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A&P Ch.4: Tissues


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What are the 4 primary tissues?
1) Epithelial
2) Connective
3) Muscle
4) Nervous
Which tissue covers and lines? Provides support? Enables movement? Controls work?
gross anatomy
The study of anatomical structures that can be seen with the naked eye.
The study of the microscopic structures of tissues and organs. AKA: microanatomy.
Which tissue acts as an interface layer that separates and defines the beginning and ending of different types of tissues?
epithelial tissue
glandular epithelia
Epithelia that engage in the manufacture and release of substances. May be individual cells or organized glands.
Anything leaving the body such as sweat, urine, feces, and hormones.
Substances that remain within the body, such as regulatory molecules and mucus.
List 6 characteristics of epithelial tissue.
1) Protects, lines, and covers.
2) Filters biochemical substances.
3) Absorbs nutrients.
4) Provides sensory input.
5) Manufactures secrestions.
6) Manufactures excretions.
polar cells
Epithelial cells that have a sense of direction relative to surrounding structures.
apical surface
The side of the cell that faces the lumen or body cavity.
basal surface
The side of the cell that faces the underlying connective tissue.
junctional complexes
Junctions that bring cells into close apposition to one another, using their lateral surfaces, and leaving little room for extracellular matrix.
Lacking blood vessels or capillaries (all cells), causing them to rely on underlying connective tissue for oxygen and nutrients.
To make a synaptic connection with an effector organ. Some epithelia such as those in the stomach, intestines, and cervix, lack nerves.
What are the three major types of cellular junctions?
1) tight junctions
2) desmosomes
3) gap junctions
tight junction
A type of cell-to-cell connection in which the cell membranes of adjacent cells form a very close binding, preventing any leaking.
Cell junction between adjacent cardiac cells that prevents cells from separating during contraction. Also in skin and uterus.
Gap junction
A small tube or channel between adjacent cells formed by transmembrane proteins. Allows ions to pass freely from cell to cell. Found at electrical synapses. Especially important in cardiac and smooth muscle cells (for quick transport of electrical signals).
Tubular channel proteins that link cells connected by gap junctions. They extend from the cytoplasm of one cell to the cytoplasm of another cell.
basement membrane
An extracellular layer of material jointly formed by and lying between the epithelial cells and the underlying connective tissue cells. It serves as a partial barrier to the cell and the underlying connective tissue.
brush border cells
The epithelial cells of the proximal convoluted tubule that have extensive microvilli on their luminal surfaces.
The opening of the oviduct.
A protective, waterprrof substance that fills skin epithelial cells.
keratinized epithelium
The accumulation of keratin as the cell matures and moves from the basal layer to the superficial layer of the integument.
What are the three characteristics that classify epithelial tissue?
1) Number of cell layers
2) Shape of cells
3) Presence of surface specializations
Where would you expect to find simple epithlia?
Protected areas of the body, such as internal compartments, ducts, vessels, and passageways becuase it provides very little protection.
Where would you find stratified epithelia?
Areas that are subjected to mechanical and chemical stress because it is thicker and stronger than simple epithelia.
How is stratified tissue named?
The topmost layer (exposed or luminal surface) gives stratified tissue its name even though other tissues may be present below it.
What are the different types of cell shapes?
What examples are surface specializations?
-keratinized (skin)
-nonkeratinized (mouth)
What are the nine types of epithelium listed in this chapter?
1) simple squamous
2) simple cuboidal
3) simple columnar
4) stratified squamous
5) stratified cuboidal
6) stratified columnar
7) pseudostratified
8) transitional
9) glandular
Where are simple squamous epithelia found?
What importance is its shape?
-Found only in protected areas of body.
-Being flat and smooth, they are important in reducing friction and are found in the lining of blood and lymphatic cessels. It also lines the lung to absorb oxygen and release carbon dioxide. *Named for locations.
Where do you find simple cuboidal?
What does it do?
How are they positioned in microscope?
Also found in sheltered regions where secretion and absorption take place. On surface of ovaries, pancreas, kidney, salivary gland. Some covered in microvilli.
-Important roles in both endocrine and exocrine tissues.
-nuclei all line up in center of cell looking like pearls.
Where are simple columnar cells located?
What do they do?
How are they microscopically positioned?
-Line GI tract from stomach to rectum.
-They absorb and secrete, and found in many excretory
-Appear closely packed with nuclei in a row at base of cell near basement membrane.
What two cells make up the gut lining, and what do they do?
