Musculoskeletal Flashcards
What type of muscle is the only voluntary type?
Skeletal muscle
What accounts for the difference in the length-tension relationship when comparing skeletal and cardiac muscle?
This is due to difference Ca2+ intracellular concentrations
What causes the movement of tropomyosin to free the myosin binding sites on actin?
The combination of Ca2+ ions and TroponinC (TpC)
What neurotransmitter is used at a neuromuscular junction?
ACh
What 3 structures make up cardiac muscle’s own excitatory system?
SA node, AV node and bundle of His
T-tubules are present in both cardiac and skeletal muscle. True or false?
True; action potential propagate along t-tubules in both types of muscle
Define Pharmo-contraction coupling.
Contraction that occurs in smooth muscle in the absence of electrical activity via hormones or neurotransmitters.
What type of neurones innervate skeletal muscle cells?
Alpha-motor neurone (I.e. somatic neurones)
Where are somatic neurones cell bodies located?
The ventral horn of the spinal cord
What is the function of SERCA pumps?
To maintain calcium ion storage in muscle cells
List the 4 steps involved in the sliding-filament model.
- ATP is hydrolysed when myosin head is unattached.
- ADP + P are bound to myosin as the myosin head attaches to actin
- ADP+P release causes myosin head to change position; the actin filament moves
- Binding of ATP causes the myosin head to return to the resting position
CYCLIC PROCESS
Define ‘tetanic contraction’ and the different between complete and incomplete.
Tetanic contraction is the sustained contraction resulting from high frequency stimulation (I.e. summation). Complete is where there is no relaxation of the contraction (graph: fused) and incomplete is where there is partial relaxation of the contraction (graph: infused).
What is the difference of isometric and isotonic muscle contraction?
Isometric contraction involves the muscle contraction without any visible movement of the joint of muscle, whereas, isotonic contraction is when the muscle contracts and shortens.
Compare and contrast the two types of muscle fibres: slow and fast twitch fibres.
Slow twitch fibres *red *type I *lots of mitochondria *high levels of myoglobin; oxygen binding *highly aerobic *fatigue resistant; endurance Fast twitch fibres *white *type II *fewer mitochondria *glycolytic metabolism *fatigue quickly *rapid, intense, short duration contraction
What metabolites cause muscle fatigue?
Lactic acid, inorganic phosphate, increase ADP, reactive oxygen species and an ionic imbalance (of sodium and potassium)
Describe dystrophy and name an example disease.
Dystrophy is a muscle destroying disease that is the progressive degeneration of muscle fibres.
Define autoregulation
The intrinsic ability of an organ/tissue to maintain a constant blood pressure despite changes in perfusion pressure.
What type of nerve fibres richly innervate skeletal muscle?
Sympathetic vasoconstrictor fibres.
What has more control over arterial pressure during strenuous exercise: metabolic or nervous control?
Metabolic; increase of tissue metabolism = increase blood flow
What portion of oxygen does muscle extract from blood at rest compared to during exercise?
At rest: 25-30%
During exercise: 80-90%
What does oxygen debt during exercise result in?
Post-exercise hyperaemia (due to a fall in vascular resistance - vasodilation)
Why does increased production of lactic acid result in pain after exercise?
The increases lactic acid levels stimulate nociceptive C fibres which result in the sensation of pain
Name some functional adaptations of vascular beds in order to maintain adequate blood flow to muscles and skin.
- Variable oxygen extraction
- Participation in vascular reflexes
- Dominant metabolic vasodilation
- Vasodilator response to adrenaline
- Skeletal muscle pump
Name the 3 functional adaptations of cutaneous circulation.
- Sensitivity to ambient temperature
- Cold-induced vasodilation
- Rise in core temperature to reduce body temperature
What are the 3 classifications of joints based on their range of movement?
- Synarthroses: do not move at all (e.g. sutures in skull)
- Amphiarthroses: limited movement (e.g. pubic symphysis)
- Diarthroses: movement on several planes (e.g. knee joint)
What are the 6 types of synovial joints?
Ball & socket, hinge, pivot, gliding/plane, saddle and condyloid.
Name and describe the two membranes of an articular capsule of a synovial joint.
- fibrous membrane: composed of dense irregular connective tissue and forms the outer layer of the articular capsule
- synovial membrane: composed of a specialised connective tissue and has a rich capillarity network and contains synovial-fluid producing cells called synoviocytes. It has no epithelial lining but still have good regenerative powers.
Compare and contrast the two types of synoviocytes.
TYPE A: macrophage-like cell and acts by removing debris via phagocytosis. They are derived from bone marrow and contribute slightly to the production of synovial fluid.
TYPE B: fibroblast-like cells which an abundant rough ER. They are the main producer cells of synovial fluid.
How can synovial fluid be used to diagnose certain joint diseases?
An arthrocentesis can be preformed where a sample of synovial fluid is taken from the patient and the physical, chemical and microscopic characteristics of the fluid are analyses to, hopefully, lead to a diagnosis.
Why is it important to warm up being completing exercise to protect your joints?
The synovial fluid present in synovial joints plays an important role as a shock-absorber for the body. It is important to warm up before exercise as this thickens the synovial fluid to a gel-like consistency and is therefore a more efficient shock absorber.
Define proprioception.
The ability to know where our joints are without needing to see them (both in static and dynamic positions).
What type of muscle spindle is adapted to detecting rapid rates of change in joint angulation and stretch in muscles?
Gamma-motor neuron
