A&p Ch 9 Pt 1

Front 1

3 types of muscle tissue

Back 1

Three types
– Skeletal
– Cardiac
– Smooth

Front 2

prefixes for muscle

Back 2

Myo, mys, and sarco

Front 3

4 characteristic of muscle tissue

Back 3

Special Characteristics of Muscle Tissue
• Excitability (responsiveness or irritability):
ability to receive and respond to stimuli
– Stimulus: change that evokes a response i.e.,
from (-) to (+) or (+) to (-)
• Contractility: ability to shorten forcibly
when stimulated
• Extensibility: ability to be stretched
• Elasticity: ability to recoil to resting length

Front 4

4 important functions of muscle tissue

Back 4

–Movement of bones or fluids (e.g.,
blood, food, feces)
–Maintaining posture and body position
–Stabilizing joints
–Heat generation (shivering = skeletal
muscle)

Front 5

EAch muscle is served by:

Back 5

one artery, one nerve, and one or more veins

Front 6

Where do nerves, arteries, veins enter/exit

Back 6

–Enter/exit near central part of muscle

Front 7

nutrient and oxygen needs for muscle

Back 7

Huge nutrient and oxygen need;
generates large amount of waste

Front 8

Levels of skeletal muscle:

Back 8

Levels of skeletal muscle:
–Muscle
–Fascicle
–Muscle Fiber
–Myofibril or fibril
–Sarcomere
–Myofilament

Front 9

Sarcolemma

Back 9

Sarcolemma = plasma membrane

Front 10

Sarcoplasm

Back 10

Sarcoplasm = cytoplasm

Front 11

T tubules:

Back 11

T tubules: extension of sarcolemma

Front 12

sarcomeres

Back 12

sarcomeres - smallest contractile unit
–Sarcomeres contain myofilaments

Front 13

Myofibrils

Back 13

Myofibrils
• Densely packed, rod-like elements
• ~80% of cell volume• Exhibit striations - perfectly alignedrepeating series of dark A bands and lightI bands

. contain sacromeres

Front 14

Sarcomere

Back 14

Smallest contractile unit (functional unit) of
muscle fiber
• Align along myofibril like boxcars of train
• Contains A band with ½ I band at each
end
• Composed of thick and thin myofilaments
made of contractile proteins

Front 15

H zone:

Back 15

H zone: lighter region in midsection of dark A
band where filaments do not overlap

Front 16

M line:

Back 16

M line: line of protein that holds adjacent thick
filaments together

Front 17

Z disc (line):

Back 17

Z disc (line): coin-shaped sheet of proteins on
midline of light I band that anchors thin filaments
and connects myofibrils to one another

Front 18

• Thick filaments:

Back 18

• Thick filaments: run entire length of an A band

Front 19

• Thin filaments:

Back 19

• Thin filaments: run length of I band and
partway into A band

Front 20

–Actin myofilaments

Back 20

–Actin myofilaments = thin filaments
• Extend across I band and partway in
A band
• Anchored to Z discs

Front 21

–Myosin myofilaments

Back 21

–Myosin myofilaments = thick filaments
• Extend length of A band
• Connected at M line

Front 22

• Myosin

Back 22

• Myosin
• Binding sites for actin thin filaments
• Binding sites for ATP
• Myosin heads act as cross bridges
during contraction

Front 23

Actin

Back 23

Actin
–Has active site for myosin binding
–Tropomyosin and troponin - regulatory
proteins bound to actin

Front 24

Sarcoplasmic Reticulum (SR)

Back 24

Sarcoplasmic Reticulum (SR)
• Network of smooth endoplasmic reticulum
surrounding each myofibril
• Pairs of terminal cisternae form
perpendicular cross channels
• Functions in regulation of intracellular Ca2+
levels
–Stores and releases Ca2+

Front 25

T Tubules

Back 25

T Tubules
• Continuations of sarcolemma
• Increase muscle fiber's surface area
• Conduct impulses to deepest regions of
muscle fiber; reaches every sarcomere
• Associate with paired terminal cisterns to
form triads that encircle each sarcomere

Front 26

In relaxed state

Sliding Filament Model

Back 26

• In the relaxed state, thin (actin) and thick
(myosin) filaments overlap only slightly

Front 27

Sliding Filament Model

in contracting state

Back 27

During contraction, myosin (activity of its
heads) bind to actin = cross bridge, & pulls
the thin filaments toward sarcomere
center, overlapping to greater degree
• Events occur simultaneously in all
sarcomeres – so whole muscle shortens

Front 28

For skeletal muscle to contract
–Activation

Back 28

For skeletal muscle to contract
–Activation (at neuromuscular
junction)
• Must be nervous system stimulation
• Must generate action potential in
sarcolemma

Front 29

For skeletal muscle to contract

-Excitation

Back 29

–Excitation-contraction coupling
• Action potential propagated along
sarcolemma
• Intracellular Ca2+ levels must rise briefly

Front 30

The Nerve Stimulus and Events at the
Neuromuscular Junction

Back 30

Skeletal muscles stimulated by somatic
motor neurons
• Axons of motor neurons travel from CNS
via nerves to skeletal muscle
• Each axon forms several branches as it
enters muscle
• Each axon ending forms neuromuscular
junction with single muscle fiber
– Usually only one per muscle fiber