unit 10 - muscular system Flashcards
skeletal muscles
- striated
- tubular
- many nuclei
- voluntary
- attached to bone
smooth muscles
- not striated
- spindle shaped
- 1 nuclei
- involuntary
- in walls of organs
cardiac
- striated
- tubular + branched
- 1 nuclei
- involuntary
- walls of the heart
primary functions of the muscular system
- supports the body
- helps maintain body temperature
- makes the bones move
- protects internal organs
antagonistic muscles
if one muscle contracts the opposite relaxes
hierarchy of muscle fibres
- muscle
- muscle-fibre bundle
- muscle fibre
- myofils
- myofilaments
sarcolemma
muscle fibre membrane
sarcoplasm
inner material surrounding fibres
sarcoplasmic reticulum
used in transport (ie. calcium)
myofibrils
individual parallel muscle fibres within sarcoplasm
actin
- thin filaments
- 1 strand of protein
- other proteins: troponin + tropomyosin
- shorter
- no head
myosin
- thick filaments
- 2 strands of protein
- longer
- double head
how myofilaments contract
- when the myofilament contracts, the heads of the myosin move first
- actin is pulled along
- myosin heads flex on after another and myosin ‘walks’ along actin
- this requires 1 ATP molecule to reposition the myosin head so it can bind to the actin and flex again
- pulls the z lines closer together
a muscle can contract when
- calcium ions have bonded to troponin, which is a part of the actin
- this causes the tropomyosin to reposition itself exposing the myosin bonding sites of actin
- the myosin head can bond to the actin and contraction occurs
- when a muscle fibre is stimulated it releases calcium from the SR, when it is no longer stimulated the calcium is returned to the SR
ways to obtain energy for contraction - CP breakdown
- ATP is supplied by creatine phosphate
- duration of ATP is 8 seconds
- Anaerobic
CP breakdown
- ATP is supplied by creatine phosphate
- duration of ATP is 8 seconds
- Anaerobic
ways to obtain energy for contraction - Aerobic CR
- ATP comes from cellular respiration
- it lasts for a long time
- aerobic
ways to obtain energy for contraction - fermentation
- ATP supplied by glycosis
- lasts 1-2 min
- anaerobic
oxygen deficit
muscles uses fermentation to supply energy needs because it doesn’t use the left over oxygen the brain needs
three stages of muscle twitch
- latent: the period of time between stimulation and initiation of contraction
- contraction period
- relaxation period
summation and tetanus
summation is continous increasing of contraction
tetanus is the max sustained contraction
