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63 Cards in this Set
- Front
- Back
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Specialisation of Shoulder joint to deepen joint.
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Fibrocartilage labrum
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Major lymph nodes draining the lower limb (and penis) are found...
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....superficial inguinal lymph nodes (below and deep to inguinal ligament.
and deep inguinal lymph nodes (superficial ones drain to the deep ones. |
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Level at which the spinal cord ends in adult
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L1
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Connective tissue sheet that links the lamina of the vertebrae
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Ligamentum flava
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Left and right AV heart valves
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Left Mitral (bigger more powerful - simple - 2 cusps)
Right Tricuspid |
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Myofilament region which remains unchanged in length durning contraction
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A band
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Filament of which troponin C is a component of
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Thin filament
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Lymphatic capillaries ...
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Have loose junctional complexes and are highly permeable to proteins
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Lyphatic vessels originate from....
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originate from blind ending capillaries
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where do B lymphocytes mature?
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Lymph nodes
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Eversion of foot
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Sole of foot laterally
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Plantar and dorsiflexion
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Plantar flexion = point toes downwards!
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Fascia
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Connective tissue between and surrounding the other tissues of body.
Consists of fibrous tissue, adipose tissue and fluid |
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Superficial fascia
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Subcutaneous - merges with dermis of skin. Strength of attachment via fibrous tissue determines how much the skin can move.
Contains superficial blood vessels and lymphatics and nervous supply to these things. Also contain fibroblasts to secrete collagen fibres, mast cells, macrophages and plasma cells. |
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Deep fascia
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Dense fibrous tissue.
Attached to bones, covers and ensheathes muscles. Provides extra sites for muscle attachemnt too. Separates muscles into functional groups by intermuscular septa. Thickness varies - thicker in thigh mechanism of venous return, thin over pharynx - need expand. |
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Compartment syndrome
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If swelling occurs in compartment - cant escape so pressure increases -so compresses low pressure capillaries - then veins, then arteries. Ischaemia to these parts and vicious cycle of increasing pressure occurs.
Also when fracture - blood bleeds into compartment and inc pressure. Small compartments of forearm and lower leg most at risk |
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Skeletal muscle types
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1 = tonic
2a = fast twitch 2b = slow twitch |
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Innervation of myofibres
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Each myofibre innervated by 1 axon. Although 1 axon may innervate more than one fibre dependant on the degree of fine control desired.
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Machanical summation
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Skeletal muscle. Successive APs faster than the rate of relaxation increase mechanical force as summation occurs.
If repeated fast enough - get a fused tetany - maximal contraction |
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Length tension relationship of skeletal muscle
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Biphasic - if skeletal muscle longer than normal resting length contraction strength decreased, also as goes below resting length contraction force decreases.
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Evidence for requirements of muscle contraction
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Isolated muscle in bath of
Calcium solution = rigor With ATP = contraction with Ca2+, relaxation without |
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Actin
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Thin filament
Actin=globular proteins on tropomyosin strand with troponin (3 subunits I,T and C) at end of tropomyosin molecule Anchored to Z line |
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Myosin
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Thick filament with ATPase activity
Anchored to M line at centre Made up of 2 heavy chains; supercoiled alpha helical chains (tail) but with a globular head. and 2 light chain myosin molecules - with associated head groups. Arranged in parallel Head groups in crown formation - 3 pairs of head groups 14nm and 120degrees apart from each other. |
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Different bands and lines of sarcomere
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M line in middle
Hband around this (where no actin myosin overlap - just myosin) A band - H band + myosin/actin overlap Z line at edges of sarcomere to which actin attaches. Z line surrounded by region with no overlaps called I band |
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Sliding filament theory of contraction
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Crossbridges formed from thick to thin filaments.
These attach at 90 degrees and then tilt, swivel or bend Force generated from this movement results in the thin filaments sliding past the thick filaments resulting in a decrease in sarcomere length - contraction. |
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ATP and cross-bridge cycling reaction sequence
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Myosin head;
1.attaches to actin 2.release of ADP+Pi and a confomational change leading to sliding filament 3. binding of ATP and dissociation from actin 4.Hydrolysis of ATP and reattachment |
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Length tension relationship - why?
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Variable overlap - maximal overlap = max force
Overlap of actins = reduction in force as muscle shorter Less overlap ie.when strecthed = less contractile force. Also maybe due to length dependant affinity of troponin C for calcium. |
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Role of calcium in contraction
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Under resting conditions, Troponin I and tropomyosin inhibit the formation of crossbridges. Overcome by binding of Calcium to Troponin C.
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Excitation-contraction coupling
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Linking electrical stimulation to contraction.
APs travel along myofibre membrane and also down T-tubule system (cont. with ext membrane) which takes electrical signal deep into muscle fibres. |
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T tubule system
how often? |
Every A-I band boundary.
At level of each myofibril - t tubule system comes into close contact with Sarcoplasmic reticulum -calcium store - bound to calsequestrin. |
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CICR mainly in skeletal or cardiac muscle
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Skeletal = sole source of calcium!
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CICR in skeletal muscles
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VGCalcium receptors in membrane of myofibre mechanically coupled to Ryanodine receptor in SR, causes conf change, allowing calcium efflux from SR into cytoplasm.
No noticeable ca2+ influx from extracellular. |
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Relaxation of skeletal muscle
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Due to switch off of RyR by repolarisation and then rapid (100ms) calcium reuptake by SERCA (sarcoplasmic/endoplasmic reticulum Calcium ATPase) pumps.
With repeated stimulation intracellular Ca2+ stays high - enough for max contraction |
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Skeletal muscle cells....
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develop from mesenchyme precursor stem cells which diff to myoblasts - which then fuse and terminally differentiate become myocytes - which are multinucleate (peripherally positioned). Cytoskeletal proteins attach the protein components of the sarcomere to the sarcolemma and defects in these result in disordered muscle function and disease.
Organised in single direction in funct units, so their molec interactions are translated into linear tension. |
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Muscle stem cells and myogenesis
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Pluripotent mesenchymal stem cells of somites are patterned by sonic hedgehog, and the lateral dermomyotome region migrate to give rise to myoblasts in all muscle areas of the developing organisms. These differentiate to myocytes
These withdraw from cell cycle and differentiate and fuse into multinucleated myocytes. |
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Satellite cells
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An important population of myoblast stem cells remain undifferentiated into adult life.
Response to muscle injury and disease - regenerate muscle. |
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Titin
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Attaches myosin to Z discs
Intrinsic elastic properties - able to reset and to maintain sarcomere length following shortening. |
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Musculoskeletal coupling
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Coupling within sarcomere (titin and nebulin)
Cytoskeletal coupling within myocyte (desmin) Coupling to structural components in the sarcolemma (dystrophin) Coupling to ECM components |
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cardiac muscle cells
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Elongated, branched, single central nuclei
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Intercalated discs
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Join cardiac myocytes end to end. they comprise Z disc, as well as desmosome, adherens and gap junctions.
The adherens junctions proviude sites for the insertion of actin filaments of adjacent sarcomere. |
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Smooth muscle
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Spindle shaped, non streated muscle cells found surrounding the hollow viscera of the body inc gut, bladder, uterus, resp. tract and blood vessels.
Electrically and mechanically coupled (like cardiac) Mononucleate Usually arranged in outer longitudinal layers and inner circular layers. |
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Fasciciuli
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Bundle of muscle fibres
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Skeletal muscles form and function
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Parallel, pennate (feather like) and convergent (fibre originating lowest insert highest etc. spiral effect - pectoral)
More parallel - more shortening of length. More fibres (pennate) - more contraction force. |
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Role of musculotendinous units
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Produce movement
stabilise joints control movements provide sensory feedback |
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Functions of conective tissue
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Mechanical (supporting matrix, force transmitter ie. tendons)
Metabolic (route of exchange between blood and tissues, fat storage) defence and repair (Fat - cushioning ie. heel, macrophages and mast cells involved in inflamm) Growth and morphogenesis (plays an important in development and maintainance of all tissues. |
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Epimysium? Other layers
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Epi surrounds entire muscle - dense irregular connective tissue
Peri - less dense - surrounds fascicles of muscle Endo-Basal lamina surrounds each muscle fibre |
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Myogenic?
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Self excitable - cardiac myocytes
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Intercalated disc junctional specialisations
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Fascia adherens - actin anchoring sites
Desmosomes - bind the cells together Gap junction - connexins - electrically couple cells |
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Purkinje fibres
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Specialised myocardial fibres that conduct an electrical stimulus down the heart to allow coordinated contraction
No t tubules, few contractile elements Rich in glycogen and mitochondria |
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Where does the craniofacial skeleton come from
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Cranial neural crest cells
(ectoderm) |
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Axial skeleton comes from?
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Paraxial mesoderm (somites)
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Limb skeleton comes from
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Lateral plate mesoderm
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Fibrous joints
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Bones united by fibrous tissue - ie. forearm
Movement dependant on length of fibre between 2 bones in relation to its x sect area |
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Primary cartilagenous joint
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Bones united by hyaline cartilage
ie. between diaphysis and epiphysis |
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Secondary cartilagenous joint
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Articulating surface of bones covered in hyaline cartilage and these united by fibrocartilage
ie.pubic symphysis |
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Synovial joints
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Hyalin cartilage on articulating surfaces separated by thin layer of synovial fluid.
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Thixotropic
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Under pressure, the synovial fluids molecules cross linkages breakdown and it becomes less viscous
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Bursa
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Fluid filled sacs (can be extension of synovial membrane) to allow friction free movement for example tendon over bone
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Anastomoses
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Streams that branch out and then reconnect
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Origins and insertion sof muscles?
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Origin more proximal
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Veins drain?
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Superficial to deep.
Varicose veins if valves ineffective allowing backflow of blood from deep to superficial. |
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Biceps innervated by?
Nerve roots? |
Musculocutaneous
C 5,6 |
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Triceps innervated by?
Nerve roots? |
Radial
C 7,8 |
