Anatomy Flashcards
Anatomy
Anatomy is the study of the form and structure of the animal body and the relationships among its parts.
Physiology
Physiology is the study of how the body functions.
Regional Approach
The regional approach involves the study of all structures and their functions in a specific area of the body (such as the head), also individual region • neck or abdomen, etc. cells tissues blood vessels nerves muscles organs bones
Systemic Approach
systemic anatomy refers to the study of structures and functions within specific body systems (such as the nervous system or endocrine system).
Sagittal Planes
Left/right division, doesn’t have to be even
Median Plane
The median plane divides the animal down the center into equal left and right halves.
Transverse plane
A transverse plane divides the body into two sections—one containing the head and the other the tail.
Dorsal Plane
A dorsal plane, which is perpendicular to the median plane, divides the body into two parts, one containing the belly and the other the back.
Cranial
Closer to the head
Rostral
rostral is used to refer to parts of the head that are closer to the tip of the nose.
Caudel
Closer to the tail
Lateral
Farther away from the median plane
Medial
Closer to the median plan
Proximal
Proximal refers to a body part’s being closer to the main portion of the body,
Distal
distal describes a body part that’s placed farther out from the main portion of the body.
Plantar
Plantar refers to the surface that touches the ground on the rear limb
Palmer
Palmar refers to the surface that touches the ground on the front limb.
Orad
orad refers to movement within the gastrointestinal system in the direction of the mouth,
Aborad
aborad describes motion in the direction away from the mouth.
Dorsal Body Cavity
The dorsal body cavity contains the central nervous system and is subdivided into a cranial cavity and spinal cavity.
Ventral Body Cavity
The ventral body cavity is also subdivided into two compartments—the thorax and the abdomen.
Thoracic Cavity
The thoracic cavity contains the heart, lungs, esophagus, and major blood vessels.
Pleural Cavity
The thoracic cavity.
Pleura
Thin membrane that covers the thorax and organs in it
The pleura that lines the organs is the visceral layer, while the pleura that lines the thoracic cavity as a whole is the parietal layer. These two layers have a potential space between them, which contains a small amount of lubricating fluid.
Abdominal Cavity
The abdominal cavity contains all the organs of the reproductive and urinary systems, as well as the stomach and intestinal tract.
Peritoneum
Lines the abdominal cavity and it’s organs. This peritoneum has two layers with a theoretical space much like the thoracic cavity.
Ardiodactylia
Order Artiodactyla—Includes the even-toed hoofed mammals, like pigs, cows, sheep, and goats (two hooves per limb)
Perissodactyla
Order Perissodactyla—Includes the odd-toed hoofed mammals, like horses (one hoof per limb)
Scientific name of dog
Canis familiaris
Scientific name of cat
Felis domesticus
Scientific name of horse
Equus caballus
4 Tissue types
Epithelial, connective, nervous, Muscle
Planes of reference
Imaginary vertical or horizontal lines drawn through a body to describe a structure’s location and body movements
homeostasis
the physiological processes that keep a body in equilibrium
withers
near the shoulder, dorsal, where the horn of a saddle is
Barrel
The trunk, formed by rib cage and abdomen
flank
lateral surface of the abdomen between the last rib and the hind legs
Brisket
At the base of the neck, between the front legs that covers the cranial end of the sternum
Poll
top of the head between the ears
muzzle
upper and lower part of jaws
brachium
upper arm, area of thoracic limb, between the elbow and shoulder
stifle
joint between the femur and tibia, in back leg (in humans, the knee)
shin
along the tibia
hock
tarsus (hind limb, “ankle”)
canon
front leg, metacarpal/metatarsal bone of hoofed animals
fetlock
joint between cannon bone and proximal phalanx of hoofed animals
pastern
are of proximal phalanx of hoofed animals (distal of fetlock)
carpus
joint composed of the carpal bones. referred to as the knee of the horse and wrist of humans
abdominal cavity
major structures • digestive organs • urinary organs •reproductive organs
pleurisy
inflammation of the thoracic cavity
peritonitis
inflammation of abdominal cavity
disease
the result when structures or
functions of the body become
abnormal
health
a state of normal anatomy and
physiology
adipose
fat
connective tissue
tissue made up of cells and extracellular substances that connect and support cells and other tissues
inflammation
first step in healing process when body is injured. “clean up” of damaged area
skeletal muscle
striated, voluntary muscle that enables movement, moves bones and under conscious control
tailhead
dorsal part of base of tail
xiphoid process
last, most caudal sternebra
Polysaccharides
complex carbohydrates with many sugar monomers that form chains or branches. Examples include glycogen, starch, and cellulose.
