Musculoskeletal System Flashcards
What are bursae?
Fluid-filled sacs - reduce friction.
What is a ligament?
Fibrous connective tissue - joins bones/cartilage.
What is a tendon?
Fibrous connective tissue - joins muscle to one.
What are the 3 types of joints?
Fibrous, cartilaginous, synovial.
Connective tissue: fat (function) and fibrous (state the 2 types)
Fat: insulation & shock absorption.
Fibrous: (A) White fibrous (dense tissue composed of collagen bundles) - forms ligaments, tendons & protective membranes around muscle (B) Yellow (elastic).
State the 3 types of cartilage & where they are located.
Hyaline (articular cartilage in joints & respiratory system - trachea), fibrocartilage (articular discs in joints, intervertebral discs & around edge of ball & socket), & elastic (external ear, auditory tube, epiglottis & larynx).
State the 3 regions of long bone:
Epiphysis, diaphysis, metaphysis.
What & where is the epiphyseal plate? State its function.
The growth plate in the metaphysis of long bone.
Site of bone growth & ossification in children.
Describe Ruffini corpuscles & Paciniform endings.
Mechanoreceptors which detect stretch & pressure.
Describe the structure of a synovial joint.
2 bones covered by articular cartilage - joint cavity contains synovial fluid, covered by a synovial membrane and articular capsule.
Function of hinge joints.
Flexion & extension.
Function of pivot joints
Rotation around one axis.
E.g. elbow
Function of Bicondylar joints
movement in one axis & limited rotation around another axis.
E.g. Knee
Function of Condylar joints
Movement in 2 planes (biaxial) - flexion, extension, abduction, adduction.
E.g. wrist.
Function of Ball and socket joints
Movement in 3 planes (multi-axial).
E.g. hip & shoulder
Function of Saddle joints.
Biaxial.
Permit flexion, extension, abduction, adduction, circumduction.
E.g. carpometacarpal joint of thumb.
Function of synovial fluid.
Lubricates joint - reduces friction between articular surfaces.
Compare abduction & adduction.
Abduction: moving away from centre of body.
Adduction: moving toward centre of body.
State the spinal regions & no. of vertebrae in each.
Cervical (C1-7)
Thoracic (T1-12)
Lumbar (L1-5)
Below: sacrum & coccyx.
State & point to the major muscles of the body (anterior).
frontalis. zygomaticus sternocleidomastoid trapezius deltoid pectoralis major biceps brachii rectus abdomina external oblique sartorius gracilis abbudctor longus rectus femoralis vastus laterals
State & point to major muscles of body (posterior)
trapezius infraspinatus teres minor deltoid teres major triceps brachii latissimus dorsi external oblique gluteus maximus biceps femoris semitendinosus gastrocnemius calcaneal tendon
Name the 7 main Tarsal bones
Tiger Cubs Need MILC
Talus, Calcaneus, Navicular, Medical cuneiform, Intermediate cuneiform, Lateral cuneiform, Cuboid.
Define Synctium.
a multinucleated cell.
Often cells interconnected by specialized membrane with gap junctions.
Describe smooth muscle.
Involuntary, non-striated muscle.
Forms walls of blood vessels & hollow organs (stomach).
Contracts less powerfully than skeletal, but maintains for longer.
Describe skeletal muscle.
Voluntary, striated, MULTINUCLEATE.
Most attached to bones by tendons.
Develop great force, tire quickly.
Bodily movement & reaction to external stimuli.
Describe cardiac muscle.
Involuntary, striated, mononucleate, many mitochondria.
Abundant myoglobin reserve (O2 storage)
Intercalated discs.
Describe an intercalated disc.
Intercellular attachment of cardiomyocytes - gap junctions.
What is a sarcomere?
A single contractile unit: contains actin & myosin filaments.
Sarcomere: A band
Thick (myosin) filament
Sarcomere: I band
Thin (actin) filaments.
Sarcomere: M line
centre of sarcomere: thick filaments attach
Sarcomere: H zone
Thick filaments only
Sarcomere: Z disc
filamentous protein network: attaches actin myofilaments.
Sarcomere: titin filaments
elastic chains of polypeptides - align thick & thin filaments
State the resting length of a sarcomer
2-2.2ym
Mechanism of contraction (skeletal & cardiomyocytes).
Contraction: DEPOLARISATION -
- Excitation -> Na+ channels
- L-type Ca2+ channels
- Ca2+ induced Ca2+ release from RyR (ryanodine receptors) - sarcoplasmic reticulum.
- Ca2+ stimulates contraction.
Mechanism of Relaxation (skeletal & cardiomyocytes)
REPOLARISATION:
- Ca2+ reuptake into SR
- Ca2+ withdrawal to ECF
- Ca2+ exchanged for 3Na+ via Na+/Ca2+ exchanger (NCX) , then 3Na+ for 2K+ via Na+/K+ -ATPase.
- K+ channel activation.
Describe the mechanism for smooth muscle contraction.
- Excitation-depolarisation due to voltage-gated L-type Ca2+ channel opening.
- Ca2+ -induced Ca2+ release from ER/SR via RyR -> increased [Ca2+]
- Ca2+ binds calmodulin (CaM)
- Ca2+ -CaM complex activates Myosin light chain complex (MLCK)
- MLCK phosphorylates myosin head & stimulates contraction.
What is the importance of Ca2+?
- DEPOLARISATION & propagation of excitation
- Activates muscle contraction
- SIGNAL MOLECULE & SECOND MESSENGER
What are the 4 stages of muscle excitation
Twitch, wave summation, incomplete tetanus & complete tetanus.
What is a fascicle?
Bundle of parallel fibres bound by dense connective tissue.
Bound together form muscles.
Describe the phases of contraction
- REST: ATP is hydrolysed.
- ACTION POTENTIAL: Ca2+ binds to troponin -> conformational change -> MYOSIN BINDS ACTIN.
- Powerstroke occurs: sarcomere contracts; ADP & P dissociate from myosin.
- New ATP binds myosin -> detaches from actin.
ATP -> ADP + P causes reckocking of myosin head.