1) absorptive cell: most numerous, apical surface is blanketed by dense microvilli
2) goblet cell: wine-glass shape, manufacture and store lubricating mucus that is secreted onto luminal surfaces of epithelia.
What cells line the uterine tubes and respiratory tracts?
simple ciliated columnar cells; less common epithelia that have cilia on their apical surface.
How is stratified squamous epithelium created?
Cuboidal epithelia continuously divide to replace sloughing off of squamous cells. As more cells are made, they are pushed upward and further from nutrients of connective tissue. This makes them loose their cytoplasm and nuclei and become paperlike sheets.
Where is stratified squamous epithelium found?
It occurs in area as body subjected to chemical and mechanical stress such as lining the mouth, esophagus, vagina, and rectum.
What is stratified cuboidal epithelia?
Where do you find it?
Why is it important?
-This epithelia usually occurs in only two layers of cuboidal cells.
-They are found primarily along large excretory ducts such as swear glands, mamary glands, and salivary glands.
-It is important for protecting the delicate tissues in deeper layers.
What is pseudostratified epithelium?
What do you find on most of this tissue?
Where do you find it?
-This tissue is simple, but appears stratified due to varying nuclei levels and cell heights. ALL connect to basement membrane though!!
-Most cells are ciliated to move mucus towards mouth therefore preventing debris from entering lungs.
-It is mostly found in the respiratory tract and some of the males reproductive tract.
What do you find in the mucus across pseudostratified epithelia?
Protective immunoglobulins to protect against pathogens.
What is transitional epithelium?
-Why is it important?
Known for its remarkable ability to stretch.
-Found in the urinary bladder, ureters, urethra, and calyxes of the kidney.
-It forms a leakproof membrane that prevents diffusion of scalding urine from entering abdomen.
How are glands formed from epithelium?
During embryonic development surface cells grow down into connective tissue. When the connecting cells create a duct, the deep cells become secretory. The endocrine glands form when the connecting tissues die and secretions pass through sinusoids (rather than a duct).
What are 6 examples of classifying glands?
1) ducts or no?
2) Number of composing cells
3) shape of ducts
4) complexity of structure
5) secretion produced
6) stored or discharge manner of secretions
Define endocrine glands
Glands that do not have ducts or tubules and whose secretions are distributed throughout the body (hormones).
Define hormones
Regulatory chemicals/
Define exocrine glands
Glands that discharge secretions locally through ducts (goblet cell is exception without a duct). More common than endocrine glands.
What is the one exception to exocrine glands known as?
Describe it.
It is a unicellular exocrine gland without a duct.
-It is a modified columnar epithelial cell and found among columnar cells of the respiratory and digestive tracts and in conjunctiva of eye.
What does the goblet cell produce?
It secretes mucin. When mixed with water it becomes mucus.
-The mucus protects apical surface of epithelial layer and also assists with the entrapment of microorganisms and foreign particles.
What are myoepithelial cells?
Contractile cells that assist with the discharge of secretions into the glandular duct. Rate controlled by hormonal and nervous influences.
What are the two classes of branching?
1) simple
2) compound
What are the gland shapes?
1) Tubular
2) Alveolar
List the eight combinations of multicellular exocrine glands.
1) simple tubular
2) s. coiled tubular
3) s. branched tubular
4) s. alveolar
5) s. branched alveolar
6) c. tubular
7) c. alveolar
8) c. tubuloalveolar
List the eight gland locations pertaining to the "types" flashcard.
1) stomach, intestine
2) sweat glands
3) stomach, mouth, tongue, esophagus
4) Sebaceous glands
5) Sebaceous glands
6) Bulbourethral glands, mamary glands, kidney tubules, testes, mucous glands of mouth.
7) Mammary glands
8) Salicary glands, pancreas, respiratory passages
What are merocrine glands?
Secretory cells remain intact during scretory process. No damage.
How does an apocrine gland lose its apex?
They store the granules until apex is full. The cell then pinches in two and releases the top part into the duct system. The cell repairs the damage later and repeats the process.
What do holocrine glands do?
They also store granules until needed and then degenerates both releasing hormones and destroying itself.
What are serous secretions?
Watery and contain a high concentration of enzymes.
What are mucous secretions?
Thick, viscous, and composed of glycoproteins.
What are mixed exocrine glands?
These contain both mucous and serous components.
What is connective tissue derived from? Composed of?
- extracellular matrix
What does the matrix of connective tissue do?
It surrounds and separates the cells, and provides structural and nutritional support to allow further distance than epithelial.
What does vascularized mean?
It has blood supply unlike epithelial tissue. This varies according to what connective tissue it is.
What three things compose ALL connective tissue?
1) extracellular fibers
2) ground substance
3) cells
What are GAG's?
-What is the most common GAG in connective tissue?
glycosaminoglycans: unbranched chains of glycoproteins in soft connective tissues.
-hyaluronic acid combined with 2% protein
What is ground substance?
The medium through which cells exchange nutrients and waste with the bloddstream. It acts as a shock-absorbing cushion to protect enveloped cells.
What can some microbes produce to help get through ground substance?
What three fibers compose connective tissue?
-collagenous (most common)
What makes connective tissue different from one another since they all share the same fibers?
The proportions of each very greatly.
What are collagenous fibers?
Strong and thick stands of structural protein collagen.
How are collagen fibers organized?
They are in discrete bundles of long, parallel fibrils (which are composed of microfibrils)
Where are collagenous fibers mostly found?
In tendons and ligaments that are continually being pulled and stretched.
What do collagen fibers look like? What other name do they have?
When not under pressure, they look wavy. Since the fibers are white, they tissue appears white and gets the name "white fibers"
What happens when collagen is heated?
How can it be toughened?
It denatures and turns into gel.
-Tannic acid does the opposite: leather!
What are retucular fibers?
Composed of collagen but not as thick. They are thin, delicate and branched into complicated networks.
How does the shape of reticular fiber give to function?
What is it AKA?
It forms a net that supports highly cellular organs such as endocrine glands, lymph nodes, spleen, liver, and bone marrow. They are also found around blood vessels, nerves, muscle fibers, and capillaries.
-"mist net"
What are elastic fibers?
They are composed primarily of elastin. They are branched forming networks, but lack strength of collagenous fibers.
-"yellow fibers"
How are elastic fibers shaped and organized?
-found where?
They are coiled, and can contract and stretch like a rubber band. -They are often found in coval cords, lungs, skin, and walls of blood vessels.
What two cell groups make up connective tissues?
-fixed cells
-transient cells
What are fibroblasts?
Large, irrecularly shaped cells that manufacture and secrete both the fibers and ground substance of their matrix.
Able to reproduce
Metabolically active
What are the different names of fibroblasts?
chondroblasts: cartilage
osteoblasts: bone
fibroblasts: connective tissue
When fibroblasts mature and become innactive, how does their name change?
-If more matrix is required later, what can occur?
-blasts becomes -cytes.
-Cytes can convert back into blasts if needed.
What are young fat cells known as?
Adipose cells, or adipocytes.
Where do you find adipocytes?
Under the skin, behind the eyes, around kidneys, and in omentum of abdominal cavity.
What do reticular cells look like?
They are flat, star-shaped cells with long, outreaching arms connecting with other cells forming a net.
What is it agreed upon that reticular cells do?
Involved in immune response and in manyfacture of reticular fibers.
-Found primarily in tissues that are part of immune system such as lymph nodes, spleen, and bone marrow.
What are the different types of wandering cells?
-Mast cells
What are the different types of fixed cells?
*can also be macrophages
What is diapedesis?
The squeezing through the walls of tiny blood vessels to enter surrounding tissue.
What are leukocytes?
"white blood cells" found in blood and move into connective tissue in large numbers during times of infection.
How many different types of Leukocytes exist?
What are the two ways they protect the body?
5 different types of leukocytes.
Some manufacture antibodies that attach to microbes and destroy them. Most engulf and digest invading microbes.
What are mast cells?
Cell that contains heparin and histamine used in inflammatory responses. They recognize foreign invaders and release granules of histamine and heparin to increase blood flow.
What does histamin do?
It increases blood flow by making capillaries leaky.
What does heparin do?
It prevents clotting to ensure pathways remain open for increased blood flow.
What are macrophages?
Massive irregularly shaped scavengers that engulf microbes, daed cells, and debris which is then digested in lysosomes (in macrophage). Assist greatly in areas of infection to engulf microinvaders.
What are macrophages called in the liver?
Loose connective tissue?
-Kupffer cells
-microglial cells
What are the two broad categories of connective tissue?
1) connective tissue proper
2) specialized connective tissue
What are the only subtypes of connective tissue NOT in connective tissue proper?
What are the two subclasses of connective tissue proper?
1) loose
2) dense
What are the three subclasses of loose connective tissue?
1) areolar
2) adipose
3) reticular
What are the three subclasses of dense connective tissue?
