BIOL235_Chap10 Flashcards
1
Q
skeletal muscle tissue
A
mostly moves skeleton bones
some move skin or other muscles
striated - alternating light + dark bands
voluntary
controlled by neurons of somatic/voluntary nervous system
also some subconsiously - diaphram
2
Q
cardiac muscle tissue
A
only heart muscle
striated
involuntary
beats due to natural pacemaker that initiates contractions
built-in rhythm = autorhythmicity
hormones + neurotransmitters can adjust heart rate by speed/slowing pacemaker
3
Q
autorhythmicity
A
built-in rhythm of natural pacemaker in heart
4
Q
smooth muscle tissue
A
hollow organ walls
blood vessels, airways, abdominopelvic organs, skin with hair follicles
non-striated = smooth
involuntary
some have autorhythmicity like gi tract
like cardiac - regulated by neurons in autonomic/involuntary division of nervous system + endocrine hormones
5
Q
4 key functions of muscular tissue
A
producing body movements
- skeletal - moving body in any way
stabilizing body positions
-skeletal - posture
storing + moving substances within body
- smooth muscle mostly - also cardiac - moving food + allowing storage in urine or stomach
generating heat
- all muscles - shivering = involuntary skeletal contractions
6
Q
4 special properties of muscular tissue
A
electrical excitability - respond to stimuli
contractility - contract force
extensibility - stretch without damage
elasticity - return to original length+shape after contraction or extension
7
Q
muscle fibers (myocytes)
A
cells of organs of skeletal muscles
elongated shapes
muscle cell = muscle fiber
8
Q
subcutaneous layer = hypodermis
A
separates muscle from skin
composed of areolar ct + adipose tissue
provides pathway for nerves, bvs, lymph vessels to enter + exit muscles
adipose tissue of hyperdermis/subcutaneous layer stores most of body’s triglycerides + insulates
9
Q
fascia
A
dense sheet or broad band of irregular ct that lines body wall + limbs + supports + surounds muscles + organs of body
holds muscles with similar functions tog
allows ree movement of muslces, carries, nerves, bvs, lymph vessels, + fills space betw muscles
10
Q
what are the 3 layers of ct that extend from the fascia to protect + strengthn skeletal muscle?
A
epimysium (outer layer, encircling entire muscle)
perimysium (surrounds groups of muscle fibers + sepearates into fascicles/bundles
endomysium (penetrates interior of each fascicle + separates individ from each other - mostly reticular fibers
11
Q
fascicles
A
little bundles of muscles fibers
give cut of meat its grain
meat rips along fascicles
seen with naked eye
12
Q
tendon
A
ropelike combination of epimysium, perimysium, + endomysium that extends beyond muscle
attaches muslce to periosteum of bone
13
Q
aponeurosis
A
when ct elements extend as a broad, flat sheet
14
Q
skeletal muscles are well supplied with
A
nerves + blood vessels
15
Q
which type of muscle tissue has 100 or more nuclei?
A
skeletal muscles
16
Q
sarcolemma
A
plasma membrane of skeletal muscle cell
17
Q
transverse T tubules
A
thousands of tiny invaginations of sarcolemma/pm’s
they tunnel in from surface toward center of skeletal muscle fiber
18
Q
sarcoplasm
A
cytoplasm of skeletal muscle fiber
19
Q
myoglobin
A
red-coloured protein in sarcoplasm of skeletal muscle
binds oxygen molecs that diffuse into muscle fibers from interstitial fluid
releases oxygen needed by mitochonria for atp production
20
Q
myofibrils
A
little threads/small structures the sarcoplasm of skeletal muscle fibers seems to be stuffed with
contractile organelles of skeletal muscle cells
part that make it look striated
21
Q
sarcoplasmic reticulum sr
A
fluid-filled membranous sacs that encircle each myofibril of skeletal muscle fiber
similar to smooth ER in non-muscular cells
22
Q
terminal cisterns
A
dilated + end sacs of the sarcoplasmic reticulum in skeletal cells
butt against transverse T tubule from both sides
23
Q
triad
A
a transverse tubule + 2 terminal cisterns on either side
24
Q
filaments = myofilaments
A
smaller protein structures within myofibrils of skeletal muscle fibers
25
thin filaments
8 nm diameter + 1-2 um long
actin protein
directly involved in contractile process
26
thick filaments
16 nm diameter + 1-2 um long
myosin protein
directly involved in contractile process
27
sarcomeres
basic functional units of a myofibril
compartments which filaments inside a myofibril are arranged in
1 sarcomere extends from 1 Z disc to another
28
Z discs
separate 1 sarcomere from next
z disc - sarcomere - z disc - sarcomere - z disc - etc
29
A band
darker middle part of sarcomere
contains all of thick filaments + a little bit of overlap of thin filaments
30
I band
lighter + less dense area that contains only thin filaments
z-disc passes thru center of each I band
31
what are the parts of a sarcomere responsible for the striated look of skeletal + caridac muscle tissue?
