Unit 4 💪🏻 Flashcards
1
Q
Excitable (functional properties)
A
Can generate an action potential, stimulated by nerves, hormones,local signals
2
Q
Elastic (functional properties)
A
Can recall when stretched
3
Q
Extensible (functional properties)
A
. Can stretch/expand
4
Q
Contractile (functional properties)
A
Shorten w/ force/pull on attachments
5
Q
Skeletal muscle
A
Voluntary,long, striated, multinucleated, attached to bone (mostly)
6
Q
Smooth muscle
A
Involuntary, tapered,non-striated, single nucleus, hollow organs, vessels
7
Q
Cardiac muscle
A
Involuntary, branched,striated, 1-2 nuclei, intercalated discs,🫀 only
8
Q
Skeletal muscle functions
A
Movement (all locomotion), maintain posture,
Stabilize joints, protection, generate heat
9
Q
Epimysium (💀 packaging)
A
Outermost dense irregular C.t. Layer (separates muscle from organs), allows independent moves
10
Q
Perimysium (💀 packaging)
A
C.t. Surrounding fascicles ( bundles of muscle fibers), ‘grain’ of muscles, allow precise movements
11
Q
Endomysium (💀 packaging)
A
C.t. Around each fiber
12
Q
Aponeurosis (💀 packaging)
A
Sheet of collagen fibers, connect muscles to other muscles or to bone or skin
13
Q
What do skeletal muscles contain?
A
Contains lots of blood vessels ( smallest capillaries, highly interconnected) each fiber connects to motor neuron
14
Q
Myofibril💀
A
Contractile organelle (100s - 1000s per fiber) repeating sarcomere
15
Q
Sacrolemma💀
A
Plasma membrane, conduct electrical impulses that trigger contraction
16
Q
Sacroplasmic reticulum💀
A
Smooth Er (regulates ca +), striations due to myofilaments
17
Q
Actin💀
A
Part of thin filament
18
Q
Myosin💀
A
Make up thick filament
19
Q
What does myofibril contain?
A
I band, A band, H zone, m line, sacromere, Z disc
20
Q
Sacromere💀
A
Functional unit of skeletal muscle,. Thick/thin filaments, repeating unit in my fibril
21
Q
What does sacromere contain?
A
Actin, troponin +tropomyosin, thick filaments, myosin
22
Q
I band
A
Thin filaments only (light bond)
23
Q
A band
A
Thick + thin filaments (dark band)
24
Q
H zone
A
Thick filaments only W/ in A band
25
M line
Anchor thick filaments, elastic fibers
26
Z disc
Tie everything together, microscopic banding pattern, thin filaments are anchored
27
Actin
Myofilament w/ binding sites for myosin heads, thin filament
28
Myosin
Myofilament ( 300 / filament) w/ heads that bind actin
29
Troponin+ tropomyosin=
Regulatory problems
30
Sliding filament theory?
Actin filaments are pulled closer by myosin, z-discs move closer, h-bands shrink, A bands stay put (contraction, actin and myosin overlap completely)
31
Crossbridge
With Ca + present, 'cocked'myosin heads bind to actin
32
Power stroke🌉
Myosin pulls actin toward m-line
33
Cross bridge cycling steps
Crossbridge, power stroke, an 300 myosin heads on thick filament, sacromere, myofibril, myosin head detached by ATP, ATP splits and recooks head, form crossbridge, continues until no ATP or Ca
34
① ATP and muscle contraction
Active site on actin exposed as Ca binds to troponin
35
② ATP and muscle Contraction
High energy (adp+p)myosin head binds actin =crossbridge
36
③ ATP and muscle contraction
During power stroke, p released and head pivots forward, ADP released =↓ energy state
(Notice crossbridge still intact)
37
④ ATP and muscle contraction
ATP attaches to myosin head, crossbridge detaches
38
⑤ ATP and muscle contraction
Myosin head hydrolizes ATP →adp+p= recocked/high energy
39
Source of ATP - creatine phosphate
- Stored ATP used up in seconds
- regenerates ATP for 15 seconds
40
Sources of ATP - anaerobic respiration
- High demand = rapid ATP delivery
- glycolysis (breaking glucose) =2 ATP lactic acid (from pyrurate)
- very rapid, very expensive (only 2 atp/gluccse)
- about 60 sec., O2 not required
41
Sources of ATP - aerobic respiration
- Lower demand = O2 can be used
- 2 ATP from glycolysis +pyruvate sent to mitochondria = 36 ATP per glucose.'
- hour sustained activity+ resting ATP
42
Oxygen debt (post exercise excess oxygen consumption)
- Oxygen intake Î after exercise
- resting ATP, cp, and other fuels restored
- lactic acid metabolism, cell repair adaption
- until resting conditions restored (3-40hrs)
43
Muscle strength
# Of fibers / muscle does not change, genetically determined
44
Stress (muscle)
Production of more sarcomeres and myofibrils = stronger, losing it=atrophy
Use IT OR lose IT
45
Muscular dystrophy = inherited disorder
- Muscle fibers degenerate (atrophy) abnormally
- duchenne muscular dystrophy (dmd ) fatal by early 20’s
- sarcolemma
46
Isotonic
Muscle moves load (maintain same tone)
47
Concentric (isotonic)
Muscle shortens
48
Eccentric ( isotonic)
Muscle lengthens
49
Isometric
Muscle contracts, but load remains still, often load exceeds strength of muscle
50
Motor unit
-1 motor neuron + all associated muscle fibers
- small (4 fibers) to large (1000'S fiber)
-Small control fine movements (like eyes)- easily excited
-Large units - gross movements
51
Recruitment
Larger motor units 'recruited' until goal reached
- small more excitable units recruited 1st
- larger, less excitable units recruited later
- muscles exhibit 'graded' response, ex. Matches load
52
What does fiber length affect?
Tension
53
What do thick and thin filaments have to do to develop tension?
Must overlap
54
80% -120% resting muscle length =
Greatest possible tension
55
Muscle twitch=
Single contraction (1 AP)
56
Latent period (muscle twitch)
AP along sarcolemma down tubules
57
Contraction period (muscle twitch)
Ca binding troponin, cross bridges forming
58
Relaxation period (muscle twitch)
Ca pumped back to SR, tropomyosin covering binding site
- last 100 m sec, depending on fiber type
59
Single AP =
Twitch
60
Wave summation
- If 2nd AP arrives before end of relaxation period,
- more ca in sarcaplasm = more active sites exposed = more cross bridges
-↑ frequency than motor = greater tension per muscle fiber
61
Stimulation frequency, tetanus
When max tension achieved
62
Incomplete tetanus
Fiber quivers due to relaxation phases
63
Complete tetanus
Stimulation frequency ↑ enough
64
Treppe - 'staircase' effect
- max stimulation of dormant muscle generates 50% of max tension
- repeated max stimulus = gradual ↑ to max tension
- due to heat and extra ca
65
Muscle tone
Some fibers are contracting even at 'rest'
66
What does muscle tone provide?
Fiber contraction alternates to provide tone,
-Involuntary, keeps muscles ready for action
67
Hypotonia ( muscle tone)
Damage to direct nerves= lack of tone (atrophy)
68
Hypertonia. (Muscle tone)
Excessive tone, inhibitory nerve damage = spastic when stretched
69
Types of muscle fibers
Speed of ATPases (ATP splitters), ATP forming pathways (oxidative/glycatic), slow oxidant fibers, fast oxidative fibers, fast glycolytic fibers
70
Speed of ATPases (ATP splitters)
2 general fiber types = slow and fast (2x faster)
71
ATP forming pathways
- Oxidative fibers - use aerobic respiration
- glycolic fibers - use anaerobic respiration
72
Slow oxidative fibers (so)- slow ATPases
- Aerobic ATP production - lots o' mitochondria
- myoglobin - 02 carrying molecule = dark meat,
- thin, less tension, fatigue resistant (posture, joint stability)
73
Fast oxidative fibers (fo)- fast ATPase (intermediate fibers)
- aerobic ATP, lots o' mitochondria
- little myoglobin, intermediate tension (walking)
74
Fast glycolytic fibers (fg) - fast ATPase
- Anaerobic few mitochondria/myoglobin
- lots o' glycogen
75
Endurance exercise = mainly slow fibers
- More mitochondria = more aerobic ATP
- more myoglobin = extra 02
- more capillaries = angiogenesis
- not so much hypertrophy= ↓ blood flow
- all= greater endurance
76
Resistance exercise = mainly Fg fibers
Short term, powerful movements required (anaerobic)
-↑ in my fibril #=↑ in muscle fiber size
-↑ in c.t.
