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Histology I > Muscle Tissue > Flashcards

Flashcards in Muscle Tissue Deck (28):
1

Characteristics of muscle tissue

Contractility
Conductivity

2

What contributes to the contractility of muscle

Actin, Myosin, ATP

3

Major types of muscles

Skeletal
Smooth
Cardiac

4

Basic overview: Skeletal muscle

Attach to bone
Some in viscera (tongue, pharynx, proximal 1/3 of esophagus)
Striated
Voluntary
Generally fast

5

Basic overview: Smooth muscle

Typically found in viscera (walls of organs)
NO striation
Involuntary
Generally slow (faster from found in eye)

6

Basic overview: Cardiac Muscle

Found only in the heart
Striated
Involuntary
Derived from smooth muscle but structurally similar to skeletal muscle

7

Muscle cell plasma membrane

Sarcolema

8

Muscle cell cytoplasm

Sarcoplasm

9

SER of muscle cells

Sarcoplasmic reticulum

10

Skeletal muscle origin

Myoblasts form myotubes which form Postmytotic myotubes which come together to form multinucleated syncitium known as muscle cell (skeletal muscle fiber)

11

Nuclei of skeletal cell

out on the periphery of the cell

12

contents of skeletal muscle sarcoplasm

myofibrils
give striated appearance
run the whole length of the fiber
Filamentous Mitochondria
lie between myofibrils
source of ATP for contraction
Myoglobin
oxygen binding protein
allows for high [O2] in the muscle fiber

13

Skeletal muscle fiber general organization

Microfilaments (thin and thick) --> Myofibril ---> Skeletal muscle fiber --> Fascicles ---> Muscle

14

Fascicile

bundles of skeltal muscle fibers surrounded by connective tissue sheath

15

Skeletal muscle thin filament components

F-actin
Tropomyosin covering mysosin binding site
Troponin Complex (T, I, C)

16

Troponin T

Binds Tropomyosin to anchor the troponin complex

17

Troponin I

Binds to actin inhibiting the interaction with myosin

18

Troponin C

Smallest Subunit
Lies between Troponin T and Troponin I
Binds to Ca++
Responsible for conf change that moves tropomyosin subsequently exposing myosin binding site

19

Hexagonal Array of Muscle Fibers

1 thick filament (myosin) surrounded by 6 thin filaments)

20

Skeletal Muscle Thick filament

Myosin II

21

Myosin II structure

2 heavy chains
form 2 alpha helices and 2 globular heads (contain
actin and ATP binding domain)
2 pairs of LC ( 4 LC total)

22

Myosin II light chains (skeletal)

Essential Chain
Regulatory Chain

** these do not play a large role in skeletal muscle but play an important role in contraction of smooth muscle

23

A-band

Dark
Contains both thin and thick filaments

24

H-zone

located in A-band
Contains only thick filaments

25

M-zone

located in H-zone
formed by accessory proteins holding thick filaments together ( ex: myomesin)

26

I-band

Light
Primarily contains thin filaments
Conatins Titan and Nebulin

27

Z-line

Bisects I-band
Composed of accessory proteins
Function: provide anchoring point for thin filaments and support the architecture of the myofibril

28

Sarcomere

portion of the myofibril between 2 adjacent Z-disks
2-3 um

** sarcomeres of individual myofibrils are all in register to allow the whole muscle to contract