Warm-Up
1. What is a tissue?
2. The study of tissues is called ______.
3. What are the 4 main types of tissues?
Chapter 5
TISSUE: THE LIVING FABRIC
 Tissue: group of cells that are similar in
structure and function
 Histology: study of tissues
Types of Tissues:
1. Epithelium (covering)
2. Connective (support)
3. Muscle (movement)
4. Nervous (control)
Epithelial Tissue
 “epithe” = laid on, covering
 Structure:
1. Covering and lining epithelium
2. Glandular epithelium
 Function:




Protection
Absorption
Filtration
Secretion
Special Properties
1. Polarity

Apical surface = exposed free
surface or edge (some with
microvilli, cilia)
 Basal surface = lower, attached
surface
2. Specialized contacts
 Fits close together to form
continuous sheets
Special Properties
3. Supported by connective tissue

Rests on basement membrane
4. No blood supply (avascular)
 Rely on diffusion and underlying connective
tissue for food/O2
5. Regeneration – Replace lost cells
Classification
 Two names = (# cell layers) + (shape of cells)
 Cell Layers: simple (single) or stratified (many)
 Shapes: squamous, cuboidal, or columnar
Simple Epithelium
 Absorption, secretion, filtration
 Very thin
Simple Epithelium
Simple Epithelium
 Simple squamous
 Filtration, rapid diffusion
 Capillary walls, air sacs in lungs, kidney filtration
 Serous membranes: slick layer lining ventral body
cavity and its organs
Simple Epithelium
 Simple cuboidal
 Secretion & absorption
 Lines ducts of glands (salivary), kidney tubules,
ovary surface
Simple Epithelium
 Simple columnar
 Absorption and secretion
 Lines digestive tract
 Microvilli, cilia
 Mucous membranes:
lubricating mucus
Simple Epithelium
 Pseudostratified columnar
 Rests on basement membrane – false impression
(pseudo) of being multi-layered
 Secretes or absorbs
 Respiratory tract – cilia propels mucus from lungs
Stratified Epithelium
 2+ layers, more durable
 Main function = protect
Stratified Epithelium
 Stratified squamous
 Withstand abuse, friction
 Esophagus, mouth, outer portion of skin
Stratified Epithelium
 Stratified cuboidal
 Usually 2 layers
 Mainly in ducts of large glands (sweat, mammary,
salivary)
Sweat Gland
Esophageal Gland
Stratified Epithelium
 Stratified columnar
 Thick, waterproof layer
 Pharynx, male urethra, lining ducts
Transitional Epithelium
 Able to change shape (cuboidal  squamous)
 Lining of hollow urinary organs (bladder,
ureter, urethra)
 Stretches when filled with urine
Glandular Epithelium
 Gland: make and secrete a particular product
 2 Types:
 Endocrine gland: produce hormones secreted into
tissue fluid or bloodstream; ductless
 Exocrine gland: secrete products into ducts  onto
body surfaces or body cavities
 Eg. mucous, sweat, oil, saliva, bile
 Unicellular exocrine gland:
 Composed of one cell
 Goblet cell
 Multicellular exocrine gland:
• Composed of many cells
• Sweat glands, salivary glands, etc.
• Simple and compound
Exocrine Glands
Unicellular
Multicellular
 Mucus cells or goblet
cells
 Duct structure
Structural Types of
Exocrine Glands
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Tissue surface
Duct
Secretory portion
Simple tubular
Simple branched
tubular
Compound tubular
Simple coiled
tubular
Compound alveolar
Simple branched
alveolar
Types of Glandular Secretions
• Merocrine
Glands
• Fluid product
• Salivary glands
• Pancreas
• Sweat glands (also
called Eccrine)
Intact
cell
Secretion
• Apocrine Glands
• Cellular product
• Portions of cells
• Mammary glands
• Ceruminous glands
