Tissue: The Living Fabric

1
Chapter 4

• Tissue The Living Fabric
• G.R. Pitts, Ph.D, J.R. Schiller, Ph.D. James F.
  Thompson, Ph.D.

2
General

• Tissues - groups of cells with similar basic
  structures which cooperate to perform a related
  function
• Four basic types of tissues
• Epithelial linings for protection,
  coordination, synthesis, absorption, elimination
• Connective support
• Muscle for movement
• muscle tissue is a highly specialized connective
  tissue
• Nervous for control and coordination
• nervous tissue is a highly specialized epithelial
  tissue

3
Epithelial Tissue Characteristics

• Cellularity - densely packed
• Polarity
• apical surface
• basal surface (or basolateral)
• Specialized contacts - tight junctions and
  desmosomes
• Supported by connective tissue
• basal lamina (epithelial glue)
• reticular lamina (connective tissue glue)
• basement membrane - reticular and basal laminae
  together
• Innervated but avascular (no direct blood supply)
• Regeneration high capacity for regeneration

4
Classifying Epithelial Tissues

• By number of cell layers

Pseudostratified epithelium (from the respiratory
tree) appears stratified, but actually is a
single layer of cells of varying heights each
cell touches the basement membrane
5
Classifying Epithelial Tissues

• By cell shape

6
Glandular Epithelial Tissues

• functions in secretion a gland may be one cell
  or a group of specialized cells
• two major types
• exocrine glands have ducts leading to body
  surfaces
• various products are synthesized and stored for
  release
• secretions are secreted into the duct system
• e.g., sweat glands, salivary glands, etc.
• endocrine glands are ductless
• hormones are synthesized and stored for release
• hormones are secreted into the tissue fluid and
  then diffuse into the blood stream
• e.g., thyroid and parathyroid glands

7
Exocrine Gland Classification

• Unicellular glands
• single cell glands
• goblet cells

8
Exocrine Gland Classification

• Multicellular glands
• Structurally classified by duct configuration and
  by the shape of the secretory units
• simple glands have a single duct
• compound glands have branched ducts
• Merocrine glands
• Exocytosis
• Holocrine glands
• Cell rupture

9
Connective Tissue Characteristics

• Two basic components
• Cells fewer, rarely touching, surrounded by a
  matrix
• immature forms (-blasts) secrete the matrix and
  can still divide
• once the matrix is secreted, the cells mature
  into -cytes which have decreased cell divisions
  and secrete less matrix material
• chondro- cartilage, osteo- bone, fibro
  connective, etc.
• Extracellular Matrix
• ground substance (gelatinous glycoproteins)
• structural fibers (fibrous proteins, e.g.,
  collagen, elastin, reticulin)
• Common embryological origin (from mesoderm)
• Innervated and Vascular (direct blood supply)
• Cartilage is the one exception with no capillary
  beds

10
Connective Tissue Matrix

• Ground Substance
• supports cells, binds them together
• may be solid, fluid, or gel
• interstitial fluid
• Glycoproteins called proteoglycans - large
  polysaccharide molecules bound to a protein core
  (like a bottle brush)
• Hyaluronic acid gelatinous, separates cells,
  traps extracellular fluid lubricates joints
  gives shape to eyeballs fills body spaces
• Chondroitin sulfate capable of being
  mineralized cartilage, bones, skin, blood
  vessels
• Dermatin sulfate harder skin, tendons, blood
  vessels, heart valves
• Keratin sulfate - still harder bone, cartilage,
  cornea of the eyes

11
Connective Tissue Matrix

• Protein fibers are embedded in the ground
  substance
• Used for structural support, adhesion, and to
  connect cells
• Provide strength and support
• Collagen fibers
• highly polymerized, gigantic molecules
• tough, moderate flexibility
• protein collagen - parallel bundles of fibers
• bone, cartilage, tendons, ligaments
• Elastic fibers (elastin)
• branched smaller, thinner fibers than collagen
• Very flexible and elastic but also strong
• can be stretched to 150 of its original length
• require special stains to be seen
• Reticular fibers
• thin, less polymerized collagen fibers
• require special stains to be seen