Oligosaccharides-
are short chains of sugar monomers covalently bonded together. If they contain only two sugar monomers, they’re known as disaccharides. Examples of disaccharides are lactose (milk sugar) and sucrose (table sugar).
Monosaccharides-
are simple sugars composed of only one monomer. Examples are glucose, fructose, and ribose.
-saccharides
carbohydrates
Hydrogen bonding
occurs when there’s a weak attraction between a slightly negative atom in a polar covalent bond and a slightly positive hydrogen atom involved in a second polar covalent bond.
Salts
are important in many biochemical processes. Examples are sodium chloride and calcium phosphate
Electrolytes
minerals that carry an electric charge. They are salts
acid
When dissolved in water, acids release hydrogen ions, contain ionic bonds and are electrolytes
Base
bases release hydroxyl ions. contain ionic bonds and are electrolytes
Ionic bonding
occurs when atoms either donate or accept electrons from another atom. The atom that donates an electron becomes positively charged, while the atom that gains an electron becomes negatively charged. The two atoms, which now have opposite electrical charges, are attracted to each other and stay together as a result.
Ion
atoms that participate in ionic bond are referred to as ions. When ionic bonds form between mineral compounds, the resulting compounds are salts.
Anion
Negatively charged ions are called anions
Cation
An ion that has a positive charge
Ionic Bonding
when atoms either donate or accept electrons from another atom.
Covalent Bonding
Occurs when two atoms each have an unpaired electron in their outer orbitals. Each atom exerts a force on the unpaired electron of the other, pulling them together. The unpaired electrons are then shared between the two atoms. This sharing of electrons may be equal between the two atoms, producing what’s called a nonpolar bond. It may also be unequal, causing one end of the molecule to have a slight positive charge and the other end to have a slight negative charge.
Polar Covalent bonding
Unequal electron sharing produces a polar covalent bond. The bonds that hold the atoms of a water molecule together are polar covalent bonds
Proteins (Keep this one)
form enzymes and hormones and control all metabolic and biochemical reactions and processes in cells. Proteins are composed of chains of amino acids joined by peptide bonds.
Amino Acids
A protein. There are 20 different amino acids in the body, all of which contain a carbon atom bound to an amino group, a carboxyl group, and a side chain (designated R)
4 Amino Acid structures
1) highly specific sequence of amino acids in each type of protein
2) formed by hydrogen bonds at intervals along the length of the amino acid chain that cause it to coil or bend.
3) Bonding of certain amino acids causes further bending and looping of the protein
4) when hydrogen bonds or bonds between R groups join two or more polypeptide chains together
DNA and Proteins
DNA provides a template for the manufacture proteins. Cells differ, depending on which proteins are made by that particular cell. The genes within the DNA molecule control synthesis of proteins. The process of transcribing and translating the genetic message into a protein requires the molecule ribonucleic acid (RNA).
Neutral fats
known as triglycerides, are the most abundant lipids in the body and provide more than twice the energy of complex carbohydrates when they’re broken down. Triglycerides are made up of three fatty acids (a combination of saturated and unsaturated) and glycerol. Saturated fatty acids are found in butter and lard. Unsaturated fatty acids are derived from plants, such as corn oil and olive oil.
Phospholipids
made up of two fatty acids, glycerol and a phosphate group. Phospholipids are made up of both hydrophobic and hydrophilic ends which shapes them into two layers, called a lipid bilayer, when surrounded by water.
Steroids
A type of hydrophobic lipid. Examples of steroids include cortisone, estrogen, progesterone, and testosterone.