Pinched off
portion of cell
(secretion)
• Holocrine Glands
• Secretory products
• Whole cells
• Sebaceous glands
Disintegrating cell
and its contents
(secretion)
New cell
forming by
mitosis and
cytokinesis
(a) Merocrine gland
(b) Apocrine gland
(c) Holocrine gland
Warm-Up
What type of connective tissue is shown below?
1.
2.
Adipose Tissue
(Loose Connective
Tissue)
Cartilage
3.
4.
Blood
Bone
Connective Tissue
 Most abundant and widely distributed tissue
 Main classes:
Connective tissue proper (loose & dense)
2. Cartilage
3. Bone
4. Blood
1.
 Functions:
Binding and support
2. Protection
3. Insulation
4. Transport substances
1.
Connective Tissue:
Major Cell Types Present
• Fibroblasts
• Fixed cell
• Most common cell
• Large, star-shaped
• Produce fibers
• Mast cells
• Fixed cell
• Release heparin
• Release histamine
• Macrophages
• Wandering cell
• Phagocytic
• Important in injury or
infection
Connective Tissue:
Fiber Types Present
• Collagenous fibers
• Elastic fibers
• Thick
• Bundles of microfibrils
• Composed of collagen
embedded in elastin
• Great tensile strength
• Fibers branch
• Abundant in dense CT
• Elastic (stretchy)
• Hold structures together
• Vocal cords, air passages
• Tendons, ligaments
• Reticular fibers
• Very thin collagenous fibers
• Highly branched
• Form supportive networks
Connective Tissues
• Connective Tissue:
• Specialized Connective Tissue:
• Loose connective tissue
• Cartilage
• Adipose tissue
• Bone
• Reticular connective tissue
• Blood
• Dense connective tissue
• Elastic connective tissue
Classification
 Variations in blood supply
 Avascular (no blood) – cartilage
 Poorly vascular – tendons, ligaments
 Extracellular matrix
 Produced by cells, secreted to exterior
 Ground substance: “glue” - fills space between cells &
fibers
 water + adhesion proteins + polysaccharides
 Fibers: provide support
 Collagen - strength
 Elastic – stretch
 Reticular – fine network, “skeleton” of organs
Loose Connective Tissue
 Universal packing material
 Subclasses: areolar, adipose, reticular
 Structure: softer, fewer fibers, gel-like matrix
 Functions:
 Cushion & protect organs (areolar, fat)
 Store nutrients (fat)
 Internal framework (reticular)
 Fight infection (areolar)
 Cells: fibroblasts, adipocytes (fat cells)
 Locations: under skin, lymph nodes, hips,
behind eyeballs
Dense Connective Tissue
 Tendons & ligaments
 Subclasses: dense regular, dense irregular,
elastic
 Structure: mainly collagen fibers
 Functions:
 Elastic
 Resist tension
 Cells: fibroblasts
 Locations: tendons (muscle-bone), ligaments
(bone-bone), lower layers of skin
Cartilage
 Subclasses: hyaline, elastic, fibrocartilage
 Structure: flexible, no nerves or blood
 Functions:
 Support
 Compression
 Cells: chondroblasts, chondrocytes
 Locations: larynx, joints, tip of nose, ear,
intervertebral discs, rib-breastbone, knee
joint
Connective Tissue Types
• Hyaline cartilage
• Cartilage
• Rigid matrix
• Chondrocytes in lacunae
• Poor blood supply
• Three (3) types:
• Hyaline Cartilage
• Elastic Cartilage
• Fibrocartilage
• Most abundant
• Ends of bones
• Nose, respiratory passages
• Embryonic skeleton
• Elastic cartilage
• Flexible
• External ear, larynx
• Fibrocartilage
• Very tough
• Shock absorber
• Intervertebral discs
• Pads of knee and pelvic girdle
Connective Tissue Types
Three (3) types of cartilage:
Elastic fibers
Nucleus
Nucleus
Lacuna
Lacuna
Chondrocyte
Chondrocyte
Extracellular
matrix
Extracellular
matrix
(b)
(a)
(b)
Elastic Cartilage
Hyaline Cartilage