1) dense regular
2) dense irregular
3) elastic
What are the three subclasses of cartilage tissue?
1) hyaline cartilage
2) elastic cartilage
3) fibrocartilage
What are the two subclasses of bone?
1) compact
2) cancellous
What is areolar tissue?
What does it mean?
Tangle of randomly placed fibers and cells suspended in a thick translucent ground substance.
"small opening"
What is the predominant cell found in areolar tissue?
What does it do here?
fibroblasts that manufacture elastic, reticular, and collagenous fibers found in the tissue.
What is the most common type of connective tissue?
areolar tissue
What is the purpose/function of areolar tissue?
It acts as packaging to support and cushion delicate structures in the body. It surrounds every organ, vessels, nerves, and lymph nodes. It forms the subcutaneous layer that connects skin to muscle.
It is the lamina propria.
What is the lamina propria?
The areolar connective tissue located in the mucous membrane.
What fills the small open spaces of the areolar tissue?
A mixture of body fluids and ground substance.
What is the ground substance in areolar tissue made of?
It is thick and composed primarily of hyaluronic acid. The viscous texture acts as a barrier aginst invading organisms, though some have developed hyaluronidase to liquidize hyaluronic acid.
What is hyaluronic acid?
Material that composes ground substance in areolar tissue which serves as a medium through which nutrients, gases, and waste can be easily transported to and from the bloodstream.
What is an edema?
Filling of body fluid in tissue during trauma or other pathological states.
What is a pitting edema?
The same as an edema except it remains compressed when pushed in with thumb.
What type of tissue is adipose (fat) tissues?
areolar! Which also falls under loose connective tissue.
What factors affect fat metabolism?
-sympathetic nervous system
-certain hormones
-genetic influences
What importance does being vascularized have for adipose tissue?
Lipid droplets are accessible to the enzymes responsible for triglyceride breakdown and to a bloodstream that readily transports the glyceral and free fatty acid produvts to other parts of the body.
Bottom line: important energy store for animals.
What are the functions of adipose tissue?
-energy store
-thermal insulater
-mechanical shock absorber
What are the two main types of adipose tissue?
1) white
2) brown
What is brown adipose tissue?
It is a highly specialized adipose tissue and is found in newborn or hibernating animals. It is a site of heat production and known as the "hibernating gland".
Why is brown adipose tissue brown?
It has an exceptionally high number of mitochondria in the cytoplasm
How does brown fat produce heat?
-lipid stored in multiple small vesicles
-Mitochondria dissipate heat rather than ATP
-Rich vascular network helps dissipate heat to many area of body.
What are the fibers that make up reticular connective tissue?
Only reticular fibers.
What is stroma?
The cellular and matrix components that constitute the framework of several organs (liver, spleen, lymph node, bone marrow).
What is the difference between reticular fibers and reticular connective tissue?
Reticular fibers are found throughout the body, whereas reticular connective tissue is in a limited number of site.
What is dense fibrous connective tissue?
It is densely packed collagen fibers intermingled with birbroblasts. This tissue is found in smaller quantities than loose connective tissue.
What is dense regular connective tissue?
-lies in direction of exerted force
-silvery or white
-relatively avascular (slow to heal)
-makes up tendons and ligaments
-compses broad, fibrous ribbons that sometimes cover muscles or connect them to another structure
-fascial sheets that cover muscles (not all laid in same direction to help withstand forces in more than one direction).
What is dense irregular connective tissue?
Thicker bundles of collagen fibers than dense regular connective tissue.
-interwoven randomly to withstand different directional forces
-found in dermis of skin and fibrous coverings of organs (kidney, testes, liver, spleen)
-forms tough capsule fo joints.
What are elastic connective tissues?
They are dense connective tissue that is primarly compsed of elastic fibers rather than collagen.
Where is elastic connective tissue found?
Relatively few regions:
-spaces between vertebrae
-regions that require stretching (bladder, heart, walls of vessels, stomach, large airways).
What is gristle?
a tough specialized connective tissue commonly known as cartilage.
What is cartilage?
Compsed of cells and matrix. It is avascular and slow to heal. It recieves nutrition from perichondrium. 3 types of cartilage.
How does cartilage compare to bone?
More flexible than bone, but still more rigid than dense connective tissue.
Where is cartilage found?
Joints, ear, nose, vocal cords, framework for bone growth.
What is lacunae?
The hollowed-out pockets in the matrix of cartilage where chondrocytes live.
What two glucosaminoglycans can be found in the ground substance of the matrix?
