week 1 Flashcards
what is difference between isometric and isotonic contractions in skeletal muscle
isometric - length says same and tension changes (supporting object/body posture maintaince)
isotonic - tension stays the same and length changes (moving objects/moving body)
in skeletal muscles is AP longer of shorter than twitch
shorter, so repeat AP’s gives stronger contraction
tetanus causes what in muscles
sustained contraction
when is skeletal muscle at its optimum length for contraction
at rest
what are the three types of skeletal muscle fibres?
I - slow oxidative
IIa - fast oxidative
IIb/x - fast glycolytic.
knee jerk reflex tests what nerve
femoral (L3-L4)
two types of intrinsic muscle diseases
acquired (toxic, endocrine, inflammatory, non-inflammatory) and genetically determined(congenital, chronic degredation, abnormal ion surface membranes.)
symptoms of intrinsic muscle diseases
muscle weakness/tiredness, myalgia, stiffness, delayed relaxation after voluntary contraction
investigations for intrincis muscle diseases
EMG, muscle enzymes (CK), inflammatory markers (ESR/PV). muscle biopsy. nerve conduction studies.
name differences between skeletal and cardiac muscles
SKM - neurogenic, has NMJ, no gap junctions, Ca2+ entitely from S.R
CARDIAC - myogenic, no NMJ, has gap junctions, Ca2+ induced Ca2+ (from ECF to SR).
what is the transmitter at the NMJ (neuromuscular junction) in SKM
acetylecholine.
what is a motor unit
a single alpha neutron and all the skeletal muscle fibres it innervates.
why is there variation in size of motor units
because precision and power needed for different things - power= thigh, fine precision =hands/eye.
what is a sacromere and what is it made up of?
a sarcomere is the functional unit of SKM.
made form myosin (thick and darker) and actin (thin and lighter)
difference between ligaments and tendon
tendon - attach muscle to bone
ligaments attach bone to bone
difference between strain and sprain
sprain - stretching/tearing of ligaments.
strain - stretching/tearing of muscles/tendon
describe type 1 SKM fibres
slow oxidative, abundant myoglobin and mitochondria. resist fatigue (red fibres)
describe type IIa SKM fibres
fast oxidative, intermediate, uncommon, fast contracting and relatively resistant to fatigue.
describe type 11b/x SKM fibres
fast anarobic, great force, tire quick, (white fibres).
SKM description
striated, multinucleate, unbraced, voluntary, 3 types
how does cartilage get its nutrition
through ECM, as is avascular.
what are chondrocytes and what’s their function
cells found in cartilage, live in LACUNA (ECM),
actively secrete and maintain ECM.
describe cartilage
semi-rigid, permable and deformable
what is ECM in hyaline cartilage made up off?
75% water
25% organic
what are the organic constants of hyaline cartilage
organic -
60% type II collagen (finer and 3D meshwork than type 1 (found in skin, bone, tendons etc…)) + 40% proteolytic aggregates.
what are the 3 types of cartilage and how do they differ and where is each found?
elastic - ear, light yellow, addition of elastin fibres make more flexible.
hyaline - blue/white in colour, translucent, commonest. Found in articular, physeal growth plates, tracheal rings, costal cartilage.
fibrocartilage - hybrid between tendon and hyaline. densely packed collagen type 1, appears white (pubic symphysis and vertebral discs)
what is bones function?
protection, stability, leverage, calcium storage (95%), haemopoiesis.
constituents of bone?
calcium phosphate (bioapatite) and collagen. [+water and non-collagen proteins. bone constantly undergoes remodelling.
where is cortical and cancellous bone found
cortical - outer layer. makes up shaft
cancellous - end of bone
osteoclasts and osteoblast function?
osteoblast - bone forming cells found on surface of developing bone.
osteoclast - responsible for bone reabsorption.
what are osteocytes and osteoprogenitor
osteoprogenitor - located on bone surface
osteocytes - bone cell trapped in bone matrix.
what is woven bone
quick fix with collagen fibres haphazardly laid down. reformed to normal (lamellar) bone via remodelling with osteoclasts and osteoblasts.
what is secreted in making of bone?
osteoid.
this then attracts calcium phosphate and turns in to bone.
what is osteomyelitis
inflammation of bone and medullary cavity (usually in long bone). can be acute or chronic, contiguous or haematogenous.
treating osteomyelitis
debridement and antimicrobials. biopsy bone for microbiology (avoid empirical treatment)
symptoms of osteomyelitis
red, swollen, painful, loss of function.
common infectant in osteomyelitis is S.aureus. how do you treat?
flucloxacillin. step down to doxycycline
vancyomycin if allergic to penicillin.
osteomyelitis. open fracture treatment
early aggressive debridement, fixation and soft tissue cover. If wound not healing then suggest s.aureus/gram negative aerobic bacteria.
what to do for diabetes/venous insufficeny osteomyelitis
“poke to bone”, if reached the have osteomyelitis (often polymicrobial).
what to do if If unsure if infected ulcer or osteomyelitis
MRI
who is likely to get a haematogenous osteomyelitis?
PWID, pre-pubertal children, central lines, elderly, dialysis.
osteomyelitis in vertebrae
usually haematogenous, assocaited with psoas and epidural accesses. commoner in PWID, post-GU infections, IV site infections, post-op and soft skin infection
signs/symptoms and investigations of vertebrae osteomyelitis
fever, insideous pain and tenderness, neurological symptoms, inc ESR and CRP. normal WBC not unusual.
investigate with MRI
TB can be infecting organism in osteomyelitis. what extra investigation is indicated if this is the case?
HIV test
when should strep.epidermis be considered bad in osteomyelitis
prosthetic joint infection. - may need removal due to biofilm around prothesis.
risk factors for prosthetic joint infection.
RA, obesity, immunosuppression, diabetes, malnutrition.
what is septic arthritis
infection of joint space causing inflammation.
common organisms in septic arthritis.
s.aurues, strep, neisseria gonorrhoea (sexual active), h.inflenzae (use ceftraxone). coagulative negative staph.
mimic is gout
PVL s.aureus - what is it and complications
panton valentine leukocidin (toxin) causes actue sickness
skininfections, necroitising pneumonia, invasive infection (septic arthritis, bacteraemia).
what is pyomyositis?
‘pus-muscle-inflammation’. 90% staph infection causing redness and severe pain. needs debridement.
myositis
inflammed muscle cause by many things (viral post-flu, fungal, parasites.)
tetanus pathogenesis
clostridium tetani is G +ive stritly anarobic rod/spore. it is noninvasive but toxin is highly deadly.
neurotoxin causes spastic paralysis. (onset 4 days to several weeks). first symptom is “lockjaw”.
tetanus treatment
debridement, antitoxin, supportive therpay (BB, intubate prematurely, ) antibiotics (contraversial), booster vaccination.
check is have had prevention vaccination (which is a routine toxoid vaccine)
what is the function of the synovial membrane
to continually replenish and absorb synovial fluid.
name the three types of joints
fibrous, cartilaginous and synovial
synovial fluid is made of what
mucin and lubricin (hyaluronic acid and glycoprotein)
synovial membrane is made of what
vascular connective tissue with capillaries and lymphatics fibroblasts.
SF affected by septic arthritis and inflammation
inc WBC greater than 200 and straw/yellow colour
SF affected by haemorragic arthritis
red coloured SF
normal SF colour and WBC
colourless and less than 200
constituents of articular cartilage
70% water, 20% collagen type 2 (elastic), 10% proteoglycans. (all reduced with age)
cartilage is avascular and gets what from synovial fluid
o2 and nutrients
what is the catabolic mechanism in cartilage
TNF alpha + Il-1 (proteolytic enzymes, breakdown)
what is anabolic mechanism in cartilage
TGF-Beta and IGF-1 causing reduced Il-1 (and inc proteoglycans, synthesis)
markers of cartilage degradation
inc serum and synovial keratin sulphate.
inc in type 2 collagen in SF
what is the pathogenesis of Gout, OA, RA.
Gout - uric acid crystals deposition.
OA - wear and tear
RA - synovial cells inflammation and proliferation
what are the three types of pain
nociceptive, inflammatory and pathological
name some common BT in MSK system
giant cells tumour, fibrzomatosis, ganglion cyst.
ganglion cyst
derived from synovial surfaces, common around wrist.
usually asymptomatic and can be removed.
thick-walled fibrotic lesion.
peripheral and near joint capsule.
superficial fibromatoses
common EG dupytren’s contractor, plantar fascia, knuckle pads and penile also affected.
risk factors = male and alcohol.
giant cell tumours
joints, maybe neoplastic mainly inflammatory in nature. Can get in bone, tendon sheath or PVNS (same disease in larger joints.)
easily resected.
name the two types of BT concerning fat
lipoma - histoligcally normal fat, asymptomatic.
angiolipomas - multiple and peripheral lesions, painful, young age group
BT causing pain
angiolipoma, necroma (traumatic), glomus tumour, eccrine Spiradenoma, cutaneous leiomyoma.
ANGEL
what is found on biopsy of liposarcoma
lipoblasts
what is the prefix for tumours from smooth muscle, SKM, cartilage, bone
leiomyo- ma, sarcoma
chondro -enchondroma/chrondosarcoma
rhabdomyo - ma, sarcoma
osteo - osteoma (cranial bones), osteoid osteoma + osteoblastoma also BT.
multiple osteomas means what syndrome?
garner’s syndrome.
malignant bone tumour and details about
osteosarcoma.
paediatrics, long bones,
“Codman’s triangle” on radiology
how to test for tumours
biopsy
genetic testing
Hx + examination/clinical picture
histology
(if something doesn’t make sense rethink it!!!)
