Muscle Histology Flashcards
1
Q
3 main points of muscle
A
- Body movement
- Aggrates of special long cells for contrsction
- Actin and myosin
2
Q
Thin myofilament, formed from globular ____ proteins
A
Actin filament
3
Q
thick myofilament consisting of 200-300 ____ molecules
A
Myosin filament
4
Q
cells do not have cross-striations
A
Smooth musle cells
5
Q
cells have cross-striations
A
Striated Muscle cell
6
Q
Striated Muscle cell
attached to bone, responsible for movement
A
Skeletal
7
Q
Striated Muscle cell
restricted to soft tissues (tongue, pharynx, upper esophagus, lumbar part of diaphragm) no bones.
A
Visceral Striated
8
Q
Striated Muscle cell
wall of heart and base of large veins that empty into the heart
A
cardiac
9
Q
Skeletal muscles cells are ____
rich blood supply
A
Multinucleated(formed from fusion of myoblasts)
10
Q
Lenght of skeletal muscle cell depeneds on what?
A
On muscle it makes up
11
Q
Skeletal muscle cells are surroudned by what that aids in force transduction from muscle to tendon
A
Connective tissue
12
Q
How are skeletal muscle connected to bone?
A
Via tendon
13
Q
(inner most)
* CT surrounding individual muscle cells
* composed of reticular fibers, external lamina (basal lamina), and thin areolar tissue
* allows room for capillaries and nerve fibers essential for initiat muscle contraction.
A
Endomysium
14
Q
thicker CT, surrounds and defines fascicles (functional bundles of muscle fibers)
A
Perimysium
15
Q
(outer most) sheet of dense connective tissue which surrounds a collection of fascicles. surrounds entire muscle
A
Epimysium
16
Q
Types of Skeletal Muscle Fibers
- Fatigue resistant motor units
- Large numbers of mitochondria and amounts of myoglobin
- Endurance athletes
long term
A
Type I- Slow oxidative
17
Q
Types of Skeletal Muscle Fibers
- Fast-twitch, fatigue-resistant motor units
- Generate high-peak muscle tension
- Hockey players, mid distance 400-800m sprinters higher concentration.
A
Type IIa- fast oxidative
18
Q
Types of Skeletal Muscle Fibers
- Fast-twitch, fatigue-prone motor (fast) units
- Fastest of all fiber types
- Short-distance sprinters, weightlifters; higher levels of fast glycolytic fibers.
A
Type IIb fast glycolytic
sprinters
19
Q
dark bands (myosin)
A
A band
20
Q
light bands (actin)
A
I band
21
Q
anchor for actin
A
Z line
22
Q
only myosin, no actin
A
H band
23
Q
middle of sarcomere
A
M line
24
Q
Each sarcomere in contraction myosin filament stay stable in center, thick filament slide over thin filament and bring ____ closer together.
A
Z line
25
molecule that polymerizes to form double-stranded to form F-actin
G actin
26
filament in the groove of F-actin 2 in double helix.
Tropomyosin
27
What doe tropomyosin do ?
Masks myosin binding site at rest, doesnt allow actin ot bind, **prevents muscle contraction**
28
3 parts of troponin complex
1. TnC; bind Ca+
2. TnT; bind tropomyosin
3. Tn; bind actin
29
What does the **binding of calcium on TnC **of the troponin complex do?
**Moves the tropomyosin out of way** allowing **myosin and actin to ineract and contract**. Calcium is very important for muscle contraction
30
**actin capping protein** sit at end of actin filament and acts as a cap.
**Tropomodulin**
* maintains + regulate actin filiment lenfh preventing unwinding & degredation
31
Acts as a molecular ruler and adds **stability to thin filaments (actin)**
Nebulin
| lack of would resilt in diff size actin
32
3 parts of myosin thick filament
1. Tail
2. Lever arm
3. Head
33
intertwin to form thick myosin filament
Tail
34
important in movment of thick filament and**allow actin to slide over myosin**
Lever arm
35
important in **grabbing onto acitn**, hydrolyzing atp, and **forming connection btwn myosin and actin for muscle contraction**. Contain actin binding site and ATP binding site.
Head
36
zone in the M-line that has no myosin heads
bare Zone
37
____ shape allow consistent smooth contraction smooth sliding of actin filment onto myosin filament
Spiral
38
# Acessory protien
* prevents excessive stretching of the sarcomere
* One of larget portien in body
Titin
39
# Acessoru {protems
attach titin to Z-line
A-actin
40
# Acessory protiens
forms **stabilizing cross-links between myofibrils**
Desmin
41
# Acessory protiens
**attach titin to M-line**
* Titin stretch from M line to Z line, prevent over stretching.
M-line protiens
42
# Acessory protiens
**links laminin to actin filaments.**
* Important for transfer of contraction form indv sarcomere out into connective tissue for muscle contraction
**Lack of linkage will result in no mvmt in muscle.**
Dystrophin
43
mutation in dystrophin protein.
| Lose ability of transduction of muscle contraction from sarcomere to CT
Muscular dystrophys
44
**X-linked recessive trait**
* primarily affects boy
* Onset is between 3 and 5
* Lose the ability to walk by age 12 and need a respirator by age 20
Duchenne muscular dystrophy
45
**similar to DMD but progression is much slower**
* Onset 3-5 but progression much slower
* Due to mutation in dystrophine gene being different.
Becker muscular dystrophy
46
# Muscle Contraction
5 steps pf muscle contraction
1. Attachment
2. release
3. Bending
4. Force Generatation
5. Reattachemnt
| Duration of each stage depends on muscle type
47
# Muscle Contraction
Activation from CNA causes release of what?
Release of AcH which tavles via nerve to muscle cell and **attaches**
48
# Muscle Contraction
Attachment of AcH to muscle cell result in what?
Depolarizatio of cell and **release of Ca+ ions**
49
# Muscle Contraction
Release of Ca ions causes hwat?
Ca+ ions wil bind to TnC and **moving tropomyosin** from groove alowing **myosin head to acess to actin **
50
# Muscle Contraction
When ATP binds to myosin head what occurs?
Myosin head releases causingzone of hydroxylationo of ATP to ADP **bending** the myosin head
51
# Muscle Contraction
Mysoin head reaches and binds___
Binds actin, dumping phosphate off= muscle contraction.
52
what 2 components are necessary for muscle contraction?
Calcium and ATP
53
When does muscle contraction cycle end?
Muscle cell repolarized by removal of Ca+ and tropomyocin back to block
54
____ regulation is key to contraction and relaxation
**Needed to move tropomyosin out of the way for**
Calcium
55
Calcium reservoir
Most important calcium storage
Terminal cisternae
56
____ carries depolarization signal into muscle and initiates release of calcium
T-tubules
57
Lack of t-tubuled and cisternae would result in what?
Bad muscle contraction because depolarization would only occur on surface cells.
58
the connection between nervous and muscular systems
Neuromuscular junction
59
is the neurotransmitter
AcH
60
Presence of ____ will help terminate signal for muscle contraction
AChE (acetylcholine esterase)
| Toxins prevent AchE over contraction of muscles
61
Lack of AChE results in what 3 things?
Prolonged contraction
62
63
* **Transmits information about muscle stretch**
* Located within muscle
* Overactivation, inhibitory signal to spinal cord and **shut down what is causing overstreach of muscle.**
* Stretching resets muscle spinldles to **improve flexibility.**
Muscle Spindles
64
* **Monitor muscle tension and force of contraction**
* Located within tendon
* Look at development of force, designed to**shut down muscle if too much force produced, to protect from tearing muscle off the bone.**
* Sends inhibitory singal to spinal cord to **shut down m. force generation**
Golgi Tendon Organs
65
what two things protect muscle from **over generation of force and stretch.**
1. Muscle Spindle
2. Golgi Tendon Organs
66
?
Cardiac Muscle
67
* Striated muscle
* intercalated discs
* Fibers arranged end to end and branched
* Single nucleus
Cardiac muscle
68
specialized **attachment sites between adjacent cells**
Intercallated discs
69
**Contain atrial and brain natriuretic factor (ANF and BNF)**
* Diuretics which inhibit renin and aldosterone secretion
Atrial granules in atrac cardica m. cells
70
released in **cases of conjestive heart failure with stress of atria and ventricle muscle**, cells degranulate and release
ANF and BNF
71
Cardiac muscle cells have many of what 2 things?
1. Mitochondria
2. Glycogen storage granules
72
# compoent of intercallated disc
site where **thin filaments anchor to the plasma membrane** this is how muscular contraction goes to thin to think filamanets sliding.
Fascia Adherens
73
# compoent of intercallated disc
bind individual cells together
Maculae adherens
74
# compoent of intercallated disc
provide **ionic continuity between adjacent cardiac muscle cells,** help with coordination of contraction.
Gao junctions
75
Cardiac muscle contraction have longer?
Longer lasting membrane depolarization
76
What is the purpoe of delayed depolarization in cardiac muscle cells?
**causes delay from star of depo, to initiation of contraction**
* allow time for more Ca to build ip
* *Pause btwn atria and ventricular contraction*
77
* **Specialized cardiac conducting cells**
* Exhibit **spontaneous rhythmic contraction** no ext. imput required.
* Resting 100bpm
Purkinje fibers
78
Explain para vs symp stimulation of perkinji fibers
* Para= slow heart rate, decrease impulse freuqency
* SYM= increaase impuse frequency
79
* **Ischemic event in the myocardium**, no blood to area.
* Localized injury replaced muscle cels with fiborous connecitve tissue
Myocardial Infarction
80
Confirmation of suspected ____ due to blood markers TNL and TnT
MI
81
Increase severity of MI leads to what?
Conjestive heart faliure
82
fibrous connective repair tissue cannot contract causing more stretch in cardiac muscle
Conjestive heart faliure
83
* Bundles of sheets of **elongated fusiform cells**
* Thin and thick filaments are loosely arranged; **no stration**
* Connected via gap junctions
Smooth muscle
84
?
Smooth Muscle
85
# Smooth muscle
calmodulin binding protein
Caldesmon
86
# Smooth Muscle
calcium binding protein
Calponin
87
Smooth muscle thin filament contain what (2)?
1. actin
2. smooth muscle form of tropomyosin
88
Smooth Muscle Structure have what?
* Myosin with no **bare zone**
* Side polar formation
89
initiates the contraction cycle
Myosin light chain kinase
90
regulates intracellular calcium concentration
Calmodulin
91
**structural component of dense bodies**; where actin equivalents will **bind to plasma membrane which allows for contraction of smooth m protein.**
α-actini
92
1. Bundles of thin and thick filaments anchored dense body
2. Contraction actin filaments slide in opposite direction shortering myofilament
3. Corkscrew shape shorterning
Smooth muscle cell contraction
93
# Initiation of Smooth Muscle Contraction
stretching of vascular smooth muscle,
mechanical
94
# Initiation of Smooth Muscle Contraction
neural stimulation of smooth muscle
Electrical
95
# Initiation of Smooth Muscle Contraction
responses initiated by **angiotensin II or vasopressin**
Chemical
96
Cardiac and skeletal muscle contracion initiated by what?
Only electical
97
* Calmodulin complex(troponin complex in cardiac and skeletal instead);
* **binds calcium**
* Activates release calcium, binds to calmodulim then binds myosin light chain kinsanse
* Posphylation occurs opening actin binding protein,.
Smooth muscle contraction
98
Smooth muscle contraction can be what?
maintained for long-time periods
| slow, prolonged contraction
99
* **Myosin head attached to actin is dephosphorylated** which reduces ATPase activity
* **Prevents the myosin head from detaching** and keeps muscle in contracted state
| doesnt consume ATP
Latch state
| sphincters!!
100
101
102
103
104
105
Smooth muscle in uterus during pregnancy
hyperplasia.
