Chapter 11 Study Topics- Muscle Tissue Flashcards
Question's #4, #13,#19 & #24 I couldn't get on here
List and define the 5 universal characteristics of muscles.
1.Excitability (responsiveness)—to chemical signals, stretch, and electrical changes across the plasma membrane
2.Conductivity—local electrical excitation sets off a wave of excitation that travels along the muscle fiber
3.Contractility—shortens when stimulated
4.Extensibility—capable of being stretched between contractions
5. Elasticity—returns to its original rest length after being stretched
Define the following: endomysium, perimysium, epimysium
endomysium—surrounds each muscle fibers
perimysium— bundles muscle fibers into fascicles
epimysium— surrounds entire muscle
Match the components of a muscle fiber (cell) to their function: sarcolemma, sarcoplasm, myofibril, glycogen, myoglobin, SR, T tubules, myoblasts
Sarcolemma—plasma membrane of a muscle fiber
Sarcoplasm—cytoplasm of a muscle fiber
Sarcoplasmic reticulum (SR)-smooth ER that forms a network around each myofibril
Transverse (T) tubules—tubular infoldings of the sarcolemma which penetrate through the cell and emerge on the other side
Myoblasts—stem cells that fused to form each muscle fiber early in development, each contributing one nucleus
List the 3 myofilaments. What proteins are associated with each? Which proteins are contractile proteins, and which are regulatory proteins? Which regulatory protein binds to calcium?
1 Thick filaments—made of several hundred myosin molecules (myosin is a motor protein)
#2 Thin filaments—composed of three different protein types
Fibrous (F) actin—two intertwined strands of globular (G) actin subunits, each with an active site that can bind to head of myosin molecule
Tropomyosin—each blocks six or seven active sites on G actin subunits
Troponin—small, calcium-binding protein on each tropomyosin molecule
#3 Elastic filaments—made of a huge, springy protein called titin
Define a motor unit. Compare small motor units to large motor units
Motor unit—one nerve fiber and all the muscle fibers innervated by it
Small motor units provide a fine degree of control
Large motor units provides more strength that control
Describe the structure of a neuromuscular junction. What is acetylcholine?
points where a nerve fiber meets its target cell. contains synaptic vesicles with neurotransmitter
Describe the ICF and ECF environment of a cell at rest.
polarized—contains a net negative charge compared to the outside of the cell
Compare depolarization to repolarization. Describe the ion movements that occur during each.
depolarization- becoming positive
repolarization- becoming negative inside
Define “action potential”.
up-and-down voltage shift
How do toxins affect muscles? Compare spastic paralysis to flaccid paralysis.
interfering with synaptic function can paralyze muscles Some pesticides contain cholinesterase inhibitors
Spastic paralysis—a state of continual contraction of the muscles; possible suffocation
Flaccid paralysis—a state in which the muscles are limp and cannot contract
List the 4 major phases of contraction and relaxation and describe the 18 steps that occur.
1. Excitation
#1 Arrical of nerve signal #2 Acetylcholine (ACh) release #3 Binding of ACh to receptor #4 Opening of ligand- regulated ions #5 Open of voltage- regulated ion gate #2. Excitation #6 Action potentials propagated down T tubles #7 Calsium released from terminal cisterns #8 Binding of calcium to troponin #9 Shifting of tropomysin #3. Contraction #10 Activation and cooking of myosin heads(recovery) stroke #11 Formation of myosin- actin cross bridge #12 Power stroke #13 Binding of new ATP #4. Relaxation #14 Cessation of nervous stimulation and ACh released #15 ACh breakdown by Aectylcholinesterase #16 Reabsorption of calcium ions by sarcoplasmic #17 Loss of calcium ions troponin #18 Return of tropomyosin to position blocking active sites of actin
What happens to the H zones during contraction?
shorten and disappear
How do muscles ensure that they can produce the greatest force when contracting?
There will be insufficient overlap of the myofilaments and less force will be produced
Define rigor mortis. Release of which ion causes contraction?
hardening of muscles and stiffening of body beginning 3–4 hours after death.Ca2+
What are the 3 phases of a muscle twitch? What happens in each? What is the term for the minimum voltage that causes a muscle twitch?
Latent period—delay just after stimulation of muscle
Contraction phase—external tension is generated and a load is moved as the muscle fiber shortens
Relaxation phase—sarcoplasmic calcium levels fall as calcium is reabsorbed into sarcoplasmic reticulum; tension declines
What two factors affect twitch strength? How?
Muscle size— thicker forms more cross-bridge
temporal summation—greater the frequency of stimulation, the stronger the muscle contraction
What does the size principle tell us about muscle stimuli?
weak stimuli (low voltage) recruit small units, while strong stimuli recruit small and large units for powerful movements
Compare incomplete tetanus to fused tetanus
Incomplete tetanus- Only particle relaxation between stimuli resulting in fluttering
Fused Tetanus- unnaturally high stimulus frequencies cause a steady contraction
Compare isometric contraction to isotonic contraction. What are the 2 forms of isotonic contraction?
Isometric contraction—contraction without a change in length (Same)
Isotonic contraction—contraction with a change in length but no change in tension (Change)
Concentric contraction: muscle shortens as it maintains tension (example: lifting weight)
Eccentric contraction: muscle lengthens as it maintains tension (example: slowly lowering weight)
Compare anaerobic fermentation or aerobic respiration. Which one is more efficient?
Anaerobic fermentation—enables cells to produce ATP in the absence of oxygen; yields little ATP and lactate, which needs to be disposed of by the liver
Aerobic respiration—produces far more ATP; does not generate lactate; requires a continual supply of oxygen
How do muscles create/use immediate energy?
Muscles meet most ATP demand by borrowing phosphate groups (Pi) from other molecules and transferring them to ADP
How do muscles create short-term energy?
Anaerobic threshold (lactate threshold)—point at which lactate becomes detectable in the blood
Glycogen–lactate system—the pathway from glycogen to lactate
How do muscles create long-term energy?
Two enzyme systems control these phosphate transfers:
Myokinase—transfers Pi from one ADP to another, converting the latter to ATP
Creatine kinase—obtains Pi from a phosphate-storage molecule creatine phosphate (CP) and gives it to ADP
Compare the 3 types of muscle fibers. Which is fastest at contracting? Which is most fatigable? Which type is best for walking?
1. Slow oxidative fibers
Well adapted for endurance; resist fatigue by oxidative (aerobic) ATP production
Important for muscles that maintain posture (e.g., erector spinae of the back, soleus of calf)
#2. Fast glycolytic fibers
Fibers well adapted for quick responses; utilize glycolysis and anaerobic fermentation for energy
Abundant in quick and powerful muscles: eye and hand muscles, gastrocnemius of calf and biceps brachii
#3. Intermediate
walking
List 7 factors that affect muscular strength
1. Muscle size—thicker muscle forms more cross-bridges
#2 Fascicle arrangement—defines the shape and strength of a muscle
#3 Size of active motor units—the larger the motor unit, the stronger the contraction
#4 Multiple motor unit summation—simultaneous activation of more units increases tension
#5 Temporal summation—the greater the frequency of stimulation, the stronger the muscle contraction
#6 The length–tension relationship—a muscle resting at optimal length is prepared to contract more forcefully than a muscle that is excessively contracted or stretched
#7 Fatigue—fatigued muscles contract more weakly than rested muscles
Compare resistance exercise to endurance exercise
Resistance exercise—contraction of a muscle against a load that resists movement
Endurance (aerobic) exercise—contraction of a muscle against a load that resists movement
How do muscles create/use immediate energy?
Muscles meet most ATP demand by borrowing phosphate groups (Pi) from other molecules and transferring them to ADP
How do muscles create short-term energy?
Anaerobic threshold (lactate threshold)—point at which lactate becomes detectable in the blood
How do muscles create long-term energy?
Two enzyme systems control these phosphate transfers:
Myokinase—transfers Pi from one ADP to another, converting the latter to ATP
Creatine kinase—obtains Pi from a phosphate-storage molecule creatine phosphate (CP) and gives it to ADP
Compare the 3 types of muscle fibers. Which is fastest at contracting? Which is most fatigable? Which type is best for walking?
1. Slow oxidative fibers
Well adapted for endurance; resist fatigue by oxidative (aerobic) ATP production
Important for muscles that maintain posture (e.g., erector spinae of the back, soleus of calf)
#2. Fast glycolytic fibers
Fibers well adapted for quick responses; utilize glycolysis and anaerobic fermentation for energy Abundant in quick and powerful muscles: eye and hand muscles, gastrocnemius of calf and biceps brachii
#3. Intermediate
fast oxidative fibers type, is a good for sprinting and walking
List 7 factors that affect muscular strength.
1. Muscle size—thicker muscle forms more cross-bridges
#2 Fascicle arrangement—defines the shape and strength of a muscle
#3 Size of active motor units—the larger the motor unit, the stronger the contraction
#4 Multiple motor unit summation—simultaneous activation of more units increases tension
#5 Temporal summation—the greater the frequency of stimulation, the stronger the muscle contraction
#6 The length–tension relationship—a muscle resting at optimal length is prepared to contract more forcefully than a muscle that is excessively contracted or stretched
#7 Fatigue—fatigued muscles contract more weakly than rested muscles
Compare resistance exercise to endurance exercise.
Resistance exercise—contraction of a muscle against a load that resists movement
Endurance (aerobic) exercise—contraction of a muscle against a load that resists movement
Compare skeletal muscle to smooth muscle. Which is slower to contract? Which includes troponin and which includes calmodulin?
Cardiac Muscle— Contract with regular rhythm, highly resistance to fatigue, works in sleep, contracts must last long enough to expel blood, Includes troponin
Smooth muscle—Contract is slower than skeletal and cardiac, injured smooth muscle regenerates well, names for its lack of striation, capable of mitosis and hyperplasia includes calmodulin
Define peristalsis
Alternating contractions and relaxations of smooth muscle layers that mix and squeeze substances through the lumen of hollow organs
Define plasticity and why it’s a characteristic of smooth muscle.
The ability to adjust its tension to the degree of stretch fill in hallow organs
Describe MD myasthenia gravis, myofibrosis, and myosclerosis
Myasthenia gravis—autoimmune disease in which antibodies attack neuromuscular junctions and bind ACh receptors together in clusters
Fibrosis (myofibrosis)— Replacement of muscle fibers by excessive amounts of connective tissues (fibrous scar tissue)
Myosclerosis— Hardening of the muscle caused by calcification
