1. Lecture #21
Skeletal and Muscular
11.2 Movement

2. Essential idea: The roles of the musculoskeletal system are movement, support and protection.

3. Bones and exoskeletons provide anchorage for muscles and act as levers.
Levers: Change size and direction of forces.

4. Movement of the body requires muscles to work in antagonistic pairs.

5. Application: Antagonistic pairs of muscles in an insect leg.

6. Synovial joints allow certain movements but not others.
Knee = hinge joint Hip Joint
Movement in one plane Rotation, movement in three planes

7. Human Elbow: Structure and Function
Cartilage= cushions bones where they meet.
Joint capsule– seals the joint
synovial fluid = lubricates joint to reduce friction.
Tendons = attach muscle to bone
bones
Humerus– anchors muscle
Radius– pulled by biceps
Ulna– pulled by triceps
antagonistic muscle pair
Biceps= flexor (bend joint)
Triceps = extensor (extend joint)

8. Human Elbow: Label Draw a diagram of the human elbow joint
Be sure to include
-cartilage
Joint capsule
-synovial fluid ( around joint)
-tendons
-bones
Humerus
Radius
ulna
-biceps
-triceps
Be able to identify the antagonistic muscle pair
(biceps & triceps)

9. Striated Skeletal Muscle
Muscles: bundle of….
Muscle fibers: single cell w/ many nuclei and mitochondria
Sarcolemma = membrane of muscle fiber
Sarcoplasmic reticulum– responds to nerve impulses to cause contraction

10. Each muscle fiber consists of many:
Myofibrils: cylindrical structures composed of…
Actin and Myosin

11. Each myofibril consists of:
Sarcomeres: repeating contractile units….
Z lines~sarcomere border
Light band (I band) ~only actin protein
Dark band
A band~actin & myosin protein overlap
H zone~only myosin (at center of sarcomere)

12. Draw and Label: sarcomere
Include:
Z lines
Actin filaments
Myosin filaments with heads
Light band
Dark band

13. Muscle contraction summary
Sarcomere length reduced (Distance between Z lines becomes shorter)
Actin and myosin slide past each other (overlap increases)
Another animation:

14. Mechanism of muscle contraction
*(a specialized endoplasmic reticulum)
STEPS:
Motor neuron stimulates muscle fiber.
Sarcoplasmic reticulum* releases Ca+2 ions
Calcium ions and the proteins tropomyosin and troponin control muscle contractions.
Myosin binds to actin binding sites (termed a cross-bridge)
Steps continued on next slide…

15. Steps continued… ATP binds to myosin and breaks cross-bridge
Myosin head hydrolyzes ATP
Myosin head changes angle and reattaches to actin binding site
Makes ADP and inorganic phosphate (Pi)
Releasing ADP and Pi, myosin relaxes causing actin to slide (“power stroke”)
Binding of new ATP releases myosin head
Repeat steps 5-8 as long as muscle contracts.
Relaxation occurs when actin binding sites are blocked.

16. (1.8) Understandings: • • • The contraction of the skeletal muscle is achieved by the sliding of actin and myosin filaments. • ATP hydrolysis and cross bridge formation are necessary for the filaments to slide. • Applications and skills: • • Skill: Annotation of a diagram of the human elbow. • Skill: Drawing labelled diagrams of the structure of a sarcomere. • Skill: Analysis of electron micrographs to find the state of contraction of muscle fibres. Aims: • •

17. Analyze electron micrographs to find state of contraction of muscle fibres.

18. Muscle contraction Aim 7: Use of animations to visualize contraction.

19. Nature of science: Developments in scientific research follow improvements in apparatus—fluorescent calcium ions have been used to study the cyclic interactions in muscle contraction.

20. Aim 7: Use of grip strength data loggers to assess muscle fatigue.

21. End of IB

22. Structure and Function
Nerves – stimulate muscle contraction, coordination
Muscles – Provide force needed for movement during contraction
Tendons – attach muscle to bone
Bones – provide firm anchorage for muscles, act as levers
Ligaments– attach bone to bone, restricting movement at joints to prevent dislocation

23. Muscle contraction regulation, I
Relaxation: tropomyosin blocks myosin binding sites on actin
Contraction: calcium binds to troponin complex; tropomyosin changes shape, exposing myosin binding sites

24. The Senses Chemical Senses A. Smell
1. chemicals stimulate hair-like nerve endings in upper part of nose--> olfactory nerve--> brain (interprets)
B. Taste
1. chemicals dissolved in saliva contact taste buds (sensory receptors on tongue)--> brain and interpreted
2. Bitter= back, sweet/salty= tip, sour=sides

25. The Senses Sensing light Cornea Iris pupil lens retina Rods Cones
macula and fovea
Optic nerve
Conjunctiva covers the sclera (white of eye)
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Eye tricks/games (blind spot etc)

26. The Senses ..\..\..\bio powerpoints\Chapter 36 BDOL IC
Sensing Mechanical stimulation (hearing, touch, balance)
1. Hearing
a. vibrations of air= sound waves
b. these enter outer ear and travel down ear canal where they strike the tympanic membrane (eardrum)
c. eardrum vibrates and causes three bones in middle ear, the malleus, incus and stapes to vibrate.
d. causes fluid in cochlea to move like waves and stimulate hair cells lining the walls of the cochlea.
e. This causes the hairs to bend producing nerve impulses that travel down auditory nerve to brain where it’s interpreted
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27. The Senses
2. Touch
a. Receptors in skin respond to changes in temperature, pressure and pain.
b. Different types of receptors are more concentrated in different areas of body.
i.light pressure= fingertips, eyelids, lips, tongue, palms etc.
ii. heavier pressure= joints, muscle, certain organs
iii. pain receptors
iv. heat receptors—deep in dermis
v. cold receptors—closer to surface of skin

28. The Senses
3. Balance
a. semicircular canals in inner ear filled with fluid and lined with hair cells
b. movement of fluid causes hair cells to bend and produce impulses that are interpreted by brain.

29. Muscle contraction regulation, II
Calcium (Ca+)~ concentration regulated by the….
Sarcoplasmic reticulum~ a specialized endoplasmic reticulum
Stimulated by action potential in a motor neuron
T (transverse) tubules~ travel channels in plasma membrane for action potential
Ca+ then binds to troponin