- no significant î in mitochondria or capillaries (02 delivery not critical)
-Hypertrophy= ↑ muscle size
77
Atrophy
- Loss of muscle mass
- lack of use=atrophy
- atrophy due to aging= sarcopenia
78
What does cardiac muscle do?
* Pumps blood
- lots o' mitochondria + myoglobin (aerobic atp)
- autorythmic
-î and ↓ by ANS (autonomic nervous system)
79
Cardiac muscle contraction
-Functional synoytium (contracts-like 1 big cell) due to gap junctions.
-Long AP'S due to influx of Ca from extracellalar fluid (long contraction time)
- ca triggers contraction, but most from outside cell
80
Autorhythmic (cardiac)
Contractions via self-excitable ‘ pacemaker' cells
81
Contraction of smooth muscle
- ca enters sarcoplasm (from outside cell + sr)
- calmodulin activated → myosin kinase activated
- ATP on myosin heads.→ ADP + p
- maintain contractions for long periods, ↓power contract., not much ATP
- some ca in sarcoplasm = maintain tone
- latch bridges = some intact w/o ca
82
What stimulates smooth muscle contraction?
Ca, most stored outside cell, no sr
83
Smooth muscle stimulation
- Natural (ANS) stimulation of smooth MT= neurotransmitters released from varicosites
-Digestive tract smooth muscle contains pacesetter cells = rhythmic contraction
- other triggers include hormones and local factors ''
84
Single unit (smooth muscle organization)
- Single-unit = smooth muscles linked by gap junctions (aka visceral muscle)
- most common, 1 cell stimulated causes entire layer to contract
- often exhibit stretch-relaxation response(for storage stomach/ bladder)
85
Multi-unit (smooth muscle organization)
-Few gap junctions, each cell requires stimulation
-Much finer control (eyes,respiratory)
86
Origin
-Anchoring point, music attachment site does not move
87
Insertion
Muscle attachment sites that moves when muscle contracts
- insertion always moves toward origin
88
Prime mover(muscle interactions)
(Aka against)- muscle that contributes most to a particular movement
- biceps brachii = prime mover during elbow flexion
89
Synergism (muscle interactions)
Muscle that aids/help coordinate desired movement
- brachialis+brachioradialis help prevent undesirable rotation and also assist an elbow flexion
90
Antagonist(muscle interactions)
- Muscle w/ opposite action to prime mover
- helps maintain position /control rapid movements
91
Fixator (muscle interactions)
Type of synergism that keeps joint stable
92
Parallel(non -fusiform) fascicle arrangements
- Flat, fascicles along long axis
93
Parallel-fusiform(fascicle arrangements)
Rounded and tapered to tendons(thick middle =belly)
- circular, convergent
94
Unipernate (fascicle arrangements)
Like a feather, fascicles angled along on side of tendon
95
Step 1: the neuromuscular junction(excitable contraction)
-Each fiber innovated by motor neuron
- connection = neuromuscular junction(NMJ)
- 3 parts= synaptic end bulb (knob),synaptic cleft, motor end plate
96
Synaptic end bulb(knob)
- end of motor neuron, stores acetylcholine (ACH)
97
Synaptic cleft
- gap b/n cells, ACH diffuses across
98
Motor end plate
- sarcoma section, contains ACH receptors
99
Step 2: excitation contraction coupling
- Action potential arrives at synaptic knob
-Voltage-gated Ca channels open, ca enters knob
- 3 key paints of ACH and receptors
- voltage gated Na channels that trigger AP along sarcoma fiber officially excited
- ACH quickly degraded by acetylcholnesterace = precise control of contraction
100
Key points of excitation contraction coupling
- ACH released via exocytosis from synaptic vesicles
- ACH diffuses across synaptic cleft, bind w/ACH receptors on motor end plate
- receptors open and allow Na intosarcoplasm= depolarization
101
Resting membrane potential. (Don’t need for essay) step 3?
- Muscle fibers maintain a voltage across sarcolemma, i.e. Polarized
If enough Na, voltage gated Na channels open, propagate AP like dominos)
102
Step 4: ap travels ↓ t-tubules
- T-tubule - transverse' tubule, extension of sarcolemma w/in sarcopiasm
- terminal cistern-sr surrounding t-tubules,store Ca
103
5th step: contraction phase
- AP ↓ t-tubules stimulate Ca channels on terminal cistern to open
- Ca floods sarcoplasm
- ca binds to troponin
- troponin moves tropomyosin to reveal actin binding sites, contraction!
