Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Histology > Muscle Tissue > Flashcards

Muscle Tissue Flashcards

1
Q

What are some properties of the muscle tissue?

A

Contractility (not unique) -actin, myosin and energy (ATP)

Conductivity with each other and also with nerve cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the major types of muscle tissue?

A

Skeletal- fast, attached to bones, can be visceral (found in the head and neck regions -tongue, pharynx, part of esophagus)
Smooth muscle-Mostly visceral but found in the skin (erector pilae) and eyes (muscles of the pupils)
Cardiac muscle- evolutionary from smooth muscle but behaves like skeletal muscle.found solely in heart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the characteristics of the skeletal muscle?

A

Striated
Voluntary
Fast but gets tired quick
Originated from myoblasts which form a multinucleated syncytium (postmitotic myotube)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the composition of the skeletal muscle fibers?

A

Sarcolemma which is the plasma membrane has processes called the T-tubules which are extension of the membrane
Sarcoplasm(cytoplasm)
Sarcoplasmic reticulum which is the depot of calcium ions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the content of the sarcoplasm?

A

Cross striated elements: myofibrils
Peripheral nuclei
Filamentous mitochondria sandwich between myofibrils
Myoglobin- oxygen binding protein and gives skeletal muscle its red color
Glycogen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the organization of the skeletal muscle?

A

Named muscle (biceps,etc) divides into muscle fascicles.
Each muscle fascicle is made of skeletal muscle fibers (skeletal muscle cell)
Each skeletal muscle fiber is made of myofibrils
Each myofibril contains myofilaments
Each myofilament is made of thin and thick filaments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the structure of a myofibril?

A

Hexagonal array with 1 thick filament surrounded by 6 thin filaments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the thin filaments that made the myofibril?

A

F-actin forms a double helix
Tropomyosin form a long filament that sit in the groove, support and strength the actin and block the binding sites for myosin
Troponin complex- not present in smooth muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the composition of the troponin complex?

A

Troponin T-Binds to tropomyosin
Troponin I-Binds to actin -inhibits the actin tropomyosin binding
Troponin C- Binds calcium ions- change the confirmation of the myosin complex to allow binding to actin.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the thick filaments that made the myofibril?

A

Myosin type II made of:
2 heavy chains
2 pairs of light chains

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the characteristics of the heavy chains of the myosin Type II?

A

Form dimer
Coiled into alpha helix
Form 2 globular heads- ATP binding site and Actin binding site

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the characteristics of the light chains of the myosin type II?

A

Attach to the heads
Have essential and regulatory properties.
In skeletal muscle regulatory properties are remnants of evolutionary path

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the organization of the myofibril?

A

Light band formed by thin filaments are the I-band (isotropic)- Z disc
Dark band formed by the thick filaments are the A-band (anisotropic)
Sarcomere=distance between Z disc
H-zone= less dark area in A band made off myosin only
M-line=center of the A band

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the changes that occur during contraction?

A

Sarcomere becomes shorter
I band shrinks
H-zone becomes smaller
A band stays the same

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the accessory proteins of the myofibril?

A

Titin-Attaches myosin to Z disk
Myomesin- Holds thick filaments at M-line
Alpha-actinin- Attaches thin filaments to Z-disk
Nebulin-Helps anchor thin filaments, regulate thin filament during development
Desmin-Forms cross links between myofibrils, attaches Z disk to sarcolemma
Dystrophin- Links actin cytoskeleton to extracellular matrix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the structure of T-tubules?

A

The sarcoplasmic reticulum is a depot of calcium concentration and form terminal cisternae around the T tubules.
The T-tubules and the terminal cisternae on each side form a membrane triad

17
Q

What is the mechanism of the skeletal muscle contraction?

A

Action potential travels down the T-tubule causing and excitation of the sarcoplasmic reticulum which release calcium ions into the sarcoplasm.
Calcium ions binds to troponin C and causes a configuration change of troponin
Tropomyosin is shifted revealing myosin binding site of actin
Myosin binds ta actin =myosin “walking”
Myosin uses ATP to slide actin
No ATP= rigor mortis

18
Q

What is the mechanism of muscle relaxation?