A band - dark
I band - light
32
H zone
narrow zone in center of each A band
contains only thick filaments
I is in thin - I band = thin filaments only
H is in thick - H zone = thick filaments only
33
M line
M - Middle of sarcomere
center of H zone where supporting proteins hold thick filaments together
34
2 skeletal muscle contractile proteins
myosin
actin
35
filaments associated with myosin contractile protein
thick filaments
motor protein
36
filaments assocaited with actin contractile protein
thin filaments
37
2 regulatory proteins of skeletal muscles
tropmyosin - blocks myosin-actin bonding
troponin - changed by Ca2+ and moves tropomyosin away so that myosin can bind with actin + results in muscle contraction
38
what do skeletal muscle structural proteins do
about 12
alignemnt, stability, elasticity, extensibiliyt of myofibrisl
Titin = 3rd most plentiful protein in skeletal muscle (after myosin + actin)
39
Titin
3rd most plentiful protein in skeletal muscle after actin + myosin
big molec
spands from Zdisc to M line, spans 1/2 sarcomere - stabilizes position of thick filament
40
what are contractile proteins?
proteins that generate force during muscle contractions
myosin - thick
actin - thin
41
waht are regulatory proteins
proteins that help switch muscle contracton on/off
tropomyosin - prevents contraction by blocking contractile proteins actin/myosin
troponin - moves tropomyosin + allows contraction
42
what are stuctural proteins
proteins that keep thick + thin filaments of myofibrils in proper alignment, give myofibrisl elasticity + extensibility, + link myofibrils to sarcolemaa + extracellular matrix
Titin = connects z discs + M line of sarcomere = stabilize thick filament position
accounts for myofibril elasticity + extensibility
43
sliding filament mechanism of skeletal muscle
as thin filaments slide inward, I band + H zone narrow + eventually disappear altogether when muscle is maximally contracted
A band + thick filament length doesn't change
when contraction occurs - thin filaments slide inward, z discs get closer together + sarcomere shortens, but fibers don't change length
entire muscle shortens
44
4 steps of contraction cycle
ATP hydrolysis
(myosin head hydrolyzes ATP + becomes energized + oriented. myosin head functions like ATPase, energy from hydrolysis is stored in head/energized - products are attached to head)
90 degree angle
Attachment of myosin to actin
(myosin ehad binds to actin, forming a cross-bridge, releases phosphate group during attachment to actin = cross-bridge)
Power stroke
(myosine head pivots, pulling thin filament past thick filament toward center of sarcomere (power stroke) after power stoke, ADP released form head
head changes to 45 degree angle
Detachment of myosin from actin
as myosin head binds ATP, cross-bridge detaches from actin
myosin + actin detach, head attaches to another ATP to restart
45
excitation-contraction coupling
sequence of events that links excitation (a muscle action potential) to contraction (sliding of filaments)
occurs at triads of skeletal muscle fiber
triad = transverse T tubule + 2 opposing terminal cisterns of sarcoplasmic reticulum
triad is mechanically linked tog by 2 groups of integral membrane proteinS (voltage-gated Ca2+ channels + Ca2+ release channels)
46
what starts skeletal muscle contraction?
inc in Calcium concentration
dec stops it
47
what are the 2 groups of integral membrane proteins that triads are mechanically linked to?
voltage-gated Ca2+ channels (role = serve as coltage sensors that trigger opening of Ca2+ release channels)
Ca2+ release channels
(release large amounts of Ca2+ which can compbine with troponin which can then move tropomyosin so that myosin can bind with actin to cause contraction to occur)
48
Ca2+ - ATPase pumps
in terminal cisternal membrane of sarcoplasmic reticulum
use ATP to constantly transport Ca2+ from sarcoplasm into SR
takes Ca2+ back to SR + undoes what Ca2+ release channels do
49
calsequestrin
molecs of protein that bind to Ca2+ and allow more to be stored in SR
50
length-tension relationship
shows how forcefulness of muscle contraction depends on length of sarcomeres within muslce before contraction begins
as the sarcomre length shortens from optimal, tension that candevelop dec
usually resting muscle fiber length = very close to optimum
51
neuromuscular junction NMJ
synapse betw somatic motor neuron + skeletal muscle fiber
where muscle action potentials arise
52
somatic motor neurons
neurons that stimulate skeletal muscle fibers to contract
53
synapse
region where communication betw 2 neurons occurs
or betw neuron and target cell
betw somatic motor neuron and mucle fiber
54
synaptic cleft
small gap that separates the 2 cells at most synapses
no physical touch of cells so action potential cannot jump from cell to cell
55
how do cells communicate since there is no physical touch?
