Week 9 Flashcards
3 Types of muscle tissue
- Skeletal
- smooth
- cardiac
Skeletal Muscles
require nerve signals to work
How do muscles work?
-Contraction
-Myosin pulls on actin to shorten the muscle
-muscles contract using myofibrils
Important components for contraction
- calcium
- action potential
- energy (ATP)
- protein (actin/myosin)
Function of the skeletal/muscular system *
-movement
-protecting internal organs
-generates heat
Contraction
shortening
Layers of the muscle
- Epimysium
- Perimysium
- Endomysium
Epimysium
covers the muscle
Perimysium
contains fascicles
Fascicle
bundle of muscle fibers
Muscle fibers
-muscle cell
-is multinucleated
Endomysium
surrounds individual muscle fibers
Multinucleated
lots of nuclei to produces lots of protein
Sarcalemma
-plasma membrane
-carries AP
Sarcoplasm
cytoplasm
Sarcoplasmic Reticulum (SR)
-smooth endoplasmic reticulum
-stores calcium
Myofibril
made of actin & myosin (proteins)
Sacromere
functional unit of muscle fiber part that contracts
Neuromuscular Junction (NMJ)
where the nerve and muscle connect
Neuromuscular Junction Process
- AP gets to axon terminal
- Voltage-gated calcium channels opens; calcium enters the axon terminal
- Ach released into synapse
- Ach binds to ligand-gated receptors on muscle fibers
- Ligand-gate opens; Na rushes into muscle fiber
- AP generated along the sarcolemma of muscle fiber
Muscle Conraction
- AP carried along t-tubules of sarcolemma
- Calcium released from the SR into sarcoplasm
- calcium binds to actin at the troponin site
- troponin moves tropomyosin out of the way
- Myosin and actin connect (crossbridge)
What do we need for a muscle contraction??
- AP from brain tells muscle to contract
- Muscle requires ATP
- Needs calcium to move tropomyosin out of the way
Crossbridge
when myosin and actin connect
Relaxation of muscle
- AP stops
- Calcium goes back to the SR where it is stored
- Actin/myosin cant attach because tropomyosin is in the way