Lacuna
Chondrocyte
Nucleus
Collagenous
fiber
Extracellular
matrix
(b)
Fibrocartilage
Bone
 Osseous tissue
 Subclasses: compact, spongy
 Structure: hard, calcified matrix; blood
vessels
 Functions:
 support & protect
 Store calcium
 Blood cell formation (marrow)
 Cells: osteoblasts, osteocytes
 Locations: bones
Blood
 Vascular tissue
 Subclasses: blood cells, plasma
 Structure: fluid within blood vessels, no fibers
 Functions:
 Transport vehicle (nutrients, wastes, gases,
hormones)
 Cells: white blood cells (leukocytes), red
blood cells (erythrocytes), platelets
 Locations: blood vessels
Types of Membranes
• There are four (4) types of epithelial membranes:
1. Serous Membranes
• Line body cavities that
do not open to the
outside
• Reduce friction
• Inner lining of thorax
and abdomen
• Cover organs of thorax
and abdomen
• Secrete serous fluid
2. Mucous Membranes
• Line tubes and organs
that open to outside world
• Lining of mouth, nose,
throat, etc.
• Secrete mucus
3. Cutaneous Membranes
• Covers body
• Skin
4. Synovial Membranes
• Composed entirely of
connective tissue
• Lines joints
46
Types of Membranes
Muscle Tissue
 3 types:
 Skeletal muscle
 Cardiac muscle
 Smooth muscle
Skeletal Muscle
 Description:
 Long, cylindrical
 Multinucleate (2+ nuclei)
 Striated (banded appearance)
 Function:
 Muscles contract, pull on bones or skin  cause
body movements
 Location in the body:
 Attached to skeleton
 Other features:
 Voluntary control
Cardiac Muscle
 Description:
 Striated
 Uninucleate (1 nucleus)
 Branching cells – fit at junctions called intercalated discs
 Function:
 Propel blood through blood vessels to all parts of body
 Locations in the body:
 Walls of the heart
 Other features:
 Involuntary control
Smooth Muscle
 Description:
 No visible striations
 1 central nucleus
 Spindle-shaped (pointed ends)
 Function:
 Propel substances through hollow organs
 Locations in the body:
 Walls of organs (stomach, bladder, uterus, blood vessels)
 Other features:
 Involuntary control
 Contracts slowly
 Peristalsis: wavelike motion that moves food through
esophagus
Nervous Tissue
 Main component of nervous system
 Structure: neuron = dendrite + cell body + axon
 Function: regulates and controls body
functions
 Location in the body: brain, spinal cord, nerves
Nervous Tissue
 2 Major Cell Types:
 Neurons
 Respond to stimuli
 Transmit electrical impulses
 Neuroglial Cells
 Support and bind components of nervous
tissue
 Phagocytosis
 Supply nutrients to neurons
Tissue Repair
 Wound healing
 Two ways:
1. Regeneration: replace destroyed tissue by
same kind of cells
2. Fibrosis: form scar tissue (dense fibrous
connective tissue)
 Depends on:
 Type of tissue damaged
 Severity of injury
Steps to Tissue Repair:
1. Inflammation



Capillaries become very permeable
WBC’s and clotting proteins seep into injured area
Clot prevents loss of blood (surface dries, forms a
scab)
Steps to Tissue Repair:
2. Granulation tissue forms



Delicate pink tissue with new capillaries
Connective tissue produces collagen fibers
Epithelial cells multiply over granulation tissue
Steps to Tissue Repair:
3. Surface epithelium regenerates


Surface epithelium thickens
Fibrous tissue matures – forms scar tissue
Regenerative Capacity of Different
Tissues
Extremely
Well
Moderate
• Skin epidermis • Smooth
• Mucous
muscle
membranes
• Tendons,
• Fibrous
ligaments
connective
• Blood
• Bones
Weak
• Skeletal
muscle
• Cartilage
Virtually None
(mostly scar
tissue)
•Cardiac muscle
•Nervous tissue