Ch 4 - Tissues - book notes Flashcards
What are the 4 major tissue types?
- Epithelial tissue
- Connective tissue
- Muscle tissue
- Nervous tissue
What is a unicellular organism that lives as an individual?
a paramecium
What can a paramecium do?
it can feed itself, respire (to breathe), grow and produce or find all of the biochemical substances that it needs without the assistance of other cells
Multicellular organisms can’t do what?
can’t survive independently
What are tissues?
cells of similar type and function that are clustered into layers, sheets or groups
What are the functions of a epithelial tissue (which perform vital functions in the bodies of animials)?
- protects, covers and lines other tissues
- fiters biochemical substances
- absorbs nutrients
- provides sensory input
- manufactures secretions
- manufacturers excretions
What is the function of connective tissue?
provides support
What is the function of muscle tissue?
enables movement
What is the function of nervous tissue?
controls work
What is the study of anatomical structures that can be seen with the naked eye and includes learning the names and locations of bones, muscles, arteries, veins, and nerves?
gross anatomy
What is the study of the microscopic structures of tissues and organs?
histology or microanatomy
What are some examples of epithelial tissue that cover and line other tissues?
the bladder, mouth, blood vessels, thorax, and all of the body cavities and ducts in the body
What is an example of epithelial tissue that is absorptive?
epithelia that line the gastrointestinal tract - absorb nutrient molecules from the gut
What types of sensory input can epithelial cells provide?
detects changes in the environment, e - cells on tongue are sensitive to touch, temperature, and taste
provides the sensations of sight, sound, and smell
What is the epithelia that engage in the manufacture and release of substances
glandular epithelia
A type of glandular epithelia cell that occurs as individuals?
goblet cells
Where would a goblet cell be found?
in the intestine or in the pancreas as organized glands.
It is also found in the respiratory and intestinal tracts, that secretes mucus
What are some examples of substances produced by glandular epithelia?
biochemical substances that influence physiological events such as horomones, enzymes, milk, sweat, and musk
a lubricant which lubricate parts of the body such as mucus secreted in the colon
What are the substances called that ultimately leave the body, such as sweat, urine, and feces?
excretions
What are termed secretions?
substances that remain within the body such as regulatory molecules and mucus
What are some general characteristics of Epithelia?
- Epithelial cells are polar - have sense of direction relative to surrounding structures
- has an apical surface and a basal surface - different from each other - Epithelial cells have lateral surfaces that are connected to neighboring cells by junctional complexes
- All epithelial cells lack blood vessels or capillaries (avascular) - rely on underlying connective tissue to provide oxygen and nutrients
- Most epithelial cells are innervated and provide valuable sensory input (some epithelial lack nerves - stomach, intestines, and cervix)
What is apical surface on an epithelial cell?
the side of the cell that faces the lumen or body cavity
What is a basal surface on an epithelial cell?
the side of the cell that faces the underlying connective tissue
Epithelial cells have lateral surfaces that are connected by neighboring cells by what kind of complexes?
junctional complexes
What does avascular mean?
without blood supply
What does innervated mean?
having a nerve supply
What are junctional complexes?
the point at which epithelial cells join to one another in very close proximity
What are the 3 types of cellular junctions found between epithelial cells? - how epithelial cells are held together
- tight junctions
- demosomes
- gap junctions
What is a tight junction?
is formed by the fusion of the outermost layers of the plasma membranes of adjoining cells
Tight junctions are found in tissues where there can be no leaks, what are examples of tight junctions?
urinary bladder, where urine is held, or in the digestive tract - prevents leakage of digestive enzymes into the bloodstream
What is a desmosome?
a strong welded plaque or thickening which connects the plasma membrance of adjacent cells. The bond is a mechanical coupling formed by filaments that interlock with one another. Also, intermediate filaments called tonofilaments extend from the plaque into the cytoplasm of each cell like anchors, forming stabilizing bases for the membrane junction
What are some examples of desmosomes?
found most commonly in tissues that undergo repeated episodes of tension and stretching - skin, heart, and uterus
What are junctions that look like half of a desmosome?
hemidesmosomes - link epithelial cells to the basement membrane
Where are gap junctions most commonly found?
in the intestinal epithelial cells - the heart and smooth muscle tissue
What are some roles of gap junctions?
cardiac and smooth muscle cell centers around their ability to quickly transport electrical sigals from one cell to another
What is a gap junction?
