Chapter 12 Flashcards
What are the three types of muscles?
Skeletal, cardiac, and smooth
What is a group of muscle fibres bundled together in connective tissues called?
Muscle fascicle
What does a multinucleate muscle fibre contian?
Myofibrils
What is a sarcomere?
The basic contractile unit of muscle fiber, the drawing in class
What are Z-discs?
Attachment for filaments
What is an m-line?
Connection between adjacent think filaments
What is an a-band?
Gap between the filaments (no actin)
What is the difference between actin and myosin?
Actin is thinner
Does myosin have cross bridges?
Yes, with two heads
What does tropomyosin do?
Wraps around actin filaments and in resting skeletal muscle prevents actin and myosin from generating force
What does troponin do?
Controls binding between tropomyosin and actin and myosin
How far does titan span and what’s its function?
Stabilizes the myosin, and spans from z disk to m line
Fun fact - longest protein in the human body
What do the H-zone and I-band do when filaments overlap?
Narrow
When contraction happens is calcium released or absorbed?
Released
What is the power stroke?
How does ATP provide energy?
- ATP binds to myosin
- ATPase splits atp
- Power stroke
- Myosin releases ADP
What are the three roles of ATP
Energize, unbind, and Active transport of Ca2+
What is a motor unit?
A group of muscle fibers that function together and the single somatic motor neuron that controls them
Recruitment and asynchronous recruitment
System increases contraction force, and A-sync helps avoid fatigue
When a muscle single twitches it is different from summation why?
Because a single twitch a muscle relaxes completely, whereas summation means no relaxation fully
What does summation leading to unfused tetanus mean?
Stimuli are far enough part to allow muscle to relax momentarily
What does summation leading to complete tetanus mean?
Steady tension, and tension decreases rapidly
What type of muscle is the fastest to contract and relax?
Skeletal
