Muscles Flashcards
what is myalgia
muscle pain
what is myasthenia
muscle weakness
what is myoclonus
sudden spasm of the muscles
what are the 3 types of muscle
skeletal muscle (striated)
- voluntary muscle
- responsible for movement of the skeleton and structures such as eye and tongue
- myoglobin present
cardiac muscle (striated)
- involuntary muscle
- only in heart
- myoglobin present
smooth muscle (non-striated)
- involuntary muscle
- found in uterus/bladder and associated with tube-like structures eg. GI tract and blood vessels
- myoglobin absent
what is myoglobin
- red protein structurally similar to a single subunit of haemoglobin
- oxygen-storing molecule that provides oxygen to working striated muscles
- haemoglobin gives up oxygen to myoglobin especially at low pH
- when striated muscle dies (necrosis) or damaged (rhabdomyolysis) myoglobin is released into blood (myoglobinaemia)
- can cause renal damage as kidneys remove myoglobin from blood into urine (myoglobinuria)
components of muscle cell
- sarcolemma outer membrane of muscle cell
- sarcoplasm cytoplasm of muscle cell
- sarcosome mitochondrion
- sarcomere contraction unit in striated muscle
- sarcoplasmic reticulum smooth endoplasmic reticulum of muscle cell
structure of skeletal muscle
- muscle fibres surrounded by loose connective tissue called endomysium
- muscle fibres aranged in bundles called fascicles that are surrounded by slightly thicker loose connective tissue called perimysium
- bundles of fascicles make up the muscle surrounded by even thicker connective tissue called epimysium
structure of muscle fibres
- muscle fibres made of many myofibrils
- each myofibril made of many myofilaments (actin and myosin) that form sarcomeres
structure of sarcomere
alternating rows of actin (thin) and myosin (thick) filaments
- A band (dark) = myosin and actin
- I band (light) = actin only
- H zone = myosin only
- M line = middle of sarcomere
- Z line = end of sarcomere
