Chapter 10 - Muscle Tissue Flashcards

Question

What is a Structural Protein?

Answer 1

Protein that keep Thick and Thin Filaments of Myofibrils in proper alignment Give Myofibrils elasticity and extensibility Link Myofibrils to Sarcolemma and Extracellular Matrix (Titin, Alpha-Actinin, Myomesin, Nebulin, and Dystrophin)

Answer 2

Structural protein that connects Z Disc to M Line of Sarcomere, thereby helping to stabilize Thick Filament position Can stretch and then spring back unharmed Accounts for much of the elasticity and extensibility of Myofibrils

Answer 3

Structural protein of Z Discs that attaches to Actin molecules of Thin Filaments and to Titin molecules

Answer 4

Structural protein that forms M Line of Sarcomere Binds to Titin molecules Connects adjacent Thick Filaments to one another

Answer 5

Structural protein that wraps around entire length of each Thin Filament Helps anchor Thin Filaments to Z Discs Helps regulate length of Thin Filaments during development

Answer 6

Structural protein that links Thin Filaments of Sarcomere to integral membrane proteins in Sarcolemma, which are in turn attached to proteins in connective tissue matrix that surrounds muscle fibers Thought to help reinforce Sarcolemma and help transmit tension generated by Sarcomeres to Tendons

Answer 7

Organ made up of Fascicles that contain Muscle Fibers (Cells), blood vessels, and nerves Wrapped in Epimysium

Answer 8

Bundle of Muscle Fibers wrapped in Perimysium

Answer 9

Long cylindrical cell covered by Endomysium and Sarcolemma Contains: Sarcoplasm Myofibrils Many peripherally located Nuclei Mitochondria Transverse Tubules Sarcoplasmic Reticulum Terminal Cisternae The Fiber has a striated appearance

Answer 10

Threadlike contractile elements within Sarcoplasm of muscle that extend the entire length of the fiber Composed of Filaments

Answer 11

Contractile proteins within Myofibrils that are of 2 types Thick Filament composed of Myosin Thin Filament composed of Actin, Tropomyosin, and Troponin Sliding of Thin Filaments past Thick Filaments produces muscle shortening

Answer 12

Myosin pulls on Actin Causing Thin Filament to slide inwards Consequently, Z Discs move toward each other and Sarcomere shortens Thanks to structural proteins, there is a transmission of force throughout the entire muscle, resulting in whole muscle contraction

Answer 13

Relaxed Muscle: Normal Sarcomere Partially Contracted Muscle: H Zone shorter I Band shorter Maximally Contracted Muscle: No H Zone visible No I Band visible

Answer 14

1- Myosin head hydrolyzes ATP and becomes energized and oriented 2- Myosin head binds to Actin, forming a cross-bridge (Phosphate group leaves) 3- Myosin head pivots, pulling the Thin Filament past the Thick Filament towards the center of the Sarcomere (power stroke) (ADP leaves, ATP comes in) 4- As Myosin head binds ATP, the cross-bridge detaches from Actin

Answer 15

Concept that connects the events of a muscle action potential with the sliding filament mechanism At Relaxation: Voltage-gated Ca2+ channels closed, Ca2+ remains inside Terminal Cisternae of Sarcoplasmic Reticulum Troponin holds Tropomyosin in position to block Myosin-Binding Sites on Actin At Contraction: Voltage-gated Ca2+ channels open, releasing Ca2+ from Terminal Cisternae of Sarcoplasmic Reticulum into the Sarcoplasm Ca2+ binds to Troponin, which in turn undergoes a conformational change that moves Tropomyosin away from the Myosin-Binding Sites on Actin Therefore, Myosin heads bind to Actin and pull it, resulting in contractions

Answer 16

The force of a muscle contraction depends on the length of the Sarcomeres in a muscle prior to contraction

Answer 17

The events at the NMJ produce a muscle action potential Voltage-gated Ca2+ channels in a Neuron's Synaptic End Bulb open Resulting in an influx of Ca2+ This causes exocytosis of a Neurotransmitter (Acetylcholine - ACh) into the Synaptic Cleft NT binds to Ligand-gated Na+ channels on the Motor Endplate Causes an influx of Na+ into the muscle This depolarizes the muscle and results in Ca2+ release from Sarcoplasmic Reticulum NT gets broken down by Acetylcholinesterase, or back to neuron by cellular reuptake, or diffuse back

