NURS1108 Introduction to Anatomy & Physiology Lecture Notes PDF

NURS1108: Introduction to Anatomy & Physiology Dr. Jermaine H. Whyte FMS- UWI [email protected] Musculo-Skeletal System Skeletal System  Objectives 1. Discuss the organization of the skeletal system. 2. Discuss the class...

NURS1108: Introduction to Anatomy & Physiology Dr. Jermaine H. Whyte FMS- UWI [email protected] Musculo-Skeletal System Skeletal System  Objectives 1. Discuss the organization of the skeletal system. 2. Discuss the classification, types, location, structure and functions, the blood and nervous supply of bones, joints, cartilages and muscles. 1. Discuss the formation, growth and repair process of bones, joints, cartilages and muscles; 2. Discuss the chemical composition of bone; 3. Describe the effects of diet on bone development in children and bone maintenance in older adults; 1. Compare and contrast the structure of the four (4) bone classes; providing examples of each class. 1. Identify bone markings  CLASSIFICATION OF BONES BY POSITION BODY ARE GROUPED INTO THE AXIAL AND THE APPENDICULAR SKELETONS. THE 206 BONES OF THE HUMAN o 80 bones of the axial skeleton o 126 bones of the appendicular skeleton By age 25 the skeleton is completely hardened  Infant skeleton An infant’s skeleton contains more than 300 bones.  SKELETAL SYSTEM Bones are light, strong, and slightly flexible. FUNCTIONS OF THE SKELETAL SYSTEM SUPPORT PROTECTION MOVEMENT MINERAL STORAGE BLOOD CELL FORMATION  Bone tissue has additional functions: – Maintain and repair bones – Act as a reserve pool of calcium, magnesium, and phosphorus The concentration of these minerals in the blood must be kept constant. Muscle contraction, blood clotting, and transmission of signals depends on these minerals.  Bones and Bone Tissue Bones and Bone Tissue are Classified According to Their Gross and Microscopic Structure – Compact bone is dense, with an orderly microscopic structure that has a smooth appearance and no apparent spaces. – Spongy bone has many small open spaces that gives the appearance of a sponge.  Bone Classification Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Bone Classification: a. Long Bones (b) b. Short Bones c. Flat Bones d. Irregular Bones e. Sesamoid Bones f. Wormian Bones (c) (sutural) (d) (a) (e) 9  Classification of Bones on the Basis of Shape Figure 5.1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Classification of Bones  Long bones  Typically longer than wide  Have a shaft with heads at both ends  Used for levers and weight bearing  Contain mostly compact bone Examples: Femur, humerus Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Classification of Bones  Short bones  Generally cube-shape  Boxy, lightweight, non-weight-bearing  Contain mostly spongy bone  Examples: Carpals, tarsals Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Bone shapes  Classification of Bones  Flat bones  Thin and flattened  Usually curved  Thin layers of compact bone around a layer of spongy bone  Examples: Skull, ribs, sternum Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Classification of Bones  Irregular bones  Irregular shape  Do not fit into other bone classification categories  Example: Vertebrae and pelvis  Sesamoid bones  Small bones that form within tendons and ligaments  Patella (kneecap) Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Classification of Bones on the Basis of Shape Figure 5.1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 5.5c  Parts of a Long Bone Epiphysis Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Epiphyseal plates Distal Articular cartilage Proximal Spongy bone Proximal epiphysis Diaphysis Space containing Metaphysis red marrow Compact bone Endosteum Spongy bone Compact bone Medullary cavity Articular cartilage Yellow marrow Periosteum Periosteum Diaphysis Endosteum Medullary cavity Trabeculae Bone marrow Red marrow and yellow marrow Distal epiphysis Femur 17  Long bones Contain a diaphysis and two epiphyses – Main shaft of a long bone is the diaphysis Widens into a funnel-shaped area called the metaphysis – The epiphysis is the broadest part of the bone at each end. – A tough, fibrous membrane, the periosteum, covers most of the bone Where the bone meets another bone to form a joint, a cap called the articular cartilage replaces the periosteum.  Structure of a long bone  Under the periosteum lies a thick layer of compact bone surrounding a latticework of spongy bone The spaces in the spongy bone latticework contain red marrow. In the diaphysis, most of the spongy bone has been removed resulting in the inner medullary cavity. – This is filled with yellow marrow. The endosteum is a layer of bone-forming and connective tissue cells that lines the medullary cavity.  Epiphyseal line shows us that the bone is from an adult. In children and young adults, this is the epiphyseal growth plate. – Composed of cartilage and newly forming bone – As child grows, bone is added here. Bones need a rich blood supply. Bones have a variety of anatomic features with special names.  