Eicosanoids
made up of 20 fatty acids in a ring structure. These help to mediate complex chemical processes in the body.
phosphorylation
The phosphate bonds of ATP contain energy that’s released when enzymes break off ATP’s outer phosphate group and attach it to another molecule
Nucleotides
Small organic compounds that contain one or more phosphate groups and a five-carbon sugar attached to a nitrogenous base
Nucleic Acids
either single (as in RNA) or double (as in DNA) strands of covalently bonded nucleotides.
isotopes
Atoms that contain different neutrons (atomic mass) from the protons (atomic number)
molecule
smallest particle of a substance, composed of 2 or more atoms, that retains properties of the substance
Solvent
A component that is present in the greatest amount in a mixture
Solute
Tiny particles in a mixture that do not settle or scatter light (mineral water)
Colloid
Solute particles in a mixture that are larger and scatter light, but do not settle out (jello)
Suspension
Solute particles in a mixture that are very large and settle out and may scatter light (red blood cells)
Hydrogen bonds
weak bonds that unite hydrogen with oxygen or nitrogen
anabolic
constructive processes
catabolic
destructive processes
three types of chemical reacitons
synthesis, decomposition, exchange
organic compounds
Contain carbon covalent bonds (CC or CH) and are large and complex
Inorganic
Don’t contain CC or CH bonds, tend to be ionic and are small
Functional group
specific groups of atoms within molecules that are responsible for the chemical reactions of those molecules
4 properties of water that make it important for life
Water is a universal solvent. Water is an idea transport medium. Water has a high heat capacity and high heat vaporization. Water is used for lubrication.
Peptide
. A peptide is a molecule consisting of two or more amino acids in which the carboxyl group of one acid is linked to the amino group of the other.
Carbohydrate
essential nutrient for all life functions. Is a sugar. Quick source of energy and may be stored as glycogen. consist of carbon, hydrogen, and oxygen in a 1:2:1 ratio
lipids
Lipids are used in the body for energy and are stored in fat for future energy needs. Lipids also serve as chemical messengers in the form of some hormones. Essential nutrient for life. They’re composed of fatty acids attached to glycerol.
Enzymes
Enzymes speed up or catalyze chemical reactions without being destroyed or altered. Enzymes are specific to the reaction they catalyze and the substrates (the substances they act upon) they use.
Cell membrane
Also called plasma membrane or plasmalemma. All cells have this.
Cytoplasm
Has cytosol a colloid protoplasm that is highly structured and composed of proteins, electrolytes and metobolites, a flexible cytoskeleton and organelles
Organelles
complex structures in cells that work collaboratively to carry out metabolic functions of cells.
globular proteins
responsible for cell membrane function
integral proteins
occur within the entire width bilayer of the cell membrane, they all select substances to enter and leave the cell. Some act as pores letting water pass through
peripheral proteins
bound to the inside or outside surfaces of cell membranes they may act as enzymes to catalyze specific chemical reactions and changing cell shape
glycocalyx
sugar coating found on outside of cell, formed by sugar groups attaching to proteins and lipids on the outer surface of the cell membrane
Cell adhesion molecules
Glycoproteins that cover the surface of almost all mammal cells, they all cells to bond to extracellular molecules and each other
Caveolae
small invaginations of the plasma membrane often pinch off and migrate inside the cell to form tiny vesicles.
Basal Bodies
Where cilia and flagella originate, formed from a pair of centrioles
proteasomes
hollow cylinder inside the cell, composed of protein subunits and responsible for breaking down mislabeled or abnormal protein molecules
peroxisomes
membrane bound vesicle containing enzymes, produced by fission, which detoxifies various molecules such as alcohol and formaldehyde
Cytosol
Cytosol is the protoplasm of the cell. It is a viscous, semitransparent liquid composed of dissolved electrolytes, amino acids, and simple sugars. Proteins are also suspended in the cytosol and give it its thick, jellylike consistency.
