Flashcards in Skeletal System Deck (67)
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5 Skeletal Functions
1) Supports the body
2) Protects soft body parts
3) Produces blood cells (in red bone marrow)
4) Stores minerals (calcium and phosphate) and fat (yellow bone marrow)
5) Permits flexible body movement (via attached muscles)
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5 Types of Bones
1) Long
2) Short
3) Flat
4) Sesamoid
5) Irregular
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Long Bones
Longer than they are wide - e.g., femur
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Short Bones
Generally cube-shaped, e.g. carpals
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Flat Bones
Thin bones consisting of spongy bone sandwiched between two parallel layers of compact bone (e.g. skull bones)
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Sesamoid Bones
Embedded in tendons and increase muscle leverage (e.g., patella)
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Irregular Bones
Bones that don't fit into any other category
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A long bone is comprised of...
Compact bone and spongy bone
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Epiphysis
End of a bone
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Diaphysis
Shaft of a bone
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Medullary Cavity
Space in compact bone, especially in the diaphysis (shaft)
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Compact Bone
Living tissue composed of tubular units called osteons
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Osteocyte
Bone cells, housed in the lacunae.
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Lacunae
Spaces in which osteocyte reside
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Lamella
Layer of matrix made with calcium phosphate and collagen fiberfs
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Spongy Bone
Lighter than compact bones, but still strong. Composed of numerous thin plates called trabeculae, separated by uneven spaces, which often contain red bone marrow.
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Cartilage
Not as strong as bone, but more flexible, composed of many collagenous and elastic fibers. Lack of nerves allows for suitable "padding", but a lack of blood vessels results in slow healing.
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Chondrocytes
Cartilage forming cells that lie within lacunae
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Hyaline Cartilage
Firm but somewhat flexible; found in ends of long bones, nose, larynx, trachea
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Fibrocartilage
Stronger than hyaline; found in disks between vertebrae
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Elastic Cartilage
More flexible than hyaline cartilage. Found in ear flaps.
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Ossification
Formation of bone
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Intramembraneous Ossification
Bone development between sheets of fibrous connective tissue (used in flat bones)
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Endochondral Ossification
Cartilage provides a "template" that is replaced by bone (used by most bones)
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Mesenchyme
Undifferentiated connective tissue
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Osteoblasts
Bone-forming cells
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Epiphyseal Plate
Growth plate via which bones grow and lengthen
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Males stop growing around age...
20.
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Females stop growing around age...
16-18.
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Hormone
A chemical messenger (protein or steroid) that is produced in one part of the body and acts on another.
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Growth Hormone
Stimulates general bone growth and growth of the epiphyseal plates.
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Sex Hormones
Increases growth during adolescence by stimulating osteoblast activity (estrogen is essential for bone maintenance in adult females and males).
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Vitamin D
Converted to a hormone to allow calcium absorption in intestines.
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Osteoclast
Bone-absorbing cells
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Role of bone in homeostasis
Calcium, important in cell signaling, nerve and muscle function, and blood clotting, stored in bones. Body regulates calcium levels in the blood via hormones - parathyroid hormone and calcitonin.
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Parathyroid Hormone
Increases blood calcium by accelerating bone recycling, stimulates osteoclast.
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Calcitonin
Decreases blood calcium by stimulating osteoblast.
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Osteoperosis
Weakening of bones due to decreased bone mass.
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Bone absorption exceeds formation by when?
Age 40, usually.
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Risk factors for osteoperosis
Woman, white or Asian, thin, family history, smoking, diet low in calcium, excessive caffeine or alcohol consumption, sedentary lifestyle.
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Four stages of bone repair
1) Hematoma
2) Fibrocatilaginous callus
3) Bony callus
4) Remodeling
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Hematoma
Blood clot; forms between 6-8 hours after a bone break
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Fibrocartilaginous Callus
Forms between broken bones, about 3 weeks after a break
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Bony Callus
The fibrocartilaginous callus is converted into bone, about 3-4 months after a break.
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Remodeling
Bony callus is replaced by new compact bone tissue. Osteoclasts absorb spongy bone to create the medullary cavity.
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Articulations
Where bone meets bone (aka "joint")
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Types of Articulations
Fibrous
Cartilaginous
Synovial
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Fibrous Articulations
Usually immovable, such as the sutures between cranial bones
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Cartilaginous Articulations
Tend to be slightly movable such as the intervertebral disks
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Synovial Articulations
Freely movable joints - several classes - including the knee joint, ball and socket joint (shoulder, hip), and hinge joints (elbow).
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Flexion
Joint angle decreases
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Extension
Joint angle increases
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Adduction
Body part moves toward midline
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Abduction
Body part moves away from midline
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Rotation
Body part moves around its own axis
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Circumduction
Body part moves in a cone shape
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Inversion
Sole of foot turns inward
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Eversion
Sole of foot turns outward
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Axial Skeleton
Lies in the mid-line of the body
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Appendicular skeleton
Lies away from the mid-line axis
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Hyoid Bone
Anchors the tongue; attachment point for muscles used in swallowing
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Vertebral Column
Cervical
Thoracic
Lumbar
Sacral
Coccyx
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Cervical Vertebrae
Vertebrae 1-7
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Thoracic Vertebrae
8-19
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Lumbar Vertebrae
20-24
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Sacral Vertebrae
25-29, fused
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