1. 4
Tissue: The Living Fabric: Part B

2. Most abundant and widely distributed of primary tissues
Connective Tissue
Most abundant and widely distributed of primary tissues
Four main classes
Connective tissue proper
Cartilage
Bone
Blood
© 2013 Pearson Education, Inc.

3. Table 4.1 Comparison of Classes of Connective Tissues (1 of 2)
© 2013 Pearson Education, Inc.

4. Table 4.1 Comparison of Classes of Connective Tissues (2 of 2)
© 2013 Pearson Education, Inc.

5. Major Functions of Connective Tissue
Binding and support
Protecting
Insulating
Storing reserve fuel
Transporting substances (blood)
© 2013 Pearson Education, Inc.

6. Characteristics of Connective Tissue
Three characteristics make connective tissues different from other primary tissues
Have mesenchyme (an embryonic tissue) as their common tissue of origin
Have varying degrees of vascularity (blood vessels)
Have extracellular matrix
Connective tissue not composed mainly of cells
Largely nonliving extracellular matrix separates cells
So can bear weight, withstand tension, endure abuse
© 2013 Pearson Education, Inc.

7. Structural Elements of Connective Tissue
Three elements
Ground substance
Fibers
Cells
Composition and arrangement varies in different connective tissues
© 2013 Pearson Education, Inc.

8. Connective Tissue Fibers
Three types of fibers provide support
Collagen
Strongest and most abundant type
Tough; provides high tensile strength
Elastic fibers
Networks of long, thin, elastin fibers that allow for stretch and recoil
Reticular
Short, fine, highly branched collagenous fibers (different chemistry and form than collagen fibers)
Branch, forming networks that offer more "give"
© 2013 Pearson Education, Inc.

9. Cells "Blast" cells "Cyte" cells
Immature form; mitotically active; secrete ground substance and fibers
Fibroblasts in connective tissue proper
Chondroblasts in cartilage
Osteoblasts in bone
Hematopoietic stem cells in bone marrow
"Cyte" cells
Mature form; maintain matrix
Chondrocytes in cartilage
Osteocytes in bone
© 2013 Pearson Education, Inc.

10. Other Cell Types in Connective Tissues
Fat cells
Store nutrients
White blood cells
Neutrophils, eosinophils, lymphocytes
Tissue response to injury
Mast cells
Initiate local inflammatory response against foreign microorganisms they detect
Macrophages
Phagocytic cells that "eat" dead cells, microorganisms; function in immune system
© 2013 Pearson Education, Inc.

11. Cell types Extracellular matrix Ground substance Macrophage Fibers
Figure 4.7 Areolar connective tissue: A prototype (model) connective tissue.
Cell types
Extracellular matrix
Ground substance
Macrophage
Fibers
• Collagen fiber
• Elastic fiber
• Reticular fiber
Fibroblast
Lymphocyte
Fat cell
Mast cell
Neutrophil
Capillary
© 2013 Pearson Education, Inc.

12. Types of Connective Tissues: Connective Tissue Proper
All connective tissues except bone, cartilage and blood
Two subclasses
Loose connective tissues
Areolar
Adipose
Reticular
Dense connective tissues (also called fibrous connective tissues)
Dense regular
Dense irregular
Elastic
© 2013 Pearson Education, Inc.

13. Areolar Connective Tissue
Support and bind other tissues
Universal packing material between other tissues
Most widely distributed
Provide reservoir of water and salts
Defend against infection
Store nutrients as fat
Fibroblasts
Loose arrangement of fibers
Ground substance
When inflamed soaks up fluid  edema
© 2013 Pearson Education, Inc.

14. Figure 4.8a Connective tissues.
Connective tissue proper: loose connective tissue, areolar
Description: Gel-like matrix with all three fiber types; cells: fibroblasts, macrophages, mast cells, and some white blood cells.
Function: Wraps and cushions organs; its macrophages phagocytize bacteria; plays important role in inflammation; holds and conveys tissue fluid.
Elastic fibers
Ground substance
Location: Widely distributed under epithelia of body, e.g., forms lamina propria of mucous membranes; packages organs; surrounds capillaries.
Fibroblast nuclei
Collagen fibers
Epithelium
Photomicrograph: Areolar connective tissue, a soft packaging tissue of the body (340x).
Lamina propria
© 2013 Pearson Education, Inc.

