Module 7 Wk 1 Flashcards
what does the integument consist of?
- the skin
- the hair and a variety of skin associated glands (adnexa)
- claws, hoofs and horns – modified version so the skin as retain many processes we see in the development of the skin
Describe the different function of the integument
- Protective -wear and tear
- Barrier- microbial
- penetration/ impermeable to - - water
- Thermoregulation
- Sensory perception
- Storage organ – in the hyperdermis part of skin has white fatty deposis which is used for stored energy and making new skin
- Synthesis Vit D3
- Glandular – sebum and sweat - secretions
- Photo-protection/ sensitisation
- Immuno-surveillance - in underlying CT of skin cells sitting monitoring
- Capture of prey…..
Describe the Epidermis
stratified keratinised squamous epithelium
Describe the Dermis?
dense irregular CT
What is another name for the stuctures found in the dermis and what are they?
Adnexa - hair follicules, sweat glands, sensory innervation, venous supply and sm to deterimine if hair stands up or not
Describe the subcutis and what it is made up of?
- superficial facia
- adipose tissue - enegy and fat store
- allows skin to move over underlying muscles
What is the condition of animals coat or skin a good indicator of?
whats going on internally
Describe the embrylogical development of the skin
- Primitive Epidermis is of ectodermal origin and Dermis is of mesodermal origin
- Basal cells undergo proliferation, migration and differentiation resulting in cell death
- Stratified keratinised squamous epithelium – forms a physical and permeability barrier
- Melanocytes from neural crest origin migrate to the dermal–epidermal border. Responsible for pigmentation of the skin
What are the main types of cells in the epidermis layer and descrip them
- Basal cells - stem cells (undifferentiated)
- Keratinocytes - differianteaite, migrate and become keratonised
What are the other cell types assocaited with the epidermis
- Melanocyte - responible for the synthesis of the pigment of melanin
- Merkel cell - has sensory function
- Langerhans cell - monitoring function picking up anything getting through the top barriers
What happens to the melanin produced by melanocytes?
transferred to stem cells and sits above nuclei, protecting them from UV light
Name the two main types of hair follicle associated with the skin of domestic species
simple and compound
What are the different types of strata in epidermis
stratum basale, stratum spinosum, strata granulosum, strata lucidum and strata corneum
Describe the stratum basale layer
- Mitotically active layer where cells divide and move outwards towards stratum spinosum
What appears in the cytoplasms and is the first sign of keratinisation
Tonofilaments
Describe the stratum spinosum layer
- cells have prominent cell-to-cell junctions called desmosomes that appear as spiky membrane projections
- Tonofolaments increase in quantity becoming major feature
- Lamellar bodies appear in cytoplasm - organelles containing lipid which are extruded as cells enter granulosa - waterproofing of the skin
- Cells become progressively flattened
Describe the Stratum Granulosum layer
- nucleaus and organells start to break down.
- keratohyakin granules start to appear which are precurser proteins of filaggrin and loricrin
- laminar bodies release lipis between cells which helps with waterproofing
Describe the purpose Filaggrin has in struatum granulosum
It causes tonofilaments to aggregrate and form tonofibrils
Describe the purpose Loricrin has in struatum granulosum
It contributes to form prtective thickened cell envelopes
What do the specail cell juntion do to the dead squames and where is the process absent?
- rivet them together
- absent in the outer most layer
Describe what the control of desquamation at the surface depends on
Balance between levels of protease inhibitors & proteases (latter cause enzymatic degeneration of desomsomes junctional complexes which anchor the cells to the surface)
Describe the histological appearance of the epidermis on thick hairless skin
- Epidermis thick
- Stratum corneum (SC) is particularly thickened (12-20 layers)- subject to constant abrasive forces
- Dermal-epidermal border interdigitates – anchors epidermis to dermis – when these come away from each other si where we get blistering
- No hair follicles are present
- Sweat glands (eccrine) are often present in the dermis
Describe the histological appearance of the epidermis on thick hairy skin
- Epidermis is very thin (arrow) - different strata can still be recognised at high mag
- Characteristic feature - presence of Hair follicles (H) plus associated sebaceous (S) and sweat glands (A) all in the dermis
Describe what the Dermis (CT) consists of
- Cells
(fibroblasts*, also mast cells, plasma cells, macrophages, adipocytes, melanocytes, lymphocytes, neutrophils etc) - Fibers
Different types and proportions (Collagen, reticular, and elastic fibers) - Ground substances
Dense fluid (proteoglycans and glycoprotein)
*Fibroblasts produce /maintain the extracellular matrix
Where is the blood supply to the skin loacted?