1) chondroitin sulfate (with hyaluronic acid)
2) chondronectin
Why is the fluid in the matrix important in cartilage?
It ransports nutrients to the chondrocytes and gives cartilage it's flexible resiliency and ability to withstand compression.
What is the perichondrium?
The fibrous connective tissue surrounding the external surfave of cartilage. It is vascularized and provides a limited amount of nutrition to the cartilage.
What is hyaline cartilage?
It is the most common cartilage in body, it resembles a blue-white frosted, ground glass.
Where is hyaline cartilage found?
-at ends of long bones in joints
-connects ribs to sternum
-supportive rings in trachea
-composes most of embryonic skeleton
-in growing animals, it is found in growth plate.
What is elastic cartilage?
-Where is it found?
Same as hyaline, but with more elastic fibers (appear black microscopically)
-found in epiglottis and in pinnae
What is fibrocartilage?
Where is it found?
It contains thick byndles of collagen fibers but has fewer chondrocytes and lack a perichondrium. It is well designed to take compression and found between vertebrae, between bones in pelvic girdle, and in the knee joint.
What is bone called?
Osseous connective tissue.
What is bone composed of?
Organic collagen fibers and inorganic calcium salts, haversian canal, and tiny channels in matrix (for blood vessels in deeper portions of tissue)
Salts would normally make bone brittle. Why doesn't this happen?
When combined with collagen fibers, bone becomes more glexible with greater strength.
What is the central haversian canal?
The central canal that runs the length of a haversian system. It contains blood vessels, lymph vessels, and nerves to supply and nourish the osteocytes.
What are canaliculi?
Tiny threadlike chambers that long cellular extensions of osteocytes pass through.
What is plasma?
Liquid componant of blood that constitutes the matrix.
What are three cell types found in blood?
-leukocytes (wbc's)
-erythrocytes (rbc's)
-thrombocytes (platelets)
What are membranes?
Thin protective layers that line bnody cavities, eperate organs, and cover surfaces. Composed of milticellular epithelial sheet that is bound to underlying connective tissue.
What are the four common types of epithelial membranes?
1) mucous
2) serous
3) cutaneous
4) synovial
Where are mucous membranes found?
They always line organs with conections to outise environment.
-digestive, respiratory, urinary, reproductive tracts.
What are the layers of the mucous membrane?
Stratified squamous (or simple columnar epithelium), then the lamina propria, and usually the submucosa.
What is the submucosa?
It is another conective tissue layer that connects the mucosa to underlying structures.
What cells can be found throughout tissue near mucous membranes? What do they do?
goblet cells (or multicellular glands).
-They are responsible for the production and secretion of mucus.
What is the purpose of mucus?
To decrease friction and assist with pasage of foodstuffs or waste. It also can trap invading pathogens.
What is serosae?
Serous membranes that line the walls and cover organs that fill slosed body cavities (chest or thorax, and abdominal and pelvic).
What does serosae look like?
It is a continuous sheet that is doubled over on itself forming two layers with a narrow space in between. Parietal and visceral layers formed.
What is the parietal layer?
The protion of the serous membrane that lines the cavity wall.
What is the visceral layer?
the portion of the serous membrane that covers the outer surface of organs.
What is a transudate?
Serosal fluid that is thin and watery because of no mucin, but it does have electrolytes. Further more, it lines the serosae reducing friction between organs and the cavity wall. *Name differes upon location.
What is a hemothorax?
When blod cells and fluid may leak from ruptured capillaries into the pleural space.
What is an exudate?
When cells, protein, and other solid material mix with serous fluid it becomes denser than a transudate.
What is an effusion?
When an abnormally large amount of fluid enters a body covity. Ex; ascites.
What are adhesions and how are they problematic?
When too little serous fluid is made, contact between the parietal and visceral layers occurs. These can cause excruciating discomfort and can interfere with normal organ functions.
What are mesenteries?
Ligaments formed from merged visceral layers of serosa that secure organs to the body wall and form a frame-work for the apssage of blood vessels and nerves.
What is the cutaneous membrane known as?
The integument, or skin.
What is odd about synovial membranes?
They are composed exclusively of connective tissue, and they don't have any epithelia cells.
Where are synovial membranes found?
they line the cavities of joints.
What do synovial joints visually look like?
They are smooth shiny and white. The fluid is honey-like.
Histologically, what is the membrane like?
Compsoed of loose connective tissue and adipose tissue covered by a layer of collagen fibers and fibroblasts.
How does muscle contract?
