Cell And Tissues Flashcards
Histology; AKA microanatomy
the study of microscopic structure and function of cells and associated tissue
Cell
the smallest living unit of organization in the body
Tissue
Cells with similar characteristics of form and function are grouped together
Organ
Various tissue types are bonded together to form a somewhat independent body part that performs a specific function(s)
A collection of tissues made of similarly specialized cells
System
Organs functioning together
cellular division
Cells in a tissue undergo cellular division to reproduce themselves and replace dead tissue cells as a result of this division process, two daughter cells are formed which are identical to each other and identical to the original parent cell
Exocytosis
Active transport of material from a vesicle within the cell out into the extracellular environment
Cells are surrounded by a____ that consists predominantly of____
cell membrane (or plasma membrane); phospholipids and proteins
Phospholipids in the cell membrane serve as the_____because they_____
diffusion regulators; selectively allow certain molecules to pass through based on their size, charge, and polarity. Overall, they control movement of substances into and out of the cell, thus maintaining the cell’s internal environment
Cytoplasm
• Semifluid part contained within the cell membrane boundary
• Also includes the cytoskeleton, which provides a skeletal system of support
• Contains a number of structures called organelles
• Also contains spaces or cavities called vacuoles
Organelles
• Metabolically active specialized structures within the cell in the cytoplasm
• Allows each cell to function according to its genetic code
Vacuoles
Spaces or cavities within the cytoplasm inside the cell
Nucleus (plural, nuclei)
Largest, densest, most conspicuous organelle in the cell when viewed microscopically. The nucleus is the cell’s “data bank” because it stores the genetic code. It is also the “command center” of the cell, controlling the other organelles in the cell and is influenced by what occurs inside the cell as well as outside the cell
Primary nucleic acid in the nuceloplasm is___
deoxyribonucleic acid (DNA), in the form of chromatin
The nucleus of a cell looks like____ when viewed at lower-power microscopically
diffuse stippling
_____in the nucleus give directions for everything the cell is and will become and controls all functions the cell performs
DNA and ribonucleic acid (RNA)
Deocyribonucleic Acid (DNA)
The hereditary material in humans and almost all other organisms mostly located in the cell nucleus (where it is called nuclear DNA with a small amount found in the mitochondria where it is called mitochondrial DNA (mtDNA). Nearly every cell in a person’s body has the same DNA
The information in DNA is stored as a code made up of four chemical bases:
• Adenine (A), Guanine (G), Cytosine (C), Thymine (T)
In an actively dividing cell, chromatin _____
condenses into rodlike chromosomes.
In the nucleus, three very important types of RNA are produced:
messenger RNA (mRNA) molecules, which are complementary copies of distinct segments of DNA;
transfer RNA (tRNA) molecules, which are capable of specifically binding to and transporting amino acid units for protein synthesis;
ribosomal RNA (rRNA) molecules
centromere
A clear, constricted area near the middle of every chromosome. Chromosomes become two filamentous (threadlike) chromatids (or sister chromosomes) joined by one centromere during cell division.
during cell division Sister chromatids remain attached at the_____.these sister chromatids eventually will_____ during cell division and become____
centromere; separate; individual “daughter chromosomes” that are distributed to the newly formed daughter cells, ensuring each new cell receives a complete set of genetic information
DNA replication is the process where___
a cell duplicates its DNA, creating two identical copies of each chromosome, which are called “sister chromatids”
Neoplasm
The fluid part within the nucleus that contains molecules used in the construction of ribosomes, nucleic acids, and other nuclear materials
Surrounds the outer part of nucleus
Double layered nuclear envelope which is a membrane similar to the cell membrane but the nuclear envelope is pierced by nuclear pores which create avenues of communication between inner neoplasm and outer cytoplasm
nucleolus
Prominent, rounded, centrally placed organelle inside of nucleus
Mitochondria
The most numerous organelle in the cell associated with energy conversion and is often called the “powerhouse of the cell”
because it is responsible for generating most of the cell’s chemical energy in the form of adenosine triphosphate (ATP) through a process called aerobic respiration. In this process, mitochondria break down glucose into an energy molecule known as adenosine triphosphate (ATP). Mitochondria also help balance the concentration of water, calcium, and other ions in the cytoplasm.
