Test Two Module 5 Flashcards
What are tissues?
Organized groupings of cells and secreted materials that are connected or intertwined with each other and which perform specific, limited functions within a larger system (such as within an organ or larger grouping.)
In animals, all tissue can be grouped into one of the four major categories:
Epithelial tissue, Connective tissue, Muscle tissue, and Nervous tissue
_____ tissue lines surfaces that are subject to a lot of wear and tear?
Epithelial tissue
_____ tissue forms glands to create secretions?
Epithelial tissue
Epithelial tissue lines surfaces subject to a lot of wear and tear because they either: (2)
- cover surfaces that face the outside world (skin) or connect to the outside world (digestive tract)
- Line internal passageways for blood, lymph, and secretions
Connective tissues main functions are: (6)
- fills internal spaces
- supports other tissues
- covers and wraps internal organs
- transports materials
- stores energy
- provides insulation
What is the most versatile and diverse tissue type?
Connective tissue
_____ tissue are specialized for contraction
Muscle tissue
What are the three types of muscle tissue?
- skeletal muscle(move bones)
- cardiac muscle(contracts heart
- smooth muscle(in the walls of hollow organs)
What type of muscle is found in the walls of organs?
smooth muscle
What type of muscle contracts heart?
cardiac muscle
What type of muscle moves bones?
Skeletal muscle
_____ tissue carries electrical signals from one part of the body to another?
Nervous tissue
_____ tissue supports the cells that deliver the electrical signals?
Nervous tissue
Nervous tissue two functions? (2)
- carries electrical signals from one part of the body to another
- supports the cells that deliver the electrical signals
In animal cells, cell division is by _____?
Mitosis
What is cell differentiation?
When a cell has developed a set of structures and functions that are unique to the specific tissue it is part of; usually, but not always accompanied by a loss of the ability to undergo mitosis.
Most of the cells in a non-embryonic individual are _____ and cannot divide to produce new copies of themselves?
specialized
New cells in tissues are produced by ______?
stem cells
What are stem cells?
Undifferentiated cells able to undergo mitosis to produce two daughter cells, one of which will remain a stem cell and one of which will differentiate into a specific specialised cell within a specialised tissue.
For a short while after the fertilized egg starts dividing and forms an embryo, all the embryonic cells are _____?
stem cells
The _____ have the ability to form any cell type from any tissue type, but only for a short while.
embryonic stem cells
Somatic stem cells are basically?
Adult stem cells
After a baby is born, all tissues are present and most of the cells in the body can no longer _____ and there are also no more embryonic cells?
divide
What are somatic stem cells?
An undifferentiated cell (found in a tissue of otherwise differentiated cells) that can replicate itself and differentiate into a limited repertoire of differentiated cells.
The different types of somatic stem cells are often named for either:
The location they are found of the cells they differentiate into
Neural stem cell are found where?
in the brain
Dental pulp stem cells are found where?
Interior of teeth
Most somatic stem cells can only differentiate into:
One or at most a few different cell types
Neural stem cells in the brain can only differentiate into _____?
Neurons
Liver stem cells can only differentiate into _____?
Liver cells
One epithelial (singular) tissue is known as an _____?
epithelium
What is an epithelium?
A layer of epithelial cells covering an internal or external surface
Epithelial are always _____ of some sort?
Linings
Some but not all epithelial linings _____ onto their surface?
Secrete fluids
What is a glad?
A single epithelial cell that has differentiated/specialised into a cell that produces secretions.
Or
A group of epithelial cells that form a structure where some of the epithelial cells produce secretions that travel through a duct to the surface of the rest of the epithelial tissue.
Is a gland one cell or many cells working together?
Both
Epithelial cells (both glandular and non-glandular epithelia) usually have a straightforward appearance of?
boxy and tightly packed together
All cells in epithelia have five important characteristics:
- polarity
- attachment
- regeneration
- association
- avascularity
Describe the what the polarity of epithelial tissue means:
The two “ends” of the epithelial cells are not the same.
One end of an epithelial cell is closer to the exterior surface it lines = apical surface of the cell.
The other end is closer to the base of the tissue where it connects to other tissues = basolateral surface of the cell.
What is the apical surface of the cell?
The one end of an epithelial cell that is closer to the exterior surface it line (the top of the cell)
What is the basolateral surface of the cell?
The other end of the cell tissue where it connects to other tissues (the bottom of the cell that attaches to the basement membrane)
The cytoplasm of epithelial cells has its organelles distributed _____ between the apical and basolateral surfaces?
unequally
Describe what attachment of epithelial tissue means?
