Chapter 10: Muscle Tissue Flashcards
Three types of muscle
Cardiac
Smooth
Skeletal
What are some muscle similarities?
Excitability
Contractility
Elasticity
Muscle contraction depends on what two kinds of myofilaments
Actin and myosin
Microscopic appearance of skeletal muscle
Elongated
Multinucleate
Striated
Nervous system control of skeletal muscle
Voluntary nervous system
Somatic motor neurons
What are the functions of the skeletal muscles?
Moves the bones, maintains posture and body position, supports soft tissues, guards body entrances, and exits, maintains body temperature, and stores nutrients
Cardiac Muscle Microscopic appearance
Branching cells, single central nucleus , straited and joined to another muscle cell at the intercalated disc.
Nervous system control of cardiac muscle
Involuntary autonomic nervous system
Function of cardia muscle
pumps oxygen, nutrients throughout the body
Microscopic appearance of smooth muscle
Spindle-shaped, single central nucleus, no striations
Location of smooth muscles
Around hollow organs including blood vessels.
Origin
Attach to bone and does not move.
Insertion
Crosses a joint and attaches to bone. Insertion will move towards the origin.
When a muscle contracts, the _____ is pulled toward the _________.
Insertion
Origin
Levels of organization of Skeletal Muscle
Skeletal muscles, fascicles, muscle fiber, myofibrils, sarcomere.
Skeletal Muscle
organ
bundle of fascicles
contains epimysium
Fascicles
Bundle of fibers
contains perimysium
Muscle fiber
cell
Bundles of myofibrils.
Contains endomysium
Myofibrils
Repeating contractile units that are called sarcomeres
Sarcomeres
Organized unit of myofilaments.
Myosin and actin
A bands are ____
I bands are ______
dark
light
M line
Anchor for myofilaments, it is the horizontal line in the middle of the sarcomeres.
H band
The area where there is only myosin
A band or Zone of Overlap
Where both myosin and actin are
Z lines
Separates the sarcomeres and marks the beginning of the end of a sarcomere
Titin
Stretchy protein that helps it pop back to its original position
I band
This is where it is only actin
Epimysium
surrounds the skeletal muscle
Perimysium
surrounds the fascicle
Endomysium
surrounds muscle fiber
Blends into connective tissue attachments like tendon (cord-like) or aponeuroses (sheet-like)
Sites of muscle attachments
Bones
Cartilage
and connective tissue coverings
Thick Filaments
Myosin
Each myosin molecule has a rod-like tail and two globular heads.
Thin Filaments
Actin
Actin subunits contain an active site (which myosin heads attach to)
What two regulatory subunits does actin contain
Tropomyosin and troponin
Tropomyosin
covers the active site of actin, prevents myosin from attaching
Tropinin
Can bind to calcium, and when calcium attaches to troponin, it causes tropomyosin to shift away from the active sites on the actin.
Sarcolemma
Plasma membrane
T-Tubules
extended from sarcolemma into sarcoplasm.
Carry electrical currents action potentialfrom sarcolemma into the cell interior.
Triggers contraction
Sarcoplasm
The cytoplasm of the muscle fibers.
Each myofibril is surrounded by ___________.
Sarcoplasmic Reticulum
How does calcium interact with troponin and affect tropomyosin?
When calcium binds to troponin, it causes tropomyosin to shift away from the active sites on the actin.
What does SR store?
Calcium
Acetylcholine
ACh is a chemical signal that will initiate muscle movement.
Neuromuscular Junction
A synapse between a neuron and a muscle cell.
Neurotransmitter
Chemical Sign
Sliding Filament Theory of Muscle contraction
The concept is that a sarcomere shortens as the thick and thin filaments slide past one another.
Synaptic Cleft
Narrow space between a somatic motor neuron and the motor end plate.
Recruitment
The process by which more and more motor neurons are activated.
Motor Unit
Consists of a single motor neuron and all the muscle fibers controls.
What are the two basic mechanisms by which the nervous system produces graded contractions?
*Varying the number of fibers that contract
*Varying the rate at which fibers are stimulated
Rigor Mortis Occur
Muscles remain locked in a contracted state because there is no ATP for relaxation.
Action Potential
A propagated change in the membrane potential pf excitable cells in initiated by a change in the membrane permeability to sodium ions.
Twitch
Results from a single action potential in a motor neuron
How many phases does a single twitch have? and what are they?
Latent period
Contraction phase
Relaxation phase
Treppe
A stair-step increase in tension caused by repeated stimulations immediately after the relaxation phase.
(Stimulus frequency <50/Sec)
Seen in cardiac muscles
Wave summation
Increasing tension due to the summation of twitches. Caused by repeated stimulations before the end of the relaxation phase.
(Stimulus >50/sec)
Tetanus
Maximum tension
Incomplete Tetanus
Muscle produces near-maximum tension.
Caused by rapid cycles of contraction and relaxation
Complete Tetanus
Higher stimulation frequency eliminates the relaxation phase. Muscle is in continuous contraction. All potential cross-bridges form.
What are the two types of muscle contractions?
Isotonic and Isometric
Isotonic Contraction
Skeletal muscle changes in length. Resulting in motion.
Isotonic Concentric Contraction
Muscle tension > load resistance
Muscle shortens!
Isotonic Eccentric Contraction
Muscle Tension < load (resistance)
Muscle elongates!
Isometric contraction
Skeletal muscle develops tension that never exceeds the load.
Muscle does not change length.
Anaerobic Metabolism
Breakdown of glucose in the absence of oxygen.
Lead to build up of lactic acid.
Causes muscle fatigue.
Yields 2 ATP from one glucose
Aerobic Metabolism
Breakdown of glucose in the presence of oxygen.
High yield- of approximately 36 ATP.
Slow Twitch
ATP broken down slowly
Contract slowly
Aerobic metabolism
Store oxygen
Rich blood supply darker in color
Endurance- jogging, swimming, biking.
Fast Twitch
ATP broken down FAST
Contract quickly
Anaerobic metabolism
Breaks down creatine-P for short bursts of energy.
Poor blood supply white in color
Fatigue quickly from lactic acid build-up.
Power and high-intensity activity such as weight lifting
Strength or Resistance Training
The amount of actin and myosin and the number of sarcomeres within muscle fibers increases.
The size of individual muscles increases.
The number of muscle fibers does not increase.
Endurance or Aerobic Training
The number of blood vessels supplying muscles increases.
Muscle fibers do not increase in size or number.
Do muscles pull or push?
Muscles ONLY pull, NEVER push.
