Flashcards in Chp10- Muscle Tissues Deck (171):
What is a primary tissue type?
• muscle tissue
What are the 3 divisions of a muscle tissue?
1. Skeletal muscle tissue
2. Cardiac muscle tissue
3. Smooth muscle tissue
What does skeletal muscle tissue do?
• attaches tithe skeletal system
• allows us to move
What are the 6 functions of skeletal muscle tissue?
1. Produce skeletal movement
2. Maintain posture and body position.
3. Support soft tissues
4. Guard entrances and exits
5. Maintain body temperature
6. Store nutrient reserves
What are the components of skeletal muscle?
1. Muscle tissue (connective cells/fiber)
2. Connective tissue
4. Blood vessels
What are the 3 layers of connective tissue?
What is the Epimysium?
• exterior collagen layer
What is the Epimysium connected to?
• deep fascia
What does the Epimysium do?
• separates muscle from surrounding tissues
What is the Perimysium?
• fibrous connective tissue
What is the Perimysium rich in??
• rich is collagen and elastin
What does the Perimysium surround?
• muscle fiber bundles (fascicles)
What does the Perimysium contain?
• blood vessels and nerve supply for the fascicles
What is the Endomysium?
• delicates connective tissue layer
What does the Endomysium surround?
• individual muscle cells/fiber
What does the Endomysium contain?
• capillaries and nerve fibers contacting muscle cells
• myosatellite cells (stem cells)
What is another name for myosatellite cells?
What does myosatellite cells do?
• repair damage
What happens when the Epimysium, the Perimysium and Endomysium come together??
• form connective tissue attachment
To what does the connective tissue attach to?
• bone matrix
What is the connective tissue called?
• tendon bundle
• aponeurosis sheet
What does muscles have ?
• extensive vascular systems
What does this vascular system supply to the muscle??
• carry away waste
How are the voluntary skeletal muscles controlled?
• nerves of the central nervous system
• brain and spinal chord
How do skeletal muscle cells develop?
• through the fusion of embryonic cells
How are the embryonic cells called?
How long can skeletal muscle cells be?
• 30 cm
• 12 inch
What does skeletal muscle cells contains?
• hundreds of nuclei
What is the sarcolemma?
• cell membrane of a muscle cell (fiber)
What does the sarcolemma surround?
• the sarcoplasm
What is the sarcoplasm?
• cytoplasm of a muscle cell
What begins contraction of a muscle?
• change in the transmembrane potential
What are the transverse tubules??
• narrow tubes that are continuous with the sarcolemma
What is another name for transverse tubules??
• T tubules
What do the T tubules do??
• transmit action potential through cell
• allow entire muscle to contract simultaneously
What are the properties of T tubules?
• same as sarcolemma
What ate myofibrils??
• lengthwise subdivision w/in muscle fibers
What makes up myofibrils?
• bundles of protein filaments
What are the protein filaments called??
What are myofilaments responsible for?
• muscle contraction
What are the types of myofilaments?
• thin filaments
• thick filaments
What are thin filaments made up of?
• protein actin
What are thick filaments made up of?
• protein myosin
What is the sarcoplasm if reticulum (SR)?
• membranous structure surrounding each myofibril
What is the structure of Sarcoplasmic Reticulum?
• similar to Smooth ER
What does the sarcoplasmic reticulum do?
• forms chambers attached to T tubules
What are the chambers formed by sarcoplasmic reticulum called?
• terminal cisternae
What is a TRIAD composed of?
• 1 T tubule
• 2 terminal cisternae
What does ciaternae concentrate??
• Ca2+ via ion pumps
Where does the cisternae release the Ca2+?
• onto sarcomeres
Why does the cisternae release the Ca2+?
• to begin muscle contraction
What are sarcomeres??
• contractile units of muscles
How are myofibrils built??
• by 10k sarcomeres attached end to end
What do these sarcomeres form?
• visible patterns (stripes) w/in myofibrils
• dark thick filaments
• light thin filaments
What are the thick filaments called?
• A bands
What are the thin filaments called??
• I bands
Where do thick and thin filaments over lap??
• in the zone of overlap
Where does the M line occur?
• the Middle
What does the Z line mark?
• boundary between adjacent sarcomeres
What are thin filaments made up of?
• F-acting filamentous
What is F-acting (filamentous)?