Dermis
Describe the blood supply in skin
- supply is taken up close to the epidermis but not in
- blood then goes into superficial plexus
- then into the middle then the deep plexus
Describe how the body adapts so heat loss is limited when cold
Due to taking it up close to the epidermis you are losing heat to the outside so the supply bybasses this step using an AV shunt so not losing heat to the surface
WEhere does hair not cover on animals?
- food pad, hoof, glans penis, mucocutaneous junctions and teat of some species
what is hair produced by?
- a hair follicule in the dermis of the skin
State the functions of hair
- mechanical protection
- thermoregulation
- sensory perception- specialised tactile hair
What is the name of the muscle associated with hair?
Arrector pili muscle - contacts to make hair stand up
Describe the structure of a simple hair follicule
- A simple hair consists of a cuticle, cortex and medulla
- The hair shaft projects above the surface of the skin epidermis
- The rest of the follicle is embedded within the dermis (and hypodermis)
- The hair is anchored within the follicle
- The root of the hair consists of the hair and surrounding root sheaths
- The bulb consists of the dermal papilla and hair matrix cells (stem cells)
- Cells become keratinized in the Keratogeneous zone
What does the activity of the matrix cells depens on?
dermal papilla
where do the migrating matrix cells pass through
the keratogenous zone
what do the matrix cells differentaite into?
to form hair and int. root sheath
What cells are responsible for the pigmentation?
melanocytes
Describe the different phases of the hair cycle?
ANAGEN = growth phase:
Hair bulb matrix cells are mitotically active
CATAGEN = regressive stage
Cellular proliferation decreases / cease
Hair bulb = flimsy disorganised column of cells
Club hair.
TELOGEN = resting or quiescent phase.
Hair remains anchored by Keratogeneous rootlets
Dermal papilla = ball of cells below the capsule of the germ cells of the hair bulb.
Dermal papilla away from deral cells but there will be recontection
Hair continuous to lengthen
RENEWED ANAGEN = formation of new hair
Re-establishment of matrix/dermal papillae relationship
Mitotic activity/ keratinisation begin.
Forces root of old hair to move towards the surface . And small hair starts growing into
Hair no longer anchored
When there is lameness is the limb of dog or cat which stuctures are usually effected?
proximal
When there is lameness is the limb of large animal which stuctures are usually effected?
distal
Define Locomotion?
ability to move body forward
Define the musculoskeltal system?
skeleton and all associated soft tissue structures
Define the function of muscle?
support and movement of body
What is the movement called of a limb moving crainally to trunk
protraction
What is the movement called of a limb moving caudally to trunk
retraction
What is the movement called of a limb moving medially to trunk
adduction - moving towards midline
What is the movement called of a limb moving laterally to trunk
abduction - moving away from midline
folding/shortening movements within limb are called what and what happens to angles between joints?
flexion - angles decrease between joints
stretching/ lengthening movements within limb are called what and what happens to angles between joints?
extension - angles increase
Describe the interaction between limbs and trunk when moving forward
each limb goes throught the 4 stages -
- folding limb - flexion
- moving limb forward - protaction
stretching limb - extention - moving limb back wards - retraction
T/F hindlimbs have the most contribution during forward perpulsion?
True
What kind of animal will have less flexibiloty in their trunks?
Herbivores with high fiber diets and bulky abdominal viscera
Where in horse does most of the perpulsion come from?
limb movement
What in cats helps with perpulsion?
flexible vertebral column
What do joints allow?
movement between bones
what do ligaments do?
hold bones together
what does skeletal muscle produce?
Movement between bones across joints - one at diatal end and one at proximal and whne contact bring together
What attaches muscle to bones across joints?
Tendons - continuation of muscle in areas where you dont want bulkyness so have the ropey like tendons
Describe long bones?
- provide support and leverage in limbs
Describe flat bones?