15. Adipose Tissue White fat Brown fat
Similar to areolar but greater nutrient storage
Cell is adipocyte
Stores nutrients
Scanty matrix
Richly vascularized
Shock absorption, insulation, energy storage
Brown fat
Use lipid fuels to heat bloodstream not to produce ATP
© 2013 Pearson Education, Inc.

16. Figure 4.8b Connective tissues.
Connective tissue proper: loose connective tissue, adipose
Description: Matrix as in areolar, but very sparse; closely packed adipocytes, or fat cells, have nucleus pushed to the side by large fat droplet.
Function: Provides reserve food fuel; insulates against heat loss; supports and protects organs.
Nucleus of adipose (fat) cell
Location: Under skin in subcutaneous tissue; around kidneys and eyeballs; within abdomen; in breasts.
Fat droplet
Adipose tissue
Photomicrograph: Adipose tissue from the subcutaneous layer under the skin (350x).
Mammary glands
© 2013 Pearson Education, Inc.

17. Reticular Connective Tissue
Resembles areolar but fibers are reticular fibers
Fibroblasts called reticular cells
Supports free blood cells in lymph nodes, the spleen, and bone marrow
© 2013 Pearson Education, Inc.

18. Figure 4.8c Connective tissues.
Connective tissue proper: loose connective tissue, reticular
Description: Network of reticular fibers in a typical loose ground substance; reticular cells lie on the network.
Function: Fibers form a soft internal skeleton (stroma) that supports other cell types including white blood cells, mast cells, and macrophages.
White blood cell
(lymphocyte)
Location: Lymphoid organs (lymph nodes, bone marrow, and spleen).
Reticular fibers
Spleen
Photomicrograph: Dark-staining network of reticular connective tissue fibers forming the internal skeleton of the spleen (350x).
© 2013 Pearson Education, Inc.

19. Dense Regular Connective Tissue
Closely packed bundles of collagen fibers running parallel to direction of pull
White structures with great resistance to pulling
Fibers slightly wavy so stretch a little
Fibroblasts manufacture fibers and ground substance
Few cells
Poorly vascularized
© 2013 Pearson Education, Inc.

20. Figure 4.8d Connective tissues.
Connective tissue proper: dense connective tissue, dense regular
Description: Primarily parallel
collagen fibers; a few elastic fibers;
major cell type is the fibroblast.
Function: Attaches muscles to
bones or to muscles; attaches
bones to bones; withstands great
tensile stress when pulling force is
applied in one direction.
Collagen
fibers
Location: Tendons, most
ligaments, aponeuroses.
Nuclei of
fibroblasts
Shoulder
joint
Ligament
Photomicrograph: Dense regular connective
tissue from a tendon (430x).
Tendon
© 2013 Pearson Education, Inc.

21. Dense Irregular Connective Tissue
Same elements but bundles of collagen thicker and irregularly arranged
Resists tension from many directions
Dermis
Fibrous joint capsules
Fibrous coverings of some organs
© 2013 Pearson Education, Inc.

22. Figure 4.8e Connective tissues.
Connective tissue proper: dense connective tissue, dense irregular
Description: Primarily irregularly
arranged collagen fibers; some
elastic fibers; fibroblast is the
major cell type.
Nuclei of
fibroblasts
Function: Withstands tension
exerted in many directions;
provides structural strength.
Location: Fibrous capsules of
organs and of joints; dermis of the
skin; submucosa of digestive tract.
Collagen
fibers
Shoulder
joint
Fibrous
joint
capsule
Photomicrograph: Dense irregular connective
tissue from the fibrous capsule of a joint (430x).
© 2013 Pearson Education, Inc.

23. Elastic Connective Tissue
Some ligaments very elastic
Those connecting adjacent vertebrae
Many of larger arteries have in walls
© 2013 Pearson Education, Inc.