Mitochondria
The mitochondrion produces 95% of the energy that fuels cellular activity. The energy is predominantly stored in the terminal phosphate bond of adenosine triphosphate (ATP) molecules. The ATP is derived from an array of biochemical processes using oxygen and nutrient molecules. Oxygen enters the body via respiration, and nutrient molecules are provided from food sources. Remarkably, mitochondria contain their own DNA, which includes the instructions for making the enzymes used to make ATP.
Protein synthesis cell process
The ribosome is the site of protein synthesis. Soluble protein intended for intracellular use is manufactured on free-floating ribosomes found throughout the cytosol, whereas protein intended for export outside the cell is synthesized on fixed ribosomes found on the rough endoplasmic reticulum (RER). Newly manufactured molecules of protein are moved internally into passageways in the RER known as cisternae, Latin for “reservoirs.” Here the proteins are modified before being moved on to the Golgi apparatus for further modification and packaging. The membrane of the RER is an extension of the outer nuclear membrane, so that RER is often found near the nucleus.
Smooth ER
Smooth ER, which is connected to rough ER, is active in the synthesis and storage of lipids, particularly phospholipids and steroids, and is therefore seen in large quantities in gland cells. In liver cells smooth ER may also function to eliminate drugs and break down glycogen into glucose.
Golgi Apparatus
The Golgi apparatus acts as a modification, packaging, and distribution center for molecules destined for either secretion or intracellular use. It also functions in polysaccharide synthesis and in the coupling of polysaccharides to proteins (glycoproteins) on the cell surface.
Lysosomes
The lysosome’s principal responsibilities are the breakdown of nutrient molecules into usable smaller units and the digestion of intracellular debris. Lysosomes may also release their enzymes outside the cell to assist with the breakdown of extracellular material. In addition, lysosomal digestion is responsible for decreasing the size of body tissues (for example, shrinkage of the uterus after parturition and atrophy of muscles in paralyzed animals).
Peroxisomes
Peroxisomes are commonly found in liver and kidney cells and are important in the detoxification of various molecules. Peroxisomes contain enzymes that use oxygen to detoxify a number of harmful substances, including alcohol and formaldehyde. They also assist in the removal of free radicals, which are normal products of cellular metabolism that can be harmful to the cell in large quantities because they interfere with the structures of proteins, lipids, and nucleic acids.
Proteasomes
Proteasomes are minute structures that consume individual, often misfolded proteins and digest them. They are found throughout the cytosol.
Vaults
Vaults are tiny, hollow transport complexes that are thought to attach to fibers in the cytoskeleton that enable rapid movement from one part of the cell to another. Vaults are able to open up and may lock into nuclear pore complexes on the nucleus, where they may pick up and drop off molecules.
Three fluid compartments in the body
. Fluid compartments in the body include: intracellular, interstitial, and intravascular.
Facilitated diffusion
The diffusion of molecules across the cell membrane with help from carrier proteins. It requires ATP and can’t be done through simple diffusion
Osmotic Pressure
Force of water moving from on side of a membrane to the other
Oncotic Pressure
Difference between osmotic pressure of blood and osmotic pressure of interstitial fluid or lymph
hydrostatic pressure
the force that pushes a liquid (blood pressure)
electroylte
An electrolyte is a charged particle (an anion or a cation) capable of conducting an electric current in solution.
Osmolality
Measurement of solute concentration in fluids
The three principles that enable molecules to diffuse into a cell
. Molecular size: Very small molecules, such as water (H2O), may pass through cellular membrane pores (approximately 0.8 nm in diameter), but larger molecules, such as glucose, cannot.
2. Lipid solubility: Lipid-soluble molecules (e.g., alcohol and steroids) and dissolved gases (e.g., oxygen [O2] and carbon dioxide [CO2]) can pass through the lipid bilayer with ease, whereas other molecules may not.
- Molecular charge: Ions are small, but their charge prevents easy passage through the membrane pores. Specialized pores called channels selectively allow certain ions to pass through but not others.
4 attributes of epithelial cells
. Epithelial cells are polar: that is, they have a sense of direction relative to surrounding structures. Each epithelial cell has an apical surface and a basal surface, which are quite different from each other. The apical surface is the side of the cell that faces the lumen or body cavity, and the basal surface is the side of the cell that faces the underlying connective tissue.
