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 Cardiac Smooth Striated, voluntary
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 Formed by cell fusion Multinucleated
m diameter
Varied length – up to entire muscle
Formed by cell fusion
Multinucleated
Peripheral nucleus
Striated
LM Demonstration
Table 10.2

7. Myofibrils Bundles of myofilaments Z discs
Muscle fiber
Myofibrils
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
(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
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 Central 1-2 nuclei Mitochondria – numerous
(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 Siding filament theory applies
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 Nonstriated Central nucleus
2-10 m diameter
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