24. Figure 4.8f Connective tissues.
Connective tissue proper: dense connective tissue, elastic
Description: Dense regular
connective tissue containing a
high proportion of elastic fibers.
Function: Allows tissue to recoil
after stretching; maintains pulsatile
flow of blood through arteries; aids
passive recoil of lungs following
inspiration.
Location: Walls of large arteries;
within certain ligaments associated
with the vertebral column; within
the walls of the bronchial tubes.
Elastic
fibers
Aorta
Heart
Photomicrograph: Elastic connective tissue
in the wall of the aorta (250x).
© 2013 Pearson Education, Inc.

25. Cartilage Chondroblasts and chondrocytes Tough yet flexible
Lacks nerve fibers
Up to 80% water - can rebound after compression
Avascular
Receives nutrients from membrane surrounding it
Perichondrium
Three types of cartilage:
Hyaline cartilage
Elastic cartilage
Fibrocartilage
© 2013 Pearson Education, Inc.

26. Figure 4.8g Connective tissues.
Cartilage: hyaline
Description: Amorphous but firm
matrix; collagen fibers form an
imperceptible network;
chondroblasts produce the matrix
and when mature (chondrocytes)
lie in lacunae.
Function: Supports and reinforces;
serves as resilient cushion; resists
compressive stress.
Chondrocyte
in lacuna
Location: Forms most of the
embryonic skeleton; covers the
ends of long bones in joint cavities;
forms costal cartilages of the ribs;
cartilages of the nose, trachea, and
larynx.
Matrix
Costal
cartilages
Photomicrograph: Hyaline cartilage from
a costal cartilage of a rib (470x).
© 2013 Pearson Education, Inc.

27. Figure 4.8h Connective tissues.
Cartilage: elastic
Description: Similar to hyaline
cartilage, but more elastic fibers
in matrix.
Function: Maintains the shape of
a structure while allowing great
flexibility.
Chondrocyte
in lacuna
Matrix
Location: Supports the external
ear (pinna); epiglottis.
Photomicrograph: Elastic cartilage from
the human ear pinna; forms the flexible
skeleton of the ear (800x).
© 2013 Pearson Education, Inc.

28. Figure 4.8i Connective tissues.
Cartilage: fibrocartilage
Description: Matrix similar to but
less firm than that in hyaline
cartilage; thick collagen fibers
predominate.
Function: Tensile strength allows
it to absorb compressive shock.
Location: Intervertebral discs;
pubic symphysis; discs of knee
joint.
Chondrocytes
in lacunae
Intervertebral
discs
Collagen
fiber
Photomicrograph: Fibrocartilage of an
intervertebral disc (125x). Special staining
produced the blue color seen.
© 2013 Pearson Education, Inc.

29. Bone Also called osseous tissue Supports and protects body structures
Stores fat and synthesizes blood cells in cavities
More collagen than cartilage
Has inorganic calcium salts
Osteoblasts produce matrix
Osteocytes maintain the matrix
Osteons – structural units
Richly vascularized
© 2013 Pearson Education, Inc.

30. Figure 4.8j Connective tissues.
Others: bone (osseous tissue)
Description: Hard, calcified
matrix containing many collagen
fibers; osteocytes lie in lacunae.
Very well vascularized.
Function: Supports and protects
(by enclosing); provides levers for
the muscles to act on; stores
calcium and other minerals and
fat; marrow inside bones is the
site for blood cell formation
(hematopoiesis).
Central
canal
Lacunae
Lamella
Location: Bones
Photomicrograph: Cross-sectional view
of bone (125x).
© 2013 Pearson Education, Inc.

31. Most atypical connective tissue – is a fluid
Blood
Most atypical connective tissue – is a fluid
Red blood cells most common cell type
Also contains white blood cells and platelets
Fibers are soluble proteins that precipitate during blood clotting
Functions in transport
© 2013 Pearson Education, Inc.

32. Figure 4.8k Connective tissues.
Connective tissue: blood
Description: Red and white blood
cells in a fluid matrix (plasma).
Red blood
cells
(erythrocytes)
Function: Transport respiratory
gases, nutrients, wastes, and other
substances.
White blood
cells:
• Lymphocyte
• Neutrophil
Location: Contained within blood
vessels.
Plasma
Photomicrograph: Smear of human blood
(1670x); shows two white blood cells
surrounded by red blood cells.
© 2013 Pearson Education, Inc.

33. Muscle Tissue Highly vascularized
Responsible for most types of movement
Three types
Skeletal muscle tissue
Found in skeletal muscle
Voluntary
Cardiac muscle tissue
Found in walls of heart
Involuntary
Smooth muscle tissue
Mainly in walls of hollow organs other than heart
© 2013 Pearson Education, Inc.

34. Figure 4.9a Muscle tissues.
Skeletal muscle
Description: Long, cylindrical,
multinucleate cells; obvious
striations.
Part of
muscle
fiber (cell)
Function: Voluntary movement;
locomotion; manipulation of the
environment; facial expression;
voluntary control.
Nuclei
Location: In skeletal muscles
attached to bones or occasionally
to skin.
Striations
Photomicrograph: Skeletal muscle
(approx. 440x). Notice the obvious banding
pattern and the fact that these large cells are
multinucleate.
© 2013 Pearson Education, Inc.

35. Figure 4.9b Muscle tissues.
Cardiac muscle
Description: Branching, striated,
generally uninucleate cells that
interdigitate at specialized
junctions (intercalated discs).
Intercalated
discs
Function: As it contracts, it
propels blood into the circulation;
involuntary control.
Striations
Location: The walls of the heart.
Nucleus
Photomicrograph: Cardiac muscle (900x);
notice the striations, branching of cells, and
the intercalated discs.
© 2013 Pearson Education, Inc.

36. Figure 4.9c Muscle tissues.
Smooth muscle
Description: Spindle-shaped
cells with central nuclei; no
striations; cells arranged closely
to form sheets.
Function: Propels substances or
objects (foodstuffs, urine, a baby)
along internal passageways;
involuntary control.
Nuclei
Location: Mostly in the walls of
hollow organs.
Smooth
muscle
cell
Photomicrograph: Sheet of smooth
muscle (720x).
© 2013 Pearson Education, Inc.

37. Nervous Tissue Main component of nervous system Neurons Neuroglia
Brain, spinal cord, nerves
Regulates and controls body functions
Neurons
Specialized nerve cells that generate and conduct nerve impulses
Neuroglia
Supporting cells that support, insulate, and protect neurons
© 2013 Pearson Education, Inc.

38. Figure 4.10 Nervous tissues.
Description: Neurons are
branching cells; cell processes
that may be quite long extend from
the nucleus-containing cell body;
also contributing to nervous tissue
are nonexcitable supporting cells.
Nuclei of
supporting
cells
Neuron processes
Cell body
Axon Dendrites
Cell body
of a neuron
Function: Neurons transmit
electrical signals from sensory
receptors and to effectors (muscles
and glands) which control their
activity; supporting cells support
and protect neurons.
Neuron
processes
Location: Brain, spinal
cord, and nerves.
Photomicrograph: Neurons (350x).
© 2013 Pearson Education, Inc.

39. Covering and Lining Membranes
Composed of at least two primary tissue types
An epithelium bound to underlying connective tissue proper
Are simple organs
Three types
Cutaneous membranes
Mucous membranes
Serous membranes
© 2013 Pearson Education, Inc.

40. Cutaneous Membranes Skin
Keratinized stratified squamous epithelium (epidermis) attached to a thick layer of connective tissue (dermis)
Dry membrane
© 2013 Pearson Education, Inc.

41. Figure 4.11a Classes of membranes.
Cutaneous membrane
The cutaneous membrane
(the skin) covers the body surface.
Cutaneous
membrane (skin)
© 2013 Pearson Education, Inc.

42. Mucous Membranes Mucosa indicates location not cell composition
All called mucosae
Line body cavities open to the exterior (e.g., Digestive, respiratory, urogenital tracts)
Moist membranes bathed by secretions (or urine)
Epithelial sheet lies over layer of connective tissue called lamina propria
May secrete mucus
© 2013 Pearson Education, Inc.