Ribosomes
Tiny, sphere shaped organelles produced in the nucleolus from RNA and protein molecules and assembled in the cytoplasm. They process the cell’s genetic instructions to create proteins. Can float freely in the cytoplasm, OR can be connected to endoplasmic reticulum
ER of cell
A network of interconnected membrane-bound sacs and tubules within a cell’s cytoplasm. Which is primarily responsible for: Synthesizing proteins (RER) and lipids (SER) and Folding and modifying proteins, and transporting molecules throughout the cell. It exists in two forms: Rough endoplasmic reticulum (RER) which has ribosomes attached to its surface and is the ER primarily involved in protein synthesis and modification. Smooth endoplasmic reticulum (SER) which lacks ribosomes and has different functions depending on the cell type but is mainly involved in lipid synthesis, carbohydrate metabolism, and detoxification in some cells
Golgi apparatus (Golgi complex)
The second largest organelle after the nucleus. Composed of stacks of 3 to 20 flattened smooth-membrane vesicular sacs arranged parallel to one another. Functions as a processing and packaging center, receiving proteins from the endoplasmic reticulum (ER), further modifying them, and then sorting and directing them to their final destinations within the cell or for secretion outside the cell newly forming vesicle. It also produces lysosomes
Lysosomes
membrane-bound vesicles of enzymes originally produced on the RER but then are transported for packaging in the Golgi complex and there develops as a bud that pinches off the end of one of the Golgi complex’s flattened sacs. Lysosomes digest various waste and foreign materials in or outside/around the cell. This function occurs during phagocytosis. Lysosomes break down many kinds of molecules using the powerful hydrolytic and digestive enzymes contained within them
The main hydrolytic enzyme in lysosomes is
hyaluronidase
Centrosome
Dense, oval shaped organelle that contain a pair of cylindrical structures, called the centrioles always located near the nucleus. They play a significant role in forming the mitotic spindle apparatus during cell division. There are two centrioles within the centrosome, and each is composed of triplets of microtubules arranged in a cartwheel pattern. Without this self-replicating centriole-centrosome unit, a cell from the body cannot reproduce
Cytoskeleton
A three-dimensional system of support for the cell made of Microfilaments, Intermediate filaments and Microtubules. This design lends basic stability to the cell as a whole. In addition, the cytoskeleton helps the cell move with Cilia - shorter, numerous projections and Flagella - fewer, longer projections
Inclusions
Non-living structures found in the cytoplasm of a cell. Made up of molecules like proteins, lipids, glycogen, and nucleic acids. Mainly formed to store reserved materials. Released by the cell and used as needed
Mitosis
A complex process of cell division involving many organelles in a cell. Before cell division, the DNA is replicated during interphase as part of the cell cycle, which is the cell’s “living” time. Following interphase, mitosis occurs in four stage (Prophase, metaphase anaphase, and telophase) with the cell’s nuclear material and other cytoplasmic components dividing so that the resulting production is of two daughter cells that are identical to the parent cell as well as to each other. Mitosis functions during tissue growth or regeneration. Its activity is dependent on the length of the individual cell’s lifespan
Describe what happens during the phases of mitosis
Interphase
The nucleolus and the nuclear envelope are distinct and the chromosomes are in the form of threadlike chromatin.
Prophase
The chromosomes appear condensed, and the nuclear envelope in not apparent.
Metaphase
Thick, coiled chromosomes, each with two chromatids, are lined up on the metaphase plate.
Anaphase
The chromatids of each chromosome have separated and are moving toward the poles.
Telophase
The chromosomes are at the poles, and are becoming more diffuse. The nuclear envelope is reforming. The cytoplasm may be dividing.
Cytokinesis
(part of telophase)
Division into two daughter cells is completed.
Tissue fluid
aka interstitial fluid, provides a medium for dissolving, mixing, transporting substances; helps carry out chemical reactions
Some cells in tissues are joined by Mechanical attachments called
intercellular junctions.
Desmosome
An intercellular junction between cells
Example: superficial layers of the skin or oral mucosa use desmosomes to connect cells
Hemidesmosome
An intercellular junction between a cell and an adjacent noncellular surface
• Example: attaching epithelium to connective tissue
Hemidesmosomes are involved in securing gingival tissue to the tooth surface by the epithelial attachment
Tissue types are categorized according to four basic histologic types:
epithelial, connective, muscle, and nerve tissue
Types of epithelium
Simple: Squamous, cuboidal, columnar, pseudostratified
Stratified: Squamous (keratinized, nonkeratinized), cuboidal, columnar, transitional
Types of connective tissue
Solid soft: Connective tissue proper, specialized (adipose, fibrous, elastic, reticular)
Solid firm: Cartilage
Solid rigid: Bone
Fluid: Blood, lymph
Types of muscle tissue
Involuntary: Smooth, cardiac
Voluntary: Skeletal
Types of Nerve tissue
Afferent: Sensory
Efferent: Motor
during prenatal development, embryonic cell layers differentiate into the various basic embryologic tissue types:
Ectoderm
Endoderm
Mesoderm
These will later form into the basic histologic tissue types of the body
Endoderm layer becomes:
1) Digestive system
2) Liver
3) Pancreas
4) Lungs (inner layers)
Mesoderm layer becomes
1) Circulatory system
2) Lungs (epithelial layers)
3) Skeletal system
4) Muscular system
Ectoderm layer becomes:
1) Hair
2) Nails
3) Skin
4) Nervous system
5) oral mucosa
For the Process regeneration of tissues, when cells die, they are
removed from the tissue and new cells take their place
Regeneration of tissue is the____ of a tissue and thus an organ produced by ______.
natural renewal; growth and differentiation of new cells into the same type of tissue that has been destroyed or from its precursor
turnover time
the time it takes for the newly divided cells to be completely replaced throughout the tissue. Turnover time differs for each of the basic tissue types in the orofacial region, as well as for specific regions of the oral cavity.
Epithelium is vascular or avascular?
Avascular
Basement membrane
Acellular Membrane located between most epithelium and deeper connective tissue
produced by the overlying epithelium as well as the adjoining connective tissue
Cellular differentiation
the process by which cells change from an immature, unspecialized state to a mature, specialized state
cells in the epithelium undergo what to regenerate?
Mitosis, and quite quickly (highly regenerative)
Simple squamous epithelium
Consists of flattened platelike epithelial cells or squames.
Simple cuboidal epithelium
consists of cube-shaped cells.
Simple columnar epithelium
consists of rectangular cells.
pseudostratified columnar epithelium
Falsely appears as multiple cell layers when viewed with lower-power magnification due to the cells’ nuclei appearing at different levels.
Make up the majority of epithelium in the body
Stratified squamous epithelium
Type of tissue in superficial layer oral mucosa
Nonkeratinized stratified epithelium tissue can be found in certain regions of the oral mucosa as well as keratinized stratified epithelium
Keratin
found within the the keratinized tissue is a tough, fibrous, opaque, and waterproof protein that is resistant to pathogenic invasion and friction
Example of keratinized stratified squamous epithelium is epidermis, which is the
superficial layer of the skin
Epidermis has varying degrees of keratinization depending on
the region of the body
Keratin is produced during the
maturation of the keratinocyte epithelial cells
The turnover time for all types of epithelium is___compared to connective tissue.
faster
Repair after injury of epithelium of the oral mucosa or skin
- Immediately after an injury to the skin or oral mucosa, a clot from blood-related products forms in the area
- Inflammatory response is triggered by the white blood cells from the blood supply as they migrate into the tissue
- Epithelial cells at the periphery of the injury will lose their desmosomal intercellular junctions and migrate to form a new epithelial surface layer beneath the clot
Connective tissue derived from_____ during prenatal development
somites
___gives rise to somites that will give rise to muscle tissue
Differentiated mesoderm
Somites are located___
on the sides of the developing central nervous system
Functions of connective tissue:
Connective tissue is involved in support, attachment, packing, insulation, storage, transport, repair, and defense
Connective tissue is composed of
Loosely packed tissue except for adipose tissue (composed of fewer cells spaced farther apart) and matrix
Soft connective tissue
includes the tissue found in the deeper layers of both the skin and oral mucosa, such as a connective tissue proper
Firm connective tissue
consists of different types of cartilage
Hard form of connective tissue consists of
bone
Fluid connective tissue consists of
blood with all its components and lymph
Both loose and dense types of connective tissue are found together in two adjoining layers as the
connective tissue proper
Connective tissue proper is found
deep to the epithelium and basement membrane, in the deeper layers of both the skin and oral mucosa
Connective tissue proper in the skin is the
dermis and is found deep to the epidermis
Deeper to the dermis is the
hypodermis or Subcutaneous tissue
Subcutaneous tissue is Composed of
loose connective tissue and adipose connective tissue, as well as glandular tissue, large blood vessels, and nerves
In oral mucosa, the connective tissue proper is considered the___
• The even deeper connective tissue sometimes present is the____, similar to the hypodermis in the skin
lamina propria; submucosa
The superficial layer of both the dermis of the skin and lamina propria of the oral mucosa is composed of___
In both the dermis and lamina propria of oral mucosa, this layer of loose connective tissue is also considered___
loose connective tissue; the papillary layer
The papillary layer Forms____ which is interdigitated with the epithelial rete ridges
connective tissue papillae
Deep to the loose connective tissue in the deepest layers of both the dermis and lamina propria is
The dense connective tissue in both the dermis and lamina propria is also considered the___
dense connective tissue; dense layer (or reticular layer)
Turnover of the connective tissue proper in skin or oral mucosa occurs as a result of
the production of fibers and intercellular substance by the fibroblasts during regeneration
Immature connective tissue is considered_____
granulation tissue and has few fibers and an increased number of blood vessels
Granulation tissue can clinically appear as
a redder soft tissue that bleeds easily after injury or surgery
• Example: In the oral cavity after a tooth extraction
Later, during the repair process, temporary granulation tissue is replaced by
paler and firmer scar tissue in the area. It is paler because scar tissue contains an increased amount of fibers and fewer blood vessels
Aging process in skin
By age 20, skin begins to deteriorate
By age 50, skin is in a rapid state of degradation
Collagen fibers begin to fall apart
Elastic fibers stiffen and thicken, which wrinkles the skin
Oil glands in skin cease production
Melanin production decreases, leading to more pallid color and gray hairs
Keratin cells cease production and already produced keratin becomes thin and stiff
Aging skin begins to heal poorly
Fibroblasts have less replication activity
Skin also becomes susceptible to disease states that include inflammation (such as with dermatitis), infection (such as with herpes zoster), and cancer (such as with basal cell carcinoma and melanoma)
Solar damage will accelerate the aging process in skin, as does increased environmental toxicity (chronic alcohol and tobacco use)
Specialized connective tissue includes:
• Adipose tissue
• Elastic connective tissue
• Reticular connective tissue
Adipose connective tissue
• Fatty tissue made of adipocyte cells that store fat inter-cellularly packed tightly together with little or no matrix
Elastic connective tissue has a large number of ___in its matrix
elastic fibers
Reticular connective tissue
a delicate network of interwoven reticular fibers
Cartilage
Firm and Flexible Nonmineralized connective tissue composed of cells and matrix.
