secreting Protect Salivary glands -
rare
Stratified Columnar Protection, secreting Pharynx, larynx, uterus -
rare
Stratified Transitional Stretches, changes shape Urinary bladder

41. Why does skin flake off? Cells at
top of skin are so far from nutrients that
they are dead.
Keratin – protein that fills dead
epidermal cells at top layer
Keratinized membrane – top layer
of skin cells that are dead and filled with
keratin.

42. Where quiz stops

43. CONNECTIVE TISSUE
FUNCTION: insulate, support
and bind (infrastructure)

44. CONNECTIVE TISSUE continued
CHARACTERISTICS:
Greater space between cells
(extracellular space) compared to
epithelial tissue
cells secrete extracellular
material or MATRIX which fills
space between cells

45. CONNECTIVE TISSUE continued
CHARACTERISTICS:
Matrix is the
material between the
cell which contains
ground substance
(non-collagenous part
of matrix) and
collagen protein

46. CONNECTIVE TISSUE continued
CHARACTERISTICS:
Connective Tissue is
classified according to the
type of extracellular
matrix it produces

47. CONNECTIVE TISSUE
TYPES:
1. connective tissue proper
2. cartilage
3. bone
4. blood

48. TYPE 1: Connective Tissue
Proper
Guess how many kinds of
connective tissue proper
there are?
4

49. TYPE 1: Connective Tissue Proper
Four types of Connective Tissue
Proper:
A. Loose connective tissue
Extracellular matrix is not strong
Is used for light binding and
flexibility
Also called areolar connective
tissue

50. TYPE 1: Connective Tissue Proper
Four types of Connective Tissue Proper:
A. Loose connective tissue
Found between the skin and the
muscles holding the skin to muscles
Has fibroblasts which make tissue’s
ground substance, protein fibers,
collagen fibers
 Mature fibroblast are called
fibrocytes

51. Loose Connective Tissue Proper
fibroblast

52. Four types of Connective Tissue Proper:
A. Loose connective tissue
B.Dense irregular connective
tissue
Part of the skin
Collagen fibers more
densely packed than loose
connective tissue

53. B. dense irregular connective tissue continued
Denser packing give tissue
more strength
Irregular because fibers
run every which way

54. Dense irregular connective
tissue proper

55. Four types of Connective Tissue Proper:
A. Loose connective tissue
B. Dense irregular connective tissue
C. Dense regular connective
tissue proper
Collagen fibers run in one
direction giving more
strength called tensile
strength
Found in tendons which hold
muscle to bones and
ligaments that hold bone to

56. c. Dense regular connective tissue proper
Tendons and
ligaments take a long
time to heal when
injured because of
dense amount of

57. Dense regular connective tissue
proper

58. Four types of Connective Tissue Proper:
A. Loose connective tissue
B. Dense irregular connective tissue
C. Dense regular connective tissue proper
D. Adipose tissue
Fatty tissue
it has fat cells in it as well
as connective tissue cells

59. D. Adipose tissue
Function is to store
energy, insulate, and
to hold organs in
place
Example – kidneys are
protected and held in
place by adipose tissue

61. CONNECTIVE TISSUE
TYPES:
1. connective tissue proper
2. Cartilage
 Supporting connective
tissue with tensile
strength and
supporting fibers of
collagen in the ground
substance

62. CONNECTIVE TISSUE
TYPES:
1. connective tissue proper
2. Cartilage
• Firmer than connective
tissue proper
• Has no blood supply
• Thin matrix
• Found in nose, ear,
larynx
• Often replaced by bone

63. CONNECTIVE TISSUE
TYPES:
1. connective tissue proper
2. Cartilage
Chondroblasts – immature
cartilage cells that produce
the matrix fibers.

64. CONNECTIVE TISSUE
TYPES:
1. connective tissue proper
2. Cartilage
Chondrocytes – mature
chondroblast that become
trapped in matrix and live
in hollow spaces called
lacuna in the cartilage
tissue.

65. Lacuna (histology),
a small space
containing an
osteocyte in bone
or chondrocyte in
cartilage

66. CONNECTIVE TISSUE
TYPES:
1. connective tissue proper
2. Cartilage
3 types of cartilage:
A. Hyaline cartilage
 occurs at end of bones, external
ear, fetal skeleton, nose, ribs and
vertebrae
 Weakest and most common

67. CONNECTIVE TISSUE
TYPES:
1. connective tissue proper
2. Cartilage
3 types of cartilage:
B. Elastic cartilage
 found in epiglottis and external
ear
 contains elastic fibers
 great flexibility and is able to
withstand repeated bending