- Epithelial cells have lateral surfaces that are connected to neighboring cells by junctional complexes. These junctions bring the cells into close apposition to one another, leaving little room for extracellular matrix. The matrix that surrounds epithelia therefore exists in very small quantities, if at all.
- All epithelial cells lack blood vessels or capillaries. They are avascular and rely on underlying connective tissue to provide oxygen and nutrients.
- Although some epithelia lack nerves (for example, those in the stomach, intestines, and cervix), most epithelial cells are innervated and provide valuable sensory input.
Epithelial cell junctions
Tight junction: formed by the fusion of the outermost layers of the plasma membranes of adjoining cells. The matrix-filled space between cells is lost at the site of a tight junction. For centrally placed cells, the fusion occurs as a strip that wraps around the entire circumference of the cell like a belt. In this way, an impenetrable barrier is formed that prevents the passage of substances from the luminal end to the basal end of the cell and vice versa. Only by passing through the body of the cell can substances pass through the epithelial layer. Tight junctions are found in tissues in which there can be no leaks—for example, in the urinary bladder, where urine is held, or in the digestive tract, where tight junctions play a critical role in preventing the leakage of digestive enzymes into the bloodstream.
- Desmosome: strong, welded plaque that connects the plasma membranes of adjacent cells. The bond is a mechanical coupling formed by filaments that interlock with one another, just as plastic fibers do in Velcro. Tonofilaments, or intermediate filaments, may also extend from the desmosomic plaque into the cytoplasm of each cell like anchors, forming stabilizing bases for the membrane junction. In this way, desmosomes form tough bonds between cells and therefore are found most commonly in tissues that undergo repeated episodes of tension and stretching, such as the skin, heart, and uterus.
- Hemidesmosome: junctions that look like half-desmosomes and link epithelial cells to the basement membrane.
- Gap junction: made of tubular channel proteins called connexons and extends from the cytoplasm of one cell to the cytoplasm of another. These transmembrane proteins allow the exchange and passage of ions and nutrients (e.g., nucleotides, sugars, and amino acids) from one cell to another. Gap junctions are most commonly found in intestinal epithelial cells, the heart, and smooth muscle tissue. The function of gap junctions in epithelial cells is not yet fully understood, but their ability to quickly transport electrical signals from one cell to another explains their presence in cardiac and smooth muscle cells, where they help coordinate contraction.
Simple squamous epithelium
Simple squamous epithelium can be found in the inner lining of the lung and in the filtration membranes of kidneys
Simple cuboidal epithelium
Simple cuboidal epithelium can be 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 gland.
Simple columnar epithelium
Simple columnar epithelium is found lining the length of the gastrointestinal tract from the stomach to the rectum.
Stratified squamous epithelium
Stratified squamous epithelium is found lining the mouth, esophagus, vagina, and rectum.
Pseudostratified columnar epithelium
Pseudostratified columnar epithelium is found in the respiratory tract and in portions of the male reproductive tract.
Transitional epithelium
• Transitional epithelium is found in portions of the urinary tract where great changes in volume occur (urinary bladder, ureters, urethra, and calyxes of the kidney).
Endocrine glands
Endocrine glands do not have ducts or tubules, and their secretions are distributed throughout the body. They produce and secrete regulatory chemicals known as hormones into the bloodstream or the lymphatic system, where they are carried to many regions of the body. The pituitary gland in the brain and the adrenal gland near the kidney are examples of endocrine glands.
Exocrine glands
Exocrine glands possess ducts. They are more common than endocrine glands and act by discharging secretions through their ducts directly into local areas, where they may cover cell surfaces or empty into body cavities. The secretions of exocrine glands act locally and do not normally enter the circulation. Examples include hepatoid, musk, sweat, and salivary glands. Exocrine glands in the liver secrete bile. The pancreas has both endocrine and exocrine glands
Goblet Cell
The goblet cell is a modified columnar epithelial cell found interspersed among the columnar cells of the respiratory and digestive tracts and in the conjunctiva of the eye. Goblet cells secrete mucin, a thick, sticky mixture of glycoproteins and proteoglycans. When combined with water, mucin becomes mucus.