Two ways that cartilage can grow
Interstitial growth
Appositional growth
Cartilage takes____ to repair than vascularized bone
longer
Cartilage Repair & Aging In the TMJ:
• Cartilage may form abnormally within an aging joint disc that is usually only composed of dense fibrous connective tissue
• May cause difficulties with movement
• With aging, the entire disc thins and may undergo this addition of cartilage in the central region
Hard and rigid form of connective tissue that constitutes most of the mature skeleton is the
bone
Bone function
protective and structural support for soft tissue and as an attachment mechanism
Aids in movement
Manufactures blood cells through its red bone marrow
Is an energy bank through its yellow marrow
Is a storehouse for calcium and other minerals
alveolus (alveolar bone)
Bone surrounds the root(s) of a tooth
Is bone vascular?
Yes
Bone hardness comes from
crystalline formation of mostly calcium hydroxyapatite.
Bone has two methods of development:
Intramembranous ossification
Endochondral ossification
The first bone to be produced by either method of ossification is
an immature bone, the primary bone (or woven bone.
Primary bone is a temporary tissue that is replaced by
the more mature secondary bone.
The overall structure of bone never remains the same and is constantly being remodeled or regenerated. True or false?
True
Localized resorption
occurs in a specific area of a bone as a result of infection, altered mechanical stress, or pressure on the bone so that it adapts by removing bone tissue
Generalized resorption
occurs over the entire skeleton in varying amounts because of endocrine activity, to increase blood levels of calcium and phosphate needed by the body
Bone mass or density can increasingly be lost in women after____
menopause with the bones losing calcium and other minerals
Blood
Blood Fluid connective tissue composed of a matrix of plasma and formed elements
Plasma
the fluid substance in the blood vessels that carries plasma proteins, blood cells, and metabolites
The most common WBC in the connective tissue proper is the
macrophage
PRP
Platelet rich plasma
a biologic therapy that uses a patient’s own blood to accelerate healing and repair
Now increase in the use of PRP
during dental surgery. Used to support both soft and hard tissue healing
PRP is made by drawing blood from a patient, spinning it in a centrifuge to separate the blood components, and concentrating the platelets in a small amount of plasma. Platelets contain growth factors that stimulate stem cells to produce new tissue
What is the turnover time for the tissues of the hard palate?
24 days
What is the turnover time for the tissues of the floor of the mouth?
20 days
What is the turnover time for the tissues of the buccal and labial mucosa?
14 days
What is the turnover time for the tissues of the attached gingiva?
10 days
What is the turnover time for the tissues of the taste buds?
10 days
What is the turnover time for the tissues of the junctional epithelium?
4-6 days
Where would you find type 2 collagen?
Hyaline and elastic cartilage
Where would you find type 3 collagen?
In granulation tissue by type 1, reticular fibers, arterial walls, skin, intestines and uterus
Where would you find type 4 collagen?
In basal laminae of basement membrane, eye lens, filtration system of capillaries, kidney’s nephron glomeruli
Location of hyaline, elastic and fibro- cartilage and function (table)
Hyaline: LOCATIONS: Between tips of ribs and bones of sternum; covering bone surfaces at synovial joints, supporting the larynx (voice box), trachea, and bronchi; forming part of nasal septum
FUNCTIONS: Provides stiff but somewhat flexible support; reduces friction between bony surfaces
ELASTIC CARTILAGE
LOCATIONS: Auricle of external ear; epiglottis; auditory tube; cuneiform
cartilages or larynx
FUNCTIONS: Provides support but tolerates distortion without damage and returns to original shape
FIBROUS CARTILAGE
LOCATIONS: Pads within knee joint; between pubic bones of pelvis; intervertebral discs
FUNCTIONS: Resists compression;
prevents bone-to-bone contact; limits relative movement
Endocytosis-
Uptake of materials from the extracellular environment into the cell
Phagocytosis-
A special form of endocytosis where large particles (microorganisms and dead cells) are ingested via large endocytic vesicles called phagosomes
Proteins in the cell membrane are the _____and serve as_______.
structural reinforcements; receptors for specific hormones, neurotransmitters, and immunoglobulins (or antibodies) and also perform various functions like transporting molecules across the membrane, cell signaling, and maintaining cell structure.
