Musculoskeletal System Physiology Mrs Brown 5 Functions of

Musculoskeletal System Physiology Mrs. Brown

5 Functions of the Skeletal System 1. Haemopoiesis: Formation of blood cells in red bone marrow Main sites of haemopoiesis

5 Functions of the Skeletal System (con’t) 2. Storage of minerals (calcium, phosphorous, etc. ) 3. Support of body 4. Protection of body organs 5. Movement- attached to skeletal muscle

Types of Bones Fig. 7. 1

Total Bones in the Skeletal System = 206 Fig. 7. 15

Major Divisions of Skeleton Axial = 80 bones Appendicular = 126 bones Fig. 7. 15

The Axial Skeleton: Skull Fig. 7. 17 Fig. 7. 19 Fig. 7. 31

The Axial Skeleton: Thoracic Region Ribs 12 pairs of ribs 1 -7 true ribs 8 -10 false ribs 11 -12 floating ribs Sternum Manubrium, body, xiphoid process Thoracic vertebrae Fig. 7. 38

The Axial Skeleton: Spinal Column 24 total vertebrae Fig. 7. 16 7 cervical (neck) vertebrae 12 thoracic (chest) vertebrae 5 lumbar (lower back) vertebrae Sacrum 5 fused vertebrae with tubercules and sacral foramina Coccyx 4 fused vertebrae Figs. 7. 32, 7. 37

The Spinal Column (cont’d) Fig. 7. 36 Vertebrae Body vs. intervertebral discs Pedicles & laminae fuse to become the spinous process Transverse process Vertebral foramen- hole for spinal cord Superior and inferior articular processes Interverterbal foramina

The Appendicular Skeleton: Arms & Legs Figs. 7. 40, 7. 45, 7. 47, 7. 48, 7. 53

Bone Structure, Gross Anatomy Fig. 7. 2 Epiphysis-lined with hyaline cartilage -compact bone forms exterior -spongy bone forms interior -contains epiphyseal plates Diaphysis-compact bone forms exterior -center composed of the medullary cavity containing marrow (red or yellow)

Bone Structure, Fine Anatomy Fig. 7. 3 7. 4

Bone Cells OSTEOCYTES = “bone” “cells” OSTEOBLASTS “bone builders” OSTEOCLASTS “bone crushers” repair maintain when minerals are needed BONE IS NEVER AT REST = homeostasis!!! Fig. 7. 13

Bone Growth Fig. 7. 8

Bone Growth, con’t. Fig. 7. 9 Postnatal Growth • Growth in length • Growth occurs in the epiphyseal plate • Cartilage cells proliferate in tall columns, causing the entire bone to lengthen • Cartilage cells at the bottom of the column die and osteoblasts replace it with spongy bone

Bone Repair pgs. 202 -203

Joints Definition: the site where two or more bones meet 1. Fibrous joints Immovable 2. Cartilaginous joints Immovable Limited Movement Fig. 8. 1 - 8. 6

Joints, con’t. 3. Synovial Joints Movable Synovial Joint Structure Hyaline cartilage Joint cavity/capsule Synovial fluid (Ligaments) Fig. 8. 7 & 8. 8

How do you move your bones? MUSCLES!! All muscles cross at least one joint Each muscle pulls from an origin (the immovable end) to an insertion (the movable end) Each muscle produces a specific movement or Fig. 9. 22 action

Muscles work in pairs The pairs are located on opposite sides of a joint Muscles ‘pull’- never ‘push’. They work together to ‘undo’ the action of its pair Prime mover or agonist- provides the major force for a specific movement Antagonist-opposes or reverses the prime mover

Muscle Actions • Joint movements describe the axis in which the body part moves Figs 8. 10 -8. 12

Major Muscles Figs. 9. 23 & 9. 24

Anatomy of a Muscle cells Fig. 9. 2 (aka muscle fibers) bundled together are called fascicles Groups of fascicles are wrapped in a connective tissue called the epimysium

FIne Anatomy of a Muscle Zoom in on one muscle fiber/cell and you will see that Each muscle cell contains many myofibrils Myofibrils are made of functional units called sarcomeres Fig. 9. 4

Fine Anatomy cont: The Sarcomeres consists of 2 overlapping filaments with a repeated pattern Thick filamentmyosin Thin filament-actin Figs. 9. 4 & 9. 5

Skeletal Muscle Contraction Actin helps to control the myosin-actin interactions in muscle contraction. Myosin heads form cross bridges between myosin and actin Fig. 9. 6

The Sliding Filament Model Fig. 9. 10

The Sliding Filament Model Fig. 9. 11

Muscle Metabolism ATP Background Information 1. “ATP” = Adenosine Tri. Phosphate * phosphate groups are attached by highenergy bonds 2. When the terminal phosphate group is cleaved off, energy is released. 3. ATP ADP + Pi + energy 4. This energy is available to perform cellular work

Muscle Metabolism, cont. Aerobic Metabolism/Cellular Respiration Occurs in mitochondria & requires oxygen Chemical Formula: Glucose + oxygen carbon dioxide + water + energy (36 ATP) When this system is used: prolonged, endurance activities which maintain a constant heart rate As long as there is enough oxygen available, a muscle will utilize aerobic metabolism.

Muscle Metabolism, cont. Anaerobic Metabolism/Glycolysis Sometimes your muscles will temporarily run out of O 2 This pathway can occur in the absence of oxygen Chemical Formula: Glucose lactic acid +energy (2 ATP) When this system is used: When large amounts of ATP are needed for periods of exercise about 90 seconds long.

Muscle Metabolism, cont. Anaerobic Metabolism/Creatine Pathway Utilizes stored energy in the molecule creatine phosphate Chemical Formula: Creatine phosphate + ADP Creatine + ATP (1 ATP) When this system is used: Mobilized at the beginning of exercise, before other pathways ‘kick in’. Creates enough energy for about 10 seconds of contraction.