Transcript Lab Exercise 5 Epithelial and Connective Tissues Portland Community College BI 231 Tissues • Groups of cells similar in structure and function • Each tissue.

Lab Exercise 5
Epithelial and Connective Tissues
Portland Community College
BI 231
Tissues
• Groups of cells similar in structure and function
• Each tissue is then further subdivided into
categories.
• All organs are made of a combination of
different tissues.
• The four types of tissues
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Epithelial
Connective
Muscle
Nerve
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Epithelium
• Covers all body
surfaces, inside and
out
• Is anchored to
connective tissue by a
layer of glycoproteins
and protein fibers
called the basal lamina
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Epithelial Tissue
Distinguishing Characteristics
1. Cellularity: Composed almost entirely of cells
2. Polarity: apical and basal surfaces (top and a
bottom)
3. Attachment: Supported by connective tissue
(basement membrane)
4. Avascular: Contains no blood vessels: obtains
nutrients by diffusion
5. Regeneration: Rapidly replaces lost cells by
cell division
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Functions of Epithelia
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Protection:
Secretion:
Absorption:
Sensory:
Filtration:
Skin
glands release secretions
Uptake nutrients
Taste buds
In the kidneys
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Classification of Epithelia
1. First name:
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Simple: one layer
Stratified: more than one layer
2. Second name:
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Based on the shape of the top layer of cells
• Squamous (flat)
• Cuboidal (square)
• Columnar (rectangle)
3. Two additional categories
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Transitional
Pseudostratified
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Classification of Epithelia
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Classification of Epithelia
• Squamous
• Cuboidal
• Columnar
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Simple Squamous Epithelium
• Single layer of flattened cells with discshaped nuclei and sparse cytoplasm
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Simple Squamous Epithelium
• Top View
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Simple Squamous Epithelium
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Simple Squamous Epithelium
• Functions:
1. Diffusion
• Alveoli in the respiratory system allows for
exchange of O2 and CO2
2. Filtration
• Capillaries allow fluid and other substances
out and holds blood cells and proteins in
3. Lubrication
• Secretes lubricating substances in serosae
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Simple Cuboidal Epithelium
• Single layer of cube like cells with large,
spherical central nuclei
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Simple Cuboidal Epithelium
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Simple Cuboidal Epithelium
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Functions:
1. Secretion
• Glands such as the thyroid are composed of
simple cuboidal epithelium and secrete
hormones ect…
2. Absorption
• In the kidney, the proximal convoluted
tubule is composed of simple cuboidal
epithelium and reabsorbs water and other
nutrients from the filtered fluid
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Simple Columnar Epithelium
• Single layer of tall cells with oval nuclei toward
the basal surface
• Goblet cells are often found in this layer
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Simple Columnar Epithelium
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Simple Columnar Epithelium
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Simple Columnar Epithelium
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Functions
1. Secretion
• Example: In the stomach, these cells
secrete digestive enzymes
2. Absorption
• Example: In the intestine, these cells
absorb nutrients
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Stratified Squamous Epithelium
• Composed of several layers of cells
• Top layer flat
• Bottom layers any shape
• Function in protection of underlying areas
subjected to abrasion
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Stratified Squamous
Epithelium
•Non-keratinized
•Composed of several
layers of cells
•Top layer flat
•Bottom layers any
shape
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Stratified Squamous Epithelium
Non-Keratinized
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Stratified Squamous Epithelium
Non-Keratinized
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Functions
1. Physical protection against abrasion and
pathogens
• Non-Keratinized is associated with “moist”
areas
• Mouth
• Throat
• Esophagus
• Anus
• Vagina
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Stratified Squamous Epithelium
Keratinized
Looks
“flakey” on
the top
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Stratified Squamous Epithelium
Keratinized
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Stratified Squamous Epithelium
Keratinized
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Functions
1. Physical Protection
• Found only in the epidermis of the skin
• Keratin is a protein that helps strengthen
the cells against abrasion
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Pseudostratified Columnar
Epithelium
• Single layer of cells with different heights;
some do not reach the free surface
• Nuclei are seen at different levels
• May be ciliated (PCCE) or non-ciliated
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Pseudostratified Columnar
Epithelium
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Pseudostratified Columnar
Ciliated Epithelium (PCCE)
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Pseudostratified Columnar
Ciliated Epithelium (PCCE)
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Functions
1. Protection
• Example: Lines the upper respiratory tract.
The cilia sweep debris toward the throat
2. Secretion
• Example: May contain goblet cells
(unicellular glands) that secrete mucus
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Transitional Epithelium
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Several cell layers, basal cells are cuboidal
Apical cells are dome shaped when not
stretched
• Apical cells are flat when stretched
• Only found in Urinary System
• Functions:
1. Allows expansion and recoil after
stretching
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Transitional Epithelium
Distended bladder
Empty bladder
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Stratified Cuboidal and Columnar
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Typically two cell layers thick
Rare
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Functions:
1. Secretion
• Found in some sweat and mammary glands
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Stratified Cuboidal Epithelium
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Stratified Cuboidal Epithelium
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Stratified Columnar Epithelium
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Limited distribution in the body
To tell the difference between this and
pseudostratified columnar, look at the nucleus.