Human DNA consists of about ____bases, and____ of those bases are the same in all people
3 billion; more than 99%
The____of these bases determines the information available for building and maintaining an organism
order, or sequence,
Before cell division, new DNA must be____. These genes, linked into chromosomes, are then____during cell division.
synthesized and every single gene must be replicated; separated into duplicate sets
Cells in tissue are surrounded by extracellular materials like
Tissue fluid and intercellular fluid
Intercellular substance
aka ground substance, shapeless, colorless, transparent material in which the cells of a tissue are imbedded; fills the spaces between cells in a tissue
Mechanical attachments or intercellular junctions can be formed between
cells or formed between cells and nearby noncellular surfaces
With the formation of intercellular junctions, the cell membranes of different cells___
come close together but do not completely attach
Epithelium is Avascular tissue that consists of
closely grouped polyhedral cells capable of rapid cell turnover surrounded by very little or no intercellular substance or tissue fluid
Epithelium function
covers and lines both external and internal body surfaces to serve as a protective covering or lining.
involved in tissue absorption, secretion, sensory, and other specialized functions.
Epithelium is unique because it can be derived from _____embryonic cell layers based on the location when developing
any of the three
Epithelium is also unique because the cells are able to undergo ____as they move from the deeper germinal layers to the surface of the tissue.
cellular differentiation
The superficial layer of the basement membrane is the
basal lamina
The superficial layer of the basement membrane is produced by
epithelium
The basal lamina consists of two sublayers:
• Lamina lucida - a clear layer that is closer to the epithelium
• Lamina densa is a dense layer that is closer to the connective tissue
The deep layer of the basement membrane is usually the
reticular lamina
The deep layer of the basement membrane consists of
type 4 collagen fibers and reticular fibers produced and secreted by the underlying connective tissue
Simple squamous epithelium is found lining
blood vessels
lymphatic vessels
heart
interfaces in the lungs
Interfaces in the kidneys
serous cavities
Simple cuboidal epithelium lines
Line the ducts of various glands, such as certain ducts of the salivary glands
Simple columnar epithelium is found lining
Lining of other salivary gland ducts, as well as the inner enamel epithelium of a maturing tooth germ, whose cells become enamel-forming ameloblasts
Pseudostratified epithelium is found lining
the upper respiratory tract, including the nasal cavity and paranasal sinuses
Makes up the superficial layer or skin and the superficial layer of the oral mucosa.
Stratified squamous epithelium
Stratified squamous epithelium
Consists of multiple layers of squamous cells on a basement membrane
Stratified squamous epithelium in the skin and oral mucosa interdigitates with
deeper connective tissue underneath forming rete ridges (or rete pegs).
Two types of stratified squamous epithelium
keratinized or nonkeratinized.
Cellular turnover of stratified squamous epithelium occurs through
cellular division (via mitosis) near the basement membrane
After undergoing mitosis at the basement membrane during regeneration of epithelium, the cells___
migrate superficially by releasing and then regaining their desmosomal connections at the intercellular junctions in the more superficial location
Turnover time for stratified epithelial tissue is the time taken for a
cell to divide during mitosis at the basement membrane and pass through the entire thickness of tissue to the surface. Older, superficial epithelial cells are being shed or lost at the same rate as the deeper germinal cells are dividing into more cells during turnover time
Epithelium of the oral mucosa generally regenerates___ than the epithelium of the skin
faster
Is connective tissue renewable?
Most connective tissue is renewable.
Are the cells of connective tissue capable of mitosis?
Its cells are capable of mitosis
Is connective tissue vascular or avascular?
In most cases, connective tissue is vascularized (except cartilage); each having its own blood supply
The most common cell in all types of connective tissue is the
Fibroblast
Fibroblasts are
fixed, flat and elongated spindle-shaped cells in connective tissue with cytoplasmic processes at each end
Fibroblasts synthesize
certain types of protein fibers and intercellular substance (matrix) needed to sustain the connective tissue
white blood cells may migrate from the blood supply into the connect tissue such as
monocytes (within tissue as macrophages), basophils, mast cells, lymphocytes (including associated plasma cells), and neutrophils.
