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Skeletal System

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Title: Skeletal System


1
Skeletal System
  • Chapter 7
  • Dr. Katherine Harris

2
Bones are alive!
  • Bone consists of a variety of active, LIVING
    tissues
  • Bone tissue
  • Cartilage
  • Dense connective tissue
  • Blood
  • Nervous tissue

3
Functions of Bone
  • Organs of the skeletal system
  • Provide points of attachment for muscles
  • Protect support softer tissues
  • House blood-producing cells
  • Store inorganic salts
  • Form passageways for blood vessels and nerves

4
Bone and Muscle
  • Both bone and muscle are living tissue
  • separately neither is able to produce movement
  • Muscular tissue contracts (gets shorter)
  • when the muscle shortens, it pulls on the bone
  • Bones are held together by joints, most of which
    permit movement between the bones
  • pulling on one bone causes movement at the
    accompanying joint

5
Body Movement
  • Bones and Muscles interact as levers.

6
Blood Cell Formation
  • Hematopoiesis

7
Bone Marrow
  • The central canal of the long bone houses the
    marrow
  • blood cells form in red marrow
  • energy (fat) is stored in yellow marrow

8
Bone Classification
  • Bones are classified by their shapes
  • Long bones
  • Short bones
  • Flat bones
  • Irregular bones
  • Sesamoid (round) bones

9
Anatomy of a Typical Bone
  • Dense compact bone surrounds the organ and spongy
    bone comprises the inner support
  • The ends of the bones, or epiphyses, include the
    epiphyseal plate, an area of cartilage where long
    bones continue to grow during childhood and
    adolescence
  • when bones cease growing, this cartilage is
    replaced by bone, leaving the epiphyseal line
  • Wherever two bones meet, you will find a layer of
    hyaline cartilage
  • this articulating cartilage prevents bone from
    grinding against bone at a joint

10
Bone Tissue
  • Two types of bone tissue
  • Compact dense
  • Spongy lighter and less dense than compact bone

11
Compact Bone
Osteon concentric rings of matrix made by
osteocytes and formed surrounding a central canal.
  • Compact bone material usually occurs at the edges
    of the bone and is composed of many individual
    osteons
  • the central canal of the osteon houses the blood
    and nerve supply for the bone tissue

12
Spongy Bone
  • Spongy bone is less organized than compact bone
    and lacks osteons
  • Instead, spongy bone has trabeculae, or struts,
    that form in response to stress

13
Bone Development Growth
  • The skeletal system begins to form during the
    first few weeks of prenatal development
  • Bones continue to develop and grow into adulthood

14
Bone Formation
  • Bones are a form of connective tissue produced by
    immature bone cells called osteoblasts
  • There are three types of cells that contribute to
    bone homeostasis.
  • Osteoblasts are bone-forming cells
  • Osteoclasts resorb or break down bone
  • Osteocytes are mature bone cells
  • An equilibrium between osteoblasts and
    osteoclasts maintains bone tissue.

15
Bone Formation Ossification
  • Ossification is the process of bone formation
  • 2 types of ossification
  • Most bones are endochondral (formed within
    cartilage)
  • Intramembranous (cartilage is not involved)

16
Bone Formation
  • Intramembranous ossification forms the flat bones
    of the skull, clavicle, and mandible
  • bone is laid down within embryonic connective
    tissue
  • bones form deep in the dermis of the skin and
    thus are often called dermal bones

17
Bone Formation
  • Bones grow longer and thicker
  • growth occurs at the outer surface of the bone
  • cells within the membrane that covers the bone,
    the periosteum, differentiate into osteoblasts
    and begin to add matrix to the exterior
  • accumulating matrix entraps these osteoblasts,
    which mature into osteocytes, creating new bone
    tissue around the exterior of the bone

18
Bone Formation
19
Bone Remodeling
  • Bones are dynamic structures, constantly being
    remodeled and perfected to suit the needs of the
    body, and continuously making subtle changes in
    shape and density
  • Bones cease growing in length at maturity, but
    continue to change shape throughout life

20
Bone Remodeling Blood Calcium
  • When the blood calcium level rises, the
    osteoblasts create new matrix, removing excess
    calcium from the blood.
  • When the blood calcium level drops, osteoclasts
    go to work to release stored calcium to the
    blood.

21
Osteoporosis
  • Bone bank
  • Calcium money
  • The more you have in your account before age 30,
    the less likely you are to develop osteoporosis!
  • Calcium rich foods
  • Dairy products -- milk, cheese and yogurt
  • Dark green leafy vegetables broccoli and
    spinach
  • Calcium fortified foods -- orange juice, cereal
    and bread
  • Nuts -- almonds

22
Avoiding Osteoporosis
  • Get at least 30 minutes of exercise daily
  • A portion should be weight bearing exercise
  • Consume enough daily calcium (1000-1200 mg)
  • Consume enough daily vitamin D (200 IU)
  • Avoid tobacco alcohol consumption

23
The Skeleton
  • The human skeleton is composed of 206 bones

24
The Skeleton
  • The skeleton is divided into
  • the axial skeleton (the central axis of the body)
  • the appendicular skeleton (the appendages and
    girdles holding them to the central axis)

25
Cranial Bones
  • Cranial bones surround and protect the brain
  • the parietal and temporal bones are paired
  • parietal bones protect the upper sides of the
    head
  • temporal bones protect the middle sides of the
    head and support the ears
  • the frontal bone, occipital bone, ethmoid, and
    sphenoid are single bones
  • All 8 cranial bones are held together by fixed
    joints called sutures

26
Facial Bones
  • The 14 facial bones protect the entrances to the
    respiratory and digestive systems, and the
    sensory organs.
  • Two facial bones are single, and 12 occur in
    pairs.