- Large surface area for muscle attachment
- Protection of underlying structures
Describe short bones?
- Some rotation of individual bones (as a group allow large range of movement)
- Ligaments attachments them
- Anti-concussive / shock absorption
Describe a sesamoid bone?
- Embedded in tendons
- Redirection of forces over angled surfaces
- Reduction of friction (damage prevention)
Describe an irregular bone?
- midline/ axail location
Describe the patella?
(equivalent to kneecap) – largest sesamoid in the bone, part of the stifle (equivalent of knee joint) embedded into quadriceps tendon. Ensures that the tendon over the stifle joint is maintained in an axial plane and protects tendon from wear and tear from the underlying femur (by providing a smooth surface for the tendon to move on).
what are the sites for attachment of importnant stuctures called on bones?
specific bony contours
Describe smooth surface areas on bones
Articular / joint surfaces
- Covered by hyaline cartilage
- Subchondral bone
- Osteochondral junction
- No periosteum
Describe rough surface areas on bones
Covered by periosteum in life
Areas for general muscle attachment
what is an Osteochondral junction
boundary between the smooth surface area and rough surface area (in life = boundary between periosteum and hyaline cartilage), etymology: osteo – bone, chondral – cartilage. The joint capsule will attach around this area.
what is a subchondral bone
smooth areas – cartilage (basically means area under the cartilage)
What is the periosteam?
thin layer of cells providing blood supply to bone
how do bones appear on radiographs
whitw/radio- opaque
in utero what is the primordail skeleton made of?
cartilidge
Describe bone growth
- endochondral ossidication (bone growth within cartiloidge
- chondrocytes become quite active and die leavinf behind holes where blood supply comes trhough with osteoblasts
- the osteoblast replace those spaces
- the same thing happens at the distal end but will stay active at the centre always creating elongation of the bone
where in the adult limb is the weakest point?
shaftw
What must you not mistake for fractures on a radiograph?
Physis/ growth plate
where in the young limb is the weakest point?
growth plate
name the 3 times of joints and examples of each
- Fibrous - skull sutures, radius and ulna
- cartilagenous - pelvic and mandibular symphysis
- synovial - elbow, stifle
describe the fibrous joints
- little movement
- bones joined by dnese conjunctive tissue
Describe cartilagenous joints
- flxible
- little movement as they grow
Describe synovial joints
- large range of movement
- most limb joints
- two articulating bones are seperated by a fluid-filled space termed joint cavity
name all 5 features of synovial joints
Hyaline cartilage
synovail fluid
synovail membrane
joint caupsule
collateral ligaments
Describe hyaline cartilage
- Covers articular surface
- Reduces friction
- Shock absorption (flexible)
- No blood vessels or nerve endings
Describe synovail fluid
- lubrication and nurtrition
- viscous fluid
what is a physical barrier of the synovail joints?
synovail membrane
what is the joint capsule
fiberous layer outside synovail membrane - incased - attaching around the osteochondral junction
what are the collateral ligaments formed from
joint capsule
what is the major muscle group located dorsal to vert column
epaxial
what is the major muscle group located ventral to vert column
hypaxail
describe extrinsic limb muscles
- origin axail and insertion appendicular skeletons
- move limb relative to trunk
describe the intrinsic limb muscles
Origin & insertion within limb so apendicular
movement within limb
what are the 3 cursorail adaptations of the proximal
1.Reduced pectoral skeleton
More cranial/ caudal movement
Clavicle absent / vestigial
Deep, narrow chest
2.Elongation at proximal end of limb
Scapula lies lateral and vertical
3.Elongation at distal end of limb
– long metacarpals, walk on toes or hooves (increased leg length)
name the joint sequence of the forelimb
shoulder, elbow, carpal, metacarpophalangeal, interphalangeal (proximal, distal)
what kind of orientation does the scapula have?
vertocal
what does the scapula increase?
limb length, increase in stride stride length and more ground covered
what is the vestigal clavicle
muscular attachment between forelimb and trunk
describe the borderes of the lateral surface of the scapula?