• 2 twisted rows of globular G-acting
What does the active (yellow) actin site do?
• Bind to myosin
What does Nebulin do?
• holds F-acting strands together
What does Tropomyosin do?
• prevents actin-myosin interaction
What does Troponin do?
• binds tropomyosin to actin
How is troponin controlled?
• by Ca2+
What does the thick filaments contain?
• about 300 twisted myosin subunits
What does Titin do?
• recoil after stretching
That does the tail of the myosin molecule do?
• binds to other myosin molecules
What does the head of myosin molecule do?
• teaches the nearest thin filament
What is the head of the myosin made up of?
• 2 globular protein subunits
What happens during contraction to myosin head?
• interact w/ actin filaments
• for cross-bridges
How is contraction initiated?
1. Ca2+ binds troponin molecule
2. Troponin-tropomyosin complex changes shape
3. Exposes active site of F-actin
What happens to thin filaments in filament theory?
• slide towards M line
What happens to the dark area of thick filaments in sliding filament theory??
• the width of A zone stays the same
What happens to the end of sarcomeres in sliding filament theory??
• Z line moves closer together
What does the process of contraction involve?
1. Neural stimulation of sarcolemma
2. Muscle fiber contraction
3. Tension production
What happens in neural stimulation if sarcolemma?
• causes excitation-contraction coupling
What happens in over contraction??
• interaction of thick and thin filaments
What is the Neuromuscular Junction?
• special intercellular connection between the. Record system and a skeletal muscle fiber
What does the neuromuscular junction control?
• calcium ion release into the sarcoplasm
What is the synaptic cleft?
• narrow space that separates the axon terminal of the neuron from the opposing motor end plate
Step 1 of neuromuscular junction.
• cytoplasm of axon contains vesicles filled w: molecules of acetylcholine
What is acetylcholine? Stp1
• a neurotransmitter
What is a neurotransmitter? Stp1
• chemical released by a neuron to change the permeability or other properties of the cell's plasma membrane
What is an action potential? Step2
• sudden change in the membrane potential that travels along the length of axon
What happens when the action potential reaches the neuron's axon terminal? Step3
• change in the permeability triggers the exocytosis of ACh into the synaptic cleft
When does exocytosis occur? Stp3
• as vesicles fuse with the neuron's plasma membrane
What is the 1st step of contraction cycle?
1. Contraction cycle begins
• arrival of Ca2+
What is the 2nd step of contraction cycle?
2. Active-site exposure
What is the 3rd step of contraction cycle?
3. Cross-bridge formation
What is the 4th step of contraction cycle?
4. Myosin head pivoting
What is the 5th step of contraction cycle?
• Cross-bridge detachment
What is the 6th step of contraction cycle?
6. Myosin reactivation
How is tension produced?
• sarcomeres shorten
• muscle pulls together
Where can muscle shortening occur?
• both ends of muscle
• one end of muscle
What determines where the shortening happens?
• the way the muscle is attached at the ends
What does contraction duration depend on?
• neural stimulus
• number of free calcium ions in sarcoplasm
• availability of ATP
What happens when the muscle relaxes.
• Ca2+ concentration falls
• Ca2+ detached from troponin
• active sites are recovered by tropomyosin
Is contraction an active process?
What does SR release?
What triggers contraction?
• Ca2+ in the sarcoplasm
What happens as thin filaments slide between thick filaments?
• skeletal muscle shortens
Is relaxation an active or passive process??
What does tension production depends on?
• number of pivoting cross-bridges
• fibers resting length at time of stimulation
• frequency of neural stimulation
What does a single. Rural stimulation produce?
• single contraction or twitch
How long does a single twitch last?
• 7-100 milliseconds
What does sustain muscular contraction require?
• many stimuli
What are the 3 stages of a twitch?
1. latent period
2. Contraction phase
3. Relaxation phase
How long does latent period last?
• 2 msec
How long does contraction phase last
• 15 Msec
How long does relaxation phase last?
• 25 msec
What is a treppe?
• stair-step increase in twitch tension
• < 50/sec
What is same summation?
• increasing tension or summation of twitches
• repeated stimulation before end of relaxation
• > 50/ sec
What is Incomplete tetanus
• when rapid stimulus continues and muscle is not allowed to relax
What is complete tetanus?
• strings frequency is high enough
• relaxation phase is completely eliminated
What does motor units contain?
