Today’s Agenda

1. Today’s Agenda 1. Journal Question: What is the function of your skeletal system? *2. Lecture: The Skeletal System 3. Film: Strength 4. Homework: Read Chapter 46 “Skeletal & Muscular System”

2. Skeletal Systems • Muscles and skeleton work together providing an efficient means of locomotion and movement of individual body parts. 1. Exoskeleton: The skeleton of arthropods is external and called an exoskeleton. 2. Endoskeleton: The skeleton lies within soft tissues.

4. Development of Bone 1. In a vertebrate fetus, most of the skeleton is made up of cartilage, a tough flexible tissue that has no minerals.

5. Development of Bone a. As the fetus grows, living cells called osteoblasts slowly replace cartilage cells and ossification begins.

6. Development of Bone b. Ossification is the replacement of cartilage with bone by the activity of osteoblasts and the addition of minerals such as calcium compounds.

7. Development of Bone c. In humans, ossification is not complete until about age 25. d. Vitamin D is needed for proper bone development because it is necessary for calcium absorption from blood.

8. Development of Bone • Vitamin D is present in milk, egg yolk, fish oils, and liver. • Vitamin D is also made in the skin in the presence of sunlight. • Rickets, a disease that results in severe bone deformities, is caused by inadequate amounts of vitamin D.

9. Structure of Bone 1. Three types of bone cells: (1) Osteoblasts form new bone. (2) Osteoclasts break down bone. (3) Osteocytes are mature osteoblasts found in most formed bone tissue.

10. Structure of Bone 2. Haversian Canals carry blood vessels and nerves that supply osteocytes in bone tissue.

11. Structure of Bone 3. Bone Marrow is found in the center of some bones.

12. Bone Marrow

13. Structure of Bone: Bone Marrow a. Found in the central hollows of the sternum, ribs, pelvis, vertebrae, skull, and the long bones of the arms and legs. b. Red marrow produces red blood cells, some white blood cells, and platelets. c. Yellow marrow stores excess fat. d. Bones without marrow are called spongy bone.

14. Joints in Vertebrates 1. Joints are points where bones connect with one another. 2. Most joints are movable and are held together by muscles and by connective tissue called ligaments.

15. Joints in Vertebrates • Ligaments are made of collagen and some elastic fibers. • Ligaments connect bone to bone.

16. Four Main Types of Moveable Joints: (1) Ball-and-Socket Joints: Shoulder & Hip

17. Four Main Types of Moveable Joints: (2) Pivot Joints: Neck Vertebrae (C1/C2)

18. Four Main Types of Moveable Joints (3) Hinge Joints: Elbow, Knee

19. Four Main Types of Moveable Joints: (4) Gliding Joints: Wrist

20. Joints in Vertebrates: 4. Fixed Joints = Bones are fused (skull)

21. Joints in Vertebrates: a. In adult humans, fixed joints are located in the …. a. Arm c. Leg b. Skull d. Finger b. Gliding joints give bones…. a. Hinge c. Reaction to stimuli b. Flexibility d. Pivot

22. Joints in Vertebrates: c. A pivot joint differs from a hinge in that a pivot joint… a. Moves in more than one direction. b. Moves only in one direction. c. Moves from side to side. d. Moves together with another joint. d. The skeleton is made up of 206 bones.

23. Movement: Vertebrates and Arthropods • Muscles are attached to the skeleton. • As a muscle contracts, it pulls on the skeleton, causing movement.

24. Movement: Vertebrates and Arthropods 3. Muscles are attached to bones by tough connective tissues called tendons. a. Tendons connect muscle to bones.

25. Movement: Vertebrates and Arthropods 4. Muscle attachment sites to bone: a. Origin: During contraction there is no movement. b. Insertion: During contraction the bone movement.

26. Movement: Vertebrates and Arthropods 5. Paired Muscles a. Muscles that cause locomotion work in pairs (or at least in two opposing groups) b. Example: The biceps (flexion/bending) and triceps (extension/straightening) work opposite each other to cause motion.