- dorsal - palpable
- cranail - palpable
- caudal - diff to palpate
what runs along the body of the scapula
scapular spine
what surface of the scapula is the gleniod cavity on
ventral
describe the glenoid cavity
- concave
- smooth subchondral surface for shoulder joints with hyland cartilage covering it
Describe the medial surface of the scapula
- flat, scapular glide, faces the ribcage
T/F cats have more rounded cranial angle than dogs in terms of scapula
true
what type of bone is the humerous
long bone
Describe the proximal end of the humerus
Head
- articular surface, convex and smooth
Greater tubercle
- cranail to head
- location of shoulder joint
Lesser tubercle
- medial
intertubercular groove
- passage of bicep tendon
- smooth surafece
Describe the distal end of the humerus
- medial epicondyle
- lateral epicondyle
- trochlea - central depression
- ulnar foss and radial fossa meet at the supertrochlear foreman
T/F horses have a supertrochlear foreman
false
what rea the 5 centres of ossification in the humerus
- proximal epophyses
- body
- condyle - medial wpicondyle, meadail ahlf and lateral half
what are the components of the shoulder joint
- glenoid cavity of scapula - concace
- head of humerous - convex
what are the palapeble landmarks at shoulder joint?
- Acromion process (scapula)
- Greater tubercle (humerus
- Depression inbetwween them where we would insert needle
Describe the bicipital bursa
- joint capsule extends into the intertubular groove
- wraps around tendon of origin if biceos brachii
- held in place by transeverse ligements
Name the two mucles which provide lateral support to the shoulder joint
supraspinatous muscle and infraspinatous muscle
where was the origin of the supraspinatous muscle
supraspinous fossa
where does the infraspinatous muscle run and insert?
down the lateral aspect of scapula into the proximal lateral humerus
what nerve suppiles the two muscle that give lateral support to shoulder joint?
sipracapular nerve
what muscles give medial support to the shoulder joint
subscapularis muscle
what is the orign and insertion point of the subscapularis muscle
origin - subcapular fossa
insertion - proximal medial humerus
whats the neve that supplies the subcapularis muscle
subscapular nerve
where does skeletal muscle attach too
- directly to bone
- via aponeuosis
- via tendons
what are the functions of skeletal muscle
Muscle fibres contract – muscle belly shortens
Points of attachment pulled closer together
what is an antagonistic pairs
opposite action one contract and one relaxed
wheres the origin and insertion point for extrinsic muscles
axail skeleton
appendicular skeleton
wheres the origin and insertion point for intrinsic muscles
origin and insertion are both in appendicular skeleton
T/F intrinsic movement have influence of movement of limb in relation to trunk
false - only have influence of movenemnts in joints within the limb
what is the origin and insertion point of brachiocephalic muscle
O - carvical vertebrae and skull
I - humerus
what effect does the brachiocephalic muscle have pm forelimb?
protractor - pulls limb crainally
what effect does the brachiocephalic muscle have on shoulder
extensor - crosses shoulder joint - attached to the cranail aspect of humerous - pulls humerous in a carinal direction when contracted whihc increases the joint angle so shoulder will extend
what is the origin and insertion point of latissimus dorsi muscle
O - thoracic vertebrae
I - humerus
whats is the function is the latissimus dorsi muscle
forelimb retractor
shoulder flexor
what is the origin and insertion point of serratus ventralis muscle
O - thoracic walls, cervical vertebrae
I - proximal scapula
what is the function of the serratus ventrailis
cranial portion - muscle attached to proximal to picortal point - pulling dorsal point craianly and roatates distal end of scapula in a caudal direction
caudal portion - as the insertion point is proximal to this point the caudal portion of muscle contracts pulling dorsal portion of scapula caudally and rotates siatal aspect cranailly
what is the origin and insertion point of trapezius muscle
O - cervival and thoracic vertebrae
I - proximal scapular spine
what happens when the trapezuis muscle contracts
pulls point of insertion closer to the vertebrae coloumn
what is the origin and insertion point of pectoral muscles
O - sternum
I - humerus
what happens when the perctoral muscles contract
brings two points closer together and brings humerus closer to midleine so assuctiosn of limb
whats is inflammation?
response of vascularised tisse to physical tissue injury, chemical tissue injury and infection
what are the 5 R’s of inflammation
- recognition of offending agent
- recruitment of leukocytes and plasma proteins and activation of theses
- removal of agents
- regulation = termination of reaction
- repair of damaged tissue
what are benififts of inflammation?
