Nucleus Muscle fiber Endomysium Striationstycmhoffman.com/commonfiles/bio201/Ch11MuscleTissue1.pdf · Neuromuscular junction Skeletal muscle fibers Spinal cord Motor neuron 1 Motor

1

Fig. 11.1

Endomysium

©Ed Reschke

Nucleus

Muscle fiber

Striations

Copyright © McGraw-Hill Education. Permission required for reproduction or display.

2

Openings intotransverse tubules

Sarcoplasmicreticulum

Musclefiber

Nucleus

A band

I band

Z disc

Mitochondria

Myofibrils

Myofilaments

SarcoplasmSarcolemma

Transverse tubuleTerminal cisternae

Triad:


Fig. 11.2

3


TailHead

(a) Myosin molecule

Myosin head

Tropomyosin Troponin complex G actin

Thick filamentThin filament

(c) Thin filament

Bare zone

(b) Thick filament

(d) Portion of a sarcomere showing the overlap of thick and thin filaments

Fig. 11.3

4


Endomysium

Linking proteins

Basal lamina

Sarcolemma

Dystrophin

Thin filament

Thick filament

Elastic filament

Fig. 11.4

5


a: ©Donald Fawcett/Visuals Unlimited

Nucleus

Sarcomere

Z disc M line

H band

I band A band I band Indi

vidu

al m

yofib

rils

12

34

5

(a)

I bandSarcomere

H bandA band

Thick filamentThin filament

Elastic filamentZ disc(b)M line

Z disc

I band

Fig. 11.5

6

Table 11.1

7


Neuromuscularjunction

Skeletalmusclefibers

Spinal cord

Motorneuron 1Motorneuron 2

Fig. 11.6

8


(b)

Nucleus

Nucleus

Motor nervefibers

Neuromuscularjunction

Muscle fibers

100 µm

Motor nerve fiberMyelin

Schwann cell

Basal lamina

Synaptic cleftSarcolemma

Sarcoplasm

Synaptic knob(a)

Synaptic vesicles(containing ACh)

Ach receptor

Junctional folds

MitochondriaMyofilaments

a: ©Victor B. Eichler

Fig. 11.7

9

Table 11.2

10

K+

Binding of ACh to receptor Opening of ligand-regulated ion gate;creation of end-plate potential

4

Opening of voltage-regulated ion gates;creation of action potentials

5

3

ACh receptor

Plasmamembraneof synapticknob

Na+

Sarcolemma

MotornervefiberSarcolemma

ACh

Sarcolemma

K+

Synapticcleft

Na+

Acetylcholine (ACh) release2Arrival of nerve signal

ACh

Ca2+ enterssynaptic knob

Synapticknob

Synapticvesicles

AChreceptors

Voltage-regulatedion gates

ACh

1

Fig. 11.8

Nerve signal


11


Binding of calciumto troponin

8 Shifting of tropomyosin;exposure of active siteson actin

9

Calcium released fromterminal cisternaeAction potentials propagated

down T tubules6 7

Ca2+

Ca2+

Ca2+

T tubuleTerminalcisternaof SR

Myosin

Ca2+Troponin

Active sites

Tropomyosin Actin Thin filament

Sarcoplasmic reticulum

T tubule

Fig. 11.9

12


Troponin Tropomyosin

ADP

Myosin

10

ATP

13

Cross-bridge:ActinMyosin

ADP

11

ADPPi

12

Z

I A I

Z

Appearance of contracting sarcomere

Pi

Pi

Fig. 11.10

Myosin

Hydrolysis of ATP to ADP + Pi;activation and cocking of myosin head

Binding of new ATP;breaking of cross-bridge

Power stroke; sliding of thinfilament over thick filament

Formation of myosin–actin cross-bridge

13

Cessation of nervous stimulationand ACh release

AChE

ACh

ACh breakdown byacetylcholinesterase (AChE)

Terminal cisternaof SR

Reabsorption of calcium ions bysarcoplasmic reticulum

Return of tropomyosin to positionblocking active sites of actin

Tropomyosin

Loss of calcium ions from troponin

Ca2+

Ca2+

Ca2+ Ca2+

14

16

15

17

18

ADP

ATP

Pi

Fig. 11.11Copyright © McGraw-Hill Education. Permission required for reproduction or display.