Proteinaceous pores that exist in the intestinal epithelial cells of most animals. These pores allow for the passage of nutrients, as well as providing a channel for intercellular communication (linked by connexon - tubular channel proteins)
Most commonly found in intestinal epthelial cells, heart, and smooth muscle tissue
What is connexon?
Proteinaceous channel that aids in the intercellular transport of nutrients that extend from the cytoplasm of one cell to the cytoplasm of the other. Also called transmembrane proteins allow the exchange and passage of ions and nutrients such as nucleotides, sugars, and amino acids, from one cell to another
What is it that gap junctions do?
The exact function is not known, but they have a role in cardiac and smooth muscle cell centers around their ability to quickly transport electrical signals from one cell to another. - in this way they coordinate the contraction of cardiac and smooth muscle.
What is a basement membrane?
the foundation of the epithelial cell - it is a nonliving meshwork of fibers that cements the epithelial cell to the underlying connective tissue. Its strength and elasticity help prevent the cell from being torn off by intraluminal pressures, such as stretching or erosion caused by the rubbing of luminal material
- can be a varying degree of thickness laid down by epithelial cells
Can act as a partial barrier between the epithelial cell and the underlying connective tissue
The surfaces of epithelial cells vary depending on where the epithelium is located in the body and what role it plays in the function of the tissue, how?
some have smooth surfaces (epithelia that lines blood vessels - to allow the easy passage of blood cells), irregular surfaces and may be covered with many fingerlike projections called microvilli or cilia
What is microvilli?
fingerlike projections
shows up on cells that are involved with absorption or secretion such as the epithelia in the intestinal and urinary tracts
What are cilia?
thousands of tiny hairs such as in the trachea, to help to propel mucus and debris up and away from the lungs toward the mouth. They are found on the free surface of cells, usually in the respiratory and urogenital tracts
What is the brush border?
The surface of a cell covered with microvilli. It greatly increases the absorptive ability of the cell
A cell with microvilli has about _______ _______ ______ surface area of a cell without them.
20 times more
What are intermediate filliaments?
also called tonofilaments - extend from the plaque into the cytoplasm of each cell like anchors, forming stabilizing bases for the membrane junction
Cilia is found in the opening of the oviduct called the ____. Cilia encourages newly expelled ___ into the oviduct.
infunibulum; ova
Ciliary movement occurs in _____? Why?
beats - enable the efficient transport of material - brought about by electrical potential
What is keratin?
a protective, waterproof substance - epithelial cells accumulate this substance as it matures and moves from the basal layer to the superficial layer of the integument.
What is integument?
the skin of the body, consisting of dermis and epidermis
What are feline panleukopenia and canine parvoviral enteritis?
two life-threatening diseases that affect cats and dogs
What is parvovirus?
causes both diseases (panleukopenia and parvoviral) - is highly contagious and is carried on clothing, shoes, and toys. - it is shed in the feces and other excretions of affected animals
Epithelial cells are classified by three characteristics, what are they?
- number of layers of cells
- shape of the cells
- presence of surface specializations
When is a tissue called stratified?
if there is more than one layer of cells - thicker and stronger and found in areas of the body that are subjected to mechanical and chemical stress
When is a tissue classified as simple?
if there is only a single layer of epithelial cells - provides little protection to the underlying connective tissue so are found in protected areas of the body such as internal compartments, ducts, vessels, and passageways.
What kinds of shapes will epithelial cells take in a cross section?
squamous, cuboidal, and columnar
The shape of cells in a cross section classification is based on… ?
shape of the cell that resides on the exposed or luminal surface of the tissue
In stratifed squamous epithelium, cubical cells are visible where?
near the basement membrane
Where are squamous cells found?
at the luminal surface; there fore the tissue is called stratified squamous, not stratified cuboidal
What terms may be added to the classification of epithelia to indicate an increased level of specialization?
the terms for surface specialization, such as cilia and keratinized