CH 12b: muscles Flashcards
What does phosophocreatine breakdown produce? what is the enzyme that breaks it down?
short burst of energy (creatine kinase - CK)
What are the most rapid, and efficient store of energy?
CHO (glucose)
- most rapid and efficient store of energy
What does anaerobic glycolysis produce? What are some characteristics of it?
- produces lactate and acid
- quick
- no oxygen required
- small amount of energy released
What is aerobic respiration — what does it produce?
- citric acid cycle and electron transport chain
- slow
- oxygen required
- large amount of energy needed
Can muscle store ATP?
YES! resting muscle stores energy from ATP in the high-energy bonds of phosphocreatine
- working muscle then uses the stored energy
What casuals central fatigue?
Due to CNS
What causes peripheral fatigue?
- due to neuron or muscle
- extended submax exercise leads to depletion of glycogen stores
- Short-duration maximal exertion leads to increased levels of Pi
- Maximal exercise leads to ion imbalances
How does muscle length influence contraction?
- Decreased length of resting fiber: too much overlap does not give room for the myofibrals to shorted causing a contraction
- Increased length of resting fiber: they are too far apart so the myosin heads can not grab onto the actin to perform a power stroke
- Needs to have the optimal resting length (2.0-2.3 cm)
- Figure 12.15
What is a single twitch?
- in a skeletal muscle
- muscle relaxes completely in between stimuli
- single twitches with space in between
What is summation?
stimuli closer together do not allow muscle to relax fully (can be constant GPs or can be varied)
What is summation leading to unused tetanus?
Stimuli are far enough apart to allow muscle to relax slightly between stimuli
What is summation leading to complete tetanus?
Muscle reaches steady tension, if muscle fatigues, tension decreases rapidly
- also called fused tetanus
- no chance for a muscle to relax in between contractions
What is a motor unit?
- consists of one motor neuron and all the muscle fibers it innervates
- a muscle may have many motor units of different types
- one muscle may have many motor units of different fiber types
How do motor units help decrease fatigue?
only a certain number are activated, and when those start to feel fatigued, then the CNS can subconsciously switch motor units on/off
How can smooth muscle me classified?
- by location
- by contraction pattern (tonic, phasic, etc)
- by their communication with neighboring cells (single unit smooth muscle, unitary smooth muscle, visceral smooth muscle, or multi unit smooth muscle)
What kind of control are the esophageal and urinary bladder sphincters under?
tonic control
Look at figure 12.22 so see what the different types of smooth muscle look like
What are single-unit smooth muscle cells?
- connected by gap junctions (enable AP to travel)
- contracts at a single unit
- don’t have to release neurotransmitter on every cell
What is a multi-unit smooth muscle cell?
- not electrically linked
- each cell must be stimulated independently
- EX: eye
Does somatic or autonomic have varicosities or both?
ONLY autonomic!
What are the caveolae?
- areas just outside
- membrane wraps around & hold it
(i THINK, check in book!)
What forms the cytoskeleton in smooth muscles?
- intermediates
- protein dense bodies
- actin attaches to the dense bodies
- each myosin molecule surrounded with actin filaments
Go back and do slides 26-32
What are slow wave potentials?
- series of depolarizations and depolarizations
- potentials fire APS when they reach threshold