neurotransmitter
56
axon terminal
the end of the motor neuron at the NMJ
57
synaptic end bulbs
cluster that the axon terminal divides into at the NMJ
the neural part of the NMJ
58
synaptic vesicles
membrane-enclosed sacs in each synaptic end bulb suspended in cytosol
100s of them
59
acetylcholine ACh
thousands of molecules that are inside synaptic vesicles
the neurotransmitter released at NMJ
60
motor end plate
region of sarcolemma opposite synaptic end bulbs
muscular part of NMJ
61
acetylcholine receptors
integral transmembrane proteins to which acetylcholine or ACh binds
the receptors are millinos of them inside motor end plates
62
junctional folds
deep grooves in motor end plate that provide a large surface area for acetylocholine ACh
acetylcholine receptors have lots of them
63
how do nerve impulse (nerve action potential) elicit muscle action potential?
release acetylcholine
activate ACh receptors
produce muscle action potential
terminate ACh activity - aided by acetylcholinesterase AChE enzyme
64
acetylcholinesterase AChE
enzyme that rapidly breaks down acetylcholine so that binding is very brief
breaks into acetyle + choline that can't activate receptor
65
what are the 3 ways muscle fibers can produce ATP?
from creatine phosphate (only muscles can do it)
by anaerobic glycolysis
by aerobic respiration
66
creatine phosphate
energy rich molec found in muscle fibers
first source of energy when muscle contraction begins
quickest formation of ATP
only 15 s of muscle contraction
creatine phosphate, formed from ATP while muscle is relaxed, transferes a high-energy phosphate group to ADP, forming ATP during muscle contraction
67
creatine
small, amino acid-like molec synthesized in liver, kidneys, pancreas + transported to muscle fibers
takes phosphate group from ATP
68
anaerobic glycolysis
occurs in cytosol + produces net gain - 2 ATP
done once run out of creatine phosphate
breakdown of muscle glycogen into glucose + production of pyruvic acid from glucose via glycolysis produce ATP + lactic acid. no O2 needed
69
glycolysis
series of reactions that break down glucose molec into 2 molecs of pyruvic acid
occurs in cytosol + produces 2 ATP
anaerobic
70
anaerobic glycolysis
no O2 needed
yields:
2 lactic acid molecs
2 ATP
buildup of lactic acid though to be causer of muscle soreness
faster than aerobic respiration
2 mins of maximal muscle activity
71
aerobic respiration
series of oxygen-requiring reactions (krebs cycle _ electrol transport chain) that produce ATP, CO2, water, + heat
when O2 present - glycolysis, krebs cycle, electron transport chain can occur
yields 30-32 ATP/glucose molec
catabolized reaction
within mitochondria, pyruvic acid, fatty acids, + amino acids are used to produce ATP via aerobic respiration,
72
muscle fatique
inability of a muslce to maintain force of contraction after prolonged activity
results mainly for cahnges in muscle fibers
factors thought to contribute to fatigue: not enough Ca ions released from SR, depleiton of creatine phosphate, not enough oxygen, depleted glycogen + nuts. buildup of lactic acid + ADP, failure of action potentials in motor neurohn to release enough acteylcholine
73
oxygen debt
added oxygen, over and above resting oxygen consumption that is taken into body after exercise
used to payback/restore metabolic conditions to resting levels
74
recovery oxygen uptake
maybe better term than oxygen dept for elevated use of oxygen after exercise
75
motor unit
1 somatic motor neuron + all skeletal muscle fibers it stimulates
76
twitch contraction
brief contraction of all muscle fibers in a motor unit in response to single action potential in its motor neuron
77
latent period
delay (about 2msec) betw application of stimulus and bgeinning of contraction
muscle action potential sweeps over sarcolemma + Ca ions are released from SR
twitch contraction
78
contraction period
lasts 10-100 msec
when Ca binds to troponin, myosin binding sites on actin are exposed + cross-bridges form
peak tension in muscle fiber
twitch contraction
79
relaxation period
10-100 msec, everything goes back to normal
twitch contraction
80
what are the 3 phases of twitch contractions?
