Question | Answer |
Four major functional characteristics of skeletal muscle? | 1.) CONTRACTility
2.) EXCITability
3.) EXTENsinility
4.) ELASTICity |
Contractility? | to shorten w/ force |
Excitability? | to respond to a stimulus |
Extensibility? | to be stretched |
Elasticity? | to recoil |
EPImysium? | (connective tissue sheath) that surrounds the skeletal muscle |
Fascia? | (connective tissue) that surrounds and separates muscles |
Msucle fasciculi (fascicle)? | visible bundles |
PERImysium? | (loose connective tissue) that surrounds fascicle |
Muscle cells? | muscle fibers in fascicle |
Muscle fibers contain _________ ________. | several nuclei |
ENDOmysium? | (connective tissue sheath) that surrounds each muscle fiber |
Each fiber is filled with __________. | myofibrils |
Myofibrils? | threadlike structure that extends from one fiber to another |
2 kinds of (protein) fibers in myofibrils? | 1.) actin
2.) myosin |
Actin myofilaments? | thin; pearls twisted together |
Myosin myofilaments? | thick; bundles of golf clubs |
What do actin and myosin form? | sarcomeres |
Sarcomeres? | basic structure and function of a muscle |
How far do sarcomeres extend? | from z line to another z line |
What do actin and myosin look like? | bands |
Are I bands light or dark? | light |
Is actin or myosin in I bands? | actin |
What is at the center of each sarcomere? | H zone |
What does the H zone consist of? | (only) myosin |
Where in the M line located? | in the middle of the H line |
Is the M line light or dark? | dark |
Outside of the membrane vs inside | outside- positively charged
inside- negatively charged |
The charge difference across membrane is called _________ ________ __________. | resting membrane potential |
Motor neurons are ________ _______ that carry ________ ________ to skeletal muscle fibers. | nerve cells/action potentials |
Axons _______ the muscles and branch. | enter |
Neuruomusclular junction? | (synapse) near the center of the cell |
Motor unit? | a single motor neuron that forms a single cell |
Enlarged nerve terminal? | presynaptic terminal |
Space between the presynaptic terminal and the muscle cell? | synaptic cleft |
Muscle fiber? | postsynaptic terminal |
What do postsynaptic terminals contain? | synaptic vesicles |
Neurotransmitter? | acetylcholine |
Acetylcholinesterase? | enzymes that break down the neuron and muscle cell |
When does muscle contraction occur? | when actin and myosin slide past each other |
When actin and myosin slide past each other during contraction it is called the __________ ___________ _____________. | sliding filament mechanism |
Muscle twitch? | contraction of entire muscle in response to stimulus |
When will the muscle fiber respond to stimulus? | when the stimulus reaches the threshold |
All-or-none response? | when muscle fiber contracts maximally |
Time between stimulus to a motor neuron and the beginning of a contraction is the ______ phase. | lag |
Time of contraction is the ________ phase. | contraction |
Time when the muscle relaxes is the __________ phase. | relaxation |
When muscle remains contracted without relaxing? | tetany |
The increase in # of motor units being activated is called __________. | recruitment |
What does ATP stand for? | adenosine triphosphate |
___ us needed for energy for muscle contraction. | ATP |
Where is ATP produced? | mitochondria |
T or F?
ATP is short-lived and unstable. | true |
When does ATP become more stable? | when it degenerates to ADP + phosphate |
What does ADP stand for? | adenosine diphosphate |
T or F?
It is necessary for muscle cells to constantly produce ATP. | true |
When at rest, can they stockpile? | no |
What CAN ATP store? | creatine phosphate |
What is creatine phosphaste? | a high-energy molecule |
During periods of inactivity, what does exess ATP used for? | synthesize creatine phosphate |
T or False?
The energy stored in creatine phospahte can be accessed quickly and used to produce ATP, then can be used in muscles contraction. | true |
Which respiration is without oxygen? | anaerobic |
Which respiration is with oxygen? | aerobic |
Which is more efficient? | aerobic |
After exercise, does respiration rate remain elevated? | yes |
Why does it remain elevated? | provides oxygen to pay back the oxygen debt |
The __________ _________ is the amount of oxygen needed in chemical reactions to convert lactic acid to glucose and to replenish the depletes stores of creatine phosphate stores in muscle cells. | oxygen debt |
When ATP is used during muscle contraction faster than it can be produced, it results in... | muscle fatigue |
Two types of muscle contraction? | isometric and isotonic |
Iso/metric? | equal/distance |
iso/(T)onic | (t)ension |
Difference between isometric and isotonic? | isometric- tension increases and the length of the muscle doesn't change
isotonic- tension remains the same, and the length changes |
Muscle tone? | constant tension |
What does muscle tension do? | keeps head up and back straight |
Fast-twitch fibers? | contract and fatigue quickly (anaerobic) |
Slow-twitch fibers? | contract slowly and are more resistant to fatigue (aerobic) |
White meat? | fast-twitch fibers |
Dark meat? | slow-twitch |