Term 1 Exam: Chapter 3 (Tissues) Objectives Flashcards
What is a tissue?
group of similar cells that usually have a common embryological origin and function together to carry out specialized activites
Define Histology
the science that deals with the study of tissues
What is a Pathologist?
A physician who examines cells and tissues for any changes that might indicate disease
What are the four major families of tissue that make up the human body?
- Epithelial Tissue 2. Connective Tissue 3. Muscular Tissue 4. Nervous Tissue
Where could you find epithelial tissue?
- covers body surfaces; - lines hollow organs, body cavities and ducts; - forms glands
What is the function of Connective tissue?
-Protects and supports the body and its organs; -Binds organs together, -Stores energy reserves as fat -provides immunity (lymph)
What is the function of Muscular tissue?
Generates physical force for movement, thereby creating body heat
What is the function of Nervous Tissue?
Detects changes in a variety of conditions and responds by initiating and transmitting nerve impulses that help control and coordinate body activities
What is a cell junction?
point of contact between neighbouring plasma membranes
There are five major types of cell junction, what are they?
- Tight junction 2. Adherens junction 3. Gap junction 4. Desmosome 5. Hemidesmosome
What is the function of a tight junction? Examples of where it would be found?
- forms a tight seal between cells (such as the epithelial cells that comprise the inner lining of the stomach, intestines and urinary bladder) -Prevent passage of substances between cells
What is the function of an adherens junction? Examples of where it would be found?
-Strongly fasten cells to each other -Found in epithelial surfaces = help resist separation during contractile activity ie lining of intestine
What is the function of a desmosome? Examples of where it would be found?
-Strongly fasten cells to each other; - prevent epidermal cells from separating under tension and cardiac muscle cells from pulling apart during contraction -Found in outer layer of skin (epidermis) and heart
What is the function of a hemidesmosome? Examples of where it would be found?
Strongly anchor cells to an underlying basement membrane -Found in all epithelial layers
What is the function of a gap junction? Examples of where it would be found?
-Formed by minute, fluid-filled tunnels that permit passage of electrical signals or chemicals (ie ions or small molecules) from one cell to another -Located in some parts of the nervous system, heart muscle, and in the gastrointestinal tract
Compare epithelial and connective tissue. Include 4 points.
- Epithelial tissue contains many, tight-knit cells and little extracellular matrix while connective tissue has an abundance of extracellular matrix btwn widely scattered cells 2. Epithelial tissue is avascular, while connective tissue has numerous blood vessels 3. Epithelial tissue ALWAYS forms surface layers 4. Epithelial tissue is always located adjacent to connective tissue
What relationship between epithelial tissue and connective tissue is important for the survival and function of epithelial tissue?
Because epithelial tissue is avascular, it depends on the blood vessels in connective tissue for oxygen and nutrients and waste disposal (diffusion)
What are 8 General Features of Epithelium (epithelial tissue)?
- covering and lining epithelial cells arranged in continuous sheets in either single or multiple layers 2. Usually closely packed cells with little extracellular matrix between 3. Cells have three surfaces: a) lateral surface b) apical (free) surface c) basal surface (connected to basement membrane) 4. Numerous cell junctions that securely attach neighbouring cells 5. Avascular tissue exchanges materials with adjacent connective tissue via diffusion 6. Innervated (has nerve supply) 7. high capacity for cell division (to replace dead or damaged cells ie skin) 8. Has numerous functions including: a) protection b) filtration c) secretion d) absorption e) excretion
What are the two major types of epithelial tissue?
- Surface Epithelium 2. Glandular Epithelium
What is the structure of surface epithelium?
cells are arranged into one or more layers to form outer coverings and inner linings of the organs, cavities, and ducts of the body
The arrangement of cell layers reflects the function of surface epithelium. What are the three arrangements?
- Simple (unilaminar) epithelium = single layer of cells 2. Stratified (multilaminar) epithelium= two or more layers 3. Pseudostratified epithelium = single layer that appears stratified
Surface epithelial cells may be one of four shapes. What are these shapes?
- Squamous: cells are flattened 2. Cuboidal: Cells are cube-shaped or hexagonal 3. Columnar: cells are tall and cylindrical 4. Transitional: Cells are able to undergo changes in shape caused by distension
The combination of cell shape and arrangement of cell layers leads to 8 Classifications of Epithelial tissue, what are they?
- Simple squamous epithelium 2. Simple cuboidal epithelium 3. Simple Columnar Epithelium 4. Pseudostratified Columnar Epithelium 5. Stratified Squamous Epithelium 6. Stratified Cuboidal Epithelium 7. Stratified columnar epithelium 8. Transitional epithelium (urothelium)
Where would you find Simple squamous epithelium? What is the main function?
Single layer of flat cells: -Located in areas subject to little wear and tear -Adapted for diffusion (alveoli of lung) and filtration (blood filtration in kidneys)
Where would you find Simple cuboidal epithelium? What is it adapted for?
-Adapted for secretion and absorption -lines kidney tubules and smaller ducts of many glands
Where would you find simple columnar epithelium? What are some adaptations in these locations?
- found in upper respiratory passageways (has cilia in this location to move materials past cells) - Found in small intestine (has microvilli to increase efficiency of absorption)
What is the function of Pseudostratified columnar epithelium and an example of where it would be found?
-Functions in secretion or movement of materials by ciliary action -Found in upper respiratory passageways
What is the function of Stratified squamous epithelium and an example of where it would be found?
-Provides protection in areas subject to wear and tear -Found in outer layer of skin and lining of mouth
What is the function of stratified cuboidal epithelium and an example of where it would be found?
Rare type -Functions in protection -Found in ducts of sweat glands
What is the function stratified columnar epithelium and an example of where it would be found?
Rare Type -Functions in protection and secretion -Found in large ducts of some glands
What is an important feature of transitional epithelium? Provide an example of where it would be found.
Contains cells that may undergo changes in shape and therefore are located in areas subject to stretching -Example: urinary bladder
What is Glandular Epithelium?
Specialized epithelial cells organized to form glands that secrete substances into ducts, onto a surface or into the blood
What are the two categories of glandular epithelium?
Endocrine Glands Exocrine Glands