Case 9 Flashcards
Troponins
Troponin I binds to actin + troponinT, and inhibits actin myosin interaction unless Ca binds troponin C.
Titin
long filamentous protein links thick filaments to Zline.
Myomesins
bind to titin, generate hexagonal packing of thick filaments.
Tropomyosin
Thin filament structural component binding to actin.
A actinin
cross links actin at the sarcomere to Z disks.
Vinvulin
binds to A actinin
Dystrophin
links actin filaments to muscle cell outer membrane.
Nebulin
determines length of thin filament
Cap Z and tropomodulin
caps the + - end of thin filaments respectively.
Desmin
lonks together adjacent myofibrils at Z disk
Type of skeletal muscle fibre
determined by pattern of gene expression which is goverened bu firing pattern of motor neurone.
Type 1 fibre type
slow twitch, slow oxidative fibres. low myosin ATPase rate. Allow steady activity. Motor neurone has constant low firing frequency. Good supply of nutrients, high SA:Vol, good blood supply. Abundant mitochondria and myoglobulin so appear red. can use fat as source of energy.
Type 2a fibre type
fast oxidative glycolytic fibres. similar slow twitch. faster contraction and higher myosin ATPase activity. relitively resistent to fatigue. utilise glucose as well as fats. show burst of activity.
Type 2B fibres
fast twitch. fast glycolitic fibres. Highest myosin ATPase activity. Short maximal force. Not adapted for efficient exchange of nutrients and waste, low SA:Vol. limited blood S. pale colour as fewer mitochondria and myoglobulin. Generate ATP by substrate level phosphorylation glucose-lactic acid. Occasional bursts of high frequency impulses.
Oxidative phosphorylation
Used in slow twitch and intermediate fibres. Reduction of O2 to H2O using electrons from NADH and FADH2. Occurs in inner mitochondrial membrane. Explained by chemiosmotic theory. Involves exergonic. transmembrane chem + electical differences drives ATP synthesis.
substrate level phosphorylation
fast twitch. Direct formation ATP by phosphorylation ADP. Produced by reactions with high free energy. Dont require O2. Glycolysis: 1,3BPG + ADP - ATP + 3PG. TCA cycle, succinyl CoA + GDP - GTP + succinate. glycogen glucose lactate.
Cori cycle
oxygen is used by liver to produce glucose from lactate.
Effects of excersize on muscles
Inc mitochondria biogenesis. Via Ca signalling pathwaysas well as imbalence of ATP demand vs production which activates signalling protein kinases. AMPK fuel gauge of cell. Leptin may also operate via AMPK pathway. lack of excersize makes inc in NF-KB and myostatin which are important cell signalling molecules for muscle atrophy.
What is fitness
physically and psychologically able to meet the demands of your environment. Health related and skill related (usually task specific.)
VO2 max
the rate of volume of oxygen consumption while working at maximum capacity. can only improve by 15%
muscle unit
muscle fibres innervated by a single motor neuron
motor unit
muscle unit plus its motor neuron
motor neuron pool
coollection of neurons innervating a single muscle
Ach synthesis
Acetyl coenzyme A + choline with Choline acetyltransferace ChAT, to coenzyme A and Ach.
myocyte and fascicle
muscle cell.
bundle of myocytes. fasciculo many fascicles.
fascicle orientation
circular(orbicularis oris) Pennation, muscle fibres orientated at angle relative to line of action. uni, bi, multipennate. Parallel same direction from origin to insertion.
alpha motor neuron
supply extrafusal muscle fibre/ Large soma, fast myelinated axon. control muscle force. LMN
y motor neuron
supply intrafusal muscle spindle muscle fibers. smaller soma and myelanted axon. control muscle spindle responsiveness. LMN. CNS stimulates y resulting in contraction of intrafusal inc sensitivity.
muscle length is measured by
muscle spindles
muscle tension is measured by
golgi tendon organs