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21 fall: histology > lecture 2 muscles > Flashcards

lecture 2 muscles Flashcards

1
Q

3 types of muscle

A

skeletal
smooth
cardiac

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2
Q

make up of muscles

A

contractile proteins
actin
myosin
proteins specialized in force delivery
ATP production

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3
Q

for muscle to work you need

A

communications: nerves
energy
structural support
contractile proteins

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4
Q

whole muscle is surrounded by ___

A

epimysium

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5
Q

Fasicle is surrounded by ___

A

perimysium

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6
Q

muscle fiber is surrounded by ___

A

endomysium

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7
Q

make up of a muscle from outside to inside

A

epimysium
-muscle (serveral fascicles)
perimysium
-fascicle (several muscle fibers)
endomysium
-muscle fiber
sarcolemma (plasma membrane of muscle fiber
myofibril- chain of sarcomeres
myofilaments

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8
Q

the plasma membrane of the muscle cell/fiber

A

sarcolemma

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9
Q

red blood cell are how big? Can you see them with a light microscope?

A

7 micrometers
yes

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10
Q

can you see myofibrils with a light microscope?

A

no

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11
Q

skeletal muscle has __ nucleus

A

many

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12
Q

nucleus of skeletal muscle are at the ___ of the cell

A

outside

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13
Q

what cells in skeletal muscle can divide and repair and regenerate?

A

satellite cells

live on the outside, moves inside when muscle is injured, fixes things then goes back out

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14
Q

satellite cells lie under the ___ but outside the ___

A

basal lamina (endomysium)

outside the sarcolemma (plasma membrane)

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15
Q

why can’t muscle cells fix themselves?

A

mature muscle cells are post mitotic, unable to divide

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16
Q

deep fascia (dense CT) that envelopes entire muscle and becomes less flexible with aging

A

epimysium

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17
Q

another name for endomysium

A

basal lamina

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18
Q

muscle cells form a ___ syncytium, sheathed by ___ layers of connective tissue. The CT serves as a pathway for ___ and ___ to reach individual muscle cells

A

multinucleated
three
vessels
nerves

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19
Q

single motor neuron and all the muscle fibers it innervates

A

motor unit

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20
Q

small motor units results in ___

A

fine control

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21
Q

large motor units occur in ___

A

large, powerful muscles that do not need fine control

1 neuron= many muscle fibers

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22
Q

each skeletal muscle contraction is initiated by an ___ from an alpha motor neuron

A

action potential

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23
Q

place where nerve interacts with muscle fiber

A

neuromuscular junction

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24
Q

there is ___ point/s of connection between a muscle fiber and its nerve

A

one

neuromuscular junction

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25
Q

motorneuron ends at the ___, where the signal is transferred from the nerve to the muscle across the ___

A

motor end plate
synaptic cleft

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26
Q

synaptic cleft

A

invagination on the surface of the muscle cell coated with basal lamina.

acetylcholine is released from the motor neuron into the synaptic cleft- binding to ACh receptors, which causes a depolarization in the sarcolemma of the muscle cell

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27
Q

there is a __ number of nuclei at the neuromuscular junction

A

high

highly active area of the muscle cell/fiber

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28
Q

Muscle Triad

A

T tubules
2 sarcoplasmic reticulum

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29
Q

action potential across a muscle travel across the sarcolemma and down into the ___. This releases ___

A

T tubules
Calcium (Ca2+)

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30
Q

Where calcium stores live in muscle fiber

A

sarcoplasmic reticulum

release calcium = muscle contracts
take back calcium= calcium ATPase Pumps= muscle relaxes

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31
Q

skeletal muscles have __:
__ T tubules and ___ SR

and cardiac muscles have ___:
__ T tubules and ___ SR

A

Triads
1 and 2

Diads
1 and 1

32
Q

___ are sarcoplasmic reticulum proteins which are linked to the depolarization of T-tubules to release calcium

A

dihydropyride receptor
Ryanodine receptor

33
Q

___ will bring calcium back into the sarcoplasmic reticulum

A

calcium ATPase pump

34
Q

a muscle cell/fiber is composed of ___

A

myofibrils

35
Q

a myofibril is composed of a repeating contractile unit known as a ___.

A

sarcomere

36
Q

the ___ is the basic contractile unit of striated muscle

A

sarcomere

37
Q

the sarcomere is composed of ___ and ___.

A

myofilaments
thin filaments: actin
thick filaments: myosin

38
Q

what is z disk

A

border of sarcomere, where thin filament, actin align

39
Q

what is I band

A

thin actin filaments only
-will reduce when muscle contracts

40
Q

What is A band

A

thick myosin filaments
the whole length of thick myosin filaments, has zone of overlap with actin

41
Q

What is H band

A

part of myosin, thick filament that does not bind with actin

center part of sarcomere

42
Q

What is M line

A

center of sarcomere where myosin filaments line up

43
Q

thin filaments

A

actin
=globular protein called G-actin
G actin form chains of F actin, two chains of F actin wrap together and create a double helix.

