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Physiology Lecture Test 3
All quizzes up to and including test 3
54
Physiology
Undergraduate 1
04/15/2012

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Term
Term: Measure changes in muscle length using lever system
Definition
Isotonic contractions
Term
Term: Lag before muscle lifts load
Definition
Latent period
Term
Term: Action potential -> Latent period -> Muscle shortens varying amounts
Definition
Isotonic twitch contraction
Term
Term: When stimulus reaches muscle with load, produces isometric first as muscle struggles to lift load but no muscle shortening
Definition
Mixed contraction
Term
What happens when the amount of force = afterload?
Definition
Muscle begins to shorten and lift load (isotonic portion)
Term
How can a contraction be entirely isotonic?
Definition
Only if no load at all
Term
What happens with a heavier afterload?
Definition
Isometric portion lasts longer, and it takes longer to increase force to lift load
Term
How can a contraction be entirely isometric?
Definition
Only if afterload is more than what the muscle can lift
Term
The lighter the load, the...?
Definition
Sooner it can be lifted
Term
The heavier the load, the...?
Definition
Less the muscle can shorten
Term
Term: Rate of doing work/force times velocity
Definition
Power output
Term
What happens at the max force a muscle can obtain?
Definition
Power output = 0 because isometric muscle doesn't shorten
Term
What happens at Vmax (no load)?
Definition
Shortening most rapid but no force is exerted so power output = 0
Term
When does power output hit max?
Definition
30% of max load
Term
Muscles are surrounded by what?
Definition
Electrically excitable plasma membrane
Term
Surface membrane of muscle can be excited to do what?
Definition
Produce AP
Term
What is AP caused in muscle plasma membrane?
Definition
Time and voltage-dependent changes in membrane permeability to Na+ and K+
Term
The diffusion problem of an AP to get to the inner-workings of a muscle is solved by what?
Definition
Transverse tubular system
Term
Term: Extensions of muscle surface membrane
Definition
Transverse tubules
Term
At rest, where is calcium highly concentrated?
Definition
Sac-like areas of Sarcoplasmic Reticulum (Terminal cisternae)
Term
If a person has diabetes melitus, what is different about their urine?
Definition
They have glucose in their urine
Term
What happens to the ACh released by an AP?
Definition
Binds to receptors on motor end plate of muscle membrane, opens channels, and allows Na+ and K+ to flow, which depolarizes end plate membrane
Term
Term: Skeletal/cardiac muscle responds to one stimulus with single AP and response
Definition
Twitch
Term
What limits the amount of force developed by a twitch?
Definition
Fast calcium uptake
Term
Term: Force produced by 2nd stimulus can add to force left from first
Definition
Summation
Term
Term: Sustained contraction with much more force than twitch
Definition
Tetanus
Term
Term: Stimuli spaced relatively far apart, force rising/falling between stimuli
Definition
Partial (unfused) tetanus
Term
Term: Stimuli close, developed force steady
Definition
Complete (fused) tetanus
Term
Term: Lowest frequency to produce fused tetanus
Definition
Tetonic Fusion Frequency
Term
What is the tetonic fusion frequency?
Definition
20-40 times per second for skeletal muscle
Term
What are the most useful contractions?
Definition
Mix of twitches and partly fused tetanic contractions
Term
Which muscle is the twitch-only type?
Definition
Cardiac
Term
How can drugs be a major factor in the amount of calcium available?
Definition
Some drugs increase overall internal supply of calcium, more released from S.R. with each beat

Some are calcium blockers and can reduce the strength of contractions and epinephrine which increases the strength of contraction by permitting an accumulation of internal calcium
Term
What does the tension produced by whole muscle contraction depend on?
Definition
The amount of force developed by each fiber and the number of active fibers in muscle
Term
Muscles that produce delicate movements have...?
Definition
A small number of fibers per unit
Term
Muscles that are large and produce less delicate movements have...?
Definition
A large number of fibers per unit
Term
Strength and susceptibility to fatigue of a muscle can be changed by...?
Definition
Exercise
Term
How does long-duration/low-intensity "aerobic" exercise decrease muscle fatigue?
Definition
Increases fibers capacity for ATP production by increasing the number of mitochondria and blood vessels in muscle, resulting in greater endurance
Term
How does short-duration/high-intensity "anaerobic" exercise increase muscle fatigue?
Definition
Increases fiber diameter due to increased synthesis of actin/myosin, resulting in increased strength. Very powerful but fatigue rapidly
Term
Term: Decline in muscle force as a result of previous contractions
Definition
Muscle fatigue
Term
The onset of fatigue depends on what three issues?
Definition
Type of fiber
Intensity and duration of contractions
Level of fitness
Term
What are the two major factors in fatigue of skeletal muscle?
Definition
Conduction failure
Lactic acid buildup
Term
Term: Muscle AP fails to be conducted in T-tubules, stops calcium release from terminal cisternae
Definition
Conduction failure
Term
Term: High proton concentration alters calcium release and function of calcium-ATPase pumps of Sarcoplasmic Reticulum
Definition
Lactic acid buildup
Term
Name one type of fatigue
Definition
Central command fatigue
Term
Term: Will to win between brain and skeletal muscle
Definition
Central Command Fatigue
Term
True/False: CNS and PNS can act independently
Definition
False
Term
Skeletal muscle depends on the __ __ for control
Definition
Somatic NS
Term
True/False: Both afferent and efferent neurons control skeletal muscle
Definition
True
Term
How do sensory neurons form muscle spindles?
Definition
They connect with intrafusal muscle fibers deep inside
Term
Term: Length detectors that act as strength receptors and increase the rate of APs when intrafusal fibers stretch
Definition
Muscle spindles
Term
Term: Tension receptors; 2nd type of muscle receptor, connects to tendons and sends out information about force produced by contraction
Definition
Golgi Tendon Organs
Term
As greater force develops during contractions, ___ generates more APs
Definition
GTOs
Term
Term: Increasing motor units active in muscle
Definition
Recruitment
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