Histology
Do Now:
Don’t forget your clickers!
Use your book to answer the following
questions in your notebook:
1. What are tissues?
2. What is the study of tissues?
3. What are the 4 main tissue types?
4 Types of Tissues
Neural
Human
Body
Tissues
Muscle
Connective
Epithelial Tissues
To the lab tables!
Materials:
Microscopes
Slides
Observation table
Pen/pencil
What are Epithelial Tissues?
Structure
• Cover internal and external surfaces
• Close together
• Avascular
• Easily regenerated
• Life span: 1-2 days
• Basement membrane: attaches epithelia to
underlying connective tissue
• Made of protein fibers
Functions
• Protection
• Permeability
• Secretion
• Exocrine glands
Epithelial Surfaces
Apical Surface
• Microvilli
• Increase surface area
• Absorption and
secretion
• Cilia
• Beat to move
materials across the
surface
Apical Surface
Basolateral Surface
Basolateral Surface
•
•
Attached to underlying
cells or tissues
Sides of the cell
Squamous Epithelium
• Simple Squamous
• Shape: thin, flat cells; 1 layer
• Function: diffusion; filtration
• Found: forms capillary walls;
lines air sacs in lungs
• Stratified Squamous
• Shape: thin, flat cells;
multiple layers
• Function: protection
• Found: skin surface; lines
tongue, mouth, esophagus, &
anus
Cuboidal Epithelium
• Simple Cuboidal
• Shape: box-shaped; 1 layer
• Function: secretion;
absorption
• Found: covering the surface
of ovaries; lining kidney
tubules, salivary ducts, &
pancreatic ducts
• Stratified Cuboidal
• Shape: box-shaped; multiple
layers
• Function: strengthen lumen
walls
• Found: ducts of large sweat
glands, salivary glands, &
pancreas
Columnar Epithelium
• Simple Columnar
• Shape: tall, rectangular; 1
layer
• Function: absorption,
secretion, & protection
• Found: lines stomach,
intestinal tract, excretion
ducts, gall bladder
• Pseudostratified Columnar
• Shape: single layer, irregularly
shaped (looks like multiple
layers)
• Function: protection,
secretion
• Found: lining respiratory
passageways & auditory tubes
Transitional Epithelium
• Transitional
• Shape: Numerous layers
of rounded cells
• Function: withstands
stretching
• Found: lines urinary
bladder and portions of
ureters & urethra
4 Types of Tissues
Neural
Human
Body
Tissues
Muscle
Connective Tissues
To the lab tables!
Materials:
Microscopes
Slides
Observation table
Pen/pencil
What are Connective Tissues?
Structure
• Highly vascular
• 3 Components:
1. Cells
2. Protein Fibers
3. Ground Substance
Functions (lots of variation!)
• Support & Protect – framework
• Transport materials – fluid with dissolved materials
• Energy reserve – fat in adipose tissue
• Defense – responds to pathogens by releasing
antibodies
• Protection of organs
3 Types of Connective Tissues
1. Connective Tissue Proper
• Syrupy ground substance
• Ex: Loose (areolar, adipose) & Dense (ligaments, tendons)
2. Fluid Connective Tissue
• Cells suspended in watery ground substance with dissolved
proteins
• Ex: Blood & Lymph
3. Supporting Connective Tissue
• Dense ground substance
• Closely packed fibers
• Ex: Cartilage (hyaline, elastic, fibrocartilage) & Bone
1. Connective Tissue Proper –
Cell Types
• Fibroblasts
• Produce and maintain connective tissue
fibers & ground substance
• Permanent
• Local maintenance & repair
• Macrophages
• Defense: Engulf pathogens & damaged
cells
• Release chemicals to stimulate immune
response
• Fixed or migrating (reinforcement)
• Adipocytes
• Fat cells
• Permanent
• Nuclei & organelles pushed to the side
1. Connective Tissue Proper –
Fiber Types
• Collagen
• Long, straight, unbranched
• Flexible
• Elastic
• Protein – elastin
• Wavy, branched, stretchy
1. Connective Tissue Proper –
Loose Connective Tissue
• Areolar Tissue
• Contains all cells and fibers of
connective tissue proper
• Separates skin from muscles
• Provides padding
• Allows movement
• Extensive blood supply
• Adipose Tissue
• Adipose (fat) cells
• Behind eyes, kidneys, heart,
abdomen, buttocks, & breasts
1. Connective Tissue Proper –
Dense Connective Tissue
• Mostly collagen
• Regular – collagen fibers
are parallel
• Tendons – connect
skeletal muscle to bone
• Ligaments – connect
bone to bone, contain
elastin
2. Fluid Connective Tissue
• Blood
• Plasma – watery matrix
with dissolved proteins
• Red Blood Cells
• White Blood Cells
• Platelets
• Lymph
• Interstitial fluid (water &
solutes) enters lymphatic
vessels
3. Supporting Connective
Tissue - Cartilage
•
•
•
•
Cartilage – gel with embedded fibers
Chondrocytes – cells found in lacunae
Difficult to repair – no blood vessels
3 Types:
1.
Hyaline – closely packed fibers, tough but flexible
• Connects ribs to sternum, supports trachea of respiratory tract,
covers bone surfaces in joints
2.
Elastic – elastic fibers, very flexible
• External flap of outer ear, epiglottis, auditory tube
3.
Fibrocartilage – little ground substance, collagen fibers,
durable & tough
• Between vertebrae, between pubic bones, around or within some
joints
Hyaline
Cartilage
Elastic
Cartilage
Fibrocartilage
3. Supporting Connective
Tissue - Bone
• Osseous Tissue – bone
• Matrix – hard calcium & flexible collagen
• Little ground substance
• Osteocytes found in lacunae
• Lacunae surrounded by blood vessels
• Canaliculi extend from central canal
4 Types of Tissues
Neural
Human
Body
Tissues
Connective
What are Muscle Tissues?
• Specialized for contraction
• 3 Types:
1. Skeletal Muscle – striated, voluntary
muscle
• Large multinucleated cells (long &
slender)
• Striations (series of bands)
2. Cardiac Muscle – striated,
involuntary muscle
• Smaller striated cells, one nucleus
• Interconnected by intercalated
discs
• only found in the heart
3. Smooth Muscle – nonstriated,
involuntary muscle
• Small, slender cells with one
nucleus
• walls of blood vessels, hollow tubelike organs
4 Types of Tissues
Human
Body
Tissues
Connective
What are Neural Tissues?
• Specialized for conducting electrical impulses
• Neurons – communicate through electrical events
• Long cell with 3 main parts
1.
2.
3.
Cell body with nucleus
Dendrites – branching projections that receive info
Axon – long projections (with synaptic terminals) that relay
signals to other cells
• Limited ability to repair
4 Types of Tissues
Human
Body
Tissues
Tissue Injury & Repair
• Inflammation
• In response to pathogens, impact, abrasion,
extreme temperatures, or chemical irritation
• Mast cells release chemicals (i.e. histamine)
that dilate blood vessels to induce swelling,
redness, heat, & pain
• Regeneration
• Fibroblasts produce dense collagen fibers
called fibrous tissue (aka scar tissue)