3 basic ingredients of connective tissue
Extracellular fibers, ground substance, and cells
7 functions of connective tissue
- Forms metabolic and structural connections between other tissues.
- Forms a protective sheath around organs.
- Helps insulate the body.
- Acts as a reserve for energy.
- Provides the frame that supports the body.
- Composes the medium that transports substances from one region of the body to another.
- Plays a vital role in the healing process and in the control of invading microorganisms
Glycosaminoglycans
(GAGs) are the ground substance in soft connective tissue. They are made of unbranched chains of glycoproteins. Animals with joint injuries are sometimes given GAGs because they may help with joint healing. Joints contain hyaluronic acid, which is the most commonly found GAG in connective tissue. GAGs are large molecules that help to orient the formation of fibers within the tissue during healing.
Three types of dense connective tissue are:
Three types of dense connective tissue are cartilage, bone, and blood.
Cartilage is similar to connective tissue proper in that it is composed of cells, fibers, and matrix. It is different in that it is more rigid than dense connective tissue.
Bone is similar to connective tissue proper in that it is also composed of cells, fibers, and matrix; however, bone is much more dense. In fact, it is the hardest, most rigid type of connective tissue.
Blood is similar in that it has a matrix, plasma, a fibrous component that is visible when blood clots, and cells. It is different in that it is almost always fluid but can clot when necessary.
Three types of cartilage
- Hyaline cartilage: Hyaline cartilage is the most common type of cartilage in the body. It is composed of closely packed collagen fibers that make it tough but more flexible than bone. Macroscopically, hyaline cartilage resembles a blue-white, frosted ground glass. It is found in the growth plates of long bones, where it supports continued bone development and the extension of bone length. Hyaline cartilage is the most rigid type of cartilage and is enclosed within a perichondrium.
- Elastic cartilage: Elastic cartilage is similar to hyaline cartilage but contains an abundance of elastic fibers, which form dense branching bundles that appear black microscopically. Elastic cartilage is found in the epiglottis of the larynx and in the pinnae (external ears) of animals.
- Fibrocartilage: Fibrocartilage usually is found merged with hyaline cartilage and dense connective tissue. Like hyaline cartilage, it contains thick bundles of collagen fibers, but it has fewer chondrocytes and lacks a perichondrium. Fibrocartilage is found in the spaces between vertebrae of the spine, between bones in the pelvic girdle, and in the knee joint.
Three types of muscle
Skeletal muscle cells are striated, or striped, because histologically they have alternating bands of light and dark. Unlike cardiac and smooth muscle, skeletal muscle is usually controlled through conscious effort and therefore is called voluntary muscle. (In other words, the animal can control its movement through conscious thought.) Thus skeletal muscle is striated voluntary muscle.
Smooth muscle is composed of small, spindle-shaped cells that lack striations or bands and therefore appear “smooth.” Like skeletal muscle, smooth muscle may be stimulated to contract by the action of nerves, but unlike skeletal muscle, the contractions cannot be consciously controlled. Smooth muscle is therefore nonstriated involuntary muscle.
Cardiac muscle exists only in the heart and possesses the remarkable ability to contract even when neural input has been altered. Specialized pacemaker cells within the heart muscle supply the signal for the heart to contract at regular intervals. This input is entirely involuntary and is responsible for initiating the pumping force that propels blood through blood vessels. Cardiac muscle is striated involuntary muscle
Two types of neural tissue
Two basic types of neural tissue are neurons and supporting neuroglial cells.
Periople
The periople itself can be seen as the thin membrane that grows from the outer edge of the coronary band and down the hoof wall.
Elastin
Fiber-like protein that gives skin flexibility
Hypodermis
Skin layer where fat is stored
Five layers of skin
stratum basale. The stratum spinosum The stratum granulosum The stratum lucidum The stratum corneum
Layers of skin for furry animals
These layers are the stratum basale, stratum spinosum, and stratum corneum.
