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Chapter 10 Muscle Tissue

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Contractile. Excitable. Extensible. Elastic (11.5a) Muscle tissue types. Skeletal ... Epimysium surrounds entire muscle/organ. Perimysium surrounds muscle fascicle ... – PowerPoint PPT presentation

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Title: Chapter 10 Muscle Tissue


1
Chapter 10 Muscle Tissue
  • Muscle tissue functions
  • Movement
  • Posture
  • Joint stabilization
  • Heat generation

(11.5a)
2
Muscle tissue properties
  • Contractile
  • Excitable
  • Extensible
  • Elastic

(11.5a)
3
Muscle tissue types
  • Skeletal
  • Striated, voluntary
  • Cardiac
  • Heart, striated, involuntary
  • Smooth
  • Nonstriated, involuntary

Table 10.2
4
Muscle tissue terminology
  • Fiber skeletal, cardiac smooth muscle cell
  • Myofilaments
  • Actin thin filaments
  • Myosin thick filaments
  • Sarcolemma plasma membrane
  • Sarcoplasm cytoplasm

5
Skeletal muscle CT
  • Epimysium surrounds entire muscle/organ
  • Perimysium surrounds muscle fascicle
  • Endomysium surrounds individual muscle fiber

(10.1a)
6
Skeletal muscle fiber
  • Cylindrical
  • 10-100 ?m diameter
  • Varied length up to entire muscle
  • Formed by cell fusion
  • Multinucleated
  • Peripheral nucleus
  • Striated
  • LM Demonstration

Table 10.2
7
Myofibrils
Muscle fiber
  • Bundles of myofilaments
  • Z discs
  • A band actin myosin overlap
  • I band actin only
  • H zone myosin only
  • Sarcomere Z to Z
  • Striations alignment of myofilaments
    myofibrils

myofibril
(10.4)
8
Sliding filament theory
  • Muscle contracts by actin and myosin sliding past
    each other
  • Myosin forms cross-bridges that attach to actin
  • Cross bridges all swing in same direction and
    pull actin along
  • Increased overlap of
  • filaments results in
  • contraction of muscle

(10.6)
9
Sliding filament theory
  • Actin and myosin do not shorten
  • A band does not change
  • I band shortens
  • Sarcomere shortens

(10.7)
10
The NMJ
  • Neuromuscular Junction (pp. 401-402)
  • Axon terminal
  • Mitochondria
  • Synaptic vesicles ACh
  • Synaptic cleft
  • Motor end plate
  • AChR
  • AP to muscle fiber

(14.5ab)
11
T tubules
  • Invaginations of sarcolemma
  • Runs between myofibrils
  • Conducts electrical impulses from sarcolemma
  • Excites SR to release Ca

(10.8)
12
Sarcoplasmic reticulum
  • SR surrounds each myofibril
  • Stores Ca
  • Release Ca for contraction
  • Ca uptake for relaxation

(10.8)
13
Muscle contraction
  • AP to axon terminal
  • ACh released
  • AChR activated
  • Muscle excited
  • Excitation travels down t-tubule
  • SR releases Ca
  • Ca activates sliding filament process
  • Muscle contracts http//www.blackwellpublishing.
    com/matthews/myosin.html

(14.5b)
14
Motor Unit
  • Definition a motor neuron and all the muscle
    fibers it innervates.
  • When a motor neuron fires, all muscle fibers in
    the motor unit contract.
  • All or none principle
  • A motor unit may contain hundreds to four muscle
    fibers (average 150)
  • Each muscle fibers receives one NMJ

(14.6)
15
Summary skeletal muscle fibers
muscle
myofibril
fascicle
Table 10.1
fiber
Myofilaments actin myosin
16
Cardiac muscle
  • Only in heart
  • Sliding filament theory
  • Striated
  • No NMJ

18.4
17
Cardiac muscle cells
  • 15 ?m wide X 100 ?m long
  • Branched
  • Intercalated discs
  • Desmosomes
  • adhesion
  • Gap junctions
  • transmit electrical impulses
  • Forms two networks atrial and ventricular

(10.10a)
18
Cardiac muscle cells
(10.10cd)
  • Central 1-2 nuclei
  • Mitochondria numerous
  • Less SR
  • Fewer T tubules
  • Myofibrils
  • Sarcomeres
  • A band
  • I band
  • Z disc
  • H zone
  • Striated

19
Smooth muscle
  • Six major locations
  • Blood vessels
  • Respiratory system
  • Digestive system
  • Urinary system
  • Reproductive system
  • Eye (lens and iris)
  • Siding filament theory applies
  • Actin myosin
  • No myofibrils no striations

20
Smooth muscle fibers
  • Spindle shaped
  • 2-10 ?m diameter
  • 20-200 ?m long
  • Nonstriated
  • Central nucleus
  • Arranged in sheets
  • Usually in layers around a tube
  • Peristalsis - waves of contraction to propel
    contents along tube

(10.12b)
21
Smooth muscle properties
  • Slower to contract vs. skeletal muscle
  • Slower to relax vs. skeletal muscle
  • Can maintain contraction longer
  • Resistant to fatigue
  • Unconscious control
  • ANS autonomic nervous system
  • Stretch
  • Hormones

22
Smooth muscle organization
  • Single unit innervation
  • Smooth muscle fibers connected by gap junctions
  • Network receives single innervation
  • Coordinated contraction
  • Multiunit innervation
  • Each fiber innervated
  • Locations
  • Iris of eye
  • Arrector pili muscle of skin
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