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
Stratified squamous epithelium may be classified as..?
keratinized stratified squamous epithelium (found in the skin) or nonkeratinized stratified squamous epithelium (found in the lining of the mouth)
What are simple squamous epithelium?
- delicate and thin, flat and smooth
- found lining surfaces involved in the passage of either gas or liquid in the inner lining of the lung, where oxygen is absorbed and carbon dioxide released; and in the filtration membranes of kidneys, where water and other small molecules are excreted as urine
- found in the lining of blood and lymphatic vessels
- given special names depending on where they are found in the body
What is the mesothelium?
the peritoneal (abdominal) cavities
What is the endothelium?
the epithelium that lines blood and lymphatic vessels
What is composed of a single layer of cubical cells?
simple cuboidal epithelium
Where does simple cuboidal epithelium occur?
in sheltered regions of the body, where secretion and absorption takes place - found on the surface of ovaries, in the secretory portions of glands, such as the thyroid, and in the lining of the ducts of the liver, pancreas, kidney, and salivary glands, with microvilli, attesting to their absorptive function.
What plays an important role in both endocrine and exocrine tissue?
Simple cuboidal epithelium
The thyroid secretes what hormone, which is carried throughout the body via the bloodstream?
thyroxine
Simple columnar eipthelium are what…?
- elongated and closely packed together
- nuclei are not centrally located, but are aligned in a row at the base of the cell near the basement membrane.
- line the length of the gastrointestinal tract from the stomach to the rectum
- are associated with absorption and secretion and are found in nany excretory ducts, as well as in the digestive tract
What two types of cells make up the gut lining?
absorptive cell - the most numerous - absorption by increasing surface contact with the nutrient-filled lumen
globlet cell - manufactuer and store lubricating mucus that is secreted onto the luminal surfaces of the epithelia
What is a less common epithelia that is covered with cilia on their apical surfaces?
simple ciliated columnar epithelia - they line the uterine tubes and respiratory tracts
What does stratifed squamous epithelium consists of ..?
- various cell layers
- occurs in regions of the body that are subject to mechanical and chemical stresses such as the lining of the mouth, esophagus, vagina, and rectum
What is a less common epithelia that is covered with cilia on their apical surfaces?
simple ciliated columnar epithelia - they line the uterine tubes and respiratory tracts
What does stratifed squamous epithelium consists of ..?
- various cell layers
- occurs in regions of the body that are subject to mechanical and chemical stresses such as the lining of the mouth, esophagus, vagina, and rectum
Stratified cuboidal epithelium occurs as what and is found where?
occurs as two layers of cuboidal cells and is found primarily along large excretory ducts, such as those of sweat glands, mammary glands and salivary glands
- important in protecting the delicate tissues in deeper layers
Stratified columnar epithelium is what..?
rare and is found only in select parts of the respiratory, digestive, and reproductive systems and along some excretory ducts
What is pseudostratified columnar epithelium
an epithelial layer that is not truly stratified
- forms a single layer and therefore considered a simple epithelium
What are disease-fighting molecules that help to protect animals from pathogens (bacterial and viruses) that have been inhaled?
immunoglobulins
Where can transitinal epithelium be found?
in the regions of the body that are reqired to expand and contract as part of their normal function. Such areas are urinary tract where great changes in volume occur, such as the urinary bladder, ureters, urethra, and calyxes of the kidney
What are the ways that glands can be classified?
They can be organized based on the following factors:
- presence or absense of ducts (endocrine or exocrine)
- number of cells that compose them (unicellular or multicellular)
- shape of the secreting ducts (simple or compound)
- complexity of the glandular structure (tubular, acinar, or tubuloacinar)
- type of secretion they produce (mucoid or serous)
- manner in which the secretion is stored and discharged (merocrine, apocrine, or holocrine
-
What is secretions?
specialized protein molecules that are produced in the rough endoplasmic reticulum, packged into granules by the golgi apparatus, and discharged from the cell.
What are the ways that glands can be classified?
They can be organized based on the following factors:
What are endocrine glands?
glands that do not have ducts or tubules and whose secretions are distributed throughout the body
What are hormones?
regulatory chemicals produced and secreted by endocrine glands into the bloodstream or the lymphatic system, where they are carried to many regions of the body.
