Muscles overview Flashcards
How much of the body weight is muscle
40%
How is muscle created
Via myogenesis
What cell does muscle create
Myoblasts
What do myoblasts form
Multiple will fuse to form myotubes which will turn into muscle fibers
What is the fascia on the muscle
Connective tissue that encases the muscles individually
Where is the muscle fascia found
Outermost layer of the epimysium
Where is the perimysium found
Subdivides muscles further into fascicles
Where is the endomysium found
Wrapped around the individual muscle fibers
What prevents muscles from sudden changes in speed and position
Fascia
What part of the muscle is the largest
Muscle belly
What makes up the fascicle
Muscle fibers
What makes up muscle fibers
myofibrils
What are myofibrils composed of
thick and thin filaments
What is a muscle fiber
Singular muscle cell
What are the contractile units of the muscle
myofibrils
How are the muscle fibers differentiated
fast twitch fibers
Slow twitch fibers
What determines the muscle twitch speed
nerve impulse
What color are fast twitch fibers and what do they do
white
have large, fast conducting nerves
more anaerobic and wear out faster
What are type 2 fibers
fast twitch fibers
What color are slow twitch fibers and how do they work
Red (Aerobic)<- hemoglobin
Will contract for longer periods of time (holding posture)
What are type. 1 fibers
slow twitch
Which gender have larger muscle fibers
Men
What is the sarcolemma
Muscular membrane which will increase the rapid spread of the electrical conduction
What does the sarcolemma do
Assists with nutritional transport and protein synthesis
What do the Na/K pumps do
Keep the charge gradient to allow for conduction (#1 pump in the body)
What do T tubules do and where are they found
Found in cardiac and skeletal muscle
Helps with rapid conduction
Where are mitochondria in the muscle found and what do they do
Found within the sarcoplasm and they form ATP
What does the sarcoplasmic reticulum do
Help with calcium transport and calcium storage
How is calcium useful in the muscle
Electrolyte that is required for muscle contraction
Where do nerves branch off of for voluntary skeletal muscle control
anterior horn
What determines the rate of muscular fatigue and fine motor movement
Number of muscle fibers innervated by each nerve branch
What does more nerve fibers allow for
Less muscle fatigue but also less precise movement
What is the funtional contractile protein of the muscle fiber
myofibril
What do sarcomeres contain
actin and myosin
Where are sarcomeres found and what are they made up of
They run parallel to the myofibril and are made up of repeating protein series
What separates sarcomeres
Z Disc
What is a thick band made up of
Myosin
What is a thin band made up of
actin
What does titin do
Help muscles spring back from contraction… muscle elasticity (Z line)
What does myosin help with
Contraction via the utilization of ATP
What does troponin do
Helps with actin-myosin activation by allowing Calcium to bind
What is tropomyosin and what does it do
Regulatory protein that helps structural support and maintains filament length
What does the troponin complex do
Keeps the active potential binding sites of the actin covered
What does creatinine measure
Kidney function
When is creatinine kinase found
Rhabdo
What is rhabdo
When a person gets rehydrated, the kidneys become flooded with creatinine and its clogs the kidney filter -> kidney failure
What are the steps in muscle contraction
excitation
coupling
contraction
relaxation
When is action potential transmitted
After the first nerve impulse reaches the neuromuscular junction
What happens when the action potential is triggered
Calcium is released
What happens during the coupling stage
calcium goes to the myofilament which causes tropomyosin to release actin
What happens during the contraction stage
When troponin is released, the actin will slide toward thick filament
Myosin head attaches to actin = cross bridging
What is released during bridging in the contraction phase
ATP is released
What happens in the relaxation phase
Calcium is reabsorbed within the sarcoplasmic reticulum
What happens with calcium is reabsorbed into the sarcoplasmic reticulum
actin is rebound
bridge is released
Relaxation occurs
What is the first step in muscle contraction
Acetylcholine is released from the terminal end of the neuromuscular junction
What happens after acetylcholine is released
The t-tubules are depolarized via the Na+/K exchange (Increasing the charge)
What does the t-tubule depolarization cause
The release of stored calcium from the sarcolemma
What will prime the muscles involved with contraction
agonist
What does an antagonist do during muscle contraction
relax in order to allow the agonist to complete the task
What does the stretch response ensure
appropriate muscle tone
What activates the stretch response
Spindles activate the stretch response
spindles are the mechanoreceptors
What type of muscle is skeletal muscle
Voluntary, striated muscle with several nuclei
What causes striations in the muscle
sarcomeres
What type of muscle is cardiac muscle and some key characteristics
Striated
involuntary
only one nucleus per cell
What are two big differences between cardiac and skeletal muscle fibers
NA+/K depolarizes more readily is cardiac muscle
CA+ induces muscular contraction more easily is cardiac muscle
Contains more mitochondria than skeletal
What type of muscle is smooth muscle
non-striated
What are characteristics of smooth muscle
Uninucleated fusiform cell
more elastic
spread of depolarization allows for a spiral corkscrew pattern
lacks sarcolemma
What are examples of unitary smooth muscle
GI/GU systems (Visceral)
What are smooth muscles controlled by
Autonomic nervous system
How do smooth muscles move
They are electrically coupled to each other to create a rhythmic contraction and connected via gap junctions
What are examples of multiunit smooth muscles
Pupils for dilation/constriction, Bronchial smooth muscle, tunica media, erector pili
How do multiunit smooth muscles move
They have their own individual nerve endings
What does creatinine measure
Kidney function
If a patient has an increase in their creatinine, what is it indicative of
Kidney failure
When is creatinine kinase found
Rhabdo
