Histology Set (Epithelium, Connective Tissue, Membrane Slides BC D3)

What 4 basic tissues make up all the organs of the body?

1. Epithelial

2. Connective

3. Muscular

4. Nervous

What is an epithelium?

Sheet of closely apposed cells that separates a lumen from underlying tissue

If you compared epithelial and lumen to a watering hose which structure would correspond with the part of the hose that you hold?

Epithelium (surrounds the inside of the hose that actually is hollow and carries water)

If you compared epithelial and lumen to a watering hose which structure would correspond with the inside of the hose where water flows?

Lumen (free space of hose where water flows)

What is the name of the epithelium that is the covering of the skin?

Epidermis

What is the epidermis?

Epithelial layer of skin that covers the body

What is the name of the epithelium that lines blood vessels?

Endothelium

What are the 5 common features of all epithelia?

1. Close apposition of cells

2. Free surface of epithelial cells is adjacent to the space that is limited

3. Basal surface is adjacent to connective tissue

4. Absence of blood vessels inside epithelial layer

5. Sheets of epithelial cells may be modified into tubes forming glands

What is the name for the side of an epithelial layer that borders the lumen?

Apical side

What is the name for the side of an epithelial layer that borders the connective tissue?

Basal side

What are the 7 functions of epithelia?

1. Protection against abrasion and desiccation

2. Lubrication

3. Secretion

4. Absorption

5. Sensory reception

6. Gas transfer

7. Ion transport

What/where is an example of epithelial executing protection?

Epidermis

What/where is an example of epithelial executing Lubrication?

Mesothelia

What/where is an example of epithelial executing secretion?

Glands

What/where is an example of epithelial executing Absorption?

Intestine

What/where is an example of epithelial executing Sensory reception?

Ear, epidermis, etc.

What/where is an example of epithelial executing Gas transfer?

Lungs

What/where is an example of epithelial executing Ion transport?

Kidney

What are the two ways to classify epithelia?

1. Number of cells

2. Shape of superficial cells

How are simple epithelial cells described?

Only one layer of cells

How are stratified epithelial cells described?

Two or more cell layers

For stratified epithelial cells how many and layer(s) contact connective tissue?

Only cells at the basal surface contact connective tissue, so 1 layer

How are pseudostratified epithelia described?

Epithelial cells that have their nuclei arranged at different levels in the epithelium that gives off a stratified appearance

In terms of connection to the connective tissue, how do stratified and pseudostratified epithelia differ?

All the cells of pseudostratified epithelia contact the basal lamina, while for stratified epithelia only cells at the basal contact connective tissue

How are squamous epithelium cells described?

Flattened in the plane of the epithelium

How are cuboidal epithelial cells described?

Cells have heights approximately equal to width

How are columnar epithelial cells described?

Cells are “taller” than they are wide

How are transitional epithelia described?

Epithelia that are capable of changing shape

Where would you find examples of simple squamous epithelia?

Endothelium and mesothelioma

Where would you find examples of Simple cuboidal epithelia?

Glands and ducts

Where would you find examples of Simple columnar epithelia?

GI tract and collecting ducts

Where would you find examples of Pseudostratified columnar epithelia?

Respiratory epithelium

Where would you find examples of Transitional epithelia?

Urinary tract

What does a goblet cell do?

Secretes mucus

Where would you typically find goblet cells in the body and surrounded by what kind of epithelia?

Found in regions of the GI tract and respiratory tracts; surrounded by simple columnar epithelium

In this sample of the GI tract, what does letter “C” point to?

Goblet cells

Although epithelial cells are typically packed tightly together, what characteristic of the binding allows for absorption and secretion to still occur?

Tight junctions are formed near the apical surface while the lateral surfaces between epithelial cells have some free intercellular space that allows for secretion and absorption to occur

What is the difference between secretion and absorption?

