Podcast
Questions and Answers
Which of the following is NOT a function of the skeletal system?
Which of the following is NOT a function of the skeletal system?
At what age does the human skeleton typically complete its hardening process?
At what age does the human skeleton typically complete its hardening process?
What classification of bone is characterized by having small open spaces resembling a sponge?
What classification of bone is characterized by having small open spaces resembling a sponge?
Which of the following correctly describes the classification of bones by position?
Which of the following correctly describes the classification of bones by position?
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What is a key role of bone tissue related to minerals in the blood?
What is a key role of bone tissue related to minerals in the blood?
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How many bones are there in the adult human axial skeleton?
How many bones are there in the adult human axial skeleton?
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Which class of bones is NOT part of the long bone classification?
Which class of bones is NOT part of the long bone classification?
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Which of the following accurately describes compact bone?
Which of the following accurately describes compact bone?
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Which vitamin is crucial for the intestinal absorption of calcium?
Which vitamin is crucial for the intestinal absorption of calcium?
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What is the active form of cholecalciferol called?
What is the active form of cholecalciferol called?
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What effect does parathyroid hormone (PTH) have on blood calcium levels?
What effect does parathyroid hormone (PTH) have on blood calcium levels?
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Which statement is true regarding bone health as people age?
Which statement is true regarding bone health as people age?
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What common fractures are observed in older adults, particularly in menopausal women?
What common fractures are observed in older adults, particularly in menopausal women?
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Which type of bone is characterized as being typically longer than wide and used for levers and weight bearing?
Which type of bone is characterized as being typically longer than wide and used for levers and weight bearing?
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What is the primary characteristic of short bones?
What is the primary characteristic of short bones?
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Which type of bone is typically thin, flattened, and usually curved?
Which type of bone is typically thin, flattened, and usually curved?
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What best describes irregular bones?
What best describes irregular bones?
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What is the function of sesamoid bones?
What is the function of sesamoid bones?
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Which of the following is NOT a characteristic of long bones?
Which of the following is NOT a characteristic of long bones?
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Which bone shape is primarily associated with boxy, lightweight structures?
Which bone shape is primarily associated with boxy, lightweight structures?
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Which of the following is an example of a flat bone?
Which of the following is an example of a flat bone?
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What is the function of the zone of resting cartilage?
What is the function of the zone of resting cartilage?
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Which zone is characterized by cells that are undergoing mitosis?
Which zone is characterized by cells that are undergoing mitosis?
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What follows the zone of hypertrophic cartilage in the growth at the epiphyseal plate?
What follows the zone of hypertrophic cartilage in the growth at the epiphyseal plate?
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What characterizes the cells in the second layer of the epiphyseal plate?
What characterizes the cells in the second layer of the epiphyseal plate?
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What is the primary ossification center in endochondral ossification?
What is the primary ossification center in endochondral ossification?
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What is the primary role of the zone of calcified cartilage?
What is the primary role of the zone of calcified cartilage?
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Which of the following describes a distinction between endochondral and intramembranous ossification?
Which of the following describes a distinction between endochondral and intramembranous ossification?
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At which location in the bone structure would you primarily find the zone of resting cartilage?
At which location in the bone structure would you primarily find the zone of resting cartilage?
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During the ossification process, how is damaged bone primarily repaired?
During the ossification process, how is damaged bone primarily repaired?
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At what stage in fetal development does the skeleton begin to form?
At what stage in fetal development does the skeleton begin to form?
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Which zone is NOT directly involved in the growth of the cartilage?
Which zone is NOT directly involved in the growth of the cartilage?
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What type of bone develops from fibrous membranes?
What type of bone develops from fibrous membranes?
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What type of tissue is primarily found in the epiphyseal plate?
What type of tissue is primarily found in the epiphyseal plate?
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What is the sequence of events in endochondral ossification?
What is the sequence of events in endochondral ossification?
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Which is a reason for bone remodeling?
Which is a reason for bone remodeling?
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Which part of the bone forms articular cartilage and the epiphyseal plate during ossification?
Which part of the bone forms articular cartilage and the epiphyseal plate during ossification?
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Study Notes
Skeletal System Organization
- Axial skeleton consists of 80 bones, Appendicular skeleton consists of 126 bones
- Fully mature human skeleton contains 206 bones
- Skeleton fully hardens by age 25
Bones and Bone Tissue
- Bone tissue functions to maintain and repair bones, and as a reserve pool of calcium, magnesium and phosphorus
- Bone classification depends on gross and microscopic structure
- Compact bone is dense with a smooth appearance
- Spongy bone contains many small open spaces
Bone Classification
-
Long bones: Longer than they are wide, have a shaft with heads at both ends, used for levers and weight bearing, mostly compact bone
- Examples: Femur, Humerus
-
Short bones: Generally cube-shape, boxy and lightweight, non-weight bearing, mostly spongy bone
- Examples: Carpals, Tarsals
-
Flat bones: Thin and flattened, usually curved, thin layers of compact bone surrounding a layer of spongy bone
- Examples: Skull, Ribs, Sternum
-
Irregular bones Irregular shape, not categorized into other bone types
- Examples: Vertebrae and Pelvis
-
Sesamoid bones Small bones that form within tendons and ligaments
- Example: Patella (kneecap)
- Wormian bones (sutural) Small, irregular bones found within sutures of the skull
Parts of a Long Bone
- Diaphysis is the shaft of the long bone
- Epiphyses are the ends of the long bone
- Epiphyseal plate is the growth plate of the long bone
Bone Formation
- Ossification is the process of bone formation, growth, remodeling and repair
- Ossification occurs in four situations:
- Initial formation of bones in the embryo and fetus
- Bone growth in children and adolescents
- Remodeling of stressed bones
- Repair of damaged bone
Bone Formation Processes
-
Endochondral ossification: Bone development from cartilage
- Cartilage model is prepared by chondroblasts
- A bony collar forms as model enlarges
- Ossification begins in the middle of the shaft (primary ossification center)
- Narrow space enlarges and bone marrow appears
- Secondary ossification centers appear at the ends of long bones
- Articular cartilage and epiphyseal plate form
-
Intramembranous ossification: Bone development from fibrous membranes
- No intermediate stage develops
- First layer of cells are closest to the epiphysis end
- Second layer of cells are undergoing mitosis
Growth at the Epiphyseal Plate
- Zone of resting cartilage anchors the epiphyseal plate to the epiphysis
- Zone of proliferating cartilage contains young cells undergoing mitosis
- Zone of hypertrophic cartilage contains mature cells
- Zone of calcified cartilage contains ossified bone of diaphysis
Calcium Homeostasis
- Body is unable to synthesize calcium, it must be consumed through diet and absorbed through the intestine
- Inadequate absorption of calcium requires cholecalciferol (vitamin D)
- Kidneys convert cholecalciferol into its active form calcitriol (1,25-dihydroxyvitamin D3)
Parathyroid Hormone (PTH)
- PTH regulates blood calcium, and ultimately increases blood calcium concentrations
- If blood calcium rises above set point, parathyroids reduce PTH secretion, and blood calcium returns to set point
Blood Cells and Bone
- Blood cells are produced in the red bone marrow
Lifespan Changes in Bone
- Decrease in height begins around age 30
- Calcium levels fall, bones become brittle
- Osteoclast outnumber osteoblasts
- Spongy bone weakens before compact bone
- Bone loss is rapid in postmenopausal women
- Hip fractures are common, as are vertebral compression fractures
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Description
Explore the fascinating organization of the skeletal system, which includes the axial and appendicular skeletons as well as key information about bone types. Understand the structure and function of different bones, including long, short, flat, and irregular bones. This quiz will test your knowledge of bone classification, composition, and growth.