27. Movement: Vertebrates and Arthropods 6. No muscle is ever completely relaxed; muscle tone.

28. Types of Vertebrate Muscles 1. Striated Skeletal Muscle a. Striped appearance when viewed under a microscope. b. Each skeletal muscle fiber is stimulated by just one nerve.

29. Types of Vertebrate Muscles c. Importance for locomotion/movement. d. Under voluntary control.

30. Types of Vertebrate Muscles 2. Nonstriated Smooth Muscle a. Moves many of the internal parts of the body.

31. Types of Vertebrate Muscles b. Makes up the walls of the hollow organs of the body, such as the digestive tract. (Peristalsis) c. Also seen in blood vessels. d. Under involuntary control.

32. Types of Vertebrate Muscles 3. Cardiac Muscle (The Heart) a. The heart is composed of this type of muscle. b. Under involuntary control (contracts rhythmically)

33. Today’s Agenda: Journal Question: What is the difference between a ligament and a tendon? *1. Lecture II: Muscle Contraction & Vertebrates 2. Film: Spinal Impact 3. Homework: Read Chapter 50 “The Nervous System” pp. 1002 – 1025.

34. Contraction of Vertebrate Skeletal Muscle 1. Muscles consist of bundles of fibers that are made up of smaller fibrils.

35. Contraction of Vertebrate Skeletal Muscle 2. Fibrils are made up of two types of protein filaments: (1) Actin (Thin Filaments) (2) Myosin (Thick Filaments)

36. Contraction of Vertebrate Skeletal Muscle 3. The thin filaments are anchored to vertical bands called Z lines. 4. The part of a fibril from one Z line to the next Z line to next is called a sarcomere.

37. The Sliding Filament Hypothesis 1. Actin and myosin filaments slide over one another to shorten the fibrils during muscle contractions.

38. The Sliding Filament Hypothesis

39. All-or-None Response 1. Once an impulse reaches a muscle fiber, there is an all or none response. 2. Either the muscle fiber contracts fully or it does not contract at all; there is no partial contraction for a given fiber.

40. All-or-None Response 3. All contractions are of the same intensity. a. The number of fibers that contract at one time determines the strength of the contraction of the whole muscle.

41. Types of Muscle Contractions:

42. Energy for Skeletal Muscle Contraction 1. During rest or very light activity, ATP is produced in muscle cells by aerobic respiration (oxygen is present)

43. Energy for Skeletal Muscle Contraction 2. During prolonged or heavy exercise, the supplies of stored energy (both ATP and CP) are quickly used. –Need for lactic acid fermentation. (Anaerobic Respiration: In the absence of oxygen)

44. Recall: Strength Refers to muscle contraction.

45. Vertebrates Rule !!! The Story of You and Your Spine The term spine is used in more than one way. The spine, spinal column and the vertebral column are synonymous terms referring to the bony components housing your spinal cord. The vertebral column protects your spinal cord. Your spinal cord is made of nervous tissue. The function of nervous tissue is to transmit information. Spinal nerves come off the spinal cord. There are 31 pairs of spinal nerves coming off of your spinal cord.

46. Vertebrates Rule !!! There are five distinct regions of the vertebral column. Each region has specific name and number of vertebral segments.

47. Vertebrates Rule !!! (1) The cervical region is made up of 7 vertebrate. Cervical refers to the neck region. (2) The thoracic region is made up of 12 vertebrate. Thoracic refers to the mid-back region.

48. Vertebrates Rule !!! (3) The lumbar region is made up of 5 vertebrate. Lumbar refers to the low back region. (4) The sacral region is made up of 5 fused vertebrate. (5) The coccyx region is made up of 2-3 vertebrate. Coccyx refers to the tail-bone region.

49. Vertebrates Rule !!! During development, the vertebral column forms curvatures with relation to the biomechanical stresses placed upon the developing regions. The vertebral column of a baby at birth exhibits one long curve. This is called the primary curve because it is the first curve to develop.

50. Secondary Curves: 1. Secondary curves develop as a result of the accommodation of the skeleton to the upright position. 2. The secondary curve in the neck region develops as an infant begins to hold its head up against gravity.