myology Flashcards
1
Q
specialized cells that use ATP to generate force
A
muscle cells
2
Q
3 types of muscle muscle
A
skeletal, smooth, cardiac
3
Q
functions of muscle tissue
A
body movement, substance movement, control of substance movement, thermogenesis
4
Q
term for maintaining body temperature
A
thermogenesis
5
Q
the ability to respond to certain stimuli by producing electrical signals called action potentials
A
electrical excitability
6
Q
the ability of muscle tissue to generate tension(force) when stimulated by an action potential
A
contractility
7
Q
the ability of a muscle to stretch (lengthen) without being damaged, can still contract when stretched
A
extensibility
8
Q
the ability of muscle tissue to return to its original shape after contraction or stretch
A
elasticity
9
Q
aka striated muscle, alternating light and dark bands. voluntary/conscious control
A
skeletal muscle
10
Q
hierarchy of skeletal muscle organization
A
muscle > fascicle > muscle fibres/cells > myofibril
11
Q
thread-like specialized organelles inside muscle cells. where the muscle contraction occurs. connect to either end of muscle fibre
A
myofibril
12
Q
a bundle of muscle cells
A
fascicle
13
Q
the cell (plasma) membrane of the muscle cell
A
sarcolemma
14
Q
prefix meaning “flesh”
A
sarco
15
Q
tiny invaginations tunnel in from the sarcolemma towards the centre of the muscle fibre
A
tramsverse tibules (T-tubules)
16
Q
cytoplasm of the muscle fibres - lots of glycogen
A
sarcoplasm
17
Q
a protein that binds oxygen that has diffused into the muscle fibre and delivers it to the mitochondria
A
myoglobin
18
Q
true or false: muscle fibres have one nucleus
A
false
19
Q
structure that holds myofibrils in place at opposite ends of a muscle fibre
A
cytoskeletal proteins
20
Q
fluid-filled tubes and sacs running along and surrounding each myofibril
A
sarcoplasmic reticulum
21
Q
functional unit of a myofibril
A
sarcomere
22
Q
name for contractile filaments
A
myofilaments
23
Q
2 myofilaments found in the sarcomere
A
actin and myosin
24
Q
myofilament that makes up the thin filaments
A
actin
25
myofilament that makes up the thick filaments
myosin
26
the overlap of thick and thin myofilaments gives muscles light and dark strips leading to a striated appearance, what does their interaction generate?
force/contraction
27
what must happen for a skeletal muscle cell to generate tension and contract?
stimulation by a nerve signal from a motor neuron
28
a neuron that conducts action potentials to muscle cells
motor neuron
29
when an axon connects with a muscle how does the structure change?
the axon branches out into axon terminals
30
name of the gap between the axon terminals and sarcolemma
synaptic cleft
31
what occurs when an action potential arrives at the axon terminal for a motor neuron
release neurotransmitter (acetylcholine/ACh) which crosses the synaptic cleft
32
junction formed between an axon and a sarcolemma of a number of different muscle cells
neuromuscular junction (NMJ)
33
the mechanism of an action potential triggering the act of myosin 'ratcheting' with actin which has been made available by calcium, provided by the sarcoplasmic reticulum, clearing the way of the binding site for myosin to connect to the actin and generating tension through contraction. When the action potential stops, the sarcoplasmic reticulum absorbs the calcium and tension stops
sliding filament mechnaism
34
the motor neuron and all the skeletal muscle fibres linked to it
motor unit
35
how much activity can the ATP stored in muscle fibres last for?
~3 seconds
36
what are the 3 energy pathways through which more ATP can be generated?