Microscopic Structure Bone cells are called osteocytes in a lacuna Osteocytes transport nutrients and wastes by cellular processes in canaliculi The extracellular matrix of bone is largely collagen and inorganic salts Collagen gives bone resilience & strength Inorganic salts make bone hard 22  Compact Bone Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Osteon Osteon aka Haversian System Endosteum Central canal containing blood Central canal vessels and nerves Perforating canal aka Periosteum Nerve Volkmann’s canal Blood Pores Central vessels canal Osteocytes Perforating canal Compact Nerve Lamellae bone Blood vessels Lacunae Nerve Bone matrix Trabeculae Bone matrix Canaliculi Canaliculus Osteocyte Lacuna (space) 23  Microscopic Anatomy of Bone Figure 5.3 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Osteoblasts – Derived from osteogenic stem cell – Produce osteoid—a special type of bone collagen Osteocytes – As they form new bone, osteoblasts become trapped in lacunae and mature into osteocytes. – Osteocytes nourish and care for bone – Connect to each other by cytoplasmic extensions that travel through a maze of tunnels called canaliculi  Osteoclasts – Very large cells with multiple nuclei – Offspring of monocytes, which also produce macrophages – Break down bone and release calcium, phosphorus, and other components into the bloodstream for recycling. – Concentrated around the edges of spongy bone.  Microscopic Anatomy of Bone  Lacunae  Cavities containing bone cells (osteocytes)  Arranged in concentric rings  Lamellae  Rings around the central canal  Sites of lacunae Figure 5.3 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Microscopic Anatomy of Bone  Canaliculi  Tiny canals  Radiate from the central canal to lacunae  Form a transport system Figure 5.3 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Microscopic structure of long bone  Spongy Bone Spongy bone is aka cancellous bone Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Spongy bone Compact bone (a) Remnant of Spongy bone Compact bone epiphyseal plate (b) Spongy Compact (c) bone bone 30 a: © Ed Reschke; b,c: Courtesy of John W. Hole, Jr.  Ossification is the formation, growth, remodeling, and repair of bone – Bone formation (ossification) occurs in four situations: Initial formation of bones in embryo and fetus Growth of bones in children and adolescents Remodeling of bones in response to stress of daily life or chronic stress Repair of damaged bone Back to chapter objectives  Fetal bone forms by endochondral or membranous ossification – Fetal skeleton first appears at six weeks – Bone that develops from cartilage is endochondral bone – Bone that develops from fibrous membranes is membranous bone  Endochondral ossification – Bone synthesis begins in the middle of the shaft (primary ossification center) 1. Chondroblasts prepare a cartilage model. 2. A bony collar forms, and the model enlarges. 3. Ossification begins. 4. Narrow space enlarges and bone marrow appears. 5. Secondary ossification centers appear at the ends of long bones. 6. Articular cartilage and epiphyseal plate form  Intramembranous ossification 1. Bone-shaped fibrous membrane appears. 2. Membrane fibroblasts and osteoblasts begin to deposit a haphazard weave of collagen fibers and bone tissue (woven bone). 3. As growth progresses, compact bone develops in the center. Two differences from endochondral ossification 1. No intermediate stage develops 2. Stage characterized by woven bone Back to chapter objectives Intramembranous Bones Intramembranous Bones These bones originate within sheet-like layers of connective tissues They are the broad, flat bones Skull bones (except mandible) Are known as intramembranous bones 35  Endochondral Bones Endochondral Bones Bones begin as hyaline cartilage Form models for future bones These are most bones of the skeleton Are known as endochondral bones 36  Endochondral Ossification Hyaline cartilage model Epiphyseal plate Primary ossification center Osteoblasts vs. osteoclasts Secondary ossification centers Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Articular Remnants of cartilage Secondary epiphyseal ossification plates Cartilaginous Developing Compact bone center model periosteum developing Spongy bone Epiphyseal plates Blood Medullary Medullary Medullary vessel cavity cavity cavity Compact bone Remnant of Epiphyseal epiphyseal Calcified Primary plate plate cartilage ossification Secondary Spongy center ossification bone center Articular cartilage (a) (b) (c) (d) (e) (f) 37  Growth at the Epiphyseal Plate Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. First layer of cells Bone tissue Closest to the end of of epiphysis epiphysis 1 Zone of resting Resting cells cartilage 2 Zone of Anchors epiphyseal plate proliferating cartilage to epiphysis 3 Zone of hypertrophic Zone of resting cartilage cartilage Second layer of cells 4 Zone of calcified Many rows of young cartilage Ossified bone of cells diaphysis Undergoing mitosis zone of proliferating cartilage (a) (b) b: © The McGraw-Hill Companies, Inc./Al Telser, photographer 38  Growth at the Epiphyseal Plate Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Third layer of cells Bone tissue Older cells of epiphysis Left behind when new 1 Zone of resting cells appear cartilage 2 Zone of Cells enlarging and proliferating cartilage becoming calcified 3 Zone of hypertrophic zone of hypertrophic cartilage cartilage Fourth layer of cells 4 Zone of calcified cartilage Thin Ossified bone of Dead cells diaphysis Calcified extracellular matrix zone of calcified cartilage (a) (b) b: © The McGraw-Hill Companies, Inc./Al Telser, photographer 39  Bones grow into early adulthood – An infant’s bones continue to grow throughout childhood and adolescence. – Some bones (such as the pelvis) achieve full growth in young adulthood. – Long bones grow both in length (longitudinal growth) and width (appositional growth)  Longitudinal growth of long bones – Occurs at epiphyseal plates – Chondrocytes continue to multiply and add extra cartilage to the side of the epiphyseal plate closer to the end of the bone. – On diaphyseal side, osteoblasts replace cartilage with bone. – Some cells convert to osteocytes – Bone growth complete between 17-21 years  Appositional growth of long bones and intramembranous bones – Along the length of the bone, osteoblasts beneath the periosteum add layers of new compact bone (similar to a tree adding new rings). – At a slower rate, osteoclasts dissolve and recycle bone materials to expand the medullary cavity, making room for bone marrow. – Intramembranous bones also grow by appositional growth; osteoclasts enlarge the cavities in the spongy bone centers.  Bone remodeling is the continual replacement of old bone by new − 5% of bone mass is remodeled every year − Bones remold themselves in response to the physical stresses placed on them. − If the stress is unusual, they will become deformed. − Imbalance of osteoblastic creation and osteoclastic reabsorption of bone can result in bone disease.  Bone growth  Homeostasis of Bone Tissue Bone Resorption – action of osteoclasts and parathyroid hormone aka parathormone aka PTH Bone Deposition – action of osteoblasts and calcitonin Occurs by direction of the thyroid and parathyroid glands Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Developing medullary cavity Osteoclast 45 © Biophoto Associates/Photo Researchers, Inc.  Factors Affecting Bone Development, Growth and Repair Deficiency of Vitamin A – retards bone development Deficiency of Vitamin C – results in fragile bones Deficiency of Vitamin D – rickets, osteomalacia Insufficient Growth Hormone – dwarfism Excessive Growth Hormone – gigantism, acromegaly Insufficient Thyroid Hormone – delays bone growth Sex Hormones – promote bone formation; stimulate ossification of epiphyseal plates Physical Stress – stimulates bone growth 46  Bone Function Bones shape, support, and protect body structures 47 Support, Protection, and Movement Support, Movement & Protection Gives shape to head, etc. Supports body’s weight Protects lungs, etc. Bones and muscles interact When limbs or body parts move 48  Blood Cell Formation Blood Cell Formation Also known as hematopoiesis Occurs in the red bone marrow 49  Inorganic Salt Storage Inorganic Salt Storage Calcium Phosphate Magnesium Sodium Potassium 50 Bone Disease  Factors Affecting Bone Growth Physical stress Adequate supply of o Vitamins A, C, and D o Minerals: calcium, phosphorus, magnesium Hormones (especially estrogen) Age o Females begin losing bone mass around age 30 o Males begin loss at about age 60  A healing fracture is a model of bone repair – A fracture is a broken bone – A pathological fracture is a break that occurs under normal daily stress  Process of fracture repair 1. The break tears blood vessels and a blood clot (hematoma) accumulates at the site. Bone near the break dies. 2. At end of first week, clot is partially replaced with granulation tissue (collagen fibers and other elements of the extracellular matrix) a. Repair progresses with the appearance of woven bone, which ossifies by intramembranous ossification i. Known as soft callus Back to chapter objectives Fracture Repair  Process of fracture repair 3. After a couple of weeks, the soft callus matures onto a bony callus. The bony callus is capable of limited weight bearing. 4. Excess spongy bone and callus are reabsorbed and replaced by dense, compact bone.  Calcium homeostasis is critical to body functioning – Abnormally high blood calcium can cause confusion, kidney stones, muscle weakness – Abnormally low blood calcium affects nerve transmission and causes muscle spasms and tingling sensations. Bone tissue is important in calcium homeostasis – Bone tissue stores 99% of the body’s calcium – Osteoclasts will break down bone to maintain calcium homeostasis even if bone health suffers.  Intestines and kidneys are important in calcium homeostasis – Body cannot synthesize calcium – Must be consumed in the diet and absorbed through the intestine – Inadequate intestinal absorption is dependent on the chemical signal cholecalciferol (vitamin D) – Kidneys convert cholecalciferol into its active form calcitriol (1,25-dihydroxyvitamin D3) Calcium Homeostasis  Hormones are important in calcium homeostasis – Parathyroid hormone (PTH) regulates blood calcium. Net effect is to increase blood calcium concentrations If blood calcium rises above its set point the parathyroids secrete less PTH, and blood calcium returns to its set point. PTH Regulates Blood Calcium Levels  What do bones have to do with blood cells?  Answer: Blood cells are produced in the red bone marrow.  Lifespan Changes Decrease in height at about age 30 Calcium levels fall Bones become brittle Osteoclasts outnumber osteoblasts Spongy bone weakens before compact bone Bone loss rapid in menopausal women Hip fractures common Vertebral compression fractures common 64  Recommended Reading McConnell, T. H. & Hull, K. L. (2011). Human form and function: Essentials of anatomy& physiology. Philadelphia: Wolters Kluwer, Lippincott Williams & Wilkins. Shier, D., Lewis, R. & Butler, J. (2002). Hole’s human anatomy & physiology. New York: McGraw Hill. Tortora, Gerard J. & Derrickson, Bryan H. (2011). Principles of anatomy and physiology. Somerset, New Jersey: John Wiley & Sons.