Chapter 7 Skeletal System *You may want to attach paper to your study guide for further room for writing

Aids to Understanding Words Complete the Aids to Understanding Words You may just write what is in the parentheses You may also want to write “key words” or “clues”

Living Tissues of Bone Bone tissue Cartilage Dense connective tissue Blood Nervous tissue

Classifying Bones by Their Shape Long bones – long longitudinal axes, expanded at each end – Thigh bones, forearms Short bones – cubelike, lengths/widths equal – Wrists, ankles Flat bones - platelike, broad surfaces – Ribs, scapula, bones of skull

Classifying Bones Irregular bones – variety of shapes, usually connected to other bones – Vertebrae, facial bones Sesamoid (round) bones – small and nodular, embedded within tendons (muscle to bone), adjacent to joints – Kneecap (patella)

Parts of a Long Bone Use the worksheet provided to label these parts AND write their functions (p.132 Fig.7.1) – Epiphysis (proximal and distal) – Diaphysis – Periosteum – Compact bone – Spongy bone – Medullary Cavity – Red Marrow (spaces) *see sheet – Yellow Marrow *see sheet

Bone Structure and Function Bones have projections called “processes” that provide attachment sites for ligaments and tendons Some bones have small holes to allow passage of blood vessels and nerve fibers Shape of bones helps them to fit together

Periosteum Vascular, fibrous tissue covering the bone Function – formation and repair of bone tissue Generally located on the diaphysis (shaft)

Compact Bone vs. Spongy Bone Compact – continuous matrix with no gaps – typically form outer walls of long bones Spongy – branching bony plates – irregular connecting spaces – lace-like appearance – found in hollow tube of compact bone (long bone)

Osteocytes Osteocytes – bone cells Found in lacunae (bony chambers) Form concentric circles around the central canal Look at page 108 to refresh your memory *cellular matrix of bone is composed of collagen (resilience) and calcium phosphate (hardness)

Flashcard Time! Use the notecards provided to make flashcards for the following: – Long bones * – Short bones * – Flat bones * – Irregular bones * – Sesamoid bones * *also list examples with the description

Flashcards Continued! Epiphysis Diaphysis Compact bone Spongy bone Medullary cavity Worth 10 points - due by the end of class!

Bone Development/Growth: Intramembranous Bone Broad, flat bones of skull - form during first weeks of embryonic development Membrane-like layers appear at future bone sites Tissues enlarge to form osteoblasts Osteoblasts deposit bony matrix  spongy bone  periosteum  compact bone (between periostem and spongy) Ossification – formation of bone

Bone Development/Growth: Endochondral Bones Most of the bones of the body – develop in fetus from masses of hyaline cartilage Models of cartilage grow rapidly and then begin to change Long bones - cartilage breaks down and disappears Periosteum forms  encircles diaphysis  blood vessels and osteoblasts form spongy bone

Ossification of Endochondral Bones Primary Ossification Center (diaphysis) – first region of bone formation, development proceeds to ends of bone Secondary Ossification Center (epiphysis) – Spongy bone forms in all directions – Epiphyseal plate (cartilage) remains between centers

Epiphyseal Plate – Epiphyseal plate contains dividing cells that lengthen the bone – When the centers meet and the plate ossifies – lengthening is no longer possible – Look at page 134, Fig. 7.5 – What happens if the plate is damaged before it ossifies?

Ossification Complete when adult size is reached Homeostasis of bone tissue – Life long process of bone remodeling – Osteoclasts (cells that erode bone) reabsorb bone matrix – Osteoblasts (bone-forming cells) replace bone matrix – Hormones that control blood calcium help control the resorption and deposition (3-5% exchanged of bone calcium exchanged each year)

How is a fracture healed? Pages Blood vessels rupture, and periosteum tears Blood spreads and develops a hematoma (blood clot) Vessels in surrounding tissues dilate – causing swelling and inflammation Osteoblasts and new blood vessles invade the hematoma and form spongy bone

Fracture Healing ( continued) Fibroblasts farther from a blood supply produce masses of fibrocartilage Phagocytes and osteoclasts remove the hematoma and other bone debris Fibrocartilage fills the gap between the ends of the broken bone The cartilaginous callus is replaced by bone tissue Phew! Smaller the fracture, faster the healing.