Secretion is the releasing of products from the connective tissue through the epithelial cells then into the lumen, while absorption works the opposite way where products move from the lumen through the epithelial cells then into the connective tissue

Why can’t microvilli be seen under a light microscope?

Their diameter is too small, so they appear to form uniform borders

What two terms are typically used to describe the boarders made by microvilli when observed under a light microscope?

1. Brush-like

2. Striated

How are cilia described?

Longer than microvilli and have a greater diameter that allows them to be seen with a light microscope

How are stereocilia described?

Long microvilli r-like structures that are found in the epididymis of the male reproductive tract and some special sensory epithelia like the inner ear

What are the 4 free surface (apical) specializations we discussed?

1. Microvilli

2. Cilia

3. Stereocilia

4. Keratin

How is keratin described?

Specialization of stratified squamous epithelia that are subject to abrasion or desiccation

What two ways are stratified squamous epithelia usually described?

1. Keratinized

2. Non-keratinized

Where are two examples of keratin epithelium?

1. Epithelium covering the skin

2. Epidermis

How are glandular epithelia described?

Glands formed by epithelial cells that secrete a fluid of different composition than blood or intercellular fluid

What are examples substances that are secreted by glandular epithelia?

Ions, secretory polypeptides/proteins, lipids, or glycoproteins

What is the difference between endocrine glands and exocrine glands?

Endocrine glands do not have a connection (ductless) to the surface from which they originated and therefore they secrete their hormones directly into the blood stream; exocrine glands retain their connection (ductless) to the surface and their secretions are transported to the surface via epithelial cells then into-lined ducts

What are the 3 glandular epithelia modes of secretion?

1. Merocrine

2. Apocrine

3. Holocene

How are merocrine secretions described?

Secretory granules leave by exocytosis with no loss of cytoplasm or part of cell itself

How are apocrine secretions described?

Secretory product and a portion of the apical cytoplasm of the gland cells are secreted

How are holocrine secretions described?

Whole cell is secreted into lumen of gland

Name the three types of glandular epithelia and an example of each

1. Merocrine//secretion of sweat

2. Apocrine//mammary glands during milk production

3. Holocrine//hair follicles

What are the two type of exocrine gland cells?

1. Serous cells

2. Mucus-secreting cells

How are serous cells described?

Often triangular shaped cells that have rounded nuclei towards the base of them; when stained and viewed the central portion is less stained due to the lack of ribosomes and nuclei acids

How are mucus-secreting cells typically described?

Cells are often columnarly shaped; when stained and viewed nuclei usually flattened at the base of the cell while the majority of the cell is pale due to the mucin content

What are some of the functions attributed to connective tissues?

• they’re supportive in nature

• Provide support for overlying epithelia of organs and provide tensile strength to areas of the body that experience mechanical stress

• Act as packing materials filling spaces and encapsulating other tissues

What are the three basic ingredients of all connective tissues?

1. Cells

2. Fibers

3. Ground substance

What re the 2 functions of the intercellular maxtrix?

1. Storage site for water, ions, and inorganic material

2. Transport of these substances from circulatory system to various tissues in the body

How do the different types of connective tissues differ from each other?

• differ in cell types

• Amount and types of fibers

• Amount and type of ground substance

How are fibroblasts described?

Cells that produce fibers and intercellular material in ordinary connective tissue

What kind of structure do fibroblasts show when stained?

Large oval-shaped nucleus with a hard to discern cytoplasm

What other cell types may be found wandering in loose connective tissue?

• eosinophils

• Neutrophils

• Lymphocytes

What are the 3 different types of fibers discussed?

1. Collagen

2. Elastic fibers

3. Reticular fibers

Going from smallest unit to largest unit, what makes a up a collagen bundle?

Collagen Fibril—>Group of Fibrils = Collagen Fiber—>Group of Fibers = Collagen Bundle

What is probably the most common protein in the body and what produces it?