12
Types of Connective Tissues

• Connective Tissue Proper
• areolar (loose fibrous) connective tissue
• adipose tissue
• reticular connective tissue
• dense (fibrous) regular connective tissue
• dense (fibrous) irregular connective tissue
• Cartilage
• hyaline cartilage
• elastic cartilage
• fibrocartilage
• Bone
• Blood

13
Connective Tissue Types
Classified by the characteristics of the matrix
Also see Table 4.1
Details covered in lab
14
Connective Tissue Diseases

• Many diseases
• Most of them very rare
• They may involve the joints but primarily affect
  other organs
• Cause(s) of these diseases unknown
• But in all of them, the immune system seems to be
  activated and causes damage to different organs
  in the body

15
Systemic Lupus Erythematosus

• Symptoms skin rash, mild arthritis, and
  generalized weakness or tiredness
• Rarer symptoms hair loss, mouth ulcers,
  headaches and poor circulation in the fingers
• Serious complications of kidney, heart, and brain
  inflammation
• 9 times more likely in women
• 4 times more likely in African-Americans

http//www.niehs.nih.gov/health/topics/conditions/
lupus/index.cfm
16
Marfan Syndrome

• Genetic defect on chromosome 15 that encodes the
  fibrilin protein

17
Nervous Tissue

• Highly specialized epithelial cells
• Convert stimuli into electro-chemical signals for
  transfer of information
• Structure
• cell body (soma) and extensions
• dendrites (highly branched) carry incoming
  signal
• axon (long, usually single strand) carry
  outgoing signal

18
Muscle Tissue Characteristics

• a high degree of cellularity
• cells contain contractile proteins
• well vascularized
• a highly specialized type of connective tissue

19
Classification of Muscle Tissues

• two types are Striated
• Skeletal muscle
• attached to bones
• multinucleate
• voluntary
• fibers are parallel and cylindrical
• Cardiac muscle
• most of the heart wall
• single nucleus (usually)
• involuntary
• branched cylinders connected by intercalated discs

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Classification of Muscle Tissues

• One type is non-striated
• Smooth muscle
• located in the walls of hollow organs
• blood vessels
• digestive tract
• airways
• bladder
• involuntary
• single nucleus
• spindle shaped

21
Epithelial Membranes

• A particular Epithelium and its underlying
  Connective Tissue support

trachea
skin
22
Cutaneous Membrane The Skin
23
Mucous Membranes

• Line body structures which open directly to the
  exterior
• Viscous mucus secretions lubricate surfaces and
  provide a defensive barrier that traps particles
  and microbes

24
Serous Membranes

• Line closed body cavities and their organs
• Watery serous fluid lubricates the cavity and its
  organs
• pleura lungs
• pericardium - heart
• peritoneum - abdominal organs
• parietal
• visceral

25
Tissue Injury Repair

• Inflammation
• redness
• swelling
• heat
• pain
• loss of function
• Organization restores blood supply
• Blood clot replaced by granulation tissue
• Regeneration and Fibrosis
• Epithelium regenerates
• Fibrous conn. tissue matures and contracts

26
Tissue Repair

• During development some cells lose their ability
  to divide with specialization
• Some cells maintain the ability to replace others
• Stem cells
• immature, undifferentiated cells
• hide in protected areas in skin/GI tract to
  replace cells
• Tissue repair
• new cells come from parenchyma (functioning
  portion) or stroma (connective tissue)
• if parenchyma cells proliferate then repair
  nearly complete if not, then we get scar tissue
  formation
• fibroblasts will produce collagen and other
  matrix materials during fibrosis a less
  functional tissue

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Conditions Affecting Repair

• Nutrition
• adequate protein in the diet for repair
• necessary vitamins and other nutrients
• Blood circulation
• transport oxygen, nutrients, antibodies and other
  defensive molecules and cells to the site
• WBCs remove debris which would otherwise
  interfere with healing
• Age
• young people heal faster and have less obvious
  scars
• young people have a better nutritional status, a
  better blood supply, and a higher metabolism

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Embryonic Germ Layers
Well see the embryonic tissues again in Chapter
28 next semester
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• End Chapter 4

Exam 1 covers Chapters 1-4
30
Connective Tissue Structure
31
Embryonic Structure