Microfilaments slide over one another making cells change shaped to be shorter or longer.
What happens to surrounding objects when muscles contract?
Movement of bones, blood, and soft tissue structures occur with appropriate results. Ex; legs run, blood circulates, foodstuffs move through intestine.
What three types of muscle tissues are there?
skeletal, smooth, and cardiac.
What is skeletal muscle?
Composed of numerous large cells (1' or more!) that contain hundreds of nuclei and mitochondrai needed to maintain cellular homeostasis.
What is skeletal muscle known as?
Striated, voluntary muscle.
How is muscle attached to bone?
fibers are clustered into bundles and held together by loose connective tissue. The collagen fibers that surround the cells merge with collagen fibers in tendons. Ta Da!
How are muscle cells stimulated to contract?
Nerve fibers are attached to cells and located throughout entire muscle belly.
What is smooth muscle?
Is it composed of small, spindle-shaped cells that lack striations. Contraction occur the same way as skeletal muscle, but is involuntary.
-nonstriated involuntary muscle.
Where is smooth muscle found?
-Walls of hollow organs (blood vessels, urinary bladder, uterus, intestines, and stomach)
-Exocrine glands
-Respiratory tract
What is cardiac muscle?
It exists only in the heart and can contract even when neural input is altered. Cells are small and contain only one nucleus like smooth muscles. Muscle branches to form a complex network and cells are striated.
What is cardiac muscle known as? What connects ead cell to the next?
-involuntary straiated tissue
-intercalated disks connect each cell end. Only in cardiac tissue!
What two cell types make up nervous tissue?
1) neurons
2) neuroglial cells
How long can neurons get?
Up to a meter in length!
What are the body parts of a neuron?
-cell body: perikaryon
-short endoplasmic extension: dendrites
-long singular extension: axon
What does the cell body of a neuron do?
It contains the nucleus which controls cell metabolism.
What do the dendrites of a neuron do?
Receive impulses from other cells
What does the axon of the neuron do?
Conducts impulses away from the cell body.
What do neuroglial cells do?
They are found in greater numbers than neurons and serve to support the neurons. Some isolate conductive membranes, others provide supportive framework to bind neural tissue together. Others phagocytize debris or help supply nurtients to neurons by connecting them to blood vessels.
What are the steps taken when an animal is injured?
1) injury
2) inflammation
3) organization
4) regeneration
What is inflammation?
The body's attempt to limit the damage caused by the injury, to isolate the area, and to prevent further damage.
Bottom line: A nonspecific reaction to injury or disease.
What is infection?
Inflammation caused by viruses, bacteria, and fungi.
What are the steps in the process of inflammation?
1) vasoconstriction (5-10min) then vasodilation, histamine and heparin release.
2) Swelling from plasma fluid
3) Clotting
4) macrophages and neutrophils: pus as they die
5) histamine and heparin disipate, capillaries normal, signs subside.
During inflammation, how do clots form?
Platelets become sticky and clump together. Fibrinogen converted to fibrin which is woven into a netlike structure surrounding platelets to give support and stability.
What are scabs?
Clots formed on surface of epidermis that dry up.
What is fibrinogen?
A protein formed in teh liver and released into the bloodstream.
How does fibrinogen become fibrin?
Thrombin acts on fibrinogen to form fibrin.
What causes the heat and redness during inflamation?
The release of heparin and histamine cause rushing of blood flow: this also increases flow of oxygen and nutrients to damaged tissue.
How does a scar form?
Macrophages clear debris leaving a layer of collagen fibers. These contract forming a permanent scar.
What is proud flesh?
When granulation tissue becomes too thick and stands out above the epithelial layer.
*Can be surgically removed to allow closure of epithelial layer.
**Occurs often in horse injuries
What is epithelialization?
epithelial cells around a wound dege actively divide to lay down new layers over the granulation tissue.
Why does a scab fall off?
Connections between the scab and thickening epithelial layer are weakened.
Why does surgically removing a foreign object INCREASE the liklihood it will happen again?
Scar tissue forms which greatly lowers elasticity of organ or area. Reentry becomes more difficult with each surgical procedure.
What are side effects that can occur from scar formation?
-less flexibility
-impaired visibility of important structures
-restrict normal shifting of bowel loops (can bind organs to body wall or omentum)
What are first-intention healing?
Skin forms primary union without formation of granulation tissue or scarring
What is second-intention healing?
Edges are separated from one another and granulation tissue closes gap: scarring occurs.
What is third-intention healing?
Gaps are usually involved and take much longer to repair.

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