Chapter 6 Flashcards
Is skeletal cartilage innervated? Is it vascular?
No, skeletal cartilage has no blood vessels or nerves
What are the three types of skeletal cartilage?
Elastic
Hyaline
Fibrocartilage
What are the functions hyaline cartilage in skeletal cartilage?
Provides support, flexibility, and resilience
has only collagen fibers- remember collagen fibers are the thickest fibers
What is the difference between hyaline and elastic cartilage?
They are similar to hyaline but contains elastic fibers (stretch and recoil so it would be located in the external ears and epiglottis)
Where would you find fibrocartilage in the body?
in between vertebrae and knees where there is great tensile strength (pushing forces)
Where would you find fibrocartilage in the body?
in between vertebrae and knees where there is great tensile strength (pushing forces)
What are the functions of bone?
Support Protection Movement Mineral and growth factor storage Blood cell formation Triglyceride storage Hormone production
What are the two types of bone textures?
Compact (dense outer layer, smooth and solid)
Spongy (honeycomb looking trabeculae)
What are the 2 parts of they typical long bone?
Diaphysis (compact bone surrounding medullary cavity)
Epiphyses (Bone ends - external compact bones and internal spongy bone)
What cartilage covers bone ends?
articular cartilage
Where is the periosteum located?
On the outside of the compact bone of the diaphysis
What is the medullary cavity lined by?
Endosteum
Where is blood made?
In the red bone marrow
Where is red bone marrow located?
In the trabecular (honeycomb) parts of the spongy bones and the dipole of flat bones (the thin plates of spongy bone surrounded by compact bone-skull)
Where is the red marrow located in new borns?
Medullary cavities and the spongy bone
Describe short bones.
Somewhat cube shaped and include the carpals, tarsals, and patellas
Describe flat bones and where you would find them in the body.
Thin, flattened, often curved bones Skull Sternum Scapulae Ribs
Describe irregular bones and where you would find them in the body.
Have complicated shapes that do not fit any other category of bone.
Vertebrae and coxae
Where is the epiphyseal line located and what does it tell about a person?
It is located between the epiphyses and diaphysis and is the remnant of the epiphyseal plate
(if the plate turns into a line, that person is done growing length wise)
Where is the location of osteogenic cells (stem cells of the bone)?
Periosteum (the external surface of the bone)
Endosteum ( connective tissue that lines the internal surface of the bone)
What are the 5 major cell types of bone tissue?
Osteogenic cells Osteoblasts Osteocytes Bone lining cells Osteoclasts
What is another name for osteogenic cells?
Osteoprogenitor cells
Where would you find osteogenic cells in the bone and what do they do?
Periosteum and endosteum
Mitotically active stem cells that can differentiate into osteoