Chapter 6 Flashcards
Five primary functions of the Skeletal System
- Support
- Storage of Minerals (calcium) and Lipids (yellow
marrow) - Blood Cell Production (red marrow)
- Protection
- Leverage (force of motion)
Small, irregular bones that are found between the flat bones of the skull
Sutural Bones
Bones that have complex shapes
• Examples: spinal vertebrae, pelvic bones
Irregular Bones
Bones that are small and thick
• Examples: ankle and wrist bones
Short Bones
Bones that are thin with parallel surfaces and are found in the skull, sternum, ribs, and scapulae
Flat Bones
Bones that are Long and thin and are found in arms, legs, hands, feet, fingers, and toes
Long Bones
Bones that are Small and flat and develop inside tendons near joints of knees, hands,
and feet
Sesamoid Bones
Term for bone markings that are found along bone surface
Depressions or grooves
Term for bone markings that are found where tendons and ligaments attach and at articulations with other bones
Elevations or projections
Term for bone markings that are found where blood and nerves enter bone
Tunnels
The shaft of the long bone that is made of a heavy wall of compact bone, or dense bone
Diaphysis
What is the central space in the diaphysis called?
medullary (marrow) cavity
Wide part at each end of the long bone that articulates with other bones; It is mostly spongy (cancellous) bone and covered with compact bone (cortex)
Epiphysis
Structure where diaphysis and epiphysis meet
Metaphysis
What is the layer of spongy bone between
the compact bone found within the cranium?
diploë
Structure that has dense, supportive connective tissue and contains specialized cells that produce solid matrix of calcium salt deposits
Bone (Osseous) Tissue
This structure forms pathways for blood vessels and exchanges nutrients and wastes
Canaliculi
This structure covers outer surfaces of bones and consists of outer fibrous and inner cellular layers
Periosteum
The bone matrix is composed of two thirds of what compound?
calcium phosphate,
Ca3(PO4)2
The bone matrix is composed of one third of what compound?
protein fibers (collagen)
Calcium phosphate reacts with calcium hydroxide in the bone matrix to form crystals of?
hydroxyapatite
four types of cells of bones
- Osteocytes
- Osteoblasts
- Osteoprogenitor cells
- Osteoclasts
Mature bone cells that maintain the bone matrix and live in lacunae and are between layers (lamellae) of matrix
Osteocytes
Two major functions of osteocytes
- To maintain protein and mineral content of matrix
2. To help repair damaged bone
Immature bone cells that secrete matrix compounds
osteogenesis
Osteoblasts
matrix produced by osteoblasts, but not
yet calcified to form bone
Osteoid
Osteoblasts surrounded by bone become what type of cells?
osteocytes
Mesenchymal stem cells that divide to produce
osteoblasts and are located in endosteum. They assist in fracture repair
Osteoprogenitor Cells
Giant, multinucleate cells that secrete acids and protein-digesting enzyme which dissolves bone matrix and release stored minerals
(osteolysis)
Osteoclasts
basic unit of a compact bone
Osteon
These structures are perpendicular to the central canal and carry blood vessels into bone and marrow
Perforating canals
Describe the characteristics of a spongy bone.
- Does not have osteons
- The matrix forms an open network of trabeculae
- Trabeculae have no blood vessels
- The space between trabeculae is filled with red bone marrow
- In some bones, spongy bone holds yellow bone marrow
Found in the space between trabeculae that forms red blood cells and supplies nutrients to osteocytes
red bone marrow
Why is the yellow bone marrow ‘yellow’?
because it stores fat
collagen fibers of the periosteum
Perforating fibers
Functions of Periosteum
- Isolates bone from surrounding tissues
- Provides a route for circulatory and nervous supply
- Participates in bone growth and repair
Incomplete cellular layer in the compact bone that lines the medullary (marrow) cavity; It covers trabeculae of spongy bone, lines central canals, contains osteoblasts, osteoprogenitor cells, and
osteoclasts and are active in bone growth and repair
Endosteum
Bone formation is called?
Osteogenesis
The process of replacing other tissues with bone
Ossification
The process of depositing calcium salts which occurs during bone ossification and in other tissues
Calcification
Two main forms of ossification
- Endochondral ossification
2. Intramembranous ossification
Form of ossification where it ossifies bones that originate as hyaline cartilage
Endochondral Ossification
Form of ossification where it occurs in the dermis and produces dermal bones such as mandible (lower jaw) and clavicle (collarbone)
Intramembranous Ossification
Intramembranous Ossification is also called?
dermal ossification
A single pair of large blood vessels that enter the diaphysis through the nutrient foramen
Nutrient Artery and Vein
Blood vessels that supply the epiphyseal cartilage
Metaphyseal Vessels
Blood vessels that supply blood to superficial osteons
Periosteal Vessels
If deposition is greater than removal, bones get ________
stronger
If removal is faster than replacement, bones get
_________
weaker
Effects of Exercise on Bone
- Mineral recycling allows bones to adapt to stress
* Heavily stressed bones become thicker and stronger
Hormone made in the kidneys that helps absorb calcium and phosphorus from
digestive tract; it is synthesized from vitamin D3 (cholecalciferol)
hormone calcitriol
Vitamin required for collagen synthesis, and
stimulation of osteoblast differentiation
Vitamin C
Vitamin that stimulates osteoblast activity
Vitamin A
Vitamins that help synthesize bone proteins
Vitamins K and B12
Hormones that stimulate bone growth
Growth hormone and thyroxine
Hormones that stimulate osteoblasts
Estrogens and androgens
Hormones that regulate calcium
and phosphate levels
Calcitonin and parathyroid hormone
Hormone produced by parathyroid glands in neck which increases calcium ion levels
Parathyroid Hormone (PTH)
How does PTH increase calcium ion levels?
by:
- Stimulating osteoclasts
- Increasing intestinal absorption of calcium
- Decreasing calcium excretion at kidneys
Secreted by C cells (parafollicular cells) in thyroid that decreases calcium ion
Calcitonin
How does Calcitonin decreases calcium ion levels?
by:
- Inhibiting osteoclast activity
- Increasing calcium excretion at kidneys
Four steps of fracture repair
- Bleeding
- Cells of the endosteum and periosteum
- Osteoblasts
- Osteoblasts and osteocytes remodel the fracture for
up to a year