What is known as the endocrine system?
endocrine glands that are apart of a complex, biochemical network
What are examples of endocrine glands?
the pituitary gland in the brain and the adrenal gland near the kidney
Does exocrine glands possess ducts?
yes, withthe exception of the goblet cell
What is known as the endocrine system?
endocrine glands that are apart of a complex, biochemical network
What are examples of endocrine glands?
the pituitary gland in the brain and the adrenal gland near the kidney
Does exocrine glands possess ducts?
yes, with the exception of the goblet cell
What are some examples of exocrine glands?
in animals there are hepatoid, musk, sweat, and salivary glands. These glands can also be found in the liver and pancreas, where exocrine glands secrete bile and digestive enzymes, respectively
What gland possesses endocrine and exocrine properties?
the pancreas because it is responsible for producing many hormones and for secreting digestive enzymes
What is an example of a unicellular exocrine gland?
the ductless goblet cell, so named because of its resemblance to a drinking goblet
What is mucin?
a thick, sticky mixture of glycoproteins a proteoglycans that when mixed with water becomes mucus
Mucus functions in two ways, what are they?
- it helps protect the apical surface of the epithelial layer
- it assists with the entrapment of microorganisms and foreign particles
Multicellular exocrine glands are made up of two distinct components, what are they?
- a secretory unit in which secretions are produced by secretory cells
- a duct that carries the secretion to the deposition site.
What are myoepithelial cells?
contractile cells that assist with the discharge of secretions into the glandular duct
The rate of secretion production and discharge is controlled by..?
hormonal and nervous influences
Classification of exocrine glands with examination of the glandular ducts:
If the main duct is unbranched, the gland is considered..?
a simple gland
Classification of exocrine glands with examination of the glandular ducts:
If the main duct is branched, the gland is called…?
a compound gland
Examining the secretory portions of glands:
If the secretory cells form a long channel of even width, the gland is called..?
a tubular gland
Examining the secretory portions of glands:
If the secretory unit forms a rounded sac, the gland is called..?
an alveolar gland or an acinar gland
Examining the secretory portions of glands:
Glands with secretory units that possess both tubular and alveolar qualities are called..?
tubuloalveolar or tubuloacinar
From Table 4-1 - Classification of Multicellular Exocrine glands:
- Shape of gland is tubular (single, straight)
- type of gland is simple
What is the location of the gland?
in the stomach, intestine
From Table 4-1 - Classification of Multicellular Exocrine glands:
- shape of gland is tubular (coiled)
- type of gland is simple, coiled tubular
What is the location of gland?
sweat glands
From Table 4-1 - Classification of Multicellular Exocrine glands:
- shape of gland is tubular (mulitple)
- type of gland is simple, branched tubular
What is the location of gland?
stomach, mouth, tongue, esophagus
From Table 4-1 - Classification of Multicellular Exocrine glands:
- shape of gland is alveolar (single)
- type of gland is simple alveolar
What is the location of gland?
Sebaceous glands
From Table 4-1 - Classification of Multicellular Exocrine glands:
- shape of gland is alveolar (multiple)
- type of gland is branched alveolar (acinar)
What is the location of gland?
Sebaceous glands
From Table 4-1 - Classification of Multicellular Exocrine glands:
- shape of gland is tubular (multiple)
- type of gland is compound tubular
What is the location of gland?
Bulbourethral glands, mammary glands, kidney tubules, testes, mucous glands of the mouth
From Table 4-1 - Classification of Multicellular Exocrine glands:
- shape of gland is Alveolar (multiple)
- type of gland is compound alveolar (acinar)
What is the location of gland?
Mammary glands
From Table 4-1 - Classification of Multicellular Exocrine glands:
- shape of gland is Some tubular; some alveolar
- type of gland is compound tubuloalveolar
What is the location of gland?
Salivary glands, pancreas, respiratory passages
Glands are classified further according to the way in which they secrete their product:
How much of the cell is sacrificed in the act of secretion determines whether the gland is …?
merocrine
apocrine, or
holocrine
What are merocrine glands?
glands that package their secretions into granular units and release them via exocytosis as they are manufactured and the secretory cells remain intact during the secretory process
What are some examples of merocrine glands?
pancreas, sweat glands, and salivary glands
Secretion in apocrine glands involves what…?
the loss of the top part of the cell
The secretory cells do not release their granules as they are manufactured - instead they store the granules until the apex is full.
What is the apex of the secretory cell?
the top part of the cell
Where can apocrine glands be found?
in mammary tissue and are represented by some sweat glands
Holocrine glands store granules where…?
in the secretory cells until they are needed
- Also the entire secretory cell is destroyed in the act of releasing its secretory product.
