exam 7 Flashcards
chapter 17
what is an isotonic contraction?
is where the tension remains the same and the muscle changes length
what arw the 2 types of isotonic contraction?
- concentric
- eccentric
what is a concentric contraction?
the muscle shortens as it contracts
what is an eccentric contraction?
the muscle lengthens while under tension
what’s a isometric contraction?
where the muscle remains the same and the tension increases
what is a sarcomere?
its the segment of a myofibril that’s responsible for muscle contraction
what are the characteristics of a sarcomere? 5
- somposed of thick and thin filaments
- each sarcomere is separated by z discs
- they facilitate muscle contraction through a sliding filament mechanism
- they have A, I, and H zone
- they contain elastic proteins
what’s the A band
segment that runs the entire length of thick filaments
what’s the I band?
segement that includes the z disk and ends of thin filaments where they don’t overlap thick filaments
what’s the H band?
middle region of thick filaments where they don’t overlap thin filaments
what’s the z disc?
marks the boundary of each sarcomere
what’s the process of contraction? 10
- nerve signal
- electrical impulse that travels down t-tubules
- calcium releases
- calcium binds to troponin
- cross-bridges are formed
- where energy is released
- detachment from actin filament
8.. re-cocking making it ready to form another cross-bridge - this cycle repeats leading to muscle contraction
- relaxation of muscle
how do filaments contract?
through the sliding filament theory
what’s the sliding filament theory? 6.
- myosin and actin are 2 main filaments
- myosin bind to actin filaments making cross-bridhes
- after they bind they pull actin toward center of sarcomere called a power stroke
- filaments slide past each other
- detachment from actin and re-cock to their original position
- the cycle repeats
what ions and chemicals are involved in muscle contraction? 5
- calcium ions
- ATP
- sodium ions
- potassium ions
- acetylcholine
what do calcium ions do?
calcium binds to troponin that exposes the binding sites for myosin
what does ATP do?
required for the myosin heads to detach and re-cock
- without ATP muscles would remain in a contracted state
what do sodium ions do?
sodium channels open which initiates the contraction process
what do potassium ions do?
prepares for next muscle contraction and restores
what’s atrophy?
the reduction in size or wasting away of a muscle or tissue
why does atrophy occur?
decrease in munber of muscle fibers of loss of muscles structural proteins
what is hypotonic?
solution that has lower concentration of solutes compared to another solution
whats hypertonic?
solution that has a higher concentration of solutes compared to another solution
what is hypertrophy?
increase in size of muscle fibers which increases overall muscle mass
what is a muscle cell/fiber made up of? 6
- myofibrils
- sarcoplasm
- sarcolemma
- sarcoplasmic reticulum
- mitochondria
- nuclei
what is the order of size of the bundles?
- muscle fiber(cell) is the smallest unit
- fascicle; bundle of muscle fibers
- muscle is made up of multiple fascicles
what makes up the fascicle?
bundle of muscle fibers and is surrounded by a connective tissue sheath called the perimysium
what makes up a muscle?
multiple fascicles grouped together and surrounded by a connective tissue called the epimysium
what are the connective tissue coverings?
- endomysium which surround individual muscle fibers
- perimysium that surrounds a group of muscle fibers
- epimysium which surrounds the entire muscle
how is glucose store in the muscle?
stored in the form of glycogen
what are the characteristics of muscle cell structure and their functional reaction? 5
- striations which are responsible for contraction
- multinucleation which helps muscle repair and growth
- sarcoplasmic reticulum helps trigger the contraction process
- t-tubules allow for rapid transmission of electrical signals
- functional reaction: sliding filament theory
when does anaerobic respiration occur?
when oxygen isn’t available which typically happens in muscle cells during intense exercise
what are the steps of anaerobic respiration? 3
- glycolysis which is where the glucose is broken down into 2 pyruvate and generates a small amount of energy and doesn’t require oxygen
- fermentation; coverts pyruvate into lactic acid which can lead to muscle fatigue
- ATP production; allows energy production to continue in the absence of oxygen
what is treppe?
phenomenon where the strength of muscle contractions increases. When a muscle has contracted a few times it contracts more forcefully then after its first contraction
Why does a warm muscle contract more forcibly than a cool muscle?
a warm muscle contracts more forcibly than a cool cuscle because heat increases the speed of chemical reactions in the muscle cells, enzymes are allowed to work faster which enhances muscles ability to generate force
physiology of contraction of cardiac muscle?
contracts with rhythm and is involuntary
it has discs that allow rapid conduction
anatomical differences of cardiac muscle?
-they are branched and interconnected which forms a network that allows the heart to contract as a unit
-they have a single nucleus and have a striated appearance
physiology of contraction of smooth muscle?
contracts slowly and involuntarily and is found in the walls of hollow organs and blood vessels
anatomical differences of smooth muscle?
-they are spindle shaped with a single nucleus
- they lack striations
physiology of contractions of skeletal muscle?
contracts rapidly and is voluntary and is responsible for body movement
anatomical differences of skeletal muscle?
skeletal muscle fibers are long cylindrical cells with multiple nuclei
- they have striations
what is muscle tone?
low level of continuous contraction of the muscles of healthy individual when they’re awake
why is muscle tone important?
important for maintaining posture