Answer 18

1- A nerve action potential in a Somatic Motor Neuron triggers the release of Acetylcholine (ACh) 2- ACh binds to receptors in the Motor End Plate, ultimately triggering a muscle action potential 3- Acetylcholinesterase destroys ACh so another muscle action potential does not arise unless more ACh is released from the Somatic Motor Neuron 4- A muscle action potential traveling along a Transverse Tubule triggers a change in the Voltage-gated Ca2+ channels that causes the Ca2+ release channels to open, allowing the release of Ca2+ into the Sarcoplasm 5- Ca2+ binds to Troponin on the Thin Filament, exposing the Myosin-Binding Sites on Actin 6- Contraction: Myosin heads bind to Actin, undergo power strokes, and release Thin Filaments are pulled towards center of Sarcomere 7- Ca2+ release channels close and Ca2+-ATPase Pumps use ATP to restore low level of Ca2+ in the Sarcoplasm 8- Tropomyosin slides back into position where it blocks the Myosin-Binding Sites on Actin 9- Muscle relaxes

Answer 19

Muscles derive the ATP necessary to power the contraction cycle from: Creatine Phosphate Anaerobic Glycolysis Cellular Respiration

Answer 20

Creatine Kinase catalyzes the transfer of a phosphate group from Creatine Phosphate to ADP to rapidly yield ATP Duration of energy: 15 seconds

Answer 21

When Creatine Phosphate stores are depleted, glucose is converted into Pyruvic Acid to generate ATP Lactic Acid goes into blood Duration of energy: 2 minutes

Answer 22

Under aerobic conditions, Pyruvic Acid can enter the Mitochondria and undergo a series of oxygen-requiring reactions to generate large amounts of ATP Amino Acids from protein breakdown, Fatty Acids liberated from adipose cells, Pyruvic Acid from Glycolysis, and oxygen from hemoglobin in blood or from Myoglobin in muscle fibers go into Krebs Cycle and Electron Transport Chain in Mitochondrion Make 30-32 ATP (and heat, CO2, and H2O) Duration of energy: Several minutes to hours

Answer 23

Muscle fatigue is the inability to maintain force of contraction after prolonged activity Due to: Inadequate release of Ca2+ from Sarcoplasmic Reticulum Depletion of Creatine Phosphate, oxygen, and nutrients Build up of Lactic Acid and ADP Insufficient release of ACh at NMJ

Answer 24

Central Fatigue occurs due to changes in the CNS and generally results in cessation of exercise

Answer 25

Breath heavily after exercise to get extra oxygen Extra oxygen goes toward: 1- Replenishing Creatine Phosphate 2- Converting Lactate into Pyruvate (since Lactic Acid was accumulated, Pyruvate goes to Krebs Cycle in Mitochondria to make ATP) 3- Reloading oxygen onto Myoglobin

Answer 26

The strength of a muscle contraction depends on how many Motor Units are activated A motor Unit consists of a Somatic Motor Neuron and the Muscle Fibers it innervates Activating only a few Motor Units will generally result in a weak muscle contraction Activating many Motor Units will generally result in a strong muscle contraction

Answer 27

Motor Unit Recruitment is the process in which the number of active Motor Units increases Weakest Motor Units are recruited first, followed by stronger Motor Units Motor Units contract alternately to sustain contractions for longer periods of time

Answer 28

Twitch Contraction is the brief contraction of all muscle fibers in a Motor Unit in response to a single action potential 1- Latent Period 2- Contraction Period 3- Relaxation Period 4- Refractory Period

Answer 29

Wave summation occurs when the 2nd action potential triggers muscle contraction before the 1st contraction has finished Results in a stronger contraction Unfused Tetanus: Back to back wave contractions, strong Fused Tetanus: All waves summed together for one strong contraction

Answer 30

Even when at rest, a skeletal muscle exhibits a small amount of tension called Tone (resistance to movement) Tone is established by the alternating, involuntary activation of small groups of Motor Units in a muscle

Answer 31

Isotonic Contraction: Tension is constant while muscle length changes (Movement happening) 1- Concentric: While picking up object 2- Eccentric: While lowering object

Answer 32

Isometric Contraction: Muscle contracts but does not change length (No movement happening) ex- holding an object steady

Answer 33

1- Slow Oxidative Fiber 2- Fast Glycolytic Fiber 3- Fast Oxidative-Glycolytic Fiber

Answer 34

Myoglobin Content: Large amount Mitochondria: Many Capillaries: Many Color: Red Method and capacity for generating ATP: Aerobic Respiration High Rate of ATP hydrolysis by Myosin ATPase: Slow Contraction Velocity: Slow Fatigue Resistance: High Creatine Kinase: Lowest amount Glycogen Stores: Low Order of Recruitment: First Location where fibers are abundant: Postural muscles such as neck Primary Functions of fiber: Maintain posture and aerobic endurance activities

Answer 35

Myoglobin Content: Large amount Mitochondria: Many Capillaries: Many Color: Red-pink Method and capacity for generating ATP: Aerobic Respiration and Anaerobic Glycolysis Rate of ATP hydrolysis by Myosin ATPase: Fast Contraction Velocity: Fast Fatigue Resistance: Intermediate Creatine Kinase: Intermediate amount Glycogen Stores: Intermediate Order of Recruitment: Second Location where fibers are abundant: Lower limb muscles Primary Functions of fiber: Walking, sprinting