- dilution/ inactivation of biological and chemical toxins
- killing of foreign materials, necrotic tissue and neoplastic cells
- providing wound healing factors
- restricting movement allowing time for repair
- increasing temperature to induce vasodilation and inhibit replictaion of pathogens
State harmful consequences of inflammation
- often accompanied by local tissue damage
- it is harmful id misdirected
- it is harmful if excessive/ prolonged/ difficult to control
what can we use to dampen down the harmful consequences of inflammation?
anti inflammatory drugs
when would the onset of acute inflammation happen?
minutes or hours
what kind of immunity do we see withing acute inflammation?
innate - neutrophils
what kind of injury is realted to acute inflammation?
mid and self- limited tissue injury
what is the outcome of acute inflammation
- resolution
- abcess then fibrosis
- fibrosis
- chornic inflam then fibrosis
how long is onset of chronic inflammation?
days
what immunity do we see with chronic inflammation?
adaptive immunity
what cells do we see withing chronic inflammation
lymphocytes, macrphages, plasma cells
what kind of injuries do we see with chronic inflammation?
often severe and progressive tissue injury (fibrosis)
T/F there is more local and systemic signs within chronic inflammation to accute
False - accute has more signs
what are causes of chronic inflammation?
- persistant infection
- hypersensitivity
- prolonged exposure to potential toxic agents
what are the 4 most important mediators of inflammation?
- vasoactive amines
- lipid products
- cytokines/chemokines
- complement proteins
what are the 4 mediators of inflammation generated by?
plasma proteins
describe the action of these mediators
- circulate in inactive form
- need to be activated by stimuli
T/F most mediators are short lived
True
what is histamine produced by?
mast cells
what afe histamines released due too?
trauma, cold, heat, binding of Abs and complement fragments
what does histamine release result in?
- dilation of arterials
- increase in permabiloty
- contaction of smooth muscle
- tachycardia
what is serotonine produced by?
- platlets
what does a release of serotonine result in?
vasoconstriction
neurotransmitter in GT
what are arachnidonic acid metabolits released from?
cell membrane phosphilipids
what can stop the arachnidonic acid metabolits being released?
steroids
what happens after arachnidonic acid metabolits are released if not inhibited?
- go to cyclooxegenase and become protaglandins
- go to lipoxygenase and become leukotreins or lipoxins
T/F lioxins are anti-inflammatory
True as the inhibit recruitment of leukocytes
what are cytokines produced by?
mainly macrophages
what is the cytokines role in accute inflammation
- endothelial activation
- leukocytes activatiin
- systemic acute ohase response
what is the cytokine that is involved in loca and systemic inflammation?
IL-6
what are the two main functions of chemokines
- stimulation of leukocyte attachment to endothelium
- stimulation of leukocyte migration
what are complement proteins activated to be?
proteolytic enzymes and go onto a cascade that is controlled well by associated proteins
what is a critical step for complement proteins
proteolysis of C3
what are the 3 main functions of complement proteins
- inflammation - C3a an C5a stimulate histamine release, C5a also chemotaxis for neutrophils, monocytes.
- opsonisation and phagocytosis
- cell lysis - mac complex (C5b-9 attach itself onto cell creating pore where they can loose ions and water going in and swell up till pops
what are the three facrors determining the outcome of acute inflammation
- severity of tissue damage
- ability of cells to regenerate
- cause of the injury
what is regeneration of skin?
replacement of damaged tissue components and return to a normal state
how does regeneration work?
prolification of differentiated cells that have survived the injury and retain the capacity to prolificate
- also precenece of tissue stem cells and their progenitors contribute to resoration of tissues
what is a scar
deposition of fiberous CT
when would a scar form?
when tissue is incapable of regenration
if supporting stuctures are too severly damaged
what contibutes to full repair of a wound?
both regeneration andscar formation
what does repair of a wound require
- cell proliferation
- cell tp cell interaction
- cell - ECM interaction
what is cell proliferation driven by
growth factors
what is cell prollification dependent upon?
integrity of ECM and development of mature cells from tissue stem cells
what cells proliferate?