Where do Holocrine secretion occur principally?
in sebaceous glands
Glands can be categorized according to the type of secretion they produce:
Serous secretions are …?
watery and contain a high concentration of enzymes
Glands can be categorized according to the type of secretion they produce:
Mucous secretions are …?
thick, viscous, and composed of glycoproteins
Glands can be categorized according to the type of secretion they produce:
Secretory cells that manufacture both types of secretionsare common where?
in the digestive and repiratory tracts
Glands can be categorized according to the type of secretion they produce:
Mixed exocrine glands contain….?
both mucous and serous components
Connective tissue is found where and represents what?
everywhere in the body and represents the most abundant tissue type by weight
Connective tissue is derived from what?
mesoderm and composed primarily of nonliving extracellular matrix
in relation to connective tissue, what does the matrix do?
surrounds and separates the cells, and it provides important structureal and nutritional support that enables connective tissue cells to exist farther apart than epithelial cells.
What does vascularized mean?
region of the body supplied with a blood source via blood vessels
What is adipose connective tissue?
is a vascularized type of connective tissue whose general function are to protect, insulate, and provide a major source of energy to the body
All connective tissue is composed of 3 distinct components, what are they?
- extracellular fibers
- ground substance
- cells
What is extracellular matrix?
The mixture of fiber and ground substance
There are variations in the ground substance, fibers, and cellular components has given rise to a wide range of connective tissue. What are examples of connective tissue?
blood, tendon, fat, cartilage, bone - their textture and appearance are different from one another
Variations in the type of ground substances and in the type of fiber enable the tissue to take on many different qualities. What are these qualities?
It can be elastic and flexible, rigid, semisolid, and liquid.
What is integumentary systems?
the skin and all of its related components, such as nails, hair, hooves, and horns
What is mesoderm?
the middle layer of fetal body tissue. Located between the outer layer (ectoderm) and the inner layer (endoderm, the mesoderm gives rise to all connective and muscle tissues. (compsed of primarily nonliving extracellular matrix)
Connective tissue can withstand a wide range of forces such as ?
direct pressure, abrasion, and shearing forces that would destroy other tissue types
What are the roles of connective tissue?
forms metabolic and structural connections, forms a protective sheath around organs and helps insulates the body, acts as a reserve for energy, provides the frame that supports the body, and composes the medium that transports substances from one region of the body to another. Also, it plays a vital role in the healing process and in the control of invading microorganisms.
What is amorphous?
having no definite shape
What is ground substance in relation to connective tissue?
- nan amorphous, homogeneous material that ranges in texture form a liquid or gel to a calcified solid
- the medium through which cells exchange nutrients and waste with the bloodstream
- acts as a shock absorbing cushion and helps protect the more delicate cells that it envelopes
- its thick texture serves as an effective obstacle for invading microorganisms. some microbes have developed the ability to produce the enzyme hyaluronidase which degrades hyaluronic acid - enabling the microbe to move with greater ease through the tissue
What is homogeneous?
having a uniform composition
The major components of connective tissue is what?
ground substances - ranges from liquid to gel to solid, fibers - collagenous, reticular, elastic, cells - fixed cells (fibroblasts, adipocytes (fat cells), reticular cells), wandering cells (mast cells, leukocytes (white blood cells), macrophages (fixed and wandering)
In soft connective tissues what is the ground substance?
it is composed of unbranched chains of glycoproteins called glycosaminoglycans(GAGs)
What are glycosaminoglycans?
carbohydrates composed of amino sugars, which are found in proteoglycans
What is a glycoprotein?
a compound composed of a carbohydrate, usually in the form of sugar, and a protein
What is a proteoglycan?
the viscous intercellular material located in the gaps between the adjacent cells in the zonula adherens (Epithelial cells are held together by strong anchoring (zonula adherens) junctions). It is composed of polysaccharide chains and small proteins.
What is the most commonly found GAG (glycosaminoglycans in connective tissue?
hyaluronic acid combined with 2% protein - these large molecules help to orient the formation of fibers within the tissue
Connective tissue contains three types of fibers, what are they?
collagenous, reticular, and elastic
What is the most commonly found fiber in the body?
collagenous
Collagenous fibers are what?
- strong, thick strands composed of the structural protein collagen.
- organized into discrete bundles of long, parallel fibrils, which in turn are composed of bundled microfibrils
- found in tendons and ligaments
- look wavy when not under pressure
- fiber itself is white (sometimes known as white fibers
- fibers can range from loose to dense
What are reticular fibers?
- composed of collagen
- thin, delicate, and branched into complicated networks
- form a kind of “mist net” that provides support for highly cellular organs, such as endocrine glands, lymph nodes, spleen, bone marrow, and liver
- also found around blood vessels, nerves muscle fibers, and capillaries.
What are elastic fibers?
composed primarily of the protein elastin
- are branched and form complex networks
- composed of bundles of microfibrils - because they are coiled, they can stretch and contract like a rubber band.
- tend to occur in tissue that are commonly subjected to stretching such as vocal cords, lungs, skin,and walls of blood vessels
- because of their color they are referred to as yellow fibers
