1. Unit 3: Histology Anatomy and Physiology
PART 2: Connective Tissue

2. Histology
Histology is defined as the study of the microanatomy of animal and plant tissues
A tissue is a group of like cells of similar specialized structure which carry out similar specific functions.

3. 4 types of tissues
A tissue is a group of like cells of similar specialized structure which carry out specific functions.
Groups of tissues compose and work together to form organs.
All organs are composed of two or more types of tissues.
There are four major tissue types:
Epithelial
Connective
Muscle
Nervous

4. 2. Connective Tissue

5. 2. Connective Tissue A. Locations
Found everywhere in the body
Includes the most abundant and widely distributed tissues

6. 2. Connective Tissue B. Functions
Binds body tissues together
Supports the body
Provides protection

7. 2. Connective tissues: C. Characteristics
Connective tissues get their name because they attach or hold different tissue types together.
Produce materials which they secrete in their extracellular space to form the extracellular matrix
Extracellular matrix:
Non-living material that surrounds living cells

8. 2. Connective tissues: C. Characteristics
Often the cells are very scattered about and few in number.
This is why some connective tissues take long periods of time to heal when damaged (cartilage and bone).
Variations in blood supply
Some tissue types are well vascularized
Some have a poor blood supply or are avascular

9. 2. Connective tissues: C. Characteristics
The matrix varies depending on the connective tissue type.
Bones: are hard, solid, crystalline structure
Cartilages: flexible
Tendons and ligaments: composed of protein fibers
Dermis of skin: sponge-like rich in
Adipose: soft
Plasma of blood: liquid

10. D. Examples of Connective Tissue

11. 2. Connective tissues: D. Examples
Loose irregular connective tissue
Loose reticular connective tissue
Adipose tissue
Dense regular connective tissue
Dense irregular connective tissue
Hyaline cartilage
Elastic cartilage
Fibrocartilage
Bone
Blood

12. 2. Connective tissues: Examples I. Loose Irregular
Name: Loose irregular connective
Structure: Areolar tissue has a gel like matrix with cells called fibroblasts
Fibroblasts:
produce two types of protein fibers, collagen (larger) and elastin (small thread-like).
Areolar:
Soft, pliable tissue like “cobwebs”

13. 2. Connective tissues: Examples I. Loose Irregular
Location:
Most widely distributed connective tissue
Around the organs, under mucus membrane epithelial and surrounding capillaries.

14. 2. Connective tissues: Examples I. Loose Irregular
Functions:
Functions as a packing tissue
Holds and conveys tissue fluid.
Can soak up excess fluid (causes edema)

15. 2. Connective tissues: Examples I. Loose Irregular

16. 2. Connective tissues: Examples I. Loose Irregular
Mucosa
epithelium
Lamina
propria
Elastic
fibers
Collagen
fibers
Fibers of
matrix
Fibroblast
nuclei
Nuclei of
fibroblasts
(e) Diagram: Areolar
Photomicrograph: Areolar connective tissue, a
soft packaging tissue of the body (300×).
Figure 3.19e

17. 2. Connective tissues: Examples ii. Loose Reticular
Name: Loose reticular connective tissue
Structure: Has a network of collagen reticular fibers, which have a netted arrangement.
Location: This tissue composes the spleen, the lymph nodes, and the bone marrow.

18. 2. Connective tissues: Examples ii. Loose Reticular
Function:
These fibers form a soft internal skeleton (stroma) that supports other cell types,
Particularly erythrocytes (red blood cells) and leukocytes (white blood cells

19. 2. Connective tissues: Examples ii. Loose Reticular
Spleen
White blood cell
(lymphocyte)
Reticular
cell
Reticular fibers
Blood
cell
Reticular
fibers
(g) Diagram: Reticular
Photomicrograph: Dark-staining network
of reticular connective tissue (430×).
Figure 3.19g