Answer 36

Myoglobin Content: Small amount Mitochondria: Few Capillaries: Few Color: White (pale) Method and capacity for generating ATP: Anaerobic Glycolysis Low Rate of ATP hydrolysis by Myosin ATPase: Fast Contraction Velocity: Fast Fatigue Resistance: Low Creatine Kinase: Highest amount Glycogen Stores: High Order of Recruitment: Third Location where fibers are abundant: Extraocular muscles Primary Functions of fiber: Rapid, intense movements of short duration

Answer 37

Cardiac Muscle has the same arrangements as skeletal muscle, but also has Intercalated Discs Involuntary muscle Nucleus Striated Intercalated Discs Intercalated Discs: Contain Desmosomes and Gap Junctions that allow muscle action potentials to spread from one muscle fiber to another Cardiac muscle cells have more mitochondria and their contractions last 10 to 15 times longer than skeletal muscle contractions

Answer 38

Smooth Muscle looks quite different than Cardiac and Skeletal muscle It is thick in the middle, tapered on the ends, and not striated Single-unit (Visceral) or Multi-unit fibers Contractions start more slowly and last longer Can shorten and stretch to a greater extent Smooth Muscle fibers shorten in response to stretch Has Dense Bodies connected by Intermediate Filaments

Answer 39

Microscopic appearance and features: Long cylindrical fiber with many peripherally located nuclei Unbranched Striated Location: Most commonly attached by tendons to bones Fiber diameter: Very large Connective tissue components: Endomysium Perimysium Epimysium Fiber length: Very large Contractile proteins organized into sarcomeres: Yes Sarcoplasmic Reticulum: Abundant Transverse Tubules: Yes Aligned with each A Band junction Junctions between fibers: None Autorhythmicity: No Source of Ca2+ for contraction: Sarcoplasmic Reticulum Regulator proteins for contractions: Troponin Tropomyosin Speed of contraction: Fast Nervous control: Voluntary (Somatic Nervous System) Contraction regulation: ACh released by somatic motor neurons Capacity for regeneration: Limited via Satellite cells

Answer 40

Microscopic appearance and features: Branched cylindrical fiber One central nucleus Intercalated Discs join neighboring fibers Striated Location: Heart Fiber diameter: Large Connective tissue components: Endomysium Perimysium Fiber length: Large Contractile proteins organized into sarcomeres: Yes Sarcoplasmic Reticulum: Some Transverse Tubules: Yes Aligned with each Z Disc Junctions between fibers: Intercalated Discs contain Gap junctions and Desmosomes Autorhythmicity: Yes Source of Ca2+ for contraction: Sarcoplasmic Reticulum Interstitial Fluid Regulator proteins for contractions: Troponin Tropomyosin Speed of contraction: Moderate Nervous control: Involuntary (Autonomic Nervous System) Contraction regulation: ACh and Norepinephrine released by Autonomic Motor Neurons Several hormones Capacity for regeneration: Limited under certain conditions

Answer 41

Microscopic appearance and features: Fiber thick in middle Fiber tapered at each end One central Nucleus No striations Location: Walls of hollow viscera Airways (Trachea, Bronchi) Blood vessels Iris and Ciliary Body of Eye Arrector Pili Muscles of hair follicles Fiber diameter: Small Connective tissue components: Endomysium Fiber length: Intermediate Contractile proteins organized into sarcomeres: No Sarcoplasmic Reticulum: Very little Transverse Tubules: No Junctions between fibers: Gap junctions in Visceral Smooth Muscle None in Multi-unit Smooth Muscle Autorhythmicity: Yes In Visceral smooth muscle Source of Ca2+ for contraction: Sarcoplasmic reticulum Interstitial Fluid Regulator proteins for contractions: Calmodulin Myosin Light Chain Kinase Speed of contraction: Slow Nervous control: Involuntary (Autonomic Nervous System) Contraction regulation: ACh and Norepinephrine released by Autonomic Motor Neurons Several Hormones Local chemical changes Stretching Capacity for regeneration: Considerable (compared to other muscle, limited compared to epithelium) Via Pericytes

Answer 42

Mature skeletal muscle fibers cannot undergo mitosis Hypertrophy: Increase in size Hyperplasia: Increased number of cells, over formation Pericytes help contractions of smooth muscles

Answer 43

Most muscles are derived from the Mesoderm which develops into Somites: Myotome Dermatome Sclerotome

Answer 44

Age 30-50: About 10% of muscle tissue replaced by Fibrous Connective Tissue and Adipose tissue Age 50-80: Another 40% of muscle tissue is replaced Results: Muscle strength and flexibility decreases Reflexes slow Slow Oxidative Fibers numbers increase

Answer 45

External to Epimysium Separates different muscles while binding them together

Answer 46

Superficial to Deep Fascia Separates Muscles from skin

Chapter 10 - Muscle Tissue Flashcards

(70 cards)