Tropomyosin sit in the groove of the two actin strands- extends the length of 7 actin monomers and binds the troponin complex

  • *Troponin** - 3 subunits
  • site of anchoring for myosin, thick filaments

anchored to the Z-disk

44
Q

__ consist of 2 long proteins that sit in the groove between two actin strands

A

tropomyosin

consists of two nearly identical alpha helicl polypeptides twisted around each other, tropomyosin runs in the groove formed by F-actin strands, Each molecule of tropomyosin extends for the length of 7 actin monomers and binds the troponin complex

45
Q

Troponin

A

Troponin T: bind troponin to tropmyosin

Troponin I: binds to actin, inhibits myosin from binding to actin by covering the binding site

Troponin C: binds Ca2+

46
Q

how does Calcium work on actin

A

calcium binds to TN-C (troponin-C), it triggers a conformation change in troponin allowing for the myosin cross bridges to interact with actin

47
Q

Thick filaments

A

myosin

thick filament is composed of 200-300 myosin molecules

anchored to the M line

paired head( cross bridging) and tail (self assembly region) coiled around each other

Head has an actin binding site as well as an ATP binding site

48
Q

Head of myosin has a ___ binding site and a ___ binding site

A

actin

ATP

49
Q

light area of sarcomere in electron microscope is the ___

A

I band where thin filaments are

Z line connects two sarcomeres together

50
Q

_ bands and __ zone shrink during contaction

A

I band (thin only)

H zone (myosin only)

51
Q

Z line/disk/band

A

end of sarcomere where actin attaches

52
Q

A band

A stands for

A

A stands for “anisotropic”

53
Q

I in I band stands for

A

isotropic

54
Q

creatine kinase which helps for ATP is found in the __ band of the sarcomere

A

H

55
Q

__ keeps thick filaments in line

A

titin

56
Q

titin

A

extends from the Z disk to the M line- keep myosin in line, ends are coiled/stretchy will stretch and contract

57
Q

___ will keep actin in line

A

nebulin

58
Q

nebulin

A

extends from the Z band along the length of actin filament, keep actin inline

59
Q

___extends from the sarcolemma between the myofibrils helping maintain the conformation of the fibers during contractions

A

desmin

60
Q

desmin

A

extends from plasma membrane of muscle fiber (sarcolemma)

keep myofibrils in line

61
Q

Force Delivery

A

proteins that deliver force from sarcomere to tendon

62
Q

Cardiac muscle

A

striated

intercalated discs

central nucleus

diads instead of triads

purkinje fibers

bundle of his

63
Q

intercalated dics

A

allow contraction to go from cell to cell quickly, found in cardiac muscle in between cells

allow transmission of the electrical signal to the next cardiac cell to stimulate contraction.

64
Q

specialized cardiac cells that aid in the terminal conduction of the action potential to depolarize cardiac muscle

A

purkinje fibers

65
Q

smooth muscle

A

sheets -covered by epithelium or endothelium based on where it is

bundles in eyes

two directions- inner circular layer, outer longitudinal layer

spindle shape (long stretched out)

not striated- thin and thick lined up randomly throughout cell to allow force contraction when empty or stetched

central nucleus

connected to each other by gap junctions

66
Q

gap junctions in smooth muscles allows ___

A

synchronized overall muscle contraction

67
Q

smooth muscles lack ___ and ___

A

sarcomeres and troponin

68
Q

Most of the calcium ions initiate the contraction of smooth muscles from ___

A

outside the cell, not within

69
Q

contractile proteins

A

generate tremendous forces that can not be transmitted through a normal cell’s plasma membrane or basement membrane.

To enable this force transmission, there is a system of proteins which deliver the force from the myofibrils through the sarcolemma and on to the endomysium.

70
Q

what is the largest contractile protein

A

dystrophin

part of the dystrophin complex of proteins (also known as the costamere).

Dystrophin is an intracellular protein which connects to the myofibrils and extends to the sarcolemma, where it is attached to about 5 other smaller proteins which span the sarcolemma and pass the force on to the endomysium and then on to the tendons/bone.

71
Q

another name for dystrophin complex of proteins

A

costamere

72
Q

mutation in dystrophin protein

A

Duchene’s muscular dystrophy

makes the dystrophin protein unable to transmit force effectively and ultimately leads to the muscle degeneration seen in muscular dystrophy.

73
Q

mild form of muscular dystrophy

A

becker’s dystrophy

when there is a defect in one of the protein in the dystrophin complex of proteins other than Dystrophin

74
Q

how heart pumps

A

The atrial contractions, which occur first, push the blood through the bicuspid or tricuspid valves.

second: push the blood from the base of the ventricles upwards towards and through the valves to the aorta or pulmonary artery.

75
Q

why does the heart have more mitochondria?

A

heart muscle must be very resistant to fatigue, so having a ready supply of energy is really imperative to its health.

76
Q

why is smooth muscle disorganized, not have sarcomeres like cardiac and skeletal?

A

smooth muscle must undergo huge length changes and still generate force

77
Q

smooth muscle lack ___ and ___

A

smooth muscle lacks the troponin tropomyosin system to control contraction.

21 fall: histology (36 decks)

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