Differing types of protein fibers are found in various types of connective tissue. The main connective tissue fiber type found in the body is the
Collagen fiber
Collagen fibers are composed of
the protein collagen and smaller subunits, fibrils which are made up of microfibrils .
Over 29 types of collagen have been identified. Over 90% of the collagen in the body is types
I to IV
Type I collagen is most commonly found in
teeth, lamina propria of the oral mucosa, dermis of the skin, bone, tendons, etc.
Cells responsible for the synthesis of Type I collagen include
fibroblasts and osteoblasts, which produce fibers and intercellular substance as well as bone and odontoblasts (which produce dentin)
Elastic fiber is composed of
microfilaments embedded in the protein elastin.
Presence of Elastic fibers in CT results in
a very elastic type of tissue.
Tissue with elastic fibers has the ability to
stretch and then to return to its original shape after contraction or extension
Certain regions in the oral cavity, such as___, contain elastic fibers in the____ to allow this type of stretchy tissue movement
the soft palate; connective tissue of lamina propria
Types of connective tissue
There is soft, firm, hard and fluid connective tissue
The overall turnover time for a connective tissue proper is___ than epithelium
slower
Connective tissue proper demonstrates individual variance from region to region
When injured, the connective tissue proper in the skin and oral mucosa goes through stages of repair that are related to the events in the
more superficial epithelium
Regeneration/ Repair process of connective tissue proper after injury
- Immediately after an injury to the skin or oral mucosa, a clot from blood-related products forms in the area
- Inflammatory response is triggered by the white blood cells from the blood supply as they migrate into the tissue
- Fibroblasts migrate to produce an immature connective tissue called granulation tissue which is red due to it containing many blood vessels and less fibers.
- Epithelial cells at the periphery of the injury will lose their desmosomal intercellular junctions and migrate to form a new epithelial surface layer beneath the clot
- Meanwhile The connective tissue matures into pale less vascular for fibrous scar tissue
Adipose tissue is Found
beneath the skin, around organs and some joints, and in regions of the oral cavity
After fibroblasts, the predominant type of cell found in adipose tissue is the
adipocyte
Elastic fibers Combine ___
strength with elasticity, such as in the tissue of the vocal cords
Reticular connective tissue function
supportive framework for blood vessels and internal organs
The two types of cells in cartilage are
Immature chondroblasts and mature chondroblasts
Immature chondroblasts lie in the___ and produce____.
perichondrium; cartilage matrix and chondrocytes which are Mature chondroblasts that maintain the cartilage matrix
After the production of cartilage matrix, the chondrocyte becomes surrounded and enclosed by
the matrix with only a small space surrounding the chondrocyte within the cartilage matrix, the lacuna (plural, lacunae)
The Matrix or surrounding medium of cartilage is composed of
fibers, mostly collagen, and intercellular substance.
The matrix of cartilage is similar to soft connective tissue in composition, except that the matrix of cartilage is___.
firmer
The connective tissue surrounding most cartilage is the
perichondrium
Perichondroum
a fibrous connective tissue sheath containing blood vessels
Why is the perichondrium important?
cartilage itself is avascular, receives its nutrition from perchondrium
Importance of Cartilage in an embryo, after birth and during developement
It forms most of the temporary skeleton of an embryo
Cartilage serves as structural support for certain soft tissue after birth
Cartilage serves as a model or template in which certain bones of the body subsequently develop
Cartilage is present at articular surfaces of most___
freely movable joints, such as the temporomandibular joint
What are the three types of cartilage?
Hyaline, elastic and fibrous
Most common type of cartilage
Hyaline cartilage
What kind of fibers are in hyaline cartilages matrix?
contains only collagen fibers
Elastic cartilage is Similar to hyaline cartilage except that____
is has numerous elastic fibers in its matrix in addition to collagen fibers
Fibrocartilage is never found alone; merges gradually with its neighboring___
hyaline cartilage
Interstitial growth of cartilage
growth from deep within the tissue by the mitosis of each chondrocyte.
Interstitial growth of cartilage Produces larger numbers of
daughter cells within a single lacuna (each of which secretes more matrix), expanding the tissue.
Important in the development of bone that uses cartilage as a model for its own formation during endochondral ossification
Interstitial growth if cartilage
Appositional growth of cartilage
Layered growth on the outside of the tissue from produced by the outer layer of chondroblasts within the perichondrium.
Is cartilage vascularized and have nerve supply?
No
During repair, avascular cartilage is dependent on
neighboring connective tissue from the perichondrium for nutrition to transform it slowly into cartilage
During repair of cartilage, the chondroblasts in the perichondrium undergo mitosis and produce
newly formed cartilage that then continues to slowly proliferates and fill in the defect by appositional growth
As cartilage ages, it becomes____
less cellular with its chondrocytes dying
It may start to contain firm fibers splayed out in parallel groups, or it may even form areas of scattered mineralization. These tend to coalesce over time with the tissue becoming hard and brittle and losing flexibility
Does bone repair quickly?