- remnants of injured tissue
- vascular endothelial cells
- fibroblast
T/F labile tissues are continously dividing tissues
True
what are the cells like in stable tissues?
cells are quiescent and have only minimal proliferative activity in normal state
T/F stable tissues have high capacity to regenrate after injury?
False - limited
what are two examples of permenents tissues
neurons and cadiomyocytes
T/F perement tissues are insufficeint for tissue regeration
True
what is a significant proportion of any tissue
ECM
what are the functions of the ECM?
- mechanical support - ie anchorage, polarity and migration
- regulator of cell proliferation
- scaffolding for tissue renewal
- foundation for establishment of tissue microenviroment
what are the 2 forms of ECM?
Intersititial and basement
where is the interstitial matrix found?
in spaces between stomal cells in connective tissue
what is the interstitial martix synthesized by?
mesenchymal cells such as fibroblasts but aslo osteoblasts and chondroblasts
where would you find the basement membrane?
around the epithelial cells, endothelial cells and sm cells
what are the 3 basic components of ECM
- fibrous stuctural proteins
- water-hydrated gels
- adhesive glycoproteins
what are the 3 phases of repair
accute inflammation
proliferation
remodelling
what is the function of inflammation in repaiing wound?
eliminate offending agent and clearing debris
what happens during prolieration during repair of wound?
- angiogenesis
- fibroblasts form granualted tissue
what contibutes to neovascularistation
proliferation of endothelial cells leading to angiogenesis
What are the 2 steps of deposition of CT
- migration and Proliferation of fibroblasts into the site if injury
- deposition of ECM proteins produced by fibroblasts
what produces scar tissue?
maturation and reorganization of CT
name the factors effecting tissue repair
- infection
- nutritional status
- age
- glucocorticoids
- mechanical factoes
- poor perfusion
- foreign bodies
- extent and type of tissue repair
- underlying neoplasia
- location of injury
what do stem cells of the skin generate
- follicules and epidermis
T/F stem cells are rapidly dividing cells but only have short-lived contribution to wound response
true
describe the difference between erosion and ulceration
erosion only epidermis and ulceration is into underlying dermis
when is skin wound healing initiated?
whenever there is breach in the epidermal and dermal integrity
when would tissues be repaired by Connective scar tissue?
if the injuries to the tissue are incapable of complet restoration and/or if supporting stuctures are severly damaged
what are the non-regenerous cells replaced by in scar formation?
fibrous tissue
Healing by first and second intection differences?
- 1st - when injurys only involve epithelial layer
- 2nd - more extensive tissue loss, more intense inflammation, abundant granulation tissue
what is fibrosis?
- excessive deposition of collogen
what is fibrosis a commen consequence of?
persistant injurious stimuli
T/F ponies have increased wound contraction compared to horses?
True
Whats is the stepwise approach you use when looking at wound?
- Triage – initial, rapid evaluation of patient
- Examination of wound
- Further investigation of wound if indicated
- Diagnosis
- Treatment
- Monitoring & treatment of any complications
what can we use when evalualting patient?
- passport
- medical history
- general examination
what would be red flags when looking at the wound?
- signs od systemic disease
- severity of lameness
Name the different types of wounds?
- incision wound
- laceration wound
- abrasion
- puncture wound
- penetration wound
-confusion - hematoma
What would lead to wound becoming infected?
- gross contamination with foreign material or older wound with nectrotic tissue
what would be a key sign a wounf is infected?
purulent exudate
what develops in chronically infected wounds?
Biofilm - bacteria adherent to tossies that are protected by polysaccharide matric which they secrete
What can a large dead space present in wound cause?
Potential for blood, serum or purulent exudate to accumulate
What does nectrotic tissue prolong?
Inflammatory response
(radiography - Its role in Diagnosis)
What is the quality of an image and what is it measured in?
It is the penetratng power, so photon energy. Measured in kV
What is the quantity of the image and what is it measured in?
Its is the number of photons. It increases with area thickness. Measured in mAs
The greater the energy, the ______ the __________ of tissue the xray pass through
- greater
- thickness
What is the Film-Focal Distance FFD?
Set distance between machine and cassette/Plate
What does kV determine?
The energy that the xray photons have when they leave the xray tube.
T/F increasing kVp will increase the number if x-rays reaching the cassate and tehre for imcresing image blackening and decreasing image contrast
True
What does Milliamperes-seconds determine?
The number of x-ray photons produced
What does mAs increase?
The number of xrays produced which increases the number if xrays produced which the increases number od xrays reaching cassete in areas where the xrays have sufficient energy to penetrate through patient
What are the two parralel techniques used in dental images?
- Film paralel to tooth
- Beam perpendicular to tooth on long axis
T/F there is only 3 obliques views in equine?
No 4
What are the 4 postions for a radiograph at the level of the hock
- LM
- DP
- DPLMO
- DMPLO
What are comprimises to the thorax view?
Expiritory - mimics disease and masks lesions
inspiratory view - better defination
- breath holding when under GA
mAs = kV +10 / 2 maintains what?
image quality
Describe how you get the exposure right n small animals?
Usually a fixed machine and animal moved. Cassette perpendicular to beam. FFD static
Describe how you get exposure right in equine?
Animal stays and machine is moved around it. FFD should be constant and cassette must be perpendicular to tube .
Good tissue detial due too?
- Good penetration
- Photons have right energy
- kV setting is correct
What does it mean if there is dark background where no animal is ?
enough photons roduced and mAs setting correct
What does it mean if there is over exposure?
kV is too high
If there is under penetration what is low?
kV leading to a lack of detial
If mAs is too low what can be seen?
pale background as not enough photons to darken image
T/F when imaging exotics you cant increase mAs
True so leads to incorrect exposure
What does unsharpness led too?
blurring of edges
How can you limit unsharpness using the machine itself?
The smaller he focal spot size makes the unsharpness and blurring of edges smaller/less
How can you limit unsharpness by controlling geometrics?
- OFD - keep organ as close to plate as possible otherwise there is more scattering
- FFD at appropriate length
T/F movement needs to be controlled to reduce unsharpness?
True - via GA, sedation and restraining aids
what are issues with Radiographs and horse?
- Horizontal beam
- GA: risks
- Oblique views mandatory
Joints - Distance, Centring
What is an x-ray?
Photon of electromagnetic radiation released from electron shell
What is a gamma particle?
Photon of electromagnetic radiation released from radioactive nucleus
What is a Beta particle?
Electron released by decay of radioactive nucleus
What is an Alpha particle?
2 Protons + 2 nuetrons released by decay of radioactive nucleus
What is the absorbed dose?
Grays ( 1Gy = 1 Joule/Kg)
What is the equivilent dose?
Siverts (Grays x Quality factor)
what is sievert?
a measure of bilogical effect of radiation
What does ICRP stand for?
International commision on radiological protection
What can radiation exposure cause?
pyrexia, heamorrhage, diahorea, hair loss, cells die with no replacement
What are somatic effects of radiation?
- Non-stochastic risk
- during the lifetime of the person exposed
What are mutagenic effects of radiation?
Damage to DNA so there fore effects seen in offspring
Ehat are carcinogenic effects of radaition?
damage to cell DNA which id cancer causing
Describe the way a room should be layed out in practice if radiation is being exposed
- 2m from tube head
- best if physical boundary
- warning lights and locked door
- sheilding
- 1mm lead walls
T/F people working with radiation have certian PPE
true - lead gowns, gloves, thyroid sheilds, glasses
what are modern xrays measured in?
watts (power)
T/F in modern xrays the current gets flipped so its all going in one direction?
true
How is an xray generated?
- negative cathode and positive anaode
- apply current over filament heating up boiling electrons off around cathode
- electrons from here react in anode producing xray
What are the 3 ways xray can interact with tissue?
- transmitted
- Photoelectric effect = absorbed
- compton effect - to do with density of tissue and scatter
How to control scatter?
- kV low as possible
- collimination to limit where exposed
- using grid
What is the inverse square law?
double the distance = quadruble the area
What are the benifits of grids?
Increases image quality by decreasing blurring due to scatter, between patient and cassette.
Why when using a grid must you increase mAs?
it absorbs some of xray beam
what are the two types of digital radiohraphy?
- Computed radiography - CT
- Direct Digital radiography - DDR
T/F tissues with high cell turnover are most sensitve to radiation?
True bitch
