Unit 3 Muscle Physiology Flashcards
Sarcoplasmic Reticulum
ER of the Muscle Cells
Sarcoplasm
Cytoplasm of Muscle Cells
Sarcolemma
Plasma Membrane of Muscle Cells
Thick Filaments are made of
Myosin (200-500 Molecules)
Thin Filaments are made of
Two intertwined strands of Actin
What covers the Actin filaments?
Tropomyosin
Elastic Filaments
Titin
What is the function of Titin?
Anchor each thick filament to the Z Disk
Prevent overstretching of the Sarcomere
What are the contractile Proteins in a Muscle fiber?
Myosin and Actin
What are the regulatory proteins in Muscle Fibers?
Tropomyosin and Troponin
What is the switch that starts and stops the shortening of Muscle fibers?
Troponin and Tropomyosin
True or False: In order for muscle contraction to occur, Thin and Thick filaments must overlap
True
How do muscle cells shorten?
Because their individual sarcomeres shorten
Pulling Z discs closer together
Pulls on Sarcolemma
What is a motor Unit?
A Motor Neuron and the muscle fibers it innervates
Neuromuscular Junction
Functional connection between nerve fiver and muscle cells
What are the components of a Neuromuscular Junction?
Synaptic Knob filled with Ach
Junctional Folds (Increase Surface Area)
Synaptic Cleft
Basal Lamina
Pesticides are what type of Neuromuscular Toxin?
Cholinesterase Inhibitor
What type of Neuromuscular Toxin is Tetanus?
Spastic Paralysis caused by toxin of Clostridium bacteria
What is the function of Curare?
Faccid Paralysis (Limp Muscles) inhibits Ach and can cause Respiratory arrest
What four actions are involved in Muscle Relaxation and Contraction?
Excitation
Excitation-Contraction Coupling
Contraction
Relaxation
Contraction
Power Stroke
Power Stroke
Myosin head releases ADP and Phosphate as it flexes pulling the thin filament past the thick filament.
When ATP binds again, myosin extends to attach to new active site
How is slippage prevented in the Power Stroke?
Half of the heads are bound to a thin filament at one time
True or False: Thin and Thick filaments get shorter as contraction occurs?
False: they do not get shorter, they just slide past each other (Sliding Filament Theory)
What occurs during Muscle Relaxation
Nerve stimulation ceases and Acetylcholinesterase removes Ach from receptors. Stimulation of the muscle cell ceases
What is the role of Acetylcholinesterase?
Removes Ach from receptors
True or False: ATP is not needed for Muscle Relaxation:
False: ATP is required for contraction AND Relaxation
True or False: ATP is not needed for Muscle Relaxation:
False: ATP is required for contraction AND Relaxation
Reabsorption of Calcium Ions by the Sarcoplasmic reticulum
Relaxation
The Loss of Calcium from the Sarcoplasm moves the Troponin-Tropomyosin Complex over the active sites results in what?
Stops the production or maintenance of Tension
In relaxation, the muscle fiber returns to its original resting length. Why?
Recoil of series-elastic components and contraction of antagonistic muscles
Rigor Mortis
Stiffening of the body beginning 3-4 hours after death
Length-Tension Relationship
Overly contracted muscles
Too Stretched Muscles
Optimum Resting length
Overly contracted muscles result in
Weak Contraction
Too stretched muscles result in
Weak Contraction
Optimum resting length in muscle contraction results in
Greatest force produced
In the Latent period of a Twitch contraction, How long is the delay?
2 Milliseconds
What are the Phases of a Twitch contraction?
Latent Period
Contraction Phase
Relaxation Phase
Recruitment and Stimulus Intensity
Stimulating the whole nerve with higher and higher voltage produces stronger contractions
What happens during recruitment?
More Motor Units are being
What happens during recruitment?
More Motor Units are being recruited
When multiple motor units are being recruited?
Multiple Motor Unit Summation
Example of Multiple Motor Unit summation
Lift a glass of milk vs. Whole Gallon
Incomplete Tetanus
Shaking muscles when being used (20-40 Stimuli/sec) Generates gradually more strength of Contraction
Complete Tetanus
When the muscle is completely being used with no strength left to give. (40-50 Stimuli/sec)
Complete Tetanus
When the muscle is completely being used with no strength left to give. (40-50 Stimuli/sec)
Isometric Muscle Contraction
Muscle develops tension but does not shorten (No Movement)
Concentric Isotonic Muscle Contraction
Muscle Shortens, Tension remains constant**Movement)
Eccentric Isotonic Muscle Contraction
Muscle Lengthens while maintaining tension with Movement
What is the difference between Isotonic and Isometric Muscle contraction?
Isometric involves no movement
Isotonic involves movement
All Muscle contraction depends on
ATP
What are the two pathways of ATP Synthesis?
Anaerobic Fermentation
Aerobic Respiration
Anaerobic Fermentation
ATP Production is limited because without oxygen, the muscles produce Lactic Acid
Aerobic Respiration
More ATP is produced because it requires continuous O2 Supply and produces H2O and CO2
In short, intense exercise, how is oxygen supplied?
By Myoglobin
Phosphagen System
Results in enough power for 1 Minute brisk walk or 6 seconds of sprinting
Phosphagen System
Results in enough power for 1 Minute brisk walk or 6 seconds of sprinting
With Short-term energy needs, what occurs?
Glycogen-Lactic Acid system takes over
How long does the Glycogen-Lactic Acid system work?
Produces ATP for 30-40 seconds of maximum activity
How long does the Glycogen-Lactic Acid system work?
Produces ATP for 30-40 seconds of maximum activity
For Long-Term energy needs, what is required?
Aerobic Respiration
After 40 seconds of exercise, what is needed?
Respiratory and cardiovascular systems must deliver enough oxygen for aerobic respiration
How are long-term energy limits set in muscles?
Depletion of glycogen and blood glucose, loss of fluid and electrolytes
Fatigue
Progressive weakness from use
You are presented with the following states. What is the result:
-ATP synthesis declines as glycogen is consumed
-sodium-potassium pumps fail to maintain membrane potential and excitability
-lactic acid inhibits enzyme function
accumulation of extracellular K+ hyperpolarizes the cell
-motor nerve fibers use up their acetylcholine
Fatigue
Oxygen Debt
Heavy Breathing after strenuous exercise
Excess Postexercise Oxygen Consumption (EPOC)
Slow Oxidative, Slow twitch fibers
More Mitochondria, Myoglobin, and capillaries
Adapted for aerobic respiration and resistant to fatigue
Soleus and postural Muscles of the back
Fast Glycolytic, Fast Twitch fibers
Rich in enzymes for phosphagen and glycogen-lactic acid systems
-Sarcoplasmic Reticulum releases calcium quickly so contractions are quicker
what type of fibers are in white meat of chicken?
Slow-Twitch
What type of fibers are in dark meat of chicken?
Fast-Twitch
At what rate does the Sarcoplasmic reticulum release calcium in Fast-Twitch fibers?
7.5 milliseconds/twitch
Examples (Muscles) of Fast-Twitch Fibers
Extraocular eye muscles, gastrocnemius, and Biceps Brachii
