03_Muscular System Flashcards
What are the types of muscles in the human body?
Skeletal muscle, Cardiac muscle, Smooth muscle
What is the primary function of movement in the muscular system?
A result of muscular contraction, relying on the integrated functioning of the muscles, bones, and joints
What is thermogenesis?
Heat production to maintain normal body temperature (36.5‒37.5°C)
What is the role of sphincter muscles?
Prevent out-flow from hollow organs
What are the five properties of muscle?
- Contractility
- Excitability
- Extensibility
- Elasticity
What distinguishes striated muscles from non-striated muscles?
Striated muscles have aligned cells forming stripes; non-striated muscles have randomly arranged cells
What type of muscle is voluntary?
Skeletal muscle
What type of muscle is involuntary and autorhythmic?
Cardiac muscle
What type of muscle is found in the walls of blood vessels and the gut?
Smooth muscle
How many skeletal muscles are in the human body?
640 skeletal muscles
What is the sarcolemma?
The cell membrane of a skeletal muscle fibre
What is myoglobin?
A red colored, iron and oxygen binding protein found in muscle cells
What are the two types of myofilaments?
- Actin (thin filaments)
- Myosin (thick filaments)
What is a sarcomere?
The basic unit of striated muscle
What surrounds individual muscle fibres?
Endomysium
What is the function of the perimysium?
Surrounds bundles of muscle fibres called fascicles
What is the neuromuscular junction?
The synapse where motor neurons meet a muscle fibre
What neurotransmitter is involved at the neuromuscular junction?
Acetylcholine
What happens during muscle contraction at the neuromuscular junction?
Nerve impulse causes calcium to release from the sarcoplasmic reticulum
What is the role of calcium in muscle contraction?
Causes the myosin head to bind to actin filaments
What is muscle hypertrophy?
Increase in muscle size
What are the two main pathways for ATP synthesis?
- Aerobic respiration
- Anaerobic respiration
What is the net ATP yield from aerobic respiration?
36 ATP molecules
What is the primary product of anaerobic respiration?
Lactic acid
What is creatine phosphate’s role in muscles?
Provides a ready source of energy during the first 15 seconds of contraction
What are the two types of skeletal muscle fibres based on color?
- Red muscle fibres
- White muscle fibres
What type of muscle fibre is best for endurance?
Slow oxidative (SO) fibres
What type of muscle fibre is characterized by a large diameter and fatigue quickly?
Fast glycolytic (FG) fibres
What are the effects of strength training on muscle fibres?
Increases the size (hypertrophy) and strength of fast glycolytic fibres
What are the names of the three types of skeletal muscle fibres?
- Slow oxidative (SO)
- Fast oxidative glycolytic (FOG)
- Fast glycolytic (FG)
What is the function of the epimysium?
Surrounds the entire muscle and attaches it to fascia and tendons
What is the role of the sarcoplasmic reticulum in muscle cells?
Stores calcium needed for muscle contraction
What happens to actin and myosin during relaxation?
They slide back into starting positions
What is the function of the Z disc in a sarcomere?
Separates sarcomeres and is where actin filaments are arranged at 90° angles
What is the primary energy source during prolonged muscle activity?
Aerobic respiration
What determines the proportion of muscle fibre types in an individual?
Genetically-determined mixture and training
What are the two myofilaments needed for muscle contraction?
Actin and Myosin
Actin is a thin filament, while myosin is a thick filament.
What is muscle hypertrophy?
Increase in muscle size
Hypertrophy occurs when muscle fibers increase in size due to resistance training.
What is muscle atrophy?
Decrease in muscle size
Atrophy can result from disuse or a lack of physical activity.
Compare aerobic and anaerobic respiration.
Aerobic uses oxygen; anaerobic does not
Aerobic respiration produces more ATP than anaerobic respiration.
Why do some muscles appear red?
Due to high myoglobin content
Muscles with high myoglobin levels can store more oxygen.
What type of cell respiration do slow oxidative muscle fibers use?
Aerobic respiration
Slow oxidative fibers are designed for endurance activities.
What does ‘occipitofrontalis’ refer to?
Muscle that raises eyebrows
The name indicates its location at the back and front of the head.
What is the function of the orbicularis oculi muscle?
Closes eyes
It is a circular muscle around the eyes.
What does the masseter muscle do?
Responsible for mastication
The masseter is one of the main muscles used for chewing.
What is the action of the sternocleidomastoid muscle?
Turns and tilts head
It also pulls the head backwards.
What is the role of the trapezius muscle?
Elevates and retracts shoulders
It is involved in movements of the shoulder girdle.
What does the supraspinatus muscle do?
Initial abduction of shoulder
It is one of the rotator cuff muscles.
What is the function of the pectoralis major muscle?
Draws arms forward
It also facilitates shoulder flexion and medial rotation.
What is the action of the rectus abdominis muscle?
Bending forward (crunches)
It is involved in vertebral flexion.
What does the diaphragm muscle do?
Increases space for air in lungs
It contracts and descends into the abdominal cavity.