creatine phosphate, anaerobic glycosis, aerobic cellular respiration
37
molecule that stores high amounts of energy in its chemical bonds, when split by an enzyme the energy released is used to reform ATP. The first source of energy used when muscle contraction begins. provides energy for ~3-15 seconds of maximal contraction. no oxygen needed, no lactic acid produced
creatine phosphate (ATP-PCr)
38
when muscle activity continues and PCr is depleted, glucose is used to make ATP. occurs in the cytoplasm. a molecule of glucose is broken into 2 molecules of pyruvic acid and 2 ATP. when oxygen is not sufficiently available pyruvic acid does not got to the mitochondria and is converted into lactic acid, which diffuses out of the cell into the blood. capable of supplying energy for 30-40 seconds
anaerobic glycoysis
39
created from the breaking down of glycogen stored in the cytoplasm/sarcoplasm or from the blood
glucose
40
a metabolic by-product of anaerobic glycolysis. at lower levers of activity it is consumed by other muscle fibres, less active nearby muscles, and the heart. does not accumulate. also converted back into glucose/glycogen in the liver (the Cori cycle). has a half life of 15-25 minutes and is cleared in a matter of hours
lactic acid/lactate
41
this pathway is active when you are able to get oxygen into the cells. oxygen is delivered by myoglobin or from oxygen diffusing from the blood. in the presence of oxygen, pyruvic acid enters the mitochondira and in a series of reactions produces much more ATP than glycolysis. carbs, fats, and proteins can be used in thes process. at rest, cells of the body use this kind of metabolism to generate ATP. in activities lasting longer than 10 minutes 90% of ATP generated comes from this system
aerobic cellular respiration
42
3 main types of skeletal muscle fibres
slow oxidative (type I), fast oxidative-glycolytic (type Ia), fast glycolytic (type IIx)
43
slow-twitch muscle fibres, recruited first, fatigue resistant, used in endurance-type functions, lots of mitochondria/myoglobin/capillaries, generate ATP via aerobic cellular respiration, with imobilization they atrophy faster
slow oxidative (SO) fibres
44
muscle fibres, recruited second, moderately high resistance to fatigue, used in endurance and shorter-duration functions, intermediate amounts of mitochondria/myoglobin/capillaries, generate ATP via aerobic and anaerobic energy pathways
fast oxidative-glycolytic (FOG) fibres
45
decrease in muscle size
atrophy
46
muscle fibres, recruited third, low resistance to fatigue, used in high intensity short duration activities and shorter duration functions, relatively low amounts of mitochondira/myoglobin/capillaries, generate ATP via anaerobic energy pathways
fast glycolytic (FG) fibres
47
action potentials travel down the motor neuron to the muscle fibres, and all fibres in that unit will generate force
motor unit recruitment
48
are all motor units recruited with every contraction?
no
49
do all motor units recruited for a given action contract at different times?
yes
50
which motor units are recruited first
the smallest/weakest
51
are muscle fibre types diverse within a motor unit?
no
52
increasing the amount of force generated involves what two actions?
increase number of motor units recruited, increase frequency of neuronal action potential firing (wave summation)
53
accumulation of action potentials before muscle contraction ends
wave summation
54
length of sarcomeres within a muscle before contraction begins indicates what?
forcefulness of contraction
55
position/length for a muscle to be in to generate the most force
optimal overlap
56
there is a decreased ability to generate muscle tension at what levels of overlap?
excessive and minimal
57
muscle contraction through a range against a resistance that is not changing
isotonic contraction
58
shortening muscle contraction
concentric contraction
59
lengthening muscle contraction
eccentric contraction
60
muscle contraction in which the length of the muscle does not visibly change the resistance to match the strength curve
isometric contraction
61
muscle contraction through a range in which the equipment keeps the velocity of movement constant
isokinetic contraction
62
muscle contraction through a range in which the equipment varies the resistance to match the strength curve
variable resistance
63
the base level of resistance that a muscle has. not strong enough to produce movement
muscle tone
64
a brief contraction of all the muscle fibres in a motor unit in response to a single action potential in its motor neuron
twitch contraction
65
a lack of tone from the nerve being damaged or cut
flaccidity
66
increase in muscle size
hypertrophy
67
inability of a muscle to function at the required level. can be because of energy substrate depletion, metabolic by-products, neurological fatigue, central nervous system fatigue
fatigue
68
Connective muscle tissue, surrounds the entire muscle
epimysium
69
Connective muscle tissue, surrounds the fascilces
perimysium
70
Connective muscle tissue, surrounds the muscle fibres
endomysium
71
decrease in muscle size
atrophy
72
epimysium, perimysium and endomysium are interconnected and extend beyond muscle fibres to connect the muscle to a periosteum or another structure
tendon
73
transition from muscle tissue to tendon
musculotendinous junction
74
transition from tendon to periosteum
tendoperiosteal junction
75
broad flat tendon
aponeurosis
76
tube that surrounds a tendon to protect it
tendon sheath
77
undifferentiated muscle cells, actively involved in muscle repair and regeneration. capacity is limited
satellite cells
78
same actin/myosin arrangement as skeletal muscle. fibres are branched - ends fit tightly together with neighbouring fibres at intercalated discs. anchoring junctions hold them together and gap junctions allow for cells to communicate quickly. involuntary control
cardiac muscle
79
junctions at which neighbouring cardiac muscle fibres fit together
intercalated discs
80
specialized cells within the heart can generate their own electrical signals, the act as a pacemaker
autorhythmicity
81
spindle shaped muscle found in the walls of hollow tubes, have gap junctions, involuntary, slow long lasting contractions
smooth muscle
82
at approximately what age does capacity for skeletal strength begin to decrease? when does it become greater?
25, 50
