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Flashcards in Chapter 9 Deck (71)
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1

Muscle Tissue

Nearly 1/2 the body's mass
Function:
-Chemical energy to movement

2

Types of Muscle Tissue (3)

Skeletal
Cardiac
Smooth

3

Prefixes of Muscle Involvement (3)

Myo, Mys, Sarco

4

Skeletal Muscle Tissue

-Organs attached to bones and skin
-Muscle Fibers
-Striated
-Voluntary
-Contract rapidly, tire easily, powerful
-Require nervous system stimulation

5

Cardiac Muscle Tissue

-Only in heart, bulk in heart walls
-Striated
-Can contract without nervous system stimulation
-Involuntary

6

Smooth Muscle Tissue

-In walls of hollow organs
-No striations
-Can contract without nervous system stimulation
-Involuntary

7

Special Characteristics of Muscle Tissue

-Excitability (responsiveness)
-Contractility (contract)
-Extensibility (Stretchable)
Elasticity (Recoil)

8

Muscle Functions (8)

-Movement
-Posture
-Stabilization
-Heat
Can also
-Protect Organs
-Forms Valves
-Controls Pupil Size
-Causes "Goosebumps"

9

Skeletal Muscle

Each muscle served by one artery, one nerve, and one or more veins
-Run together in connective tissue sheaths
-Every skeletal muscle fiber supplied by nerve ending that controls its activity
-Huge nutrient and oxygen need, generates large amount of waste

10

Connective Tissue Sheaths of Skeletal Muscle

Supports cells, reinforce whole muscle
External to internal
-Epimysium
-Perimysium
-Endomysium

11

Epimysium

Dense irregular connective tissue surrounding entire muscle

12

Perimysium

Fibrous connective tissue surrounding fascicles

13

Endomysium

Fine areolar connective tissue surrounding each muscle fiber

14

Fascicles

Groups of muscle fibers

15

Skeletal Muscle Attachment

Two Places
-Insertion
-Origin

16

Insertion

Movable bone

17

Origin

Immovable/less movable bone

18

Microscopic Anatomy of Skeletal Muscle Fiber

Long, cylindrical cell
-up to 30cm long
Sarcoplasm=cytoplasm
-Glycosomes for glycogen storage
-Myoglobin for oxygen storage
Modified structures: myofibrils, sacroplasmic reticulum, and T tubules

19

Myofibrils

Densely packed, rodlike elements
-about 80% of cell volume
Contains sarcomeres contractile units
-Sarcomeres contain myofilaments
Exhibit striations- perfectly aligned repeating series of dark bands and light bands

20

Sarcomere

-Smallest contractile unit
-Align along myofibril like boxcars of train
-Composed of thick and thin myofilaments made of contractile proteins

21

Myofibril Banding Pattern

Orderly arrangement of actin and myosin myofilaments within sacromere
-Actin
-Myosin

22

Actin Myofilaments

Thin Filaments

23

Myosin Filaments

Thick Filaments

24

Structure of Thick Filament

Composed of protein myosin
Each of 2 heavy and four light polypeptide chains
-Myosin tails contain 2 heavy polypeptide chains
-Myosin heads contain 2 light polypeptide chains
--Act as cross bridges during contraction
--Binding sites for actin of thin filaments
--Binding sites for ATP

25

Structure of Thin Filament

Double strand of fibrous protein
Bears active sites for myosin head attachment during contraction
Tropomyosin and Troponin- regulatory proteins bound to actin

26

Sacroplasmic Reticulum

Network of smooth endoplasmic reticulum surrounding each myofibril
-Run longitudinally
Pairs of terminal cisterns form perpendicular cross channels
Functions in regulation of intracellular Ca2 levels
-Stores and releases Ca2

27

Sliding Filament Model of Contraction

Generation of force
Does not necessarily cause shortening of fiber

28

Sliding Filament Model of Contraction

In relaxed state, thin and thick filaments overlap only at ends of A band
Sliding filament model of contraction
-During contraction, thin filaments slide past thick filaments > Actin and myosin overlap more
-Occurs when myosin heads bind to actin > cross bridges

29

Sliding Filament Model of Contraction

Myosin heads bind to actin, sliding begins
Cross bridges form and break several times, ratcheting thin filaments toward center of sacromere
-Causes shortening of muscle fiber
-Pulls Z discs toward M line

30

Skeletal Muscle to Contract

Activation (at neuromuscular junction)
-Nervous system stimulation
-Must generate action potential in sarcolemma
Excitation-Contraction Coupling
-Action potential propagated along sarcolemma
-Intracellular Ca2+ levels must rise briefly