Muscle Physiology Flashcards
Describe the difference between somatic and autonomic
Somatic = With conscious effort Autonomic = Unconscious effort
Describe skeletal muscles
Striation on sarcomeres (stripes of muscles)
Effector of somatic nerve system
Voluntary contraction
Neuromuscular junction - Specific, multi-nuclei (fusion)
Describe smooth muscles
Elongated, no striation, effector of ANS, involuntary contraction, varicosites
(diffuse), gap junction
Describe cardiac muscles
Striation, effector of ANS, involuntary contraction, gap junctions, intercalated disks
What is the function of muscles?
Locomotion, maintaining posture/body position, stabilising joints, generate heat
Activate sarcoplasmic reticulum to release Ca as T-tubules have VG ion channels
What are the components of the skeletal muscle fibres?
Sarcolemma (plasma membrane) Sarcoplasm (cytoplasm) Myofibrils Mitochondria Sarcoplasmic reticulum (SER) Transverse tubules (T-tubule)
Describe 3 ways to form muscle energy metabolism
Glucose (oxidation), Can use fat (oxidation), Creatine phosphate
Describe the neuromuscular junction
AP to axon terminal of motor neuron, Ca2+ channels open, NT ACh released, Ligand-gated Na+ channels open when ACh binds to receptors on motor end plate (EPSP), AP generated when threshold reached, Propagation of AP on sarcolemma
Describe the components of myofibrils
Striated, sarcomere (repeating functional unit bordered by z-line), thick filament (myosin), Thin filament (actin), A-band (dark), I-band (lighter)
What is actin?
Contractile protein
What is troponin?
Regulatory protein
What is tropomyosin
Regulatory protein
Describe the sliding filament of muscle contraction (which shortens etc)
Myosin/actin filaments don’t shorten, A-band remains same, I-band/H-band shorten
Describe twitch contraction
Contraction produced in response to single AP, All or nothing for given muscle fibre
Can be induced for muscle fibre/motor unit/entire muscle
What is latency in terms of twitch contraction?
Time delay between stimulation (nerve AP/direct electrical) - E-C coupling
What is the contraction and relaxation phase?
Contraction phase - Cross-bridge cycling
Relaxation phase - Ca2+ uptake
What is the contractile force of muscle affected by?
Multiple muscle fibres in contraction / Force that individual fibres produce
Fibre diameter, Changes in fibre length, Freq of stimulation, Type of muscle fibre, Extent of fatigue
Describe frequency and summation
AP (2ms), contraction (10-200ms), Tension depends on [Ca2+]
Freq of stim inc, Ca2+ release more than uptake - When system is saturated (all troponin bind with Ca2+, cross-bridge cycling maxed out)
What is tetanus?
Long lasting contraction
What are the 3 major types of skeletal fibres?
Slow oxidative fibres
Fast oxidative fibres
Fast glycolytic fibres
Describe muscle receptors
For coordinated activities, Muscle spindles (Stretch receptors, detect muscle length)
Golgi tendon organs - Detect muscle tension, protect muscle from exercise activity
