Unit 4: Muscular System Pt. 2 Flashcards
What causes rigor mortis?
After death, calcium diffuses everywhere and triggers contractions, forming cross-bridges which run out of ATP to break resulting in frozen muscles
Why does rigor mortis wear off?
Muscle proteins begin to break down (myosin, actin)
The amount of ______ generated depends on the _____ of the muscle
Tension
Length
Overly contracted muscles are when
Thick filaments are too close to the Z discs, causing a weak result
Overly stretched muscles are when
There is too little overlap, meaning cross-bridges cannot form and there is a weak result
The greatest force of contraction happens
At optimum resting length
What is a muscle twitch
brief stimulus at the threshold voltage produces 1 quick contraction and relaxation
What are the phases of a muscle twitch
Latent
Contraction
Relaxation
Define MMU and how it affects intensity/strength
Multiple Motor Unit Summation
More motor units = more fibers contract = more intensity
Define Wave Summation and how it affects intensity/strength
Muscles are rapidly stimulated without time to relax in between
Calcium builds up in sarcoplasm
Define isometric muscle contraction
Length of muscle stays the same while tension develops
Define isotonic muscle contraction
Tension on muscle stays the same without length change
What are the 2 types of ATP sources
Anaerobic fermentation
Aerobic respiration
Which ATP source creates more ATP?
Aerobic
Anaerobic fermentation requires _______ and produces ______
No oxygen
Lactic acid
Aerobic respiration requires ______ and produces ______
Continuous oxygen
H2O and CO2
Where does the first immediate energy come from?
Phosphagen System
What is the phosphagen system?
ATP is formed by transferring phosphate from another molecule (ADP or creatine phosphate) to ADP
What takes over creating ATP after the phosphagen system?
Anaerobic fermentation produces ATP from glycogen-lactic acid system and glucose from blood
What energy system is used for long-term energy?
Aerobic respiration
What allows aerobic respiration to take place?
Increased cardiovascular and respiratory activity drawing in more O2
What limits aerobic respiration?
Loss of electrolytes and fluids
Loss of glycogen and blood glucose
What causes muscle fatigue?
Less oxygen means more inefficient anaerobic respiration
Less ATP available as glycogen depletes
Less electricity as Na-K pumps shut down
Loss of electrolytes (like calcium)
Define oxygen debt
The need to breathe heavily to replace O2 reserves and glucose after exercise
The speed of a contraction depends on
How fast myosin ATPase can split ATP and the electrical activity of neurons
What are the 3 types of skeletal muscle fibers
Slow oxidative
Fast oxidative
Fast glycolytic
Describe slow oxidative tissue (color, ATP source, speed)
More red myoglobin
Aerobic respiration (Stored O2)
Best for endurance, fatigue-resistant
Describe fast oxidative tissue (color, ATP source, speed)
Red myoglobin, less dark
Mostly aerobic, some anaerobic
Faster energy but less fatigue-resistant
Describe fast glycolytic tissue (color, ATP source, speed)
White color with no myoglobin
Anaerobic respiration
Best for short, intense movement but fatigues fast
Describe Myasthenia Gravis, its risk groups, and symptoms
Autoimmune disorder which causes antibodies to block ACh receptors, which blocks communication with muscle cells
Thymus tumor, younger women, older men
Trouble moving face and eye muscles
Muscles weaken with activity and strengthen with rest
Describe Duchenne Muscular Dystrophy, its risk groups, and symptoms
X-linked disorder which affects gene that makes protein dystrophin so muscle fibers cannot anchor
Genetic, mostly passed from mother to son
Fatigue, learning disabilities, rapidly weakening muscles
Describe Botulinim Toxin
Toxic bacteria from contaminated food which prevents the release of ACh, resulting in paralysis