What is the function of the deltoid muscle?
Flexion, abduction, and extension of shoulder joint
It is a key muscle for shoulder movements.
What does the gastrocnemius muscle do?
Flexes leg at the knee
It also contributes to plantar flexion of the foot.
What is the role of tendons in muscle mechanics?
Attach skeletal muscles to bones
Tendons enable movement by spanning across joints.
What are the four types of muscle roles?
- Prime movers
- Antagonists
- Synergists
- Fixators
These roles define how muscles work together during movement.
What is unique about cardiac muscle?
Striated and involuntary
Cardiac muscle forms the myocardium and has intercalated discs.
How does cardiac muscle maintain its rhythm?
Autorhythmic
Cardiac muscle generates its own contraction rhythm.
What is the main function of smooth muscle?
Changes diameter and shape of tissues
Smooth muscle is found in hollow organs and is involuntary.
What is muscle regeneration?
Ability of muscles to repair and grow
Different muscle types have varying capacities for regeneration.
What happens to skeletal muscle cells when damaged?
Limited regeneration by satellite cells
Satellite cells divide slowly and fuse with existing fibers.
What is muscle fatigue?
Depletion of metabolic reserve
It often results from overuse and can produce lactic acid.
What is the impact of chronic muscle contracture?
Causes muscle fatigue and strain
Prolonged contraction can lead to discomfort and joint strain.
What happens to actin-myosin filaments during continuous muscle contraction?
They remain attached
Chronic muscle contracture causes muscle fatigue and strain on skeletal muscle attachments.
What is a muscle strain?
Over-stretching of muscle fibrils or the tendon
Occurs when a joint is forced beyond its normal range.
What characterizes a muscle tear?
The muscle tears and is no longer whole
More likely to cause bruising and prevents natural complete healing.
What is the RICE method in muscle treatment?
Rest, Ice, Compression, Elevation
Commonly used for muscle strains and tears.
What is impingement syndrome?
A shoulder condition where movements are painful and limited
Involves inflammation/damage of rotator cuff tendons and/or bursa.
What are common causes of impingement syndrome?
- Overuse with arms raised overhead
- Age-related degeneration
- Positional fault of the humerus
- Bone spurs
- Oddly-sized acromion
What are signs and symptoms of impingement syndrome?
- Shoulder ache
- Pain during abduction or rotation
- Painful arc of movement
- Catching sensation on lowering the arm
- Weakness in raising the arm
What is fibromyalgia?
A chronic pain disorder associated with widespread musculoskeletal pain and fatigue
Often accompanied by anxiety, depression, and functional impairment.
What characterizes pain processing in fibromyalgia?
Central sensitisation leading to altered pain processing
High levels of substance P and excess nitric oxide production amplify pain signals.
What are potential causes and triggers of fibromyalgia?
- Poor mitochondrial functioning
- Altered stress response
- Post-viral and chronic toxic load
- Poor gut health
- Serotonin and noradrenaline deficiencies
- Sleep dysregulation
What are common signs and symptoms of fibromyalgia?
- Widespread musculoskeletal pain
- Pain from gentle pressure
- Feeling of swollen joints
- Debilitating fatigue
- Disturbed sleep
- Headaches
- Anxiety and depression
What is the diagnosis criterion for fibromyalgia?
Excess pain on palpation in at least 11 of 18 predefined anatomical points
Normal biopsy and electrical muscle tests.
What are muscular dystrophies?
Inherited muscular diseases causing muscle degeneration and weakness
Characterized by progressive skeletal muscle atrophy and death of muscle cells.
What is myasthenia gravis?
An autoimmune disease of the neuromuscular junction leading to muscle fatigue and weakness
Antibodies block acetylcholine receptors, preventing nerve impulses.
What are common symptoms of myasthenia gravis?
- Weakness of ocular muscles
- Drooping eyelid (ptosis)
- Weakness in facial muscles
- Difficulty with speech, chewing, swallowing
- Symptoms worsen throughout the day
What causes Duchenne muscular dystrophy?
A single gene defect on the X chromosome affecting males
Associated with a lack of dystrophin protein in muscle cells.
What are common symptoms of Duchenne muscular dystrophy?
- Delayed walking
- Difficulty getting up
- Clumsiness
- Waddling gait
- Speech delay
- Gowers’ sign
What is a unique feature of cardiac muscle?
Involuntary contraction
Cardiac muscle is striated and only found in the heart.
What is the function of the hamstrings?
Flexion of the knee
Also assists in hip extension.
What is the function of the tibialis anterior?
Dorsiflexion of the foot
Also supports the arch of the foot.
What is the function of the biceps brachii?
Flexion of the elbow and supination of the forearm
Important for lifting and pulling movements.
What is the function of the masseter?
Elevation of the mandible
Major muscle involved in chewing.
Where is oxygen stored in a muscle fibre?
In myoglobin
Myoglobin binds oxygen for use during muscular activity.
Where is calcium stored in a muscle fibre?
In the sarcoplasmic reticulum
Calcium release triggers muscle contraction.
