Epithelial Tissue: Sheet of cells that covers the body or lines a body cavity.
Can be separated into two basic overall types: a) covering and lining epithelia and b) glandular epithelia.
Special Characteristics of Epithelium include cellularity (made of close packed cells leaving very little extracellular material), specialized contacts (i.e. tight juctions and desmosomes), polarity (free apical surface and attached basal surface), supported by connective tissue (all epithelial sheets rest upon connective tissue), avascularity (contains no blood vessels) and regeneration (has a high capacity to regenerate).
Classification of Epithelial Tissue
A) Covering and Lining Epithelia
1. Simple Squamous Epithelium
-Squashed cells in a single thin, permeable layer with very little cytoplasm.
-Nuclei are centered and disc-shaped.
-Its function is to filter or rapidly diffuse substances.
Ex: lining of the heart
Simple Squamous Epithelium (www.technion.ac.il)
2. Simple Cuboidal Epithelium
-Cube shaped cells in a single layer.
-Nuclei are centered and spherical.
-Its function is to absorb and secrete.
Ex: kidney tubules
Simple Cuboidal Epithelium (www.technion.ac.il)
3.Simple Columnar Epithelium
-Single row of tall, column-like cells.
-Nuclei are round.
-Cilia may be present.
-Its function is to absorb and secrete.
-Secretes mucus.
-Cilia movement propels substances and cells.
Ex: lining of digestive tract
Simple Columnar Epithelium (www.technion.ac.il)
4. Pseudostratified Columnar Epithelium
-Column shaped cells in a single layer, but all vary in height.
-Cilia may be present.
-Its function is to secrete and absorb.
Ex: lining of respiratory tract
Pseudostratified Epithelium (http://erl.pathology.iupui.edu/HISTO/GENER60.HTM)
5. Stratified Squamous Epithelium
-Several layers of cells thick.
-The top layer is squamous cells and the deeper layers are cuboidal or columnar cells.
-Its function is to protect underlying tissues in areas of the body that are subjected to abrasion.
Ex: Epidermis
Stratified Squamous Epithelium (www.visualsunlimited.com)
6. Stratified Cuboidal Epithelium
-Two layers of cuboidal cells
Ex: mammary glands
Stratified Cuboidal Epithelium (www.keele.ac.uk)
7. Stratified Columnar Epithelium
-Apical layer is columnar cells.
Ex: pharynx
Stratified Columnar Epithelium (www.anatomy.dal.ca)
8. Transitional Epithelium
-Basal layer is cuboidal or columnar.
-Apical layer varies, depending upon how distended the area is.
-Its function is to stretch to allow distension.
Ex: lining of the urinary bladder
Transitional Epithelium (www.faculty.une.edu)
B) Glandular Epithelia
1. Endocrine Glands
-Ductless glands.
-Produce hormones, which secrete into extracellular space, then into blood and then travel to specific
organs to increase response.
-Secretions vary from amino acids to steroids.
Ex: adrenal gland
2. Exocrine Glands
-Have ducts.
-Secrete products onto skin or into body cavities
Ex: mucous glands
a. Unicellular Exocrine Glands
-one celled
Ex: Goblet cell in intestinal and respiratory tracts
b. Multicellular Exocrine Glands
-many celled
-have an epithelium-based duct and a secretory unit
1. Simple Multicellular Exocrine Glands
-unbranched duct
2. Compound Multicellular Exocrine Glands
-branched duct
3. Tubular Multicellular Exocrine Glands
-Secretory cell forms tubes
Ex: Intestinal glands
4. Alveolar Multicellular Exocrine Glands
-Secretory cells form small sacs
Ex: Mammary glands
5. Tubuloalveolar Multicellular Exocrine Glands
-both types of secretory units
Ex: Salivary glands
Connective Tissue: Most abundant tissue and it is found everywhere in the body.
It functions to bind and support, protect, insulate and transport (in the case of blood).
Special Characteristics of Connective Tissue include that it originates from mesenchyme, has a full range of vascularity, it is mainly composed of extracellular matrix (which gives it the ability to endure weight, tension, trauma and abrasion). The extracellular matrix is made up of ground substance and fibers (collagen, elastic or reticular).
Types of Connective Tissue
1. Mesenchyme (Embryonic Connective Tissue)
-First tissue formed from mesoderm
-Made up of mesenchymal cells and fluid ground substance with fibrils
-specializes into all other types of connective tissue.
2. Connective Tissue Proper
A. Loose Connective Tissue
1. Areolar Connective Tissue
-Most abundant connective tissue
-Binds body parts together, but allows for movement of these parts.
-It is wrapped around small blood vessels,nerves and glands.
