Skeletal muscle is made up of …., …. in diameter, and vary from mm to ~10cm. Myofibrils (roughly 1 μm diameter).
long parallel cells (fibres), 30 - 100 μm
Cardiac muscle cells are …. in diameter, … in length, connected end to end at intercalated discs for mechanical and electrical continuity, at desmosomes (fascia adherens) and gap junctions, respectively; myocardium, functional syncytium.
10-20 μm, 50-100 μm
Smooth muscle cells are about …. μm wide and …. μm long. They are joined together both mechanically (at intermediate junctions) and electrically (at gap junctions), to form functional units in bundles or sheets.
2-10, 100-400
Activation of Muscle
Skeletal muscles are activated by ... Cardiac and most smooth muscle have an intrinsic rhythm that is modulated by ....
action potentials in the motor nerves
–neurogenic contractions
action potentials in autonomic nerves
–myogenic contractions
Przypomnienie: Skeletal muscle innervation
- Skeletal muscles are supplied by nerve fibres that are myelinated and have their origin in the CNS.
- Such nerves are called motor nerves.
- When a motor nerve fibre enters a muscle, it branches so that one motor axon makes synaptic contact with a number of muscle fibres.
- The motor neuron, its axon and all the muscle fibres supplied by the axon and its branches form a motor unit.
…. holds tropomyosin in position to block myosin-binding sites on actin.
However, Ca2+ binds to …., which changes the shape of the troponin-tropomyosin complex and uncovers them, causing contraction because myosin binds to actin
Troponin
Opisz Type I and Type II skeletal muscle cells
Type I Slow Oxidative
Type II A Fast Oxidative II B Fast Glycolytic
The Power of Muscles
Force =
Work =
mass x acceleration
force x distance moved by load
Power = ….
jednostki force, work and power
work ÷ time = (force x distance) / time = force x velocity
Force= 1 Kg x 1m s-1 = 1 Newton (1 N)
Work = (1 Kg x 1m s-1 ) x 1 m = 1 Newton Metre (1 N.m) or Joule (J)
Power = (1 Kg x 1m s-1 x 1 m) / time = Joule / second ( J s-1 ) or Watts (W)
Opisz co się dzieje z książką gdy:
Isotonic Concentric
Isotonic Eccentric
Isometric
– książka w górę
- książka w dół
– brak ruchu
The force developed by a muscle depends on (5):
- The number of active motor units
- The cross-sectional area of the muscle
- The frequency of stimulation: – summation of contractions
- The rate of shortening
- The initial length of the muscle
