Muscles Flashcards
3 types of muscles
Cardiac Muscle
Smooth Muscle
Skeletal Muscle (AKA striped or striated muscle)
What are Cardiac and Smooth muscles controlled by
Involuntarily controlled by autonomic nervous system
What is Skeletal Muscle controlled by
Voluntarily controlled by somatic nervous system
Whats a Sacromere
The basic contractile unit
What is the structure of muscle
Each muscle is attached to the skeleton by tendons and is under voluntary control
What is the structure of bundle muscle
Composed of a series of bundles, these are groups of muscle fibres which are surrounded by connective tissue containing blood vessels and nerves
What is the structure of fibre muscle
the cells fuse during development to form a very long, strong, multinucleated cell. This can withstand very high tension
What is the structure of myofibril muscle
Each fibre contains a large number of myofibrils within the cytoplasm, they like the fibres exhibit a distinctive striated pattern under the microscope
What is the structure of the sarcomere muscle
the pattern of bonding on a myofibril is cause by the sarcomeres. These are smallest contractile units in a muscle which are arranged end-to-end for the entire length of each myofibril
What is the structure of protein filaments muscle
Each sarcomere is formed from thousands of protein filaments. These proteins can slide together shortening the sarcomere. This is the basis of muscle contraction
What is the A zone in the sarcomere
Same length as the myosin filaments - Contains H zone and M line. Actin and myosin interlock within the A band
What is the I band in sarcomere
regions that contain only actin filaments. The lightest coloured bands of sarcomere when viewed under microscope
What is the H zone in sarcomere
Lies within A band. It is the part of A band that only contains myosin filaments. H zone ends where myosin and actin filaments begin to interlock
What is the Z line in sarcomere
define the limits of the sarcomere - appear as thin dark lines under a microscope
What is the M line in a sarcomere
found at centre of myosin filaments - no myosin heads in this region of the myosin filaments
What reduces the length of the sarcomere
Interlocking structure of thick and thin filaments allow them to slide past one another
What is the sliding filament theory
Light bands formed by actin shrink as filaments become more interlocked
How does the sliding filament theory work
a muscle fiber contracts when myosin filaments pull actin filaments closer together and thus shorten sarcomeres within a fiber