68. CONNECTIVE TISSUE
TYPES:
1. connective tissue proper
2. Cartilage
3 types of cartilage:
C. Fibrous cartilage
 Strongest
 Dense collagen fibers with limited
ground substance
 Found in disk between vertebrae and
skull
 Where bears great amount of weight
 Has fibrous appearance

69. CONNECTIVE TISSUE - Cartilage

70. CONNECTIVE TISSUE
TYPES:
1. connective tissue proper
2. Cartilage
3. Bone:
 Hardest connective
tissue
 Consist of cells, collagen
fibers, and mineralized
(calcium and phosphate)
ground substance

71. CONNECTIVE TISSUE
TYPES:
1. connective tissue proper
2. Cartilage
3. Bone:
 Ground substance
becomes hard or
calcified through a
process known as
calcification

72. CONNECTIVE TISSUE
TYPES:
1. connective tissue proper
2. Cartilage
3. Bone:
 Has a rich blood supply
 Properly known as
osseous tissue

73. CONNECTIVE TISSUE
TYPES:
1. connective tissue proper
2. Cartilage
3. Bone
Types of bone cells:
A. Osteoblasts- make
components of bone

74. CONNECTIVE TISSUE
TYPES:
1. connective tissue proper
2. Cartilage
3. Bone
Types of bone cells:
B. Osteocytes – mature
osteoblasts found in
lacuna

75. CONNECTIVE TISSUE
TYPES:
1. connective tissue proper
2. Cartilage
3. Bone
Types of bone cells:
C. Osteoclasts – reasorb
bone and remodel it

77. CONNECTIVE TISSUE
TYPES:
1. connective tissue proper
2. Cartilage
3. Bone
4. Blood
 transports
 Also known as vascular
tissue
 Two types of cells – red
and white

78. CONNECTIVE TISSUE
TYPES:
1. connective tissue proper
2. Cartilage
3. Bone
4. Blood
 Ground substance =
proteins in blood
 Has fluid part – blood
plasma
 Has clotting fibers

79. QUIZ

80. New Topic: Membranes
Membrane = layers of
tissue
There are three categories of
membranes:

81. New Topic: Membranes
There are three categories of membranes:
1. Mucous
 found in linings of organ
systems that open to the outside

82. New Topic: Membranes
There are three categories of membranes:
1. Mucous
Ex. Respiratory system,
reproductive system, digestive
system
Traps foreign material

83. New Topic: Membranes
There are three categories of membranes:
2. Serous
 line the body cavities that do not
open directly to the outside
they cover the organs located in
those cavities

85. New Topic: Membranes
There are three categories of membranes:
2. Serous
 are covered by a thin layer of
serous fluid that lubricates and is
secreted by the epithelium

86. New Topic: Membranes
There are three categories of membranes:
2. Serous
Serous fluid lubricates the
membrane and reduces friction
and abrasion when organs move
against each other or the cavity
wall.

87. New Topic: Membranes
There are three categories of membranes:
3. Synovial membranes
 connective tissue membranes that
line the cavities of the freely
movable joints such as the shoulder,
elbow, and knee.

89. New Topic: Membranes
There are three categories of membranes:
3. Synovial membranes
secrete synovial fluid into the joint
cavity, and this lubricates cartilage
on the ends of the bones so that
they can move freely and without
friction.

90. New Topic: tissue repair
Remember: Tissues are made up of
cells.
Two types of cells that make up tissue
based on function:
1. Stromal cells – provide structure and
support to tissue; usually connective
tissue

91. New Topic: tissue repair
Remember: Tissues are made up of cells.
Two types of cells that make up tissue based on function:
1. Stromal cells – provide structure and support to tissue
2.Parenchymal cells – cells that
actually perform the function of
the tissue

92. Organ Parenchyma
kidney nephron
alveoli, respiratory
bronchiole, alveolar
lungs
duct and terminal
bronchiole
white pulp and red
spleen
pulp
brain neuron
liver hepatocyte

93. New Topic: tissue repair
Categories of cells based on ability to
reproduce or regenerate:
1. Labile cells
 cells that multiply constantly
throughout life
 Most of cells in body
 ex. Parenchymal epithelial cells
replace themselves quickly

94. New Topic: tissue repair
Categories of cells based on ability to reproduce or regenerate:
2. Stable cells
 only multiply when receive
external stimulus to do so
 ex. Bone parenchymal cells
when a bone is broken can
reproduce and repair the broken
bone

95. New Topic: tissue repair
Categories of cells based on ability to reproduce or regenerate:
3. Permanent cells
 do not have the ability to multiply
 Nervous system parenchymal
cells (neurons) are permanent;
can’t be replaced.

96. New Topic: tissue repair
So, if cells are parenchymal permanent
and die they will be replaced by labile
stromal cells..
This is why brain damage or heart
damage is said to be irreversible.