-Makes up the subcutaneous tissue that cushions and attaches the skin to structures.
-Defends against infection.
-Stores nutrients as fat.
-Ex: lamina propria of mucous membranes
Areolar Connective Tissue (www.science.tjc.edu)
2. Adipose (Fat) Tissue
-Makes up 18% of average person’s body weight.
-Very vascular, indicating high metabolic activity.
-Functions as a shock absorber and insulation. Also prevents heat loss.
Ex: Abdomen
Adipose Tissue (www.science.tjc.edu)
3. Reticular Connective Tissue
-Reticular fibers are the only fibers in the matrix
-Forms a stroma that supports free blood cells (mainly lymphocytes)
Ex: lymph nodes
Reticular Connective Tissue (www.udel.edu)
B. Dense Connective Tissue
1. Dense Regular Connective Tissue
-Made up of dense collagen fibers running parallel to the direction of pull.
-Its function is to attach muscles or bones to bones.
-Has high tensile strength in one direction.
Ex: Tendons
Dense Regular Connective Tissue (www.pathology.mc.duke.edu)
2. Dense Irregular Connective Tissue
-Collagen fibers run in more than one plane.
-Has high tension strength in more than one direction.
Ex: Dermis of the skin
Dense Irregular Connective Tissue (www.sru.edu)
Can be separated into two basic overall types: a) covering and lining epithelia and b) glandular epithelia.
Special Characteristics of Epithelium include cellularity (made of close packed cells leaving very little extracellular material), specialized contacts (i.e. tight juctions and desmosomes), polarity (free apical surface and attached basal surface), supported by connective tissue (all epithelial sheets rest upon connective tissue), avascularity (contains no blood vessels) and regeneration (has a high capacity to regenerate).
Classification of Epithelial Tissue
A) Covering and Lining Epithelia
1. Simple Squamous Epithelium
-Squashed cells in a single thin, permeable layer with very little cytoplasm.
-Nuclei are centered and disc-shaped.
-Its function is to filter or rapidly diffuse substances.
Ex: lining of the heart
Simple Squamous Epithelium (www.technion.ac.il)
2. Simple Cuboidal Epithelium
-Cube shaped cells in a single layer.
-Nuclei are centered and spherical.
-Its function is to absorb and secrete.
Ex: kidney tubules
Simple Cuboidal Epithelium (www.technion.ac.il)
3.Simple Columnar Epithelium
-Single row of tall, column-like cells.
-Nuclei are round.
-Cilia may be present.
-Its function is to absorb and secrete.
-Secretes mucus.
-Cilia movement propels substances and cells.
Ex: lining of digestive tract
Simple Columnar Epithelium (www.technion.ac.il)
4. Pseudostratified Columnar Epithelium
-Column shaped cells in a single layer, but all vary in height.
-Cilia may be present.
-Its function is to secrete and absorb.
Ex: lining of respiratory tract
Pseudostratified Epithelium (http://erl.pathology.iupui.edu/HISTO/GENER60.HTM)
5. Stratified Squamous Epithelium
-Several layers of cells thick.
-The top layer is squamous cells and the deeper layers are cuboidal or columnar cells.
-Its function is to protect underlying tissues in areas of the body that are subjected to abrasion.
Ex: Epidermis
Stratified Squamous Epithelium (www.visualsunlimited.com)
6. Stratified Cuboidal Epithelium
-Two layers of cuboidal cells
Ex: mammary glands
Stratified Cuboidal Epithelium (www.keele.ac.uk)
7. Stratified Columnar Epithelium
-Apical layer is columnar cells.
Ex: pharynx
Stratified Columnar Epithelium (www.anatomy.dal.ca)
8. Transitional Epithelium
-Basal layer is cuboidal or columnar.
-Apical layer varies, depending upon how distended the area is.
-Its function is to stretch to allow distension.
Ex: lining of the urinary bladder
Transitional Epithelium (www.faculty.une.edu)
B) Glandular Epithelia
1. Endocrine Glands
-Ductless glands.
-Produce hormones, which secrete into extracellular space, then into blood and then travel to specific
organs to increase response.
-Secretions vary from amino acids to steroids.
Ex: adrenal gland
2. Exocrine Glands
-Have ducts.
-Secrete products onto skin or into body cavities
Ex: mucous glands
a. Unicellular Exocrine Glands
-one celled
Ex: Goblet cell in intestinal and respiratory tracts
b. Multicellular Exocrine Glands
-many celled
-have an epithelium-based duct and a secretory unit
1. Simple Multicellular Exocrine Glands
-unbranched duct
2. Compound Multicellular Exocrine Glands
-branched duct
3. Tubular Multicellular Exocrine Glands
-Secretory cell forms tubes
Ex: Intestinal glands
4. Alveolar Multicellular Exocrine Glands
-Secretory cells form small sacs
Ex: Mammary glands
5. Tubuloalveolar Multicellular Exocrine Glands
-both types of secretory units
Ex: Salivary glands
Connective Tissue: Most abundant tissue and it is found everywhere in the body.
It functions to bind and support, protect, insulate and transport (in the case of blood).
Special Characteristics of Connective Tissue include that it originates from mesenchyme, has a full range of vascularity, it is mainly composed of extracellular matrix (which gives it the ability to endure weight, tension, trauma and abrasion). The extracellular matrix is made up of ground substance and fibers (collagen, elastic or reticular).
Types of Connective Tissue
1. Mesenchyme (Embryonic Connective Tissue)
-First tissue formed from mesoderm
-Made up of mesenchymal cells and fluid ground substance with fibrils
-specializes into all other types of connective tissue.
2. Connective Tissue Proper
A. Loose Connective Tissue
1. Areolar Connective Tissue
-Most abundant connective tissue
-Binds body parts together, but allows for movement of these parts.
-It is wrapped around small blood vessels,nerves and glands.
-Makes up the subcutaneous tissue that cushions and attaches the skin to structures.
-Defends against infection.
-Stores nutrients as fat.
-Ex: lamina propria of mucous membranes
Areolar Connective Tissue (www.science.tjc.edu)
2. Adipose (Fat) Tissue
-Makes up 18% of average person’s body weight.
-Very vascular, indicating high metabolic activity.
-Functions as a shock absorber and insulation. Also prevents heat loss.
Ex: Abdomen
Adipose Tissue (www.science.tjc.edu)
3. Reticular Connective Tissue
-Reticular fibers are the only fibers in the matrix
-Forms a stroma that supports free blood cells (mainly lymphocytes)
Ex: lymph nodes
Reticular Connective Tissue (www.udel.edu)
B. Dense Connective Tissue
1. Dense Regular Connective Tissue
-Made up of dense collagen fibers running parallel to the direction of pull.
-Its function is to attach muscles or bones to bones.
-Has high tensile strength in one direction.
Ex: Tendons
Dense Regular Connective Tissue (www.pathology.mc.duke.edu)
2. Dense Irregular Connective Tissue
-Collagen fibers run in more than one plane.
-Has high tension strength in more than one direction.
Ex: Dermis of the skin
Dense Irregular Connective Tissue (www.sru.edu)
posted by Melissa's Anatomy Blog at 5:54 PM
4 Comments:
Hi Melissa,
I really like how organized and neat you are when you do your outline formats. I rreally liked the images, but when I clicked on some web adresses to see where you got your pics from I couldn't find, perhaps you can tell me where to find. Your simple squamos looked kinda stratified so I went to check the image to see if it was labeled that way when you uploaded it to blogger, only because I thought simple squamous had only a single layer and if it can look like that I need to reprogram my brain to it looking like that also.hehe! Y aknow what I mean? The things I had a difficult time with was not seeing a visual for the glands, I had my book which I was able to look at to try to make out certain features of the different subtypes but it was difficult for me to look back at the screen and find where I was. I love your style in the way you outline, brief anf to the point. Like when you touched osubject on the glands you definately had all of the information there, just a friendly suggestion because you did awsome on the rest but I had to look at the definition in my book for glandular epithelia to understand what exactly you were going into and every subdivision ran right into the next without explanation of why you were starting another #. For example unicellular and multicellular ex glands, maybe a little brief something on what goblet cells are and what they produce(mucin), and how multi cellular ex glands have more cells because they are far more complex and then go into structeral classification and brief on how they have subdivsions based on their ducts structures and secretory units. Ok now it's your turn to read my entry, don't hold back, throw whatever you think at me. hehe!
Melissa,
I can hardly add anything to Courtney's very complete comment above. I agree this is very nicely done...great outline style, nice addition of pictures. I can't see it right now, but did you reference the sources for the pictures...if not, be sure to do that.
Keep up the great work,
LF
Wow,so organized! Easy to read,easy to follow,neat and orderly!I like that it is concise,too..you stuck to the facts,and didn't add every fact on earth about them! heh Great use of illustrations.
I'd like to see a little bit more of your personality in the blogs..whether it be your opinions(not always something we have on this material,i know),sense of humor or whatever. That makes it much more interesting to read. Good work!
I enjoyes the set up of your blog. Your pictures are in great order and you went into great detail on each topic. I'm not totally comfortable leaving any negative feedback because my images and overall organization of my blog did not come out as I had planned. So keep up the great work!
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