20. 2. Connective tissues: Examples ii. Loose Reticular

21. 2. Connective tissues: Examples iiI. Adipose Tissue
Name: Adipose tissue
Location: under the skin, around the kidneys, heart, within the abdomen, and breasts of females

22. Connective Tissues Types Adipose Tissue Distribution

23. 2. Connective tissues: Examples iiI. Adipose Tissue
Structure:
Matrix is an areolar tissue composed of collagen and elastin fibers
Adipocytes (fat cells) are present: large cells with their nuclei pushed to the side by large lipid (fat) deposits
Functions:
Insulates the body
Protects some organs
Serves as a site of fuel storage

24. 2. Connective tissues: Examples iiI. Adipose Tissue
Nuclei of
fat cells
Vacuole
containing
fat droplet
Nuclei of
fat cells
Vacuole
containing
fat droplet
(f) Diagram: Adipose
Photomicrograph: Adipose tissue from the
subcutaneous layer beneath the skin (430×).
Figure 3.19f

25. 2. Connective tissues: Examples iV. Dense Regular
Name: Dense regular connective tissue (dense fibrous tissue)
Structure:
Main matrix element is collagen fibers tightly packed together.
Some elastin fibers are present.
Fibroblast (cells that make fibers) are present

26. 2. Connective tissues: Examples iV. Dense Regular
Locations:
Tendons—attach skeletal muscle to bone
Ligaments—attach bone to bone at joints
Dermis—lower layers of the skin

27. 2. Connective tissues: Examples iV. Dense Regular

28. 2. Connective tissues: Examples iV. Dense Regular
Functions:
Can withstand great pulling force when it is applied in one direction.
Attaches muscles to bone or muscles to muscles.

29. 2. Connective tissues: Examples iV. Dense Regular
Ligament
Tendon
Collagen
fibers
Collagen
fibers
Nuclei of
fibroblasts
Nuclei of
fibroblasts
(d) Diagram: Dense fibrous
Photomicrograph: Dense fibrous connective tissue
from a tendon (500×).
Figure 3.19d

30. Video Clip Dense Regular: 2:22
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31. 2. Connective tissues: Examples V. Dense Irregular
Name: Dense irregular connective
Structure:
Matrix is primarily composed of collagen and elastin fibers irregularly arranged (not parallel).
Fibroblast are the cells present and produce the matrix

32. 2. Connective tissues: Examples V. Dense Irregular
Location: in the dermis of the skin, the submucosa of the digestive tract and the fibrous capsules surrounding certain joints and organs.
Function:
This tissue is able to withstand tension or stress exerted in many directions.
Also provides structural strength.

33. 2. Connective tissues: Examples V. Dense Irregular

34. 2. Connective tissues: Examples VI. Cartilage
Cartilage General Structure:
Cartilage is a connective tissue which has qualities between dense connective tissue and bone.
Cells called chondroblasts secrete the matrix.
When the cells mature they are trapped within cavities called lacunae.
These mature cells surrounded by matrix are called chondrocytes
Avascular and lacks nerve fibers

35. 2. Connective tissues: Examples VI. Cartilage
There are three types of cartilages and they differ in the composition of their matrix:
Hyaline cartilage
Elastic cartilage
Fibrocartilage

36. 2. Connective tissues: Examples VI. Hyaline Cartilage
Name: Hyaline cartilage (most common type of cartilage in body)
Structure:
The matrix is amorphous (without any particular shape) and rubbery
Has a network of collagen fibers present that are not visible.
It appears bluish white and glassy (semi- translucent)

37. 2. Connective tissues: Examples VI. Hyaline Cartilage
Location:
At the end of long bones
Forms the cartilages of the rib cage, nose, trachea, and larynx (Adam’s apple)
Entire fetal skeleton prior to birth
Function:
Support, reinforcement, cushioning, and resistance to compressive stress

38. 2. Connective tissues: Examples VI. Hyaline Cartilage
In a young child the majority of the appendicular skeleton is composed of this type of cartilage which is eventually replaced by bone tissue as the child matures.