• The nuclei are lined up in a straight row
Function
1. Protection
• Found in the pharynx, male urethra, lining
some glandular ducts, and anus
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Stratified Columnar Epithelium
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Stratified Columnar Epithelium
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Connective Tissue
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4 Types
1. Connective Tissue Proper
2. Bone
3. Blood
4. Cartilage
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Connective Tissue Features
1. Specialized cells
2. Matrix: Nonliving material between the cells
that makes up most of the volume (ground
substance + fibers)
• Extracellular fibers
• Ground substance: Composed chiefly of
interstitial fluid, cell adhesion proteins, and
proteoglycans
• Specific composition varies between
tissues (Blood=fluid, Cartilage=gel like,
Bone=Solid)
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Connective Tissue Fibers
• 3 types of fibers include collagen,
elastic and reticular
• Collagen Fibers: Fibrous protein
molecules
• Extremely tough
• High tensile strength
• Strongest type of fibers in connective
tissue.
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Connective Tissue Fibers
• Elastic Fibers: Form branching networks
• Elastin: a rubber like protein that allow it to act like
a rubber band and snap back to its original shape
after it is stretched
• Reticular Fibers: Forming delicate networks
• Fine collagenous fibers (with a different
chemical structure) branch extensively
• Surround small blood vessels and
support soft tissue organs
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Blast cells
• Undifferentiated cells (blast = forming)
• Fibroblasts- fount in loose and dense
connective tissues (secrete matrix)
• Chondroblasts in cartilage
• Osteoblasts in bone
• Hemocytoblasts in blood
• ‘cytes’ are the mature forms
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Cells of Connective Tissue Proper
1. Reticular cells: specialized fibroblasts found in
reticular connective tissue
2. Macrophages: Scavenger cells that engulf
pathogens or damaged cells
3. Adipocytes: Fat cells
4. Plasma cells: produce antibodies
5. Mast cells: Stimulate local inflammation:
contain histamine and heparin
6. Leukocytes: WBC involved in immunity
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Mesenchyme
• Embryonic
Connective tissue
• Gel-like ground
substance with fine
protein fibers and
immature cells; gives
rise to all other
connective tissues
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Areolar Connective Tissue (Loose)
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Gel like matrix
Contains all 3 fiber types
Functions:
1. Wraps and cushions organs
2. Holds and conveys tissue fluid
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Locations:
1. Under epithelial tissues
2. Packages organs
3. Surrounds capillaries
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Areolar Connective Tissue (Loose)
Fibroblast
Collagen fiber
Macrophage
Elastic fiber
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Adipose Tissue (Loose)
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Function:
1. Storage of lipid
molecules
2. Insulation
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Reticular Connective Tissue (Loose)
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Network of reticular fibers in a loose
ground substance
Functions
1. Soft internal skeleton that supports other cell
types
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Locations
1. Lymph nodes
2. Bone marrow
3. Spleen
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Reticular Connective Tissue (Loose)
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Dense Regular Connective Tissue
• Primarily parallel collagen fibers
• Major cell type: fibroblast
• Functions:
1. Withstands great tensile stress pulling in one
direction
• Locations:
1. Tendons
2. Ligaments
3. Aponeuroses
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Dense Regular Connective Tissue
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Dense Irregular Connective Tissue
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Irregularly arranged collagen fibers
Functions:
1. Withstands tension exerted in many directions
2. Provides structural strength
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Locations:
1. Dermis of skin
2. Submucosa of digestive tract
3. Fibrous capsules of organs and joints
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Dense Irregular Connective Tissue
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Elastic Connective Tissue (Dense)
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Dense regular CT dominated by elastic fibers
Functions:
1. Stabilizes positions of vertebrae and penis
2. Cushions and permits expansion and
contraction of organs
• Locations:
1. Between vertebrae
2. Ligaments supporting penis, transitional
epithelia
3. Blood vessel walls
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Elastic Connective Tissue (Dense)
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Hyaline Cartilage
• Functions:
1.Stiff but flexible support
2.Reduces friction
between bony surfaces
• Locations:
1.Articular surfaces
2.Larynx
3.Trachea
4.Nasal septum
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Elastic Cartilage
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Functions:
1. Support, but
flexible
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Locations:
1. Ear
2. Epiglottis
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Fibrocartilage
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Functions:
1. Resists
compression
2. Prevents bone-tobone contact
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Locations:
1. Meniscus of knee
2. Pubic symphysis
3. Intervertebral
discs
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Bone: Osseous Tissue
• Functions:
1.Lever for muscles
2.Mineral storage
3.Protection
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Blood: Hematopoietic Tissue
• Functions:
1.Transportation
2.Immunology
3.Hemostasis
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The End
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