Collagen most abundant and is made by fibroblasts

What two unusual amino acids are integrated in the composition of elastic fibers that give them their rubber like qualities?

Desmosine and isodesmosine

How do reticular fibers differ from collagen fibers?

They lack periodicity and are smaller in diameter

How is the storm as of reticular fibers described?

Flexible network of support in areas that are subject to changes in form or volume

What kind of cells are reticular fibers that give most commonly associated with?

Lymphatic cell and the immune system

How is ground substance described?

Product of fibroblasts that fills in the spaces between fibers and cells

What is the ground substance important for in terms of intercellular spaces?

Retention of water and ions

What determines the diffusion rate through loose connective tissue?

D the state of the large molecules comprising the ground substance

What are the 9 different classifications of connective tissue discussed?

1. Mesenchymal

2. Mucoid

3. Loose (areolar)

4. Dense irregular

5. Dense regular

6. Reticular

7. Elastic

8. Adipose tissue

9. Hard

How is Mesenchymal connective tissue described?

Connective tissue derived from mesoderm in early embryo that fills the space between other structures

How do the Mesenchymal cells of the Mesenchymal connective tissue change in the embryo as it moves forward in development?

The Mesenchymal cells will migrate and differentiate into different cell types depending on their final destination

How is mucoid connective tissues differ described?

Connective tissue found in the umbilical cord that acts as a packing material around the two umbilical arteries and one umbilical vein

What is Wharton’s jelly?

Intercellular gelatinous matrix associated with mucoid connective tissue

What is the intercellular gelatinous matrix associated with the mucoid connective tissue called?

Wharton’s jelly

What is another name for loose connective tissue?

Areolar connective tissue

How is areolar connective tissue described?

Flexible but non-resistant to mechanical stress

Where is areolar connective tissue commonly found?

Underlying the epithelium of the trachea, esophagus, and GI tract

How is dense irregular connective tissue described?

Connective tissue fibers that are r arranged in an irregular fashion where an increase in the amount and arrangement of the fibers gives the tissue more strength to withstand mechanical stress

Where is dense irregular connective tissue commonly found?

Found in dermis of skin and deep fascia surrounding tendons and nerves

How is dense regular connective tissue described?

Fibers are arranged in an irregular very regular and parallel fashion that can handle a great deal of mechanical stress

Where is dense regular connective tissue commonly found?

Tendons (attachments from muscles to bones) and ligaments ( attachments of bone to bone)

How is reticular connective tissue described?

Similar to fibroblasts connective tissue but has a more delicate nature while providing structural support

Where are reticular connective tissues found?

Supporting lymph nodes, spleen ,liver, and many glands

How is hard connective tissue described?

Consisting of bone and types of cartilage

How is adipose connective tissue described?

Serves as a great means of packing to soften mechanical stress and acts as storage site for fat

How is elastic connective tissue described?

Being found in areas of the body where the mechanical stresses require pliability and resiliency

Where is elastic connective tissue commonly found?

Walls of arteries and vocal cords

What are the three types of surface lining membranes?

1. Mucous

2. Serous

3. Cutaneous

How are mucous membranes described?

Membranes that’s line the internal surfaces of visceral (hollow) organs that are kept moist by secretions or other bodily fluids

What are the two layers of mucous membranes referred as?

Top layer = epithelium

Lower layer = laminate propia

Which membrane is the laminate propia associated with?

Mucous membranes

How are the mucous membranes associated with the exterior of the body?

All the organs and associated organ systems lined by a mucous membrane are continuous with the external body; digestive (lips and anus), respiratory (nostrils and lips), urogenital (genital area)

How are the serous membranes described?

Smooth membranes consisting of a thin layer of epithelial cells which secrete serous fluid, overlying a loose connective tissue layer

What is the serous membrane’s associate with the ventral organs?

Serous membrane lines and encloses the ventral body cavities secreting a lubricating fluid to reduce friction from muscle movement