of 22
7/31/2019 10 Muscle Tissue
1/22
Chapter 10 Muscle Tissue
Muscle tissue
functions Movement
Posture
Joint stabilization
Heat generation
(11.5a)
7/31/2019 10 Muscle Tissue
2/22
Muscle tissue properties
Contractile
Excitable
Extensible
Elastic
(11.5a)
7/31/2019 10 Muscle Tissue
3/22
Muscle tissue types
Skeletal
Striated,voluntary
Cardiac
Heart,
striated,involuntary
Smooth
Nonstriated,
involuntary Table 10.2
7/31/2019 10 Muscle Tissue
4/22
Muscle tissue terminology
Fiberskeletal, cardiac & smooth muscle
cell Myofilaments
Actinthin filaments
Myosin
thick filaments Sarcolemmaplasma membrane
Sarcoplasmcytoplasm
7/31/2019 10 Muscle Tissue
5/22
Skeletal muscle CT
Epimysiumsurrounds entiremuscle/organ
Perimysiumsurrounds muscle
fascicle Endomysium
surrounds individualmuscle fiber (10.1a)
7/31/2019 10 Muscle Tissue
6/22
Skeletal muscle fiber
Cylindrical
10-100 m diameter Varied lengthup to entire muscle
Formed by cell fusion
Multinucleated Peripheral nucleus
Striated
LM Demonstration
Table 10.2
7/31/2019 10 Muscle Tissue
7/22
Myofibrils
Bundles ofmyofilaments
Z discs
A band
actin &myosin overlap
I bandactin only
H zonemyosin only
SarcomereZ to Z
Striationsalignmentof myofilaments &
myofibrils (10.4)
Muscle fiber
myofibril
7/31/2019 10 Muscle Tissue
8/22
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)
7/31/2019 10 Muscle Tissue
9/22
Sliding filament
theory
Actin and myosin do
not shorten A band does not
change
I band shortens
Sarcomere shortens
(10.7)
7/31/2019 10 Muscle Tissue
10/22
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)
7/31/2019 10 Muscle Tissue
11/22
T tubules
Invaginations ofsarcolemma
Runs betweenmyofibrils
Conducts electrical
impulses fromsarcolemma
Excites SR to release
Ca++
(10.8)
7/31/2019 10 Muscle Tissue
12/22
Sarcoplasmic reticulum
SR surrounds each
myofibril
Stores Ca++
Release Ca++ for
contraction
Ca++ uptake for
relaxation
(10.8)
7/31/2019 10 Muscle Tissue
13/22
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)
7/31/2019 10 Muscle Tissue
14/22
Motor Unit
Definition: a motor neuron andall the muscle fibers itinnervates.
When a motor neuron fires, allmuscle fibers in the motor unitcontract.
All or none principle
A motor unit may containhundreds to four muscle fibers(average ~ 150)
Each muscle fibers receivesone NMJ (14.6)
7/31/2019 10 Muscle Tissue
15/22
Summary: skeletal muscle fibers
muscle
fascicle
fiber
myofibril
Myofilaments :actin & myosinTable 10.1
7/31/2019 10 Muscle Tissue
16/22
Cardiac muscle
Only in heart
Sliding filament theory
Striated
No NMJ
18.4
7/31/2019 10 Muscle Tissue
17/22
Cardiac muscle cells
15 m wide X 100 m long
Branched
Intercalated discs
Desmosomes
adhesion
Gap junctions
transmit electrical impulses
Forms two networksatrial
and ventricular
(10.10a)
7/31/2019 10 Muscle Tissue
18/22
Cardiac muscle cells
Central 1-2 nuclei
Mitochondrianumerous
Less SR
Fewer T tubules
Myofibrils
Sarcomeres
A band I band
Z disc
H zone
Striated
(10.10cd)
7/31/2019 10 Muscle Tissue
19/22
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 myofibrilsno striations
7/31/2019 10 Muscle Tissue
20/22
Smooth muscle fibers
Spindle shaped
2-10 m diameter
20-200 m long
Nonstriated
Central nucleus
Arranged in sheets
Usually in layersaround a tube
Peristalsis - waves ofcontraction to propel
contents along tube(10.12b)
7/31/2019 10 Muscle Tissue
21/22
Smooth muscle properties
Slower to contract vs. skeletal muscle
Slower to relax vs. skeletal muscle
Can maintain contraction longer
Resistant to fatigue
Unconscious control ANSautonomic nervous system
Stretch
Hormones
7/31/2019 10 Muscle Tissue
22/22
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