1. Chapter 5 Skeletal System

2. Functions of Bone -Support -Movement -Storage- store fat & minerals
- How do bones contribute to homeostasis?
-Protection
-Support
-Movement
-Storage- store fat & minerals
-Blood cell formation- blood cells are formed within the marrow cavities of certain bones
-Protection (Internal organs, brain, spinal cord)
-Support- bones act as pillars to support body trunk, spine supports torso, ricb cage protects thoracic wall
-Movement
-Storage- store fat & minerals
-Blood cell formation- blood cells are formed within the marrow cavities of certain bones

3. Anatomy of Bone

4. Types of Bone Compact Bone: Spongy Bone: Compact Bone: Spongy Bone:
How many bones make up our skeleton?!?
-206!
All bones fall under these two basic types:
Compact Bone:
-Dense
-Smooth
Spongy Bone:
-Composed of small pieces of bone
-Lots of space
Compact Bone:
-Dense
-Smooth
Spongy Bone:
-Composed of small pieces of bone
-Lots of space

5. Types of Bone Long Bone Flat Bone -4 types of shape:
After a bone is classified as either compact or spongy they are further classified according to their shape
-4 types of shape:
Long Bone
Flat Bone
-thin, flattened
-usually curved
-made up of layers of spongy bone squished between 2 compact bones
-longer then they are wide
-mostly compact bone
Long bone
-consist of all bones of the limbs except wrist & ankle Length exceeds width and consist of a
Diaphysis- shaft composed mainly of compact bone
Metaphysis- flared portion at ecah end of diaphysis. Mostly spongy bone
Epiphysis- epiphyseal line
Thickest toward middle because…
Medullary cavity
Clavicle, humerus, radius, ulna, femur, tibia and fibula
Flat
Need for extensive muscle attachment or protection for soft/vital parts of the body
Usually curved, 2 flat plates
Sternum, ribs, scapula, some parts of the skull

6. Types of Bone Cont’d Irregular Bone Short Bone
-bones that don’t fit into the other categories
-cubed shaped
-mostly spongy bone
Irregular Bone
Spongy enclosed by thin layer of compact
Vertebrae and ossicles of the ears
ex: vertebrae & hip bones (irregular bone)
Short Bone
-Lack long axis
Somewhat irregular shape
Thin layer of compact over mostly spongy
Carpal and tarsal
-ex: bones in wrist & ankle (short bone)

7. Classification of Bones
- Take a few minutes to classify the bones of the skeleton

8. Closer look at long bones
-important structures of long bone: in the picture your femur
-diaphysis
-periosteum
-epiphyses
-articular cartilage
-epiphyseal line
-epiphyseal plate

9. Closer look at long bones
-important structures of long bone:
-diaphysis: AKA the shaft
-makes up the bone’s length
-covered in protective fibrous connective tissue called periosteum
epiphyses: ends of long bone
-covered by protective cartilage, articular cartilage

10. Closer look at long bones
-important structures of long bone:
-epiphyses: 2 ends of the bone
-proximal epiphyses
-remember what proximal means?
-closer to trunk/torso
-distal epiphyses
-distal is the opposite, further away from the trunk/torso

11. Closer look at long bones
-important structures of long bone:
-epiphyseal line: found in adult bones
-remnant of epiphyseal plate
-which is seen in young growing bones
-cause growing of long bones
-end of puberty hormones stop growth of long bones, the plate is replaced by bone leaving a line to mark its location

12. Microscopic look at long bones
-important structures of compact bone that is only visible under a microscope:
-riddled with passageways carrying nerves, blood vessels & provide living bone cells with nutrients
-osteocytes: mature bone cells
-found in tiny cavities within the matrix called lacunae
-lacunae arranged in circles called lamellae around central canals
-each complex contains a central canal & matrix rings are known as osteon or Haversian system

13. -osteocytes: mature bone cells
-found in tiny cavities lacunae
-lacunae arranged in circles called lamellae around central canals
-each complex contains a central canal & rings are called osteon or Haversian system

14. Red & Yellow Bone Marrow
Yellow Marrow
-middle cavity of a long bone shaft stores yellow marrow,
AKA medullary cavity
-made of adipose fat tissue
Red Marrow
-in infants middle cavity forms blood cells & red marrow
-in adults red marrow is confined to the cavities in spongy none
- Found in flat bones (ribs, vertebrae, pelvic bones)

15. Hyaline Cartilage
Abundant cartilage fibers hidden by a rubbery matrix with glassy blue-white appearance

17. Bone Growth and Formation
Babies
-Embryo: hyaline cartilage
-Infant: cartilage replaced by bone
Fibrous membranes connecting flat bones
Adults
-Almost entirely bone
-Isolated cartilage remains (nose, ear, etc)
Flat bones replace connective membranes
Most of baby is hyaline cartilage

18. Bone Growth and Formation
-bones use cartilage as “models” during bone formation (ossification)
-ossification happens in two steps:
1.Hyaline cartilage model is superficially covered with bone matrix by osteoblasts
2.Hyaline cartilage is broken down, leaving behind an empty, medullary cavity.

19. Ossification
Appositional growth- osteoblasts add bone tissue to diaphysis while osteoclasts in the endosteum remove bone from the inner face of the diaphysis wall

20. Ossification Cont’d
After birth, only two regions of cartilage remain: articular cartilages and epiphyseal plates
-articular cartilage covers ends of long bones

22. Bone Remodeling Bones change as the body grows. Why is this necessary?
As the body changes in size and weight, our bones must compensate for the additional mass.
Additionally, bones become thicker & form projections where bulky muscles attach

23. Bone Remodeling occurs in response to two factors:
Blood Calcium Levels
- Healthy balance must exist between Ca stored and excreted
-Proper [Ca] is controlled by endocrine system
Calcitonin- storing calcium
Parahormone- release calcium into bloodstream
Pull of gravity and muscles on the skeleton
Determines where skeleton is remodeled

26. Axial & Appendicular Skeleton
Our skeleton is divided into two parts:
Axial Skeleton:
-divided into 3 parts:
-skull
-vertebral column
-bony thorax
Appendicular Skeleton:
-composed of 126 bones of the limbs
-pectoral & pelvic gridle

27. Skull, vertebral column, bony thorax
Axial Skeleton
Skull, vertebral column, bony thorax

28. Appendicular Skeleton
Bones of the limbs and girdles

29. Joints in our body Place where two bones come together
Classified by the amount of movement they allow
-immovable
-slightly movable
-freely movable

30. Joints in our body 4 types of joints in our body:
1. Hinge- only one single action is allowed
-similar to opening & closing a door
Ex:
-our elbow & fingers
2. Ball & socket- rounded curved shape surface of one bone fits into concave, cup shaped surface of another bone
-allows for 360 degree movement
Ex:
-our hip & shoulder bone

31. Joints in our body 4 types of joints in our body:
3. Pivot- movement occurs in a half circle, rotation of one bone around another
Ex:
-joint between the axis & atlas of neck
4. Plane/gliding- surfaces are flat, only sliding & twisting movements are allowed without any circular movement
Ex:
-carpals in our wrist, tarsals in our ankle

32. Healing a Bone Occurs in 4 Steps: 1.Hematoma is formed
2.Break is splinted by fibrocartilage
3.Bony callus is formed
4.Bone remodeling occurs