Yes
Bone
rigid, hard connective tissue made of cells in matrix
undergone the most developmental differentiation of all the connective tissue
Bone
Outer part of bone is covered by
periosteum
Periosteum
a double-layered, dense connective tissue sheath containing blood vessels and nerves in the outer layer and a single layer of cells that give rise to bone-forming cells, the osteoblasts in the inner layer.
Deep to the periosteum is
a dense layer of compact bone
Deep to the compact bone is
a spongy bone or cancellous bone.
Both compact bone and cancellous bone have the same cellular components, but each has a
different arrangement of those components.
Compact bone is strong and heavy because it has_______. Cancellous bone is light because it is____
fewer soft tissue spaces; formed by pieces of solid bone that join to form a lattice and has more soft tissue spaces
Lining the medullary cavity of bone on the inside of the layers of compact bone and cancellous bone is the___.
endosteum
Endoosteum Has the same composition as the periosteum but is___
thinner
Deep to the endosteum lining of bone is the
medullary cavity
In the Medullary cavity is the
bone marrow
Bone marrow
Gelatinous substance; where the stem cells of the blood are located, lymphocytes are created, and B cells mature
calcium hydroxyapatite crystal other than in bone is found in differing percentages in the
hard dental tissue, such as enamel, dentin, and cementum
The matrix of bone is composed of
50% inorganic material (CHA), organic type 1 collagen fibers and intercellular substance
Bone matrix is initially formed as
osteoid
Bone matrix is initially formed as osteoid. Osteoid later undergoes_____
mineralization
Osteoid is produced by
osteoblasts
Osteoblasts
which are cuboidal cells that arise from fibroblasts
Osteoblasts are involved in the____ to form bone
Production of Osteoid and later mineralization of osteoid
Osteoblasts are always present in the
periosteum
Why are Osteoblasts are always present in the periosteum?
Allows constant remodeling of bone or repair of injured bone
The cells Within fully mineralized bone are
osteocytes
Osteocytes
Entrapped, mature osteoblasts
The cell body of the osteocyte is surrounded by bone, except for
the space immediately around it, the lacuna
___of the osteocyte radiate outward in all directions in the bone
Cytoplasmic processes
Cytoplasmic processes of the osteocyte radiate outward in all directions in the bone and are located in
tubular canals of matrix or canaliculi
Purpose of canaliculi
These canals provide for interaction between the osteocytes
Bone matrix in compact bone is layered into
closely apposed sheets, or lamellae
Within and between the lamellae are
embedded osteocytes with their cytoplasmic processes in the canaliculi
The highly organized arrangement of concentric lamellae in compact bone is the
Haversian system
In the Haversian system, lamellae form concentric layers of matrix into
cylinders or osteons
the unit of structure in compact bone
The osteon; consists of 5 to 20 lamellae
The Haversian canal (or central canal) is a
central vascular canal within the each osteon, surrounded by the lamellae
The Haversian canal contains
longitudinally running blood vessels, nerves, with a small amount of connective tissue and is lined by endosteum
Haversian canals communicate
not only with each other but also with the osteocytic processes in the canaliculi, providing cellular nutrition for the surrounding bone
This organized system of bone is noted within the structure of the alveolar bone proper
Haversian system
Perpendicular canals Located on the outer part of the Haversian system in compact bone are
Volkmann canals
Volkman canals
perpendicular nutrient canals that contain the same vascular and nerve components as the Haversian canals
Volkman canals are lined by
endosteum
These canals are noted within the alveolus or tooth socket so that it is sometimes referred to as the cribriform plate because they appear grossly as perforating holes
Volkman canals
In contrast to highly organized compact bone, cancellous bone Has its bone matrix formed into____
trabeculae
Lamellae of the matrix of cancellous bone are
not arranged into concentric layers around a central blood vessel as with the compact bone, but rather their concentric rings are formed into cone-shaped spicules
For cancellous bone, Osteocytes in lacunae with their cytoplasmic processes are located
between the lamellae of the trabeculae
Intramembranous ossification
Formation of osteoid between two dense connective tissue sheets, which then eventually replaces the outer connective tissue
The maxilla and the majority of the mandible are formed by ___ossification
intramembranous
Endochondral ossification
Formation of the osteoid within a hyaline cartilage model that subsequently becomes mineralized and dies
The head of the mandibular condyle is formed by____ ossification
endochondral
The bone produced by the two ossification methods is microscopically
the same; only the process of formation is different
Within primary bone, the lamellae are indistinct because of the
irregular arrangement of the collagen fibers and lamellae.
