1. Anatomy and Physiology, Sixth Edition
Rod R. Seeley Idaho State University
Trent D. Stephens Idaho State University
Philip Tate Phoenix College
Chapter 7
Lecture Outline*
*See PowerPoint Image Slides for all figures and tables pre-inserted into PowerPoint without notes.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2. Chapter Plan The Muscular System Study Guide Projects Lab:
Research: Diseases of the Muscular System
One section a day – Due Fridays
Location of Superficial Muscles (Group QUIZ)
Lab:
Quick Recall (GROUP QUIZ)
Muscle Fatigue Lab
Mastery Learning Activity (INDIVIDUAL QUIZ)
Chicken Wing Dissection
Final Learning Challenges (GROUP QUIZ)
The Muscle System Tour
Muscular System Lab (part 2 & 3 only)
Quizzes/Exams
Case Studies
Quizlet
Parts of a Muscle Quiz
The Tired Swimmer
Chapter Test
Media:
Video of runner/sprinter

3. Key Vocabulary

4. Muscular System: Histology and Physiology
Chapter 7
Muscular System: Histology and Physiology

5. Muscular System Functions
Body movement
Maintenance of posture
Respiration
Production of body heat
Communication
Constriction of organs and vessels
Heart beat

6. Properties of Muscle Contractility Excitability Extensibility
Ability of a muscle to shorten with force
Excitability
Capacity of muscle to respond to a stimulus
Extensibility
Muscle can be stretched to its normal resting length and beyond to a limited degree
Elasticity
Ability of muscle to recoil to original resting length after stretched

7. Muscle Tissue Types Skeletal Smooth Cardiac Attached to bones
Nuclei multiple and peripherally located
Striated, Voluntary and involuntary (reflexes)
Smooth
Walls of hollow organs, blood vessels, eye, glands, skin
Single nucleus centrally located
Not striated, involuntary, gap junctions in visceral smooth
Cardiac
Heart
Striations, involuntary, intercalated disks

8. Connective Tissue, Nerve, Blood Vessels
Endomysium
Perimysium
Epimysium or Fascia
Nerve and blood vessels
Abundant

9. Checking in… Put the following in order from greatest to least
Endomysium
Perimysium
Epimysium
What do each of these connective tissue surround?

10. Parts of a Muscle

11. Quick Recap Put these muscle parts in order from largest to smallest
Myofibril
Skeletal muscle
Muscle fiber
Muscle fasciculi
Myofilament (actin or myosin)
On which of these muscle parts would you find:
Sarcolemma?
Sarcomere?
Capillary and nuclei?
Mitochondria?

12. Structure of Actin and Myosin

13. Components of Sarcomeres

14. Sliding Filament Model (p.163)
Actin myofilaments sliding over myosin to shorten sarcomeres
Actin and myosin do not change length
Shortening sarcomeres responsible for skeletal muscle contraction
During relaxation, sarcomeres lengthen

15. Sarcomere Shortening

16. Physiology of Skeletal Muscle
Nervous system
Controls muscle contractions through action potentials
Resting membrane potentials
Membrane voltage difference across membranes (polarized)
Inside cell more negative and more K+
Outside cell more positive and more Na+
Must exist for action potential to occur

17. Ion Channels Types Ligand-gated Voltage-gated
Example: neurotransmitters
Voltage-gated
Open and close in response to small voltage changes across plasma membrane

18. Action Potentials Phases All-or-none principle Propagate Frequency
Depolarization
Inside plasma membrane becomes less negative
Repolarization
Return of resting membrane potential
All-or-none principle
Like camera flash system
Propagate
Spread from one location to another
Frequency
Number of action potential produced per unit of time

19. Gated Ion Channels and the Action Potential

20. Action Potential Propagation

21. Neuromuscular Junction
Synapse or NMJ
Presynaptic terminal
Synaptic cleft
Postsynaptic membrane or motor end-plate
Synaptic vesicles
Acetylcholine: Neurotransmitter
Acetylcholinesterase: A degrading enzyme in synaptic cleft

22. Function of Neuromuscular Junction

23. Excitation-Contraction Coupling
Muscle fiber
Mechanism where an action potential causes muscle fiber contraction
Involves
Sarcolemma
Transverse or T tubules
Terminal cisternae
Sarcoplasmic reticulum
Releases Ca2+
Troponin
Ca binds to this

24. Action Potentials and Muscle Contraction

25. In pictures describe each of the following steps

26. Cross-Bridge Movement
In words, describe each of the following steps

27. Checking in…
Rigor mortis (stiffness + death) is a condition in which the muscles of a deceased person remains rigid. Explain why this might happen using what you learned about cross- bridges and muscle contraction.
Answer: A new ATP must bind to mysoin before the cross- bridge can be released. When ATP is not available after a person dies, the cross-bridges that have formed are not released, causing the muscle to become rigid

28. Predict…
Predict the consequences of having the following conditions develop in a muscle in response to a stimulus:
Inadequate ATP is present in the muscle fiber before a stimulus is applied
Adequate ATP is present within the muscle fiber, but action potentials occur at a frequency so great that calcium ions are not transported back into the sarcoplasmic reticulum between individual action potentials
Answer:
Energy from ATP is stored on the myosin heads. W/O ATP, no cross-bridges are formed, no muscle contraction
Ca2+ is needed to bind to troponin molecules which exposes myosin attachment sites for cross-bridges to form. No Ca2+, no muscle contraction

