1. Muscular System (Review) Flashcards
What are the primary functions of the muscular system?
What are the 5 things muscular system produces?
Primary function- transform chemical energy into mechanical energy
This produces:
Equilibrium- posture (tension generation under isometric contraction)
Force- changes in velocity of muscle shortening (F=ma)
Work- displacement in the direction of force (W=Fs)
Transport- circulation & digestion
Heat production- maintain bod temp
What are the 3 types of muscle tissue?
Nuclei, twitching, purpose, voluntary or involuntary
Skeletal muscle- multinucleated, fastest muscle twitch
Attached to bone by tendon, made for locomotion and balance (posture)
Voluntarily controlled and involuntary
Lacks pace making capability
Cardiac muscle- uninucleated
Attached to blood vessels, used for blood circulation with adequate volume and pressure
Involuntary
Smooth muscle- uninucleated, slowest muscle twitch
Attached to wall of organs and blood vessels
Used for blood pressure control, digestion, bladder control, air flow
Involuntary
Slide 4-8 Sept 5
What regulates the action for smooth and cardiac muscle?
What regulates action for skeletal muscle
Cardiac/smooth
Involuntarily by Autonomic nervous system and endocrine system
Skeletal
Mainly voluntarily by somatic nervous system
Can also be subconscious (posture, diaphragm contract/relax)
What are the 5 special properties of muscle are tissue?
- Excitability- ability to respond to stimuli by producing action potentials (cardiac/smooth have electrical stimulus, skeletal has chemical)
- Contractibility- ability of muscular tissues to contract forcefully when stimulated by action potentials (greater change in velocity of muscle fibre shortening, greater force of contraction)
- Extensibility- ability of muscular tissues to stretch without being damaged (connective tissues keep stretch in range of physiological contractile range of muscle cells)
- Elasticity- ability of muscular tissues to return to its original length and shape after contraction or extension
- Adaptability- muscular tissues have ability to undergo hypertrophy or atrophy
Slides 12-16 Sept 5
What are the 4 properties of the skeletal muscle?
Force of contraction
Contraction speed
Endurance
Oxidative/glycolytic capacity (related to energy production to sustain muscle)
What are the 2 phenotypes of muscle fibers in skeletal muscle?
Slow-twitch oxidative fibers (type I)- rate ATP break is slower than that of other types of muscle fibers (require good supply of oxygen)
Fast-twitch oxidative/glycolytic fibers (type II) Type II divides into two smaller groups: Type IIa (fast-twitch oxidative fibers) Type IIb/IIx (fast-twitch glycolytic fibers)
Type IIb express myosin heavy chain (MyHC) gene which is homologous to that of typeIIx gene in rodents
Slide 21 table sept 5
What is a motor unit?
All the muscle fibers being innervated by a single motor neuron
Muscle fibers belonging to one motor unit are all of the same MyHC type (muscle type)
How is the type II muscle fibers differentiated?
Type IIa- ATP break is quicker than type I (velocity of shortening is quicker)
Require good supply of O2 (aerobic respiration)
Fatigue resistant but less endurance compared to slow-twitch
Creating phosphate is reservoir for ATP storage
Type IIb- ATP break is much quicker than the rest of muscle fibers (velocity much faster)
Anaerobic respiration
Easily fatigable and low in endurance
Slides 22-29 Sept 5
What are the 4 main events in excitation-contraction coupling?
- Ach is released from the somatic motor neuron
- Ach initiates an action potential in the muscle fiber
- Action potential travels along the sarcolemma into the T-tubules and triggers Ca2+ release from the sarcoplasmic reticulum (SR)
- Ca2+ binds with TnC and initiates muscle contraction
Slides 32-40 Sept 5
How do you end a contraction?
Ca2+ must be removed from the cytosol back to SR through sarco-endoplasmic reticulum ATPase (SERCA)