Epithelial cells are tightly bound to one another via cell-to-cell interactions, and they are also tightly attached to the material below/basolateral to them. (they are attached through junctions and the basement membrane)
Describe what regeneration means for epithelial tissue?
Because epithelial cells are at surfaces, they are worn away at a fast pace.
Some of the cells within any epithelial layer are able to act as somatic stem cells that divide and replace any lost epithelial cells all throughout the tissue. These stem cells can only specialize into epithelial cells, no other types.
Describe what association mans for epithelial tissue?
Epithelial tissue always sits on top on and is tightly associated with a different underlying tissue.
(The underlying tissue is almost always connective tissue.)
What is almost always the underlying tissue of epithelial tissue ?
connective tissue
What does avascularity mean for epithelial tissue?
Epithelial cells lack blood vessels running through or between them.
Blood vessels only run below epithelia through the connective tissue that underlies it.
Blood vessels travel through underlying connective tissue but not through epithelial tissues, so transfer of material to epithelial tissue has to travel through _____?
Many cells to get to or from blood
What are the four main function of epithelial tissue?
- provide physical protection
- control permeability
- provide sensation
- produce specialized secretions
How does epithelial tissue provide physical protection?
As the outside-world-facing layer of most surfaces, they prevent undesired material from getting in and desirable material from getting out.
How does epithelial tissue control permeability?
As the outside-world-facing layer of most surfaces, they are the gateway to the interior tissues; so the membrane transporter proteins on epithelial cells will determine what gets in or out of the body.
Most materials allowed into the body have to cross into and out of epithelial cells.
Some materials can squeeze between epithelial cells.
The cells and how tightly they are packed control what gets in on one side and out the other.
Most materials allowed into the body have to cross into and out of _____ cells?
epithelial
How do epithelial cells control permeability in the body?
By controlling what travels through them and between them
How do epithelial tissue provide sensation?
While epithelia lack blood vessels, epithelia are well-supplied with nerves;
this allows them to provide information about their external and internal environments
The _____ of the digestive tract (like that of the skin) is constantly sending sensory information to the brain via nerves that attach to or between epithelial cells.
epithelia
How do epithelial tissue produce specialized secretions?
Glands can be either single cells, or multicellular structures, but both are specialized epithelial cells that produce and release secretions that coat the exterior of the epithelial layer.
What do cell biologists call a membrane?
The lipid bilayer around the cell
What is sandwiched between the epithelial tissue and connective tissue?
The basement membrane
What is the basement membrane?
A thin layer of extracellular protein fibers that is found beneath epithelial tissues and which is attached to both the epithelial cells above it and to the connective tissue below it.
What is the basement membrane made of?
Protein fibers
What is the first portion of the basement membrane called?
Basal lamina
What is the second portion of the basement membrane?
Reticular fibers
What is the basal lamina?
The first part of the basement membrane that is made up of protein fibers secreted by the epithelial cells above the basement membrane
What are the reticular fibers?
the second portion of the basement membrane that is made up of protein fibers secreted by the connective tissue cells below the basement membrane
What is he function of the basement membrane?
to ensure epithelial layers cannot be easily separated from the lower layers of tissue
What is the basement membrane made of?
The basal lamina and the reticular fibers
The epithelial layer surrounding an organ can either be?
Tight or leaky depending on how tightly the epithelial cells are sealed together
_____ epithelia does not allow extracellular fluid to pass freely through them?
tight
_____ epithellia do allow extracellular fluid to pass freely through them?
leaky
What happens with leaky epithelia?
Extracellular fluid and other materials can easily move from one side of the epithelial layer to the other
What are three main specialized structures made up of protein fibers serve as cell-to-cell junctions, sealing epithelial cells to one another either tightly, or more loosely?
- Tight junctions (occluding junctions)
- Desmosomes (macula adherens)
- Gap junctions
An epithelium with many tight junctions between its cells will _____?
not be leaky
What are the tightest junctions?
Tight junctions
_____ junction consist of a branching network of interlocking proteins that cross between two adjacent cells, sealing them tightly together.
tight junctions
What is also known as occluding junctions?
tight junctions
_____ junction is a large complex of densely packed interlocking protein fibers that start in the cell, cross the membrane, then lock up with equivalent protein fibers from the adjacent cell.
Desmosomes (macula adherens)
_____ are distinguished by the disc of proteins on each side of the attached membranes, with protein fibers extending into the cytoplasm before they lock up
Desmosomes
What is also known as macula adherens?