104
Rhythmic contraction(smooth muscle stimulation
Digestive tract smooth muscle contains pacesetter cells = rhythmic contraction
105
Tendons
Tough, rope -like structures that connect muscle →bone
106
Sarcoplasm💀
Cytoplasm of muscle fibers, contains enzymes and organelles for muscle function
107
Terminal cisternal
Large chambers in sr of muscle cells that store ca and release to start contraction
108
Why does skeletal fiber appear striated?
Highly organized arrangement of contractile proteins- actin and myosin, w/in their myofibrils, creating bands of light and dark sarcomeres
109
Thick filaments
- Main protein: myosin,
- function: provide motor protein that generate force for contraction
110
Thin filaments
- Protein: actin
- function: act as the track along which the myosin heads moving during contraction
111
Neuromuscular junction (Nmj)
•Synaptic connection between the terminal end of a motor nerve and a muscle
• synaptic knob, synaptic deft-motor end plate
112
What stimulates ACH release?
- Neurotransmitter released by motor neurons at NMJ
113
What is action potential?
- Rapid electrical signal that travels along a nerve cell membrane, generated by opening of voltage gated Na, cause rapid depolarization of membrane, propagating signal
114
What is ache, why is it important?
- acetylcholinesterase in NMJ,
-Immediately breaks down and hydrolyses ACH
115
Triad
- Substructure of SKM that coordinates excitation contraction, made up of 2 terminal cistern of s/r
116
Function of triad
- Translate: action potential from plasma membrane to sr, initiates calcium flow to cytoplasm/ contraction
117
Role of ATP
Provide energy needed for myosin head to detach from actin, allowing muscle to relax and prepare for new contraction
118
Why does rigor morris occur?
When someone dies, ATP prod. ↓, leading actin and myosin becoming permanently bound tg, causing muscles to stiffen and remain contracted due to lack of energy to detach
119
What causes muscles to relax?
When motor protein myosin in sarcomere releases actin
120
Tetanus
Serious bacterial infection that affects nervous system and muscle
121
Intercalated disc
Correction point between. Individual cardiac cells, allowing ↑ electrical impulses and mechanical fro force through heart
122
Varicosity (smooth)
Enlargement of neuron that ↑ neurotransmitter,
123
Dense body (smooth)
Anchor thin filaments n sm,
124
Calmodulin
Protein that regulates calcium dependent signals
125
Fascicle
Bundle of skeletal muscle fibers running parallel to each other, enveloped by perimysium
126
What is role of acetylcholine ( ACH )
Stimulate muscle contraction
127
What is a myofibril?
Rod - like unit within muscle fibers
128
What structure is responsible for the striated look of a skeletal muscle
Sarcomere
129
What protein blocks the myosin-binding site?
Tropomyosin
130
What causes muscles to relax?
Break ↓ of acetylcholine
131
What are the sources of ATP in skeletal muscle
Creative phosphate, glycolysis, and oxidative phosphorylation
132
What is oxygen debt *
Amount of oxygen required to oxidize lactic acid and replenish ATP stores after exercise
133
What is a isotonic contraction
Contraction where muscle length changes while generating force
134
What is an isometric contraction?
Contraction where the muscle length remains constant while generating force
135
How does recruitment help determine overall contraction strength?
Increasing the # of of motor units activated
136
How does stimulation frequency affect contraction strength?
Higher frequency of stimulation leads to stronger contractions
137
What is wave summation *
↑ in muscle contraction strength due to rapid stimulation
138
What is tetanus?
Sustained muscle contraction due to rapid stimulation
139
What are the 3 different skeletal muscle fiber types?
Slow oxidative, fast oxidative, fa fast glycolytic
140
What determines each category of skeletal muscle finer type?
ATPases activity and respiratory pathway
141
What are slow oxidative fibers adapted for?
Endurance and continuous contraction
142
What are fast glycolytie fibers adapted for?
Short bursts of power and speed
143
How do muscles adapt to resistance exercise?
↑ in muscle fiber size and strength
144
What is a variscosity in smooth muscle?
Swelling along a nerve finer that releases neurotransmitters