• 100s of muscle fibers that contract at the same time
What is isotonic contraction?
• skeletal muscle changes length
What are the 2 types of isotonic contraction?
What is concentric contraction?
• muscle shortens
• tension is greater than load
What is eccentric contraction?
• muscle lengthens
• muscle tension is lesser than load
What is isometric contraction?
• skeletal muscle does not change in length
• still develops tension
What happens when as the heavier the load?
• longer time for shortening to begin
• less muscle will shorten
What is creating phosphate?
• storage molecule for excess ATO energy in testing muscle
What is aerobic metabolism??
• primary energy source of testing muscles
How many ATP are produced with aerobic metabolism?
What is anaerobic glycolysis?
• primary energy source of peak muscular activity
How many ATP are produced in anaerobic glycolysis?
• 2 ATP molecules per molecule of glucose
What happens in anaerobic glycolysis?
• breaks down glucose from glycogen stores I skeletal muscles
What happens when skeletal muscles are at rest?
• it metabolizes Fatty acids
• store glycogen, build CP reserves
What happens during moderate activity?
• generate ATO through aerobic breakdown of carb
What happens if glycogen reserves are low during moderate activity?
• uses lipids or amino acids
• ALL ATO is used as
What happens during peak activity?
• energy is provided by anaerobic reactions (glycolysis)
• generate lactic acid as byproduct
What are the results of muscle fatigue??
• depletion of metabolic reserves
• damage to the sarcolemma and sarcoplasmic reticulum
• low PH (lactic acid)
What happens in recovery period?
• oxygen becomes available
• mitochondrial activity returns
What is the cori cycle?
• removal and recycling of lactic acid
• glucose is released from the liver to recharge muscle
What is the oxygen debt?
Body needs more oxygen than usual to normalize metabolic activities
• heavy breathing
What is another name for oxygen debt?
• excess post exercise oxygen consumption (EPOC)
Up to what percent can be lost in heat?
• 70% of muscle energy
What is the only muscle tissue part of the muscular system?
• skeletal muscle tissue
What are the 4 hormones of muscle metabolism?
1. Growth hormone
3. Thyroid hormone
What do fast fibers do?
• contract very quickly
Describe fast fibers
• larger in diameter
• large glycogen reserves
• few motors
• strong contraction
• fatigue fast
What do slow fibers do?
• contract slowly and slow to fatigue
Describe slow fibers
• small in diameter
• more mitos
• high oxygen supply
• contain myoglobin
What are intermediate fibers?
• mid sized fibers
Describe intermediate fibers
• resemble fast fibers
• have intermediate capillary network and mitochondrial content
What are white muscles mostly formed by?
• fast fibers
What are red muscles mostly formed by?
• slow fibers
What types of fibers do most humans have
• mixed fibers
• pink appearance
What is hypertrophy?
• muscle growth from heavy training
What happens in hypertrophy?
• increase diameter of muscle fiber
• increase number of myofibrils
• increase mitochondria
• increase glycogen reserves
What is atrophy?
• lack of muscle activity
What happens in atrophy?
• reduced muscle size
• reduce in tone and power
What kind of fibers are used in anaerobic activities?
• fast fibers
What are some examples of anaerobic activities?
• 59 meter dash
What is aerobic activities?
• prolonged activities
• aerobic classes
How is aerobic activities supported?
• by mitochondria
How is aerobic endurance improved?
• training fast fibers to be more like intermediate fibers
Where are cardiac muscles found?
• only in the heart
• they are striated
Describe cardiac muscles
• single nucleus
• short, wide T tubules
• no terminal cisternae
• are aerobic
• have intercalated discs
What are intercalated discs?
• specialized contact points between cardio cures
What are the functions of intercalated discs?
• maintain structure
• enhance molecular and connections to potentials
What are the functional characteristics of a cardiac muscle tissue?
• variable contraction tension
• extended contraction time
What is automaticity?
• contraction w/o neural stimulation
• co trolled by pace makers
What is variable contraction tension?
• controlled by nervous system
What is extended contraction time?
• 10x as long as skeletal muscle
Where does smooth muscle form?
• around other tissues
• reproductive system
What signals the stimulus for ACh release? Stp2
• arrival of an electrical impulse
• action potential at the axon terminal
What are the characteristics of smooth muscle?
• nonstriated tissue
• different internal organization of actin and myosin