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Optimum resting length(2.0–2.25 µm)

z z

Overly contractedz z Overly stretched

z z

1.0

0.5

0.01.0 2.0 3.0 4.0

Sarcomere length (µm) before stimulation

Rel

ativ

e te

nsio

n ge

nera

ted

upon

stim

ulat

ion

Fig. 11.12

15


Contractionphase

Relaxationphase

Latentperiod

Time

Mus

cle

tens

ion

Time ofstimulation

Fig. 11.13

16


Stimuli to nerve

Proportion of nerve fibers excited

Responses of muscle

Threshold

1 2 3 4 5 6 7 8 9

987654321

Tens

ion

Stim

ulus

vol

tage

Maximum contraction

Fig. 11.14

17


(a) Low stimulus frequency

Muscle twitches

Mus

cle

tens

ion

Temporal summationand incomplete tetanus

Complete (fused) tetanus

Stimuli(b) Physiologicially normal stimulus frequency (c) Unnaturally high stimulus frequency

StimuliStimuli

Fig. 11.15

18


Muscle developstension but doesnot shorten

No movement

(a) Isometric contraction

Muscle shortens,tension remainsconstantMovement

(c) Isotonic eccentric contraction(b) Isotonic concentric contraction

Muscle lengthenswhile maintainingtension

Movement

Fig. 11.16

19


Leng

th o

r Ten

sion Muscle

tensionMusclelength

Isometricphase

Isotonicphase

Time

Fig. 11.17

20


Repayment ofoxygen debt

40 seconds

Mode of ATP synthesis

Duration of exercise10 seconds0

Aerobic respirationusing oxygen frommyoglobin

Phosphagensystem

Glycogen–lactic acidsystem(anaerobicfermentation)

Aerobicrespirationsupported bycardiopulmonaryfunction

Fig. 11.18

21


ADP

AMP

Creatinephosphate

Creatine

Myokinase

Pi

ADP

ATP

ADP

Creatinekinase

Pi

ATP

Fig. 11.19

22

Table 11.3

23

Table 11.4

24

Table 11.5

25


Single-unitsmooth muscle

Synapticvesicle

Varicosities

Mitochondrion

Neurotransmitterreleased

Autonomicnerve fiber

Fig. 11.21

26


Mucosa:

EpitheliumLamina propriaMuscularismucosae

Muscularis externa:Circular layerLongitudinallayer

Fig. 11.22

27

Copyright © McGraw-Hill Education. Permission required for reproduction or display.Fig. 11.23

Autonomicnerve fibers

Varicosities

Gap junctions

(a) Multiunitsmooth muscle

(b) Single-unitsmooth muscle

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(a) Relaxed smooth muscle cells

Intermediate filamentsof cytoskeleton

Actin filaments

Dense bodies

Myosin

(b) Contracted smoothmuscle cells

Fig. 11.24

29


INTEGUMENTARY SYSTEMFacial expressions result from the action of muscles on the skin.

LYMPHATIC/IMMUNE SYSTEMMuscle contractions aid flow of lymph; exercise elevates levels of immune cells and antibodies in circulation; excessive exercise can inhibit immunity.

RESPIRATORY SYSTEMMuscle contractions ventilate the lungs; muscles of the larynx and pharynx regulate airflow; CO2generated by muscular activity stimulates respiration; abdominal muscles produce pressure bursts of coughing and sneezing and aid in deep breathing.

URINARY SYSTEMA skeletal muscle sphincter retains urine in bladderuntil convenient for release; abdominal and pelvic muscles aid in compressing and emptying bladder; muscles of pelvic floor support bladder; bulbospongios us muscle helps clear urine from male urethra.

DIGESTIVE SYSTEMMuscles enable chewing and swallowing; muscles control voluntary aspect of defecation; abdominal muscles produce vomiting; abdominal and lumbar muscles protect digestive organs.

REPRODUCTIVE SYSTEMMuscles are involved in sexual responses including erection and ejaculation; abdominal and pelvic muscles aid in childbirth.

CIRCULATORY SYSTEMMuscle contractions affect blood flow in many veins; exercise stimulates growth of new blood vessels.

ENDOCRINE SYSTEMSkeletal muscles provide protective cover for some endocrine glands; muscle mass affects insulin sensitivity.

NERVOUS SYSTEMMuscles give expression to thoughts, emotions, and motor commands that arise in the central nervous system.

SKELETAL SYSTEMMuscles move and stabilize joints and produce stresses that affect ossification, bone remodeling, and the shapes ofbones.

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Nucleus Muscle fiber Endomysium Striationstycmhoffman.com/commonfiles/bio201/Ch11MuscleTissue1.pdf · Neuromuscular junction Skeletal muscle fibers Spinal cord Motor neuron 1 Motor