39. 2. Connective tissues: Examples VI. Hyaline Cartilage

40. Chondrocyte
(Cartilage cell)
Chondrocyte
in lacuna
Lacunae
Matrix
(b) Diagram: Hyaline cartilage
Photomicrograph: Hyaline cartilage
from the trachea (500×).
Figure 3.19b

41. 2. Connective tissues: Examples VII. Elastic Cartilage
Name: Elastic cartilage
Structure:
The matrix is similar to hyaline cartilage – amorphous with collagen fibers
BUT the matrix is rich in elastin fibers which are visible and usually stain dark purple.
Location: It is located in the pinna (outer ear) and the epiglottis of the throat.
Function: This cartilage maintains the shape of a structure while allowing great flexibility.

42. 2. Connective tissues: Examples VII. Elastic Cartilage

43. 2. Connective tissues: Examples VIII. Fibrocartilage
Name: Fibrocartilage
Structure:
The matrix of this cartilage is less firm than that of hyaline cartilage
has many thick, visible collagen fibers present
Location: intervertebral discs, the knee and the pubic symphysis.
Function: the absorption of compressive shock

44. 2. Connective tissues: Examples VIII. Fibrocartilage

45. 2. Connective tissues: Examples VIII. Fibrocartilage
Chondrocytes
in lacunae
Chondro-
cites in
lacunae
Collagen fiber
Collagen
fibers
(c) Diagram: Fibrocartilage
Photomicrograph: Fibrocartilage of an
intervertebral disc (110×).
Figure 3.19c

46. Cartilage Video Clips Hyaline Cartilage: 4:27
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Elastic Cartilage: 1:58
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Fibrocartilage: 1:48
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47. 2. Connective tissues: Examples IX. Osseous Tissue
Name: Bone or Osseous tissue
Structure:
Bone tissue matrix is secreted by cells called osteoblasts.
The matrix is composed of collagen fibers and calcium (hydroxyapeptite crystals).
The bone matrix is constantly being broken and reabsorbed by cells called osteoclasts.

48. 2. Connective tissues: Examples IX. Osseous Tissue
Structure (cont’d):
The cells which are in the lacunae and surrounded by the matrix are called osteocytes.
The bone tissue is highly vascularized and has nerve fibers present.
The blood vessels and nerve supply are located in tunnel-like structures which run through the matrix called Harversian Canals.

49. Bone cells in
lacunae
Central canal
Lacunae
Lamella
(a) Diagram: Bone
Photomicrograph: Cross-sectional view
of ground bone (300×).
Figure 3.19a

50. 2. Connective tissues: Examples IX. Osseous Tissue
Function:
Support, protection,
Provides levers to which muscles act on to produce movement,
Storage of calcium, phosphorous, and other mineral
The marrow inside the bone is the site of blood cell production

51. 2. Connective tissues: Examples IX. Osseous Tissue

52. 2. Connective tissues: Examples X. Blood
Name: Blood
Function: transport of nutrients and the removal of waste from the body’s tissues
Structure:
Blood is composed of formed elements (cells) suspended in a fluid matrix called plasma.
Fibers are visible during clotting

53. 2. Connective tissues: Examples X. Blood

54. 2. Connective tissues: Examples X. Blood
Structure (cont’d):
There are three types of formed elements, each with a specific function.
Erythrocytes or red blood cells function in the transport of oxygen.
Leukocytes or white blood cells are involved with our body’s defense against infection.
Thrombocytes or platelets are actually fragments of cells which are involved in blood clot formation to prevent blood loss.

55. 2. Connective tissues: Examples X. Blood
Blood cells
in capillary
Neutrophil
(white blood
cell)
White
blood cell
Red blood
cells
Monocyte
(white blood
cell)
Red
blood cells
(h) Diagram: Blood
Photomicrograph: Smear of human blood (1300×)
Figure 3.19h

56. Video Clips Blood Smear: 6:10
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