part 1 Flashcards
What are the three types of muscle tissue?
Skeletal - striated - for support and movement
Smooth - non striated - found in GIT and intestines
Cardiac - striated - To pump blood around the body and regulates BP
What are the functions of muscle tissue?
For protection and movement
Generates heat
Stabilizing body position
Storing and moving substances
What are the properties of muscles?
Excitability
Elasticity
Contractility
Electric excitability
Muscle fibers are formed during the development of myobLasts. TRUE OR FALSE?
TRUE
Muscle growth is via hypertrophy. TRUE OR FALSE?
TRUE
Where is calcium stored?
In sarcoplasmic reticulum
Sarcoplasm does not contains glycogen for ATP and myoglobin for oxygen. TRUE OR FALSE?
FALSE
What is myofibrils?
It is a contractile organelle
What are filaments and how are they arranged?
Filaments are thin and long and are directly involved in contractile of the muscles, they are arranged in sacromeres
Describe the basic functional units of muscle
Z-discs - separate the sacromeres
A-band - Darker middle part which extends the length of thick filaments
End of A-band - zone of overlap with thin filaments
H-band - Within the overlap - center of A-band with thick but no thin filaments
M-Line - is the middle of the sacromere
I-band - is lighter area with thin filaments only
What are the two muscle proteins?
Actin and myosin
Myosin is the thick filaments, it functions as a protein molecule converting chemical energy ATP into mechanical energy. STATEMENT TRUE OR FALSE?
TRUE
Actin is the main component of thin filaments and it joins to form a helix, each actin molecule has a myosin binding site. TRUE OR FALSE?
TRUE
Tropomyosin is a component of thin filaments and troponin is thin filament that binds calcium. STATEMENT TRUE OR FALSE?
TRUE
What does titin do?
It connects Z disc to M-line
What does alpha actinin do?
Z disc protein that binds actin and titin
What does myomesin do?
M-line protein that binds titin
What does nebulin do?
it wraps around thin filaments
What does dystrophin do?
it binds to thin filaments
Calcium concentrations in the cytosol does not regulate contraction and relaxation. TRUE OR FALSE?
FALSE
Describe the events of muscle contraction?
- Myosin head hydrolyzes ATP into ADP +Pi
- Myosin head binds to actin forming a crossbridge
- Myosin head rotates towards center of the sarcomere (known as a power stroke)
- As myosin head binds ATP , crossbridge detaches from myosin and back to start.
AP propagates into t-tubules and induces ca release from sarcoplasmic reticulum, ca binds troponin which alters the conformation, tropomyosin uncovers myosin binding sites on actin. TRUE OR FALSE?
TRUE
After termination of AP, ca is pumped back into the SR . TRUE OR FALSE?
TRUE
Describe the different stages of twitch contraction?
Latent period - Action potential occurs and ca is released from Sarcoplasmic reticulum
Contraction period - Formation of crossbridges and tension development (lasts 10-100msec)
Relaxation period - Ca is brought back to Sarcoplasmic reticulum (lasts 10-100msec)
Refractory period - Resistant to re-stimulation
What are the two types of skeletal muscle fibres?
Red muscle fibres - Have high myoglobin, mitochondria concentration and are rich in capillaries
White muscle fibres - Are low in myoglobin concentration.
What are the three main types of muscle fibres? (that can cause fatigue)
Slow oxidative
Fast oxidative glycolytic
Fast glycolytic
Describe slow oxidative muscle fibres
The least powerful and shortest in diameter, has slow contraction twitch and resistant to fatigue (used to maintain posture and for long endurance activities)
Describe fast oxidative glycolytic muscle fibres
Have high concentration of myoglobin and capillaries, they generate ATP by aerobic cellular respiration, they also generate ATP from glycogen
They have faster twitch contraction and are used for activities such as walking
Describe fast glycolytic fibres
Longest in diameter, and most powerful
Low myoglobin, mitochondria and few capillaries
Strong fast contractions
ATP is produced via glycolysis using glycogen
Meant for quick anaerobic movement for short durations for example weight lifting
Length of sarcomere determines the rate of contraction. TRUE OR FALSE?
TRUE
What is the Neuromuscular junction?
Site between synapse and muscle cell
Synaptic cleft - AP cannot jump across so needs NT
Axon terminal - synaptic vessicles containing ACh molecules
Motor end plate - ACh receptors - ligand gated ion channel
ARE ALL THESE TRUE OF FALSE?
TRUE
Describe the events of NT at neuromuscular junction
- ACh is released from synaptic vessicles
- Ach binds to ACh receptors
- Muscle action potential is produced
- ACh is broken down
Botulinum toxin , blocks exocytosis so muscle contraction does not occur and breathing stops (can also be used for treatment of botox and wrinkles)
Curare - Blocks ACh receptors - so no ion channels open
Anticholinesterase agents - slows ACh removal and prolongs its action. ARE ALL THESE STATEMENTS TRUE OR FALSE?
TRUE
What are the different types of ways for making ATP for muscles?
- From creatine phosphate
- ATP from anaerobic glycolysis
- ATP from aerobic cellular respiration
What is proprioception input?
It allows the brain to know where limbs are and it allows for distribution of weight for example muscle spindles
What do muscle spindles do?
They monitor changes in skeletal muscle length, it consist of nerve endings wrapped around in intrafusal muscle fibres and is surrounded by a connective tissue capsule
What is muscle fatigue?
The inability of muscles to maintain force of contraction after prolonged period of time.
What are the mechanisms that cause muscle fatigue?
- Oxygen insufficiency - glycogen depletion
- Production of lactic acid
- Creatine phosphate levels also decrease
- inadequate release of ca from SR
- Decreased Ach release
What is polymositis and how can it be treated?
It is an inflammatory autoimmune disease, leads to destruction of muscle fibres, gradually obtain muscle weakness.
It can be treated with steroid glucocorticoids
What is muscle dystrophy and how can it be treated?
It is a group of inherited diseases, which causes mutation in different genes/the severity of it can vary as it can appear in childhood.
Treatments include providing medication to help with cardiac complications, corticosterioids in duchenne MD and pace maker in emerydreifuss MD.
What is myasthemia gravis?
It is an autoimmune disease where the body produces antibodies against Ach, it causes muscle weakness after prolonged use.
It is treated with acetylcholinesterase inhibitor, steroids, immunosuppressants and in emergency IV ig