27
Inferior View of Skull
28
Sagittal Section of Skull
29
Vertebrae
  • These bones allow upright posture and protect
    vital organs of the thoracic cavity
  • There are 24 vertebrae, one sacrum, and three to
    five coccyx bones in the adult vertebral column
  • The sacrum is actually five fused vertebrae that
    form a solid base for the pelvic girdle
  • The tailbone, or coccyx, is our post-anal tail

30
Vertebrae
  • A typical vertebra is composed of three parts
  • the vertebral body
  • the vertebral arch
  • the vertebral articular processes
  • serve as points of attachment between adjacent
    vertebra and sites for muscle attachment

31
Vertebral Column
  • The vertebral column is divided into 5 regions
  • the cervical region
  • the thoracic region
  • the lumbar region
  • the sacrum
  • the coccyx
  • Moving down the column, the bodies of the
    vertebrae grow larger, because they must support
    more weight

32
Vertebral Column
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  • Between each vertebra is a pad of fibrocartilage
    called the intervertebral disc
  • the disc serves as a shock absorber, preventing
    vertebrae from rubbing against one another and
    crushing under the body's weight
  • allows limited motion between vertebrae

33
Vertebrae
  • Vertebrae in different regions of the vertebral
    column have special characteristics.

34
Sacrum Coccyx
  • Sacrum
  • Composed of 5 fused vertebrae
  • Forms base of vertebral column
  • Rows of openings provide passageways for nerves
    and blood vessels

35
Sacrum Coccyx
  • Coccyx (tailbone)
  • Lowest part of vertebral column
  • Composed of 4 fused vertebrae

36
Ribs and Sternum
  • 24 ribs, 1 pair attaches to each of the twelve
    thoracic vertebrae.
  • 7 true ribs
  • 5 false ribs
  • 2 floating ribs
  • The sternum, or breastbone, protects the anterior
    of the chest and has 3 parts
  • Upper manubrium articulates with clavicle
  • Middle body
  • Lower xiphoid process

37
The Appendicular Skeleton
  • The appendicular skeleton includes all the bones
    that are attached, or appended, to the axial
    skeleton
  • the pectoral girdle
  • (shoulder bones)
  • the upper appendages
  • (arms and hands)
  • the pelvic girdle
  • (hips and pelvic bones)
  • the lower appendages
  • (legs and feet)

38
The Pectoral Girdle and Upper Appendages
  • Human bodies have two pectoral girdles
  • each consisting of a clavicle and scapula
  • The upper appendages
  • the humerus is the longest and strongest bone in
    the upper appendicular skeleton
  • the ulna and radius make up the forearm
  • the elbow is the joint formed by the distal end
    of the humerus and the proximal ends of the
    radius and ulna
  • The carpals (wrist bones) are in two rows of four
    short bones
  • the metacarpals make up the structure of the hand
  • the phalanges (finger bones) are considered long
    bones

39
Pelvic Girdle
  • The pelvic girdle
  • composed of the hip bones and lower vertebrae
  • denser, stronger, and less flexible than the
    appendicular girdle
  • The acetabulum is the curved recess that serves
    as a socket for the head of the femur
  • The pelvis is technically made of two large coxal
    bones (hip bones) which make up the pelvic
    girdle, plus the sacrum and the coccyx

40
Right Hip Bone
  • The hip bone emerges from three bones that fuse
    in early puberty
  • the ilium
  • the ischium
  • the pubic bone
  • the femur articulates at the junction of these
    three bones

41
Right Lower Limb
  • The femur is the longest and heaviest bone of the
    body. Makes up the upper leg.
  • The fibula and tibia are found in the lower leg.
  • The patella or knee cap is counted as a bone
  • The tarsals, metatarsals and phalanges form the
    feet and toes.

42
Joints
  • Joints link the skeletal system together they
    exist wherever two bones meet
  • Joints are classified by function or structure
  • Functionally, joints are
  • immovable or synarthrotic
  • semimovable or amphiarthrotic
  • freely movable or synovial (most common)
  • Structurally, a joint is considered a fibrous,
    cartilaginous, or synovial joint

43
Fibrous Joints
  • Fibrous joints lie between bones that closely
    contact one another
  • A thin layer of dense connective tissue joins the
    bones, as in a suture between a pair of flat
    bones of the skull

44
Cartilaginous Joints
  • Hyaline cartilage or fibrocartilage connect the
    bones of cartilaginous joints.
  • This type of joint is found between the vertebrae
    of the vertebral column

45
Synovial Joints
  • Most common joint found within the skeletal
    system
  • Allow free movement and are more structurally
    complex than fibrous or cartilaginous joints.
  • Synovial fluid lubricates the joint.

46
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47
Lab This Week
  • Intro to the skeletal system, skull vertebral
    column
  • Bring your textbook and lab manual
  • Well be covering Labs 12-14
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