43. Figure 4.11b Classes of membranes.
Mucous membranes
Mucous membranes line body
cavities that are open to the
exterior.
Mucosa of
nasal cavity
Mucosa of
mouth
Esophagus
lining
Mucosa of
lung bronchi
© 2013 Pearson Education, Inc.

44. Serous Membranes Serosae—found in closed ventral body cavity
Simple squamous epithelium (mesothelium) resting on thin areolar connective tissue
Parietal serosae line internal body cavity walls
Visceral serosae cover internal organs
Serous fluid between layers
Moist membranes
Pleurae, pericardium, peritoneum
© 2013 Pearson Education, Inc.

45. Figure 4.11c Classes of membranes.
Serous membranes
Serous membranes line body cavities that are closed to the exterior.
Parietal
pleura
Visceral
pleura
Parietal
peritoneum
Parietal
pericardium
Visceral
pericardium
Visceral
peritoneum
© 2013 Pearson Education, Inc.

46. Necessary when barriers are penetrated Cells must divide and migrate
Tissue Repair
Necessary when barriers are penetrated
Cells must divide and migrate
Occurs in two major ways
Regeneration
Same kind of tissue replaces destroyed tissue
Original function restored
Fibrosis
Connective tissue replaces destroyed tissue
Original function lost
© 2013 Pearson Education, Inc.

47. Steps in Tissue Repair: Step 1
Inflammation sets stage
Release of inflammatory chemicals
Dilation of blood vessels
Increase in vessel permeability
Clotting occurs
© 2013 Pearson Education, Inc.

48. Scab Epidermis Vein Blood clot in incised wound Inflammatory chemicals
Figure Tissue repair of a nonextensive skin wound: regeneration and fibrosis.
Slide 1
Scab
Epidermis
Vein
Blood clot in
incised wound
Inflammatory
chemicals
Migrating white
blood cell
Artery 1
Inflammation sets the stage:
• Severed blood vessels bleed.
• Inflammatory chemicals are released.
• Local blood vessels become more permeable, allowing white blood cells,
fluid, clotting proteins, and other plasma proteins to seep into the injured area.
• Clotting occurs; surface dries and forms a scab.
© 2013 Pearson Education, Inc.

49. Steps in Tissue Repair: Step 2
Organization restores blood supply
The blood clot is replaced with granulation tissue
Epithelium begins to regenerate
Fibroblasts produce collagen fibers to bridge the gap
Debris is phagocytized
© 2013 Pearson Education, Inc.

50. Organization restores the blood supply:
Figure Tissue repair of a nonextensive skin wound: regeneration and fibrosis.
Slide 2
Regenerating
epithelium
Area of
granulation
tissue
ingrowth
Macrophage
Budding capillary
Fibroblast
Organization restores the blood supply:
• The clot is replaced by granulation tissue, which restores the vascular
supply.
• Fibroblasts produce collagen fibers that
bridge the gap.
• Macrophages phagocytize dead and dying cells and other debris.
• Surface epithelial cells multiply and migrate over the granulation tissue. 2
© 2013 Pearson Education, Inc.

51. Steps in Tissue Repair: Step 3
Regeneration and fibrosis
The scab detaches
Fibrous tissue matures; epithelium thickens and begins to resemble adjacent tissue
Results in a fully regenerated epithelium with underlying scar tissue
© 2013 Pearson Education, Inc.

52. Regeneration and fibrosis effect permanent repair:
Figure Tissue repair of a nonextensive skin wound: regeneration and fibrosis.
Slide 3
Regenerated
epithelium
Fibrosed area 3
Regeneration and fibrosis effect permanent repair:
• The fibrosed area matures and contracts; the epithelium thickens.
• A fully regenerated epithelium with an underlying area of scar tissue results.
© 2013 Pearson Education, Inc.

53. Regenerative Capacity in Different Tissues
Regenerate extremely well
Epithelial tissues, bone, areolar connective tissue, dense irregular connective tissue, blood-forming tissue
Moderate regenerating capacity
Smooth muscle and dense regular connective tissue
Virtually no functional regenerative capacity
Cardiac muscle and nervous tissue of brain and spinal cord
New research shows cell division does occur
Efforts underway to coax them to regenerate better
© 2013 Pearson Education, Inc.