Factors Affecting Bone Growth/Development Nutrition – Vitamin D for proper absorption of Calcium Hormonal secretions – Growth hormones stimulate cell division – Sex hormones stimulate ossification of ephiphyseal plates (Why sex hormones?) Physical exercise – Provides stress needed to thicken and strengthen bones

Book Work! Page 171, Chapter Assessments #s 1-8 Save this paper! You will be adding to it!!!

Bones that Provide Support Lower limbs Pelvis Backbone All of these support the weight of the body

What bones protect viscera? *Viscera – organs in body cavities Skull – protect eyes, ears, brain Rib cage and shoulder – protect heart and lungs Pelvic girdle – protects lower abdominal and internal reproductive organs

Body Movement Bones move because muscles contract and pull on the bone Movement is produced when bones and muscles interact as levers (4 parts) – Rigid bar – Pivot (bar turns) – Object moved against resistance – Force that supplies energy to move the bar *Figure 7.7, page 138

Blood Cell Formation Embryo – Yolk sac is initial site of blood cell formation – Formed in liver and spleen Infant – Red marrow in cavities of most bones Adult – Red marrow in spongy bone of skull, ribs, sternum, clavicles, vertebrae, hip bones *refer back to marrow handout

Yellow Marrow vs. Red Marrow Yellow – Stores fat – Plays no role in blood formation – Can be converted to red marrow if need for blood cells increases Red – Primary marrow in infants – Produces blood cells: red, white, platelets – Color comes from oxygenated pigment hemoglobin

Storage of Inorganic Salts Major salt stored in bones – Calcium phosphate Other salts/metals stored – Potassium – Sodium – Magnesium – Lead

Movement of Calcium Parathyroid gland responds to low blood calcium levels by stimulating osteoclasts to break down bone tissue to release calcium When calcium levels rise, calcitonin from the thyroid gland stimulates osteoblasts to form bone tissue to store excess calcium

Book Work! Page 171, Chapter Assessments #s 9-10 ADD THIS TO YOUR SHEET FROM YESTERDAY!!!! Due Thursday! Worth 20 Points

How much do you already know? Pop Quiz! Don’t stress – this is not a grade….yet! Close your books!!!! Fill in everything you can on the blank skeleton worksheet – no talking, no books

Skeletal Organization Axial Skeleton – bony and cartilaginous parts that support and protect organs of the head, neck, and trunk Appendicular Skeleton – bones of upper and lower limbs and the bones that anchor the limbs to the axial skeleton

Skeletal Organization (continued) Axial Skeleton Bones – Skull – Hyoid bone – Vertebral column – Thoracic cage Appendicular Skeleton Bones – Pectoral girdle (scapula and clavicle) – Upper limbs – Pelvic girdle – Lower limbs

Skull – Cranial Bones Use page 141, table 7.1 answer questions 1-3 from 7.6 Part A With a partner, locate the following cranial bones – Occipital bone – Temporal bone – Frontal bone – Parietal bone *bones not visible are the ethmoid and sphenoid bones

Skull – Facial Bones With a partner, locate the following facial bones – Maxilla – Palatine – Zygomatic – Lacrimal – Nasal – Vomer – Mandible

Skull (continued) The mandible is the only facial bone that is movable. Infant skull – Incompletely developed at birth – Permits some movement of bones of skull – why? Adult skull – Joints in adult skull are immovable – Skull is rigid box for brain to sit in

Worksheet Time! Complete Diagrams A, B, and C by labeling the bones listed, as well as the structures indicated by leader lines Due Tomorrow during class – you will have the remainder of class today, as well as the first 15 minutes of class tomorrow.