Anagen
Anagen is the active phase of the hair. The cells in the root of the hair are dividing rapidly. A new hair is formed and pushes the club hair (a hair that has stopped growing or is no longer in the anagen phase) up the follicle and eventually out.
Catagen
The catagen phase is a transitional stage and about 3% of all hairs are in this phase at any time. This phase lasts for about two to three weeks. Growth stops and the outer root sheath shrinks and attaches to the root of the hair. This is the formation of what is known as a club hair.
Telogen
Telogen is the resting phase and usually accounts for 6% to 8% of all hairs. This phase lasts for about 100 days for hairs on the scalp and longer for hairs on the eyebrow, eyelash, arm, and leg. During this phase, the hair follicle is completely at rest and the club hair is completely formed
Healing stages
Blood flow to the area is increased, which in turn causes the clinical signs of heat and redness. Blood flow also increases the supplies of oxygen and nutrients to the active cells of the damaged tissue.
Plasma fluid, composed of enzymes, antibodies, and proteins, pours into the affected area, causing swelling of the soft tissue structures. This swelling irritates delicate nerve endings and causes pain and tenderness in the affected area.
Clot formation begins to take place, which slows bleeding. The clot also helps isolate the wound from the invasion of pathogens and helps prevent bacteria and toxins from spreading to surrounding soft tissue structures. A clot first forms when platelets become sticky and clump together. Fibrinogen, found in rich quantities in the swollen tissue, is converted to an insoluble protein called fibrin. Fibrin is woven into a netlike structure that surrounds the platelets and provides support and stability to the newly formed clot. It also forms a framework to support the movement of cells throughout the site. Clots that form on the skin eventually dry and become known as scabs.
Large cells, such as macrophages and neutrophils (types of white blood cells), move through blood vessels and can squeeze through dilated capillaries to assist in the removal of debris and microinvaders. The phagocytic cells are short lived, however, and can function for only a few hours before dying. Pus, which is an accumulation of dead and degenerated neutrophils and macrophages, may therefore collect in the injured area.
With increased blood flow, histamine and heparin are dispersed, and their levels drop in the affected area. The decrease in these molecules causes the return of normal capillary size and permeability. When capillaries return to normal size, blood flow and fluid leakage into the affected area abate. Swelling, heat, and redness begin to subside.
To sum up the sources of the clinical signs accompanying inflammation: Heat and redness are caused by increased blood flow to the area. Swelling is caused by fluid from plasma, composed of enzymes, antibodies, and proteins, pouring into the affected area. This swelling irritates delicate nerve endings and causes pain and tenderness in the affected area.
Granulation
Granulation tissue is a bright pink tissue that forms as macrophages work to clear debris from beneath the overlying blood clot or scab. Composed of a layer of collagen fibers manufactured by fibroblasts, granulation tissue is richly infiltrated with small permeable capillaries that have branched off existing capillaries in the deeper layers of the damaged tissue. These new tiny vessels push up into the bed of collagen fibers and provide rich supplies of nutrients and oxygen to hard-working cells such as fibroblasts, macrophages, and neutrophils. Macroscopically, the capillaries appear to be minute granules and are therefore called “granulation tissue.” Granulation tissue keproduces bacteria-inhibiting substances, making it highly resistant to infection.
Keratinization
As older cells travel from the basal to the superficial layers, they undergo profound changes: they fill with keratohyalin granules; lose their nuclei, cytosol, and organelles; and ultimately become lifeless sheets of keratin
Layers of skin for furry animals
These layers are the stratum basale, stratum spinosum, and stratum corneum.
Periople
Soft, horny covering at the proximal end of the hoof wall
Apocrine
Type of sweat gland - unlike eccrine sweat glands, apocrine glands empty into hair follicles rather than onto the surface of the skin. In the dog, apocrine glands are located in the external ear canal.
Hypodermis
Skin layer where fat is stored
Elastin
Fiber-like protein that gives skin flexibility
Dermis
Skin layer with collagen
Three parts to the hoof
The wall, sole and frog
Three phases of hair growth
anagen, catagen, and telogen.
