Histology

…pass the tissues please…

I. Intro to Histology

Tissue definition: A group of similar cells working towards one unifying goal

Tissues components1. Similar cells2. Extracellular Matrix

- water, NaCl, ions, calcium, fibers, nutrients, etc..

The 4 types of tissues1. Epithelial

        * covers body surfaces        * lines hollow organs        * lines body cavities and ducts        * forms glands and secretions

2. Connective        * protection and support        * binding together (like glue)        * energy storage

3. Muscle * movement and force (including peristalsis)

4. Nervous * coordinates body activities

I. Intro to Histology

I. Critical Thinking Question?

What tissue type does blood belong to?A. Epithelial

B. Connective

C. Muscle

D. Nerve

E. Blood isn’t a tissue

Location Covers external

surfaces Lines internal surfaces

such as cheeks, blood vessels, organs etc…

Glands

II. Epithelial Anatomy

Apical Surface

Basal(basement)

Basic Anatomy Cells bound tightly together Classified by shape of cells

and number of layers Avascular Contain Stem cells Has an exposed surface

(Apical membrane) Has a surface bound to

connective tisuuse (basal membrane)

Connective tissue

II. Epithelial Anatomy

III. Epithelia Physiology

Function Provides protection internally and externally Controls permeability Provides for touch/stimuli Produces secretions:

exocrine – released onto surfaces digestive enzymes, sweat

endocrine – releases into tissue fluid and blood Hormones (chemical messengers) from pancreas,

thyroid, pituitary, etc

II. Epithelial Anatomy

Basic Anatomy Apical Surface may contain

specialized structures Cilia for movement Microvilli for increased

absorption (Brush Borders)

II. Epithelial Anatomy

The Brush Border

II. Epithelial Anatomy

Basic Anatomy Basal Membrane: “Basement”

Provides strength to epithelium Creates barriers to prevent

molecules from entering connective tissue

II. Epithelial Anatomy

Shape Squamous: Flat Cubodial: cube-like Columnar: column-like Transitional: changes

By Layers Simple: single Stratified: multiple Pseudostratified:

appears multiple, but really simple

Classification Systems

Example. Simple cubodial = 1 cell thick of cube shaped cells

Simple Squamous Anatomy Lining of body cavities,

organs, blood vessels, alveoli lung surface

Serous Membranes

Physiology Diffusion Secretions

IV. Epithelial Tissues: Simple Squamous

Simple Squamous

IV. Epithelial Tissues: Simple Squamous

Simple Squamous

IV. Epithelial Tissues: Simple Squamous

Simple CuboidalAnatomy Digestive tract, Kidney

tubules, glands

Physiology Absorption and

Secretions

IV Epithelial Tissues: Simple Cuboidal

IV Epithelial Tissues: Simple Cuboidal

Simple Cuboidal

Simple ColumnarAnatomy Lining of digestive tract Modified by presence of

cilia Contains “Goblet cells”

Physiology Help move surface

material Absorption

IV Epithelial Tissues: Simple Columnar

IV Epithelial Tissues: Simple Columnar

Simple Columnar

Simple Columnar

IV Epithelial Tissues: Simple Cuboidal

IV Epithelial Tissues: Simple Columnar

Simple Columnar

Stratified SquamousAnatomy Outer most layer-

squamous cells Inner- cuboidal or

columnar Lining of mouth,

esophagus, skin Can be keratinized

Physiology Protection Secretion Moistens membranes

IV Epithelial Tissues: Stratified Squamous

Stratified Squamous – non keratinized

IV Epithelial Tissues: Stratified Squamous

IV Epithelial Tissues: Stratified Squamous

Keratinized Stratified Squamous Keratin: Waxy protective coverings Waterproofs

IV Epithelial Tissues: Pseudostratified Columnar

Pseudostratified ColumnarAnatomy One layer All attach to the basal

membrane Appears stratified Upper respiratory tract

Physiology Move material

Pseudostratified Columnar

IV Epithelial Tissues: Pseudostratified Columnar

V. Connective Tissue Abundant extracellular material

Matrix (dominant part) or ground substance Fiber, cells in liquid, gel, or solid matrix

Never exposed to “outside environment” If exposed, causes a response for “damage

control” (ie. Bleeding)

Functions Bind and/or support other tissue Energy storage Defense of the body

Classification is based on the composition of matrix…

1. Connective Tissue Proper – loose and dense. subcutaneous, fat, tendons and ligaments

2. Fluid connective tissue

3. Supporting connective tissue

V. Connective Tissue

Connective Tissue

Tissue Proper Fluid Supporting

Blood Lymph

Cartilage Bone

Dense Regular

DenseLoose

Dense Irregular

V. Connective Tissue

VI. Connective Tissue ProperTissue Proper:

- Either loose or dense- Examples: subcutaneous, fat, tendons and ligaments

Tissue Proper is composed of … Fibroblasts – homeostasis of tissue Macrophages – engulf waste Fat cells – permanent residents Mast cells – near blood vessels, release chemicals to

elicit injury response

3 Fibers Collagen - long and straight, most

common fibers, strong but flexible

Elastic – branched and wavy, contains elastin, are elastic

Reticular – less common, thin, branching, interwoven framework of fibers

VI. Connective Tissue Proper

Loose or areolar Fewer fibers but all kinds Cushioning and support Deep to skin, between muscles, around

vessels Dense Fibrous

abundant, organized collagen fibers Tendons and ligaments Dense Regular or Dense irregular

VI. Connective Tissue Proper

Dense Regular collagen runs parallel, packed

tightly, aligned with forces Tendons and ligaments Provides attachements

Dense Irregular with collagen to provide

support and strength Gives skin its strength

VI. Connective Tissue Proper

VII. Adipose Adipose Connective

Tissue Loose connective Store large droplets of

fat Large “marshmellow”

looking cells Nuclei squished to

one side

Blood Plasma: Liquid matrix RBC’s WBC’s

Lymphatic System Lymph: fluid portion Part of your immune

system

VIII. Fluid Connective Tissue

Cartilage Connective Tissue Rubbery consistency (matrix) Avascular

IX. Supporting Connective

Types of Cartilage Hyaline – most common

Joints, rib cage, respiratory tract Elastic

Mostly elastic fibers, Very flexible Outer ear, nose, epiglottis

Fibrocartilage Mostly collagen fibers, durable, strong, tough Backbone (resist compression, absorb shock…)

IX. Supporting Connective

Bone Osteocytes: bone cells Hardest connective

tissue Spongy bone

Ends of long bones Compact

Shafts of long bones Tightly organized

IX. Supporting Connective

Bone Connective Tissue

Three types

1. Skeletal

2. Smooth

3. Cardiac

Functions: Cells have ability to contract Locomotion Support Other body movement

X: Muscle

X: Muscle: Skeletal Voluntary movement Long and cylindrical

(up to 25 cm) Transverse striation multi-nucleated

X: Muscle: Smooth Involuntary movement Long, spindle shape Single nucleus Internal organs

X: Muscle: Cardiac Striations Involuntary One nucleus Intercalated disks Heart muscle

XI: Nervous Cells very high ability to

Respond to stimuli Transmit impulses

Two types of cells Neurons – conduct nerve impulses Neuroglia – provide physical support, maintain

chemical composition of tissue fluids, nutrients…

XI: Nervous Cell Body(3) Dendrites (5) Axon(1)

Can’t be replaced Very LONG cells Create the human

“electrical system”