Musculoskeletal system Flashcards
What are the types of muscle cells?
Skeletal muscle cells
- Skeletal 40-50% of total body weight
- Voluntary (Controllable)
- Mostly function as moving body parts
- Stabilizing body positiongs
- Striated
- Multiple nuclei
- Very long, can be 30cm
Cardiac muscle cells
- Involuntary
- Heart only, develops pressure for arterial BF
- Striated and branched
- Joined together with intercalated discs
Smooth muscle cells
- Involuntary
- Grouped in walls of hollow organs
- Nonstriated
- One nucleus
- Thick in the middle
- Sphincters regulate flow in tubes, maintain diameter of tubes
- Move materials in GI tract and reproductive organs
- Contain thick fil, thin fil, intermediate fil, and dense bodies
- Can be either visceral (single unit) or multiunit
- Duration of contraction and relaxation is longer than for skeletal
- Has muscle tone too
- Contract in response to nerve stimuli, hormones, stretching, and local factors
Muscular dystrophy
Group of muscle diseases that results in increasing weakening and breakdown of skeletal muscles over time. The disorders differs in affected muscles, degree of weakness and how fast they worsen.
Myasthenia gravis
Autoimmune neuromuscular disease where the neurotransmittor function is damaged.
Muscle rupture
Muscle rupture, strain, or pulled muscle. Occurs when overstretched or torn. Usually result of fatigue, overuse, or improper usage. More common that tendons rupture.
Relative ratio is regarding the ratio of fast glycolytic (FG) and slow oxidative (SO) fibers, how does it change physical performance.
FG strong in intense activity like weight lifting.
SO better endurance like long distance running.
Genetic ratio but can be altered with training.
What happens to the muscles during aging?
Progressive loss of mass, just as for the bones.
Ratio SO increases over FG fibers.
What are the functions of skeletal muscles?
Movement
Stabilization
Store and move substances
Produce heat, by for ex shivering
Sarcolemma
Membrane of muscle fiber (skeletal muscle cell)
Sarcoplasm
Cytoplasm in muscle cells
What are the three sheets of connective tissue covering different bundles of fibers called?
Endomyosin covers muscle fiber (muscle fibers consists of multiple myofibrils)
Perimyosin covers fascicles of muscle fibers
Epimyosin cover entire muscle where the fascicles are bundled together
What is the transverse tubules?
Tunnel from surface to center, permit rapid transmissions of the action potential into the cell. Also helps regulate Ca concentration.
What is myoglobin?
Protein that stores oxygen, similar to hemoglobin. Is used when the cell is not getting enough from the blood, must be recharged after use. “Oxygen recovery”
What is the sarcoplasmic reticulum?
Network in muscle cell that stores Ca ions
What are the two skeletal muscle filaments, and what are they made of?
Thick filament, consists of myosin.
Thin filament, consists of actin, troponin, and tropomyosin.
What is the functional unit of the muscle fiber called, and how does it work?
Sarcomere. When Ca ions are released by the sarcoplasmic reticulum, it reacts with the troponin which together with tropomyosin clear the path to the actin. Now the heads of the myosin can react with ATP and bind to the actin molecules and do the power stroke. Contraction. ATP is then used to unbind and relax the sarcomere. Relaxation. The neurotransmittor Acetylcholine (ACh) is then digested by the enzyme acetylcholinestrase to end the signal and the Ca ions are put back into the sarcoplasmic reticulum.
What are the different areas of the sarcomere called?
HAII and Z.
H-band between thin filaments.
A-band entire thick filaments.
I-bands are the two remaining areas between the end of the thick fil to the Z-disc.
Z-discs are the ends/connections between the sarcomeres and has a Z like shape.
What is a muscle tone?
Muscle tone is the maintenance of partial contraction of a muscle, important for generating reflexes, maintaining posture and balance, and controlling proper function of other organ systems.
What is a motor unit?
A neuron plus the triggered fibers. (The more precise movement needed, the fewer fibres are activated)
Neurotransmittor ACh is used by all skeletal muscles, what does it stand for? How is it transported?
Acetylcholine, and travels in the active transport vesicles and then diffuses across the synaptic cleft in the neuromuscular junction.
What are the three sources of ATP production for the muscle cell?
Aerobic respiration. Ordinary cellular resipration in mitochondria, requires oxygen and glucose. Produces CO2, H2O and heat. By far most efficient alternative, 36 ATP/glucose.
Anaerobic glycolysis. Glucose is converted into pyruvic acid in the reactions of glycolysis, which yield two ATPs without using oxygen. These reactions, referred to as anaerobic glycolysis, can provide enough ATP for about 2 minutes of maximal muscle activity.
Creatine phosphate. The transfer of a high-energy phosphate group from creatine phosphate to ADP forms ATP. This could go on for maximal contraction of about 15 sec before it runs out.
What is fatigue, and what are the limiting factors?
Inability to contract forcefully after prolonged
activity.
Limiting factors can include: Ca2+ Creatine Phosphate Oxygen Build up of acid Neuronal failure
What happens in a recovery phase when the cells are filled with lactic acid, are out of creatine phosphate, and out of oxygen in the myoglobin proteins?
Lactic acid is transported to liver where it’s converted into glucose.
Creatine phosphate is resynthesized.
Oxygen is restored to the myoglobin.
What are the different periods of a myogram called?
Latent, contraction and relaxation period.
What is wave summation?
Is the response in muscle activity to multiple activation potentials in a short time span. The more AP the harder the contraction.
Tetanus is the sustained muscle contraction due to multiple AP of motor nerve. Can be unfused or even fused when it is maximally stimulated.
What are the three different muscle fiber classifications?
The classes are recruited in the following order:
- Slow oxidative (SO)
- Fast oxidative-glycolytic (FOG)
- Fast glycolytic (FG)
Skeletal muscles are often paired as agonist-antagonist, what are muscles called depending on in which dimension it is moving?
Flexor - extensor.
Abductor - adductor.