29. More to check in…
Why does a person’s body temperature increase after exercise? Why does a person shiver?

30. Muscle Twitch
Muscle contraction in response to a stimulus that causes action potential in one or more muscle fibers
Phases
Lag or latent
Contraction
Relaxation

31. Stimulus Strength and Muscle Contraction
All-or-none law for muscle fibers
Contraction of equal force in response to each action potential
Sub-threshold stimulus
Threshold stimulus
Stronger than threshold
Motor units
Single motor neuron and all muscle fibers innervated
Graded for whole muscles
Strength of contractions range from weak to strong depending on stimulus strength

32. Multiple Motor Unit Summation
A whole muscle contracts with a small or large force depending on number of motor units stimulated to contract

33. Multiple-Wave Summation
As frequency of action potentials increase, frequency of contraction increases
Incomplete tetanus
Muscle fibers partially relax between contraction
Complete tetanus
No relaxation between contractions
Multiple-wave summation
Muscle tension increases as contraction frequencies increase

34. Types of Muscle Contractions
Isometric: No change in length but tension increases
Postural muscles of body
Isotonic: Change in length but tension constant
Concentric: Overcomes opposing resistance and muscle shortens
Eccentric: Tension maintained but muscle lengthens
Muscle tone: Constant tension by muscles for long periods of time
Keeps back & legs straight, head held upright, abdomen from bulging

35. Muscle Length and Tension

36. Fatigue
Decreased capacity to work and reduced efficiency of performance
Types
Psychological
Depends on emotional state of individual
Muscular
Results from ATP depletion
Synaptic
Occurs in NMJ due to lack of acetylcholine

37. Energy Sources
ATP provides immediate energy for muscle contractions from 3 sources
Creatine phosphate
During resting conditions stores energy to synthesize ATP
Anaerobic respiration
Occurs in absence of oxygen and results in breakdown of glucose to yield ATP and lactic acid
Aerobic respiration
Requires oxygen and breaks down glucose to produce ATP, carbon dioxide and water
More efficient than anaerobic
Where does anaerobic respiration occur in the cell? Aerobic?

38. Checking in…
Scenario: After a 10-mile run with a sprint at the end, a runner continues to breathe heavily for a time. Indicate the type of metabolism that is producing energy during the run, during the sprint, and after the run
Answer:
During the run, aerobic respiration is used to break down glucose to produce ATP, CO2 and H2O.
During the sprint, anaerobic respiration is used to yield small amounts of ATP and lactic acid
After the run, respiration rate and volume remain elevated to pay back the O2 debt. This is needed to convert lactic acid to glucose, replenish ATP and creatine phosphate in muscle fibers and replenish O2 in the lungs, blood, and muscles

39. Slow and Fast Fibers Slow-twitch or high-oxidative
Contract more slowly, smaller in diameter, better blood supply, more mitochondria, more fatigue-resistant than fast-twitch
Fast-twitch or low-oxidative
Respond rapidly to nervous stimulation, contain myosin to break down ATP more rapidly, less blood supply, fewer and smaller mitochondria than slow-twitch
Distribution of fast-twitch and slow twitch
Most muscles have both but varies for each muscle
Effects of exercise
Hypertrophies: Increases in muscle size
Atrophies: Decreases in muscle size

40. Checking in…
When eating turkey, which do you prefer white or dark meat?
Why is there such a difference?
Answer:
White meat (especially in chicken breast) is composed of mostly fast twitch muscle fibers – good for contracting rapidly for short periods of time and fatigues quickly
Dark meat (especially in the chicken legs or duck’s breast) is composed myoglobin, richer blood supply and stores oxygen

41. Smooth Muscle Characteristics Types Not striated
Dense bodies instead of Z disks as in skeletal muscle
Have noncontractile intermediate filaments
Ca2+ required to initiate contractions
Types
Visceral or unitary
Function as a unit
Multiunit
Cells or groups of cells act as independent units

42. Smooth Muscle Contraction

43. Electrical Properties of Smooth Muscle

44. Functional Properties of Smooth Muscle
Some visceral muscle exhibits autorhythmic contractions
Tends to contract in response to sudden stretch but no to slow increase in length
Exhibits relatively constant tension: Smooth muscle tone
Amplitude of contraction remains constant although muscle length varies

45. Smooth Muscle Regulation
Innervated by autonomic nervous system
Neurotransmitter are acetylcholine and norepinephrine
Hormones important as epinephrine and oxytocin
Receptors present on plasma membrane which neurotransmitters or hormones bind determines response

46. Cardiac Muscle Found only in heart Striated
Each cell usually has one nucleus
Has intercalated disks and gap junctions
Autorhythmic cells
Action potentials of longer duration and longer refractory period
Ca2+ regulates contraction

47. Effects of Aging on Skeletal Muscle
Reduced muscle mass
Increased time for muscle to contract in response to nervous stimuli
Reduced stamina
Increased recovery time
Loss of muscle fibers
Decreased density of capillaries in muscle

48. Disorders of Muscle Tissue
Cramps
Fibromyalgia
Hypertrophy & Atrophy
Muscular Dystrophy
Myasthenia Gravis
Tendinitis