Ch 36 Skeletal, Muscular, and Integumentary Systems

I. The Skeletal System A. Purpose 1. structural support a. hydrostatic 1) soft bodied invertebrates b. exoskeleton 1) arthropods c. endoskeleton 1) mammals

2. protects internal organs 3. provides for movement 4. stores mineral reserves 5. provides a site for blood cell formation (only in some bones)

B. The Skeleton 1. 206 bones in adult humans 2. Axial skeleton a. skull b. vertebral column c. rib cage 3. Appendicular skeleton a. arms b. legs c. pelvis d. shoulder/pectoral girdle

C. Structure of Bones 1. solid network of living cells and protein fibers that are surrounded by deposits of calcium salts 2. osteocytes – mature bone cells 3. Ca and P – maintain levels in blood to support metabolic activities 4. compact bone a. resists mechanical shock b. Haversian canals 1) contains blood vessels

The Structure of Bone Spongy bone Haversian canal Compact bone Periosteum Bone marrow Haversian canal Osteocyte Artery Vein

5. Periosteum a. protective covering 6. spongy bone a. add strength w/o lots of mass b. red marrow 1) site of blood formation c. yellow marrow 1) fatty area providing protection 2) converts to red marrow if needed

D. Development of Bone 1. cartilage a. includes network of protein fibers including collagen and elastin b. embryo starts with cartilage then later turns to bone c. does not contain blood vessels d. relies on diffusion to obtain nutrients

2. ossification a. cartilage is replaced by bone 3. long bones have growth plates at both ends until early 20’s or late teens

E. Types of Joints 1. Immovable Joints or Fibrous a. fixed b. ie – bones in skull 2. Slightly Movable or Cartilaginous a. between tibia and fibula b. between vertebrae 3. Freely Movable or Synovial Joints a. Ball-and-Socket (shoulder) b. Hinge (knee) c. Pivot (elbow) d. Saddle (hand/fingers)

Freely Movable Joints and Their Movements Ball-and-Socket Joint Pivot Joint Clavicle Ball-and-socket joint Scapula Humerus Humerus Radius Pivot joint Ulna Hinge Joint Saddle Joint Femur Patella Hinge joint Tibia Fibula Metacarpals Carpals Saddle joint

Figure 36-5 Knee Joint Muscle Tendon Femur Patella Bursa Ligament Synovial fluid Cartilage Fat Fibula Tibia Figure 36-5 Knee Joint

F. Structure of Joints 1. ligament a. holds bones together 2. Bursa a. small sacs of synovial fluid b. acts as tiny shock absorbers

II. Muscular System A. Types of Muscle Tissue 1. Skeletal

2. Smooth

3. Cardiac

Figure 36-7 Skeletal Muscle Structure Section 36-2

B. Muscle Contraction – Sliding-Filament Model 1. muscle contracts when the thin filament in the muscle fiber slides over the thick filament decreasing distance between the Z lines

2. sarcomeres a. myosin 1) thick filaments of protein b. actin 1) protein making up most of the thin filament c. Z lines 1) separate sarcomeres 2) anchor sarcomeres 3. requires lots of ATP a. produced by cellular respiration b. requires Phosphorus

Cycle Diagram Myosin forms cross-bridge with actin 1 Myosin forms cross-bridge with actin 5 Myosin returns to original shape 2 Cross-bridge changes shape 4 3 Cross-bridge releases actin Actin pulled

C. Control of Muscle Contraction 1. CNS via motor neurons control muscle contractions 2. difference in electrical charge across plasma membrane 3. Neuromuscular junction a. the point of contact between a motor neuron and a skeletal muscle cell b. acetylcholine (ACo) 1) the neurotransmitter in the vesicles of motor neurons

c. impulse causes Ca2+ ions to be released d. Ca affects regulatory proteins which cause actin and myosin to interact e. ACo release stops f. enzyme destroys excess ACo g. Ca2+ pumped back in to cell h. contraction ends

4. Phosphorus taken from ATP or from creatine phosphate a. ATP comes from glucose in blood or glycogen breakdown in cells 5. strong vs. weak contraction a. brain stimulates many or only a few muscle cells

D. How Muscles and Bones Interact 1. Tendons a. connect muscles and bones b. cause bones to work like levers 2. most skeletal muscles work in opposing pairs 3. the weight of an object’s pull and gravity also pull on muscles

Figure 36-11 Opposing Muscle Pairs Section 36-2 Movement Movement Biceps (contracted) Biceps (relaxed) Triceps (relaxed) Triceps (relaxed)

III. Integumentary System A. Purpose 1. serves as barrier against infection and injury 2. helps to regulate body temp 3. removes waste from body 4. protects against UV radiation B. Skin

Figure 36-13 The Structure of Skin Section 36-3

B. Skin 1. epidermis a. outer layer b. dead cells on outside c. inner layer – rapid cell division d. tough, flexible, waterproof e. melanocytes produce melanin

2. dermis a. inner layer b. contains collagen fibers, blood vessels, nerve endings, glands, sensory receptors, smooth muscles, hair follicles c. glands 1) sweat glands a) cools body, rids waste 2) sebaceous glands a) oil secretion (waterproof)

3. under dermis is layer of fat and loose connective tissue

End