Chapter 4 Tissues Flashcards
What are tissues?
A group of cells with a common embryonic origin that function together to carry out specialized activities
What is histology?
The science that deals with the study of tissues
What are pathologists?
Specialize in laboratory studies of cells and tissues for diagnoses
What are 4 types of tissues?
- Epithelial
- Connective
- Muscular
- Nervous
What is Epithelial Tissue?
Covers body surfaces and lines hollow organs, body cavities, ducts, and forms glands
What are connective tissues?
Protects, supports, and binds organs, while also storing energies such as fat, providing immunity
What is muscular tissues?
Generates the physical force needed to make body structures move and generate body heat
What is nervous tissues?
Detects changes in body and responds by generating nerve impulses
Tissues of the body develop from what three primary germ layers?
Endoderm, Mesoderm, and Ectoderm
What type of tissue develops from all three germ layers?
Epithelial
All Connective tissues and most muscle tissues derive from what?
Mesoderm
Nervous tissue develops from what?
Ectoderm
What are cell junctions?
Contact points between the plasma membranes of tissue cells
What are the 5 most common types of cell junctions?
- Tight junctions
- Adherens
- Desmosomes
- Hemidesmosomes
- Gap Junctions
What are tight junctions?
Web-like strands of transmembrane proteins
What do tight junctions do?
Fuse cells together and seal off passageways between adjacent cells. (This helps retard the passage of substances between cells and leaking into the blood or surrounding tissues)
Where are tight junctions common?
epithelial tissues of the
1. stomach
2. Intestines
3. urinary bladder
What are Adherens Junctions?
Dense layer of proteins called Plaque, which resist separation of cells during contractile activities
Where is Adherens Junctions located?
inside the plasma membrane attached to both membrane proteins and microfilament of the cytoskeleton
What are Cadherins?
Transmembrane glycoproteins which insert into the plaque and join cells
What are adhesion belts ?
In epithelial cells they encircle the cell
What is the Desmosomes?
- They contain plaque and cadherins that extends into the intercellular space to attach adjacent cells together.
- They also prevent epidermal cells from separating under tension and cardiac muscles cells from pulling apart during contraction
Desmosomes plaques attaches to intermediate filaments that contain what ?
A protein called keratin
What are hemidesmosomes?
They resemble half a desmosome and do not link adjacent cells but anchor cells to the basement membrane
What do Hemidesmosomes contain?
A transmembrane glycoprotein called integrin
What do Integrins do?
Attach to intermediate filaments and the protein laminin present in the basement membrane
What are gap junctions? and what do they do?
Plasma membranes which are separated by a very narrow intercellular gap. They also connect neighboring cells via tiny fluid filled tunnels called connexons
What happens in the gaps of Gap junctions?
Communication of cells via ions, nutrients, waste, chemical and electrical signals which travel through the connexons from one cell to another
What are the 3 major functions of epithelial tissues?
- Selective barrier that regulates the movement of materials in and out of the body
- Secretory surfaces that release products onto the free surface
- Protective surfaces against the environment
How are the cells of epithelial tissues arranged?
- Cells are closely packed and held tightly together
- functions in covering and lining the body
- has a free surface
- can be arranged in continuous sheets, single sheets, or multiple layers
Do Epithelial tissues have their own nerve supply?
Yes
Epithelial tissues are avascular, what does that mean?
They lack their own blood supply
In Epithelial tissues how do they get nutrients and eliminate waste?
Blood vessels in the connective tissues take care of that
What does the cell division rate for epithelial tissue look like?
High rate of cell division
What type of role does the Epithelial tissue play in the body?
Numerous roles such as protection and filtration
What are two different types of Epithelium Tissue?
- Covering and lining epithelium
- Glandular Epithelium
What is covering and lining epithelium?
Outer covering of skin and some internal organs
What is Glandular epithelium?
Secreting portion of glands (thyroid, adrenal, and sweat glands)
What are different kinds of Simple epithelium?
- Simple squamous epithelium
- Simple cuboidal epithelium
- Simple Columnar epithelium
- Pseudostratified Columnar epithelium
What are simple squamous epithelium?
Simple layer of cells that resemble a tiled floor on the surface
Where are simple squamous epithelium found generally?
At sites for filtration or diffusion
What are different kinds of simple squamous epithelium/ covering and lining epithelium?
Endothelium and Mesothelium
What are endothelium’s ?
They type of simple squamous that lines the heart, blood vessels, and lymphatic vessels
What are mesothelium’s?
The type of epithelial layer of serous membranes such as the pericardium, pleura, or peritoneum
What do endothelium and mesothelium have in common?
They are both derived from embryonic mesoderm