latent period - time from stimulus sent to contraction start
contraction period
relaxation period
81
refractory period
period of lost excitability when right after being stimulated it is unresponsive to another stimuli
characteristic of all muscle + nerve cells
82
wave summation
phenomenon when stimuli arriving at diff times cause larger contractions
when another stimulus after refractory period is over is applied, its contraction will be larger than the initial
83
unfused (incomplete tetanus)
sustained wavering contraction
when skeletal muscle is stimulated 20-30/sec
only partial relaxation betw stimuli
84
fused (complete) tetanus
when sustained contraction where individual twitches can't be detected
stimulated 80-100/sec
85
motor unit recruitment
process in which # of active motor units increases
weakest motor units recruited first, then progressively stronger motor units till can do the force required
produces smooth/not jerky movements
small units recruited for precise activities
large units recruited for things needing more tension but less precision
86
muscle tone
small amount of tautness or rension in muscle due to weak involuntary contractions of motor units even in resting tissues
87
flaccid
limpness of muscle where muslce tone is lost due to the damaging of motor neurons serving skeletal muscle
88
isotonic contraction
muscle contraction where tension (force of contraction) developed in muscle remains almost constant while muslce changes in length
body movements + moving objects
concentric isotonic contractions
+ eccentric isotonic contractions
89
concentric isotonic contraction
isotonic contraction where muscle shortens + pulls on another structure like tendon to produce movement + reduce joint angle
raising book
walking uphill
90
eccentric isotonic contraction
isotonic contraction where length of muscle increases
more muscle damage than o
concentric
lowering book
walking downhill
91
isometric contraction
tension generated istn't enough to exceed resistance to object being moved
muslce done'st change length
important for maintaining posutre + supporting things in fixed position
92
red muscle fibers
skeletal muscles with higher myoglobin content
darker coloured
dark meat on chicken legs
more mitochonria + more blood capillaries
93
white muscle fibers
skeletal muscle fibers with lower myoglobin content
appear lighter
white meat of chicken breast
94
slow oxidative SO fibers
dark red
high myoglobin
lots blood capillaries
large mitochondria
mainly aerobic respiration - but slow ATP hydrolysis
resistant to fatique + good for prolonged sustained contractions for many hrs
slow-twitcch + fatigue resistant
maintain posute + aeoriboc runngin
95
fast oxidative-glycolytic FOG fibers
largest fibers
high myoglobin
lots blood capillaries
dark red
high fatigue resistance
anaerobic glycolysis mostly
faster hydrolysis of ATP
briefer duration than SO fibers
walking + sprinting
96
fast glycolytic FG fibers
low myoglobin
few blood capillaries
few mitochondria
white
lots glycogen + ATP via glycolysis
weightlifting
intence anaerobic
muscle enlargement due to hypertrophy of FG fibers
97
cardiac muscle tissue
principal tissue of heart wall
have z dics + myosin + actin
also have unique: intercalated discs
involuntary
98
intercalated discs
unique feature of caridac muscle tissue
microscopic structures that are irregular transverse thickenings of sarcolemma that connect ends of cardiac mucle fibers to each other
contain desmosomes + gap junctions
99
desmosomes
hold cardiac muscle fibers tog
100
gap junctions
allow muscle action potentials to spread from one caridac muscle fiber to another
101
smooth muscle tissue
usually involuntary
2 types;
visceral (single-unit) smooth muscle tissue (most common)
multi-uint smooth muscle tissue
102
visceral (single-unit) smooth muscle tissue
in skin + tubular arrangements that form part of artery + veing walls + line hollow organs like stomach, intestines, uterus, urinary bladder
most common
autorhythmic
gap junctions
103
multi-unit smooth muscle tissue
individ fibers each with its own motor neuron terminals + a few gap junctions
walls of large arteries, lung airways, arrector pili muslce of hair follicles, iris muscle that adjuts pupil diameter
104
what kind of filaments does smooth muscle contain
thick + thin filaments
but not arranged in striations
also have intermediate filaments
105
caveolae
small pouchlike invaginations of plasma membrane of smooth muscle fibers that contain extracellular Ca2+ for muscle contraction
106
dense bodies
structures that thin filaments attach to in smooth muscle fibers
similar to z discs
107
differences betw physiology of smooth mucle tissue from cardiac + skeletal
contraction in smooth = slower + longer than skeletal
smooth can shorten + stretch more than other muscle types
still use Ca2+ concentration to initiate contraction
108
calmodulin
regulatory protein in smooth muscle tissue that binds to Ca2+ in sarcoplasm
does troponin's job
regulates contraction + relaxation of smooth muscle cells
109
smooth muscle tone
state of continued partial contraction
delayed relaxation of smooth muscle tissue due to slow exit of calcium ions
sustains long-term tone = important for GI tract
110
stress-relaxation response
allows smooth muscle to undergo great changes in length while retaining abiilty to contract effectively
phenomenon where smooth muscle fibers can stretch considerably + maintain contractile function
111
hypertrophy
enlargement of existing cells
cause of growth of skeletal muscle after birth
112
hyperplasia
inc in # of fibers
113
muscle fibers regenerate via
hypertrophy for skeletal
hypertrophy + hyperplasia for cardiac + smooth
