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Chapter 6- Muscles

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
Created by: kstep24