Desmosomes
______ are among the leakiest of junctions, they hold cells together, but not all that closely?
Desmosomes
_____ are secure but not particularly tight junctions?
Desmosomes
_____ junctions is a ring of proteins that cross both membranes of adjacent cells, both sealing them, and creating a pore connecting their cytoplasm?
gap junctions
____ junctions allows cells to adhere adjacent to one another but also allow them to share cytoplasmic contents?
Jap junctions
What are CAMs?
Cell adhesion molecules
_____ are the proteins that collectively make up the junctions?
CAMs (cell adhesion molecules)
Individual specific CAMs have names like:
Cadherins, integrins, connexins
The cells in epithelial tissues always attach to the _____ a fibrous matrix of proteins secreted by both the epithelial cells and also by connective tissue below it?
Basement membrane
Epithelial cells attach to the basement membrane via?
hemidesmosomes
What are hemidesmosomes?
They are similar to desmosomes, but instead of attaching one cell to another, it attaches one cell to the basement membrane
_____ are distinguished by one disc of proteins (inside the cell) and protein fibers that extend and attach to the basement membrane protein fibers below it?
hemidesmosomes
What are the two main ways we categorize epithelia?
Shape and layers
What is the types of shape epithelia can have?
Squamous= thin and flat cubiodal= square shaped Columnar= tall columns or rectangular shapes
What is the types of layers epithelia can have?
Simple= one single layer Stratified= several layers pseudostratified= appears to have many layers
When trying to identify the shape of a cell you always refer to what part?
The apical or top row is used for determining shape
In multilayered epithelia which row is used to determine the shape name for epithelium?
The top row
Some layers of simple squamous epithelia have been given special names, but they are still just types of simple squamous epithelia, what are they?
Mesothelium
endothelium
endocardium
What is the mesothelium?
The simple squamous epithelia that forms the epithelial layer of serous membranes found in the ventral body cavities
What is some example of mesothelium?
The epithelial layer of the pleural membrane (lungs, of the pericardium (heart), and of the peritoneum (abdominal organs
What is he endothelium?
The simple squamous epithelium lining blood vessels
What does endothelium always line?
blood vessels
What is the endocardium?
The simple squamous epithelia lining the interior of the heart (facing blood in heart chambers)
What is pseudo-stratified columnar epithelia?
Epithelia that at first glance appear to have multiple layers, but really they do not
What is transitional stratified epithelia?
Several layers of epithelial cells that cant be classified by shape because they change shaped.
Why can’t transitional stratified epithelia be classified by shape?
Because they change shape
______ epithelia are found lining organs or structures that have to stretch, like the bladder, ureters, and urethra.
Transitional epithelia
What are the two categories glands can be?
endocrine glands and exocrine glands
What is a endocrine glad?
Specialised epithelial cells that release signal molecules (hormones) directly into the extracellular fluid and have no ducts for delivery of the secretion.
_____ gland is just a specialized epithelial cell that releases a secretion just by dumping it outside the cell, where it quickly crosses blood vessel walls and enters the blood.
Endocrine gland
What is a exocrine gland?
Specialised epithelial cells that release secretions onto non-specialized epithelial cells that form a duct, or passageway to the tissue surface.
Which gland can be further sub categorized by mode of secretion?
exocrine glands
What are the 3 other sub categories exocrine glands can be further categorized into?
- merocrine
- apocrine
- holocrine
What is merocrine secretion?
The secreted material is produced in the Golgi apparatus and then packaged into vesicles (membrane-bound delivery sacs).
The vesicles travel from the Golgi to the plasma membrane, where the vesicles fuse with the membrane and release the vesicle contents (secreted material
What is some examples of merocrine secretion?
salvitory glands and most sweat glands
_____ is membrane bound secretion?
merocrine
What is appocrine secretion?
The secreted material is produced in the Golgi apparatus and then packaged into vesicles (membrane-bound delivery sacs).
The vesicles travel from the Golgi to the plasma membrane, where the secreted material is released en masse with the surrounding cytoplasm by shedding an entire section of the cell, although remainder of cell remains intact.
What is some examples of appocrine secretion?
mammary glands and some sweat glands
_____ a part of the cell releases during secretion?
appocrine
What is holocrine secretion?
Secreted material is produced inside the cells.
Secreted material is released by cells bursting, killing the entire gland cells but also releasing all its contents, including the newly-synthesized material.
Gland cells are replaced by stem cells so gland is never depleted
What is some examples of holocrine secretion?
sebaceous glands in skin
_____ whole cell bursts during secretion and releases all contents?
holocrine
What is always under the basemment membrane to which epithelial tissue is attached?
Connective tissue
The epithelial cells that make up both exocrine and endocrine glands are surrounded by ______?
connective tissue