Secondary bone has a ___arrangement of collagen fibers and___ lamellae
well-organized; distinct
How function of the bone can be maintained in a healthy body during bone remodeling?
Bone undergoes removal in certain areas and new bone formation in other area.The two processes balancing each other
Growth and repair of bone is thru ___growth
Appositional
Appositional growth of bone is
accomplished by the
osteoblasts, which later become entrapped as osteocytes
After bone fracture and during the repair of bone, bone also goes through the stages of bone formation, no matter how the bone initially developed. In the area to be repaired, bone forms initially as ___
primary bone, which matures into secondary bone to complete the repair.
The repair of bone depends on
adequate blood supply, the presence of periosteum with active osteoblasts, and adequate mineral and vitamin levels
Resorption of bone involves
the removal of bone.
The cell that causes resorption of bone is the
Osteoclast
Osteoclast is a ________cell located on the ____
a large multinucleated cell; surface of secondary bone in a large shallow pit created by this resorption, a Howship lacuna
Osteoclasts are formed from
the fusion of numbers of macrophage blood cells.
Each osteoclast contains a_____ in its cytoplasm.
large number of lysosomes
The lysosomes in osteocytes are discharged into the surrounding tissue. The enzymes of the lysosomes then
break down the bone when the osteoclast attaches by way of its ruffled border
Resorption of bone can occur in an___ during active advanced periodontal disease. Can also occur in a ____with orthodontic therapy
uncontrolled manner; controlled manner
Loss of bone mass and density from menopause can become accelerated with the___
systemic bone disease of osteoporosis, especially for older women
Osteoporosis is more common in
women
Osteoporosis
is a pathophysiologic condition that develops when bone mineral density and bone mass decreases, or when the quality or structure of bone changes
Blood Serves as a
transport medium for cellular nutrients (respiratory gases like oxygen and carbon dioxide; metabolites for the body).
Blood is carried in____-lined blood vessels
endothelium
Most blood cells come from
a common stem cell in the bone marrow
Formed elements in the blood include
numerous red blood cells, white blood cells and platelets.
___are the most common/numerous cell in the blood (erythrocytes).
RBCs
____are smaller than RBCs, disc-shaped, and also have no nucleus.
platelets or thrombocytes
In even smaller numbers in the blood is the white blood cell (WBC) or___
leukocyte.
WBCs form from
bone marrow stem cells.
WBCs later mature in the
bone marrow or in various lymphatic organs.
The most common WBC in the blood is the
neutrophil or polymorphonuclear (PMN) leukocyte.
These are the first cells to appear at an injury site when the inflammatory response is triggered.
Neutrophils
Large numbers of the PMNs can be present in the____, in certain cases seen locally at the site of inflammation
suppuration or pus
PMNs constitute___ of the total blood WBC count
54% to 62%
The second most common WBC in the blood
lymphocyte
lymphocyte makes up___ of the WBC count
25% to 33%
There are three functional types of lymphocytes
B cell, T cell, and natural killer (NK) cell.
___are produced by____ and are chemical mediators of the immune response
Cytokines; B and T cells
B cells mature in the
bone marrow and gut-associated lymphoid tissue such as lymph nodes
The B-cell lymphocytes divide during the immune response to form
plasma cells
Once mature, plasma cells produce
an immunoglobulin (Ig), or antibodies and one of the blood proteins.
There are five distinct classes of immunoglobulins:
IgA (serum or secretory types), IgE, IgD, IgG, and IgM.
Each plasma cell produces only
one specific class of immunoglobulin in response to a specific immunogen or antigen (body considers as foreign—triggers immune response)
The T-cells mature in the
thymus gland
NK cells mature in the
bone marrow.
NK cells are large cells that are involved in
the first line of defense against tumor- or virally-infected cells by killing them and thus are not considered part of the immune response
The most common WBC in the connective tissue proper is the
macrophage which was considered a monocyte before it migrates from the blood into the tissue.
NK have a___ lifespan than PMNs but constitute only___of the WBC count
longer; 2% to 10%
Macrophages contain___ enzymes
lysosomal
Macrophages contain lysosomal enzymes, and are involved in___ (as are PMNs)
phagocytosis
Macrophages are actively____and have the ability to respond to_____
mobile; chemotactic factors and cytokines
Macrophages assist in the immune response to facilitate___
immunoglobulin production
The eosinophil is usually only ___of the WBC count. Its percentage is increased during
6% ; a hypersensitivity response (allergy) and in parasitic diseases.
The eosinophils primary function is
is the phagocytosis of immune complexes
The basophil is normally found in___% of the WBC count
less than 1
The basophil is involved in
hypersensitivity response releasing bioactive products
Other WBCs located in the connective tissue include the mast cell, which is similar in structure to the___. Mast cells are involved in
basophil; a type of primitive hypersensitivity response that also releases bioactive products
