Week 2 - Muscle Contraction Flashcards
Name the three types of muscle
cardiac, smooth, skeletal
What type of muscle is under voluntary control?
skeletal
What types of muscle are striated?
skeletal, cardiac
Why are skeletal and cardiac muscle described as striated?
they have a repeating series of cross bands across their length, due to their contractile myofilaments
What are the properties of skeletal muscle cells?
long, multinucleated, commonly called myofibres, overlap in bundles to form fascicles
What are myofibrils composed of?
actin and myosin
What is the dark-staining region of a myofibril known as?
A (anisotropic)-band dArk
What is the light-staining region of a myofibril known as?
I (isotropic)-band lIght
What line is at the centre of the I-band?
Z-line
What line is at the centre of the A-band?
M-line
What is the lighter stained zone in the centre of the A-band?
H-zone
How is the length of a sarcomere defined?
extends from one Z-line to another
What is the thick filament of the sarcomere composed of?
myosin and titin protein
What is the thin filament of the sarcomere composed of?
actin with its associated proteins tropomyosin and troponin
How does myosin appear under a microscope?
What are the features of myosin that are essential for muscle contraction?
globular head has binding site for ATP, ADP and Pi
myosin head binds reversibly to actin
myosin heads have a calcium ion dependant ATPase activity
Explain the development of rigor mortis
after death there is an increase in calcium ions in the sarcoplasm and a decrease in ATP, this leads to tight binding between myosin and actin forming rigid muscle tissue
What is the microscopic unit of skeletal muscle?
fasciculus: bundle of muscle cells
What is the cellular unit of skeletal muscle?
myofiber cell: long multinucleated cell
