Histology-Study of tissue types

Chap 4

Main tissue types

• Epithelial

• Connective

• Nervous

• Muscle tissue

Epithelial Tissue

• Coverings and boundries

• Functions:– Protection– Absorption– Filtration– Excretion– Secretion– Sensory reception

Epithelial Tissue Characteristics

• Cellularity- cells packed close together

• Specialized contacts- communication and attachment between cells– Tight Junctions– Desmosomes

• Polarity- have a top and bottom– Apical surface– Basal surface

Epithelial Tissue Characteristics

• Supported by connective tissue– Basement membrane

• Avascular but innervated- few blood vessels, has nerve fibers

• Regenerative- can repair “easily”

Simple vs Stratified epithelium cellsSquamous

• Simple - adapted for filtration and reducing friction (aveoli, body cavities, kidney-loop of Henle)

• Multilayered structure of stratified - adapted for surfaces exposed to wear and tear (skin, mouth, esophagus)

Cuboidal

• Simple (almost all)- secretion or absorption (pancreas, salivary glands Thyroid hormones)

• Stratified (rare) – (along ducts of sweat glands)

Columnar

• Simple- Secretion, absorption, protection from chemical stress (small intestine, stomach)

• Psudostratified – typically have cilia (nasal cavity, trachea, male reproductive tract)

• Stratified (rare) – (small areas of pharynx, epiglottis, anus, mammary gland, urethra)

Glandular Epithelia

• Contain gland cells specialized for secretion– Endocrine glands-hormones

• Pancreas, thyroid , thymus, pituitary

– Exocrine glands – have tubular ducts to the surface

• Perspiration, tears, milk, mucus

Goblet Cell

Figure 4.3b

For your pictures

1. Simple Squamous- (lung)

2. Stratified Squamous

3. Simple cuboidal

4. Simple columnar (cilliated)- (trachea)

5. Pseudostratified columnar

6. Transitional epithelial

7. EC- Stratified Columnar

Connective Tissue

• Found throughout the body; most abundant and widely distributed in primary tissues

– Connective tissue proper– Cartilage– Bone– Blood

Functions of Connective Tissue

• Binding and support

• Protection

• Insulation

• Transportation

Characteristics of Connective Tissue

• Connective tissues have:– Mesenchyme as their common tissue of origin– Varying degrees of vascularity– Nonliving extracellular matrix, consisting of

ground substance and fibers

Pg 121

Connective Tissue Proper

Loose Connective tissues– Areolar – gel-like: cushions– Adipose – fatty: fuel reserve, insulation– Reticular – fiborous: internal, cell support

Connective Tissue Proper

Dense Connective tissue – collagen fibers, elastin fibers (fibroblast cells) – Regular – attach muscle to bone, muscle to

muscle, bone to bone (Ligaments and tendons)

– Irregular – structural strength (Dermis of skin, submucosa of digestive tract)

Cartilage

Solid matrix of Colloagen fibers (condrocytes- mature condroblasts)- avascular

- Hyaline – very hard and solid – connected to bone

- Elastic – more flexible (ears, epiglottis)- Fibrocarilage – in between flex – absorbs

shock (between vertebra)

Bone

-calcified matrix w/ collagen fibers – ostoblast cells mineralize and become ostecytes in lacunae (cavities) - vascularized

Blood

red and white bc

For your pictures:

1. Embryonic- (fetal)2. Areolar-loose3. Adipose-loose4. Reticular- loose (only 2 slides – silver stained)5. Dense regular- (collagenous fibers- regular)6. Dense irregular-(collagenous fibers- irregular)7. Hyaline cartilage8. Elastic Cartilage9. Fibrocartilage (fiberous)10.Bone11.Blood

Same slide

Nerve Tissue

• Function: Respond to stimuli and transmit impulses.– Generate and conduct electrical impulses– Regulate and control body functions

• Cells are called neurons– Composed of cell body, axon and dendrites. – Single cell may run up to several feet long.

• Supporting cells– Support– Insulation– Protection

• (We’ll discuss in detail in Chap 11)

Muscle tissue

• Myofilaments for movement– Actin– Myocin

• Look for striations perpendicular to fibers

• Lots of mitochondria

Muscle tissue types

• Skeletal- very striated– Voluntary Muscle

• Cardiac – more loose structure, striated– Inertercolated discs (connection between

branching cells)

• Smooth – barely visible striations– Involuntary Muscle

For your slides

• Nerve tissue– Mammal Neuron motor nerve

• Muscle tissue– Skeletal– Cardiac– smooth

Quiz yourself

• http://www.yvcc.edu/academics/biology/seveyka/Histology%20Zoomer/histology_zoomer_page.asp

• http://www.keele.ac.uk/depts/ms/resources/anatomy/histologyimages/homepage.html

• Email me and I’ll send you the links

Tissue Repair

• 1. Inflammation– Trauma causes damaged cells , macrophages

and mast cells to release inflammatory chemicals

– Capillaries dilate, allow WBC, clotting proteins and antibodies into damaged area

– Clots form to isolate area (hardening forms scab)

Tissue Repair

• 2. Organization restore blood supply– Granulation tissue

• Capillaries• Fibroblasts

– growth factors– Collagen fibers

Tissue Repair

• 3. Regeneration and fibrosis– Epithelial cells regenerate– Collagen (fibrous tissue) contracts to pull

edges together• Some left behind to form scar tissue

Infections

• Simple– Pimple or sore throat– Regeneration only, no fibrosis– No clotting

• Severe– Destructive– Scar tissue formed

• Scar tissue– Mostly collagen fibers, shrink and compact– Replaces original tissue type- does not function as

original tissue type– Very strong, not very flexible

Cancer

• Tumor or neoplasm – loss of apoptosis (programmed cell death)– Benign- polyp - localized extra growth of cells,

encapsulated– Malignant – Metastasis – spread to other

parts of the body, often “de”-differentiate

• Oncogenes – cancer causing genes

• Carcinogenic – cancer causing “chemical”

Types of Cancer

- Adenoma adenocarcinoma – Epithelial glands– Papilloma carcinoma – epithelial squamous– Nevus (mole) melanoma – melanocytes (pigmented

skin cells)– Sarcoma – connective and muscle– Lymphoma – lymphatic tissue– Leukemia – blood– Osteoma – bone– Condroma – cartilage– Lipoma – adipose– Fibroma – fibrous connective tissue

Cancer treatment

• Surgery – can be effective for benign tumors

• Systemic treatment– Radiation Therapy – Chemotherapy– Kills ALL types of rapidly growing cells– Unpleasant side effects

• Nausea/ vomiting• Hair loss

Silver stain (GMS) to detect presence of fungal hyphae in tissue x200

Gram’s stain to detect bacteria in tissue (oil immersion x1000)

USE OF HISTOCHEMISTRY TO DETECT INFECTIOUS ORGANISMS

Luxol Fast Blue for myelinFontana-Masson for melanocytes

MORE EXAMPLES OF HISTOCHEMISTRY

Review Assignment

• Read pg 142-143 (cancer)• Scan Chap summary

– Pg 110-112 (cells)– pg145-146 (histology)

• DO Review Questions– Pg 112-113 (cells)– Pg 147 (histology)– Be sure to discuss all Crit think /Clinical App.

Questions w/ a partner! We will go over these in class last ½ hr