A

calcium activated ATPase membrane pumps pull back calcium ions into SR
Dissociation of calcium ions and troponin C
Myosin binding site of coin concealed by tropomyosin
Contraction stops

19
Q

How do skeletal muscle fibers regenerated?

A

Regeneration is possible through satellite cells that are precursor cells that differentiate into skeletal muscle after injury.
After extensive damage the muscle is replaced by fibrous scar

20
Q

What are the CT of the skeletal muscle?

A

Epimysium- Dense collagenous CT, surrounds the whole muscle
Perimysium-Dense collagenous CT, surrounds the muscle fascicles
Endomysium- Reticular fibers, surrounds individual muscle fibers

21
Q

What are the characteristics of smooth muscle ?

A 
No cross striations
Slow/rhythmic contractions 
Involuntary
Made of myocytes (20-200 microns)
Possess long cigar shaped central nuclei
Poorly organized myofilaments
Thin filaments attached to anchoring points-dense bodies (alpha actinin)
Dense bodies anchored to network of filaments formed by desmin
22
Q

What is the structure of smooth muscle cells ?

A

Sarcoplasm with SR, mitochondria and myofilaments
Sarcolemma possess caveolae which are invaginations to pass AP, and gap junctions
CT are basal lamina and reticular fibers

23
Q

What are the thin filaments of the smooth muscle ?

A

F-actin
Tropomyosin-not masking the myosin binding sites
Caldesmon- Calcium dependent protein, masks the myosin binding sites.
No troponin

24
Q

What are the thick filaments of the smooth muscle cells ?

A

Myosin type II
Possess 2 heavy chains and 4 light chains
Folded when dephosphorylayted
Binds to actin when phosphorylated

25
Q

What are the modes of excitation of smooth muscle?

A

Neural stimulation through the postganglionic fibers of autonomic nervous system, Neurotransmitters(norepinephrine, acetylcholine) are released in the vicinity since all muscle cell do not receive terminal nerves, impulse transmission done through gap junctions
Chemical stimulation through angiotensin II and vasopressin
Mechanical stimulation by passive stretching

26
Q

What is the mechanism of smooth muscle contraction?

A

Calcium ions binds to calmodulin
Calcium ions-calmodulin complex binds to caldesmon opening the myosin binding site
Complex also activates myosin light chain kinase
Myosin light chain kinase phosphorylates myosin
Myosin unfolds and actin binding site opens
Myosin head binds to actin
Sliding of filaments
Shortening of the cell- nucleus becomes corkscrew

27
Q

What is the mechanism of relaxation of the smooth muscle cell?

A 
Calcium ions back into SR
Calcium ions in the sarcoplasm drop
Calmodulin dissociates
Light chain kinase deactivated
Myosin dephosphorylated 
Slow action
Muscle able to prolonged effect by latch state mechanism
Latch state uses for long term contractions and toxine of blood vessels
28
Q

What are the locations of the smooth muscle?

A 
Large hollow organs
Walls of blood and larger lymphatic vessels
Large ducts of glands
GI tracts
Reproductive tract
Urinary system 
Iris and ciliary body
Arrector pilorum muscles
29
Q

Does muscle cell regenerated?

A

Active regeneracvtive response possible through mitosis

Moderate blood supply

30
Q

What are the characteristics of cardiac muscle ?

A 
Striated
Involuntary 
Extensive blood supply
No regeneration 
Central rounded nuclei
Numerous mitochondria
Branching chains of cells
Intercalated disks with transverse portion (desmosomes, fascia adherens) and lateral portion (gap junctions)
T tubules formed diads along Z disks
31
Q

What is the mechanism of cardiac muscle contraction?

A

SER have terminal cisternae not well developed
Mechanism similar to skeletal muscle
Not initiated by nervous system but nervous system able to regulate it
Initiated by cardiac conducting system

32
Q

What are the characteristics of the cardiac conducting system?

A

Purkinje fibers are cardiac conducting cells-modified cardiac myocytes
Purkinje fibers possess few myofibrils and much glycogen
Purkinje fibers form nodes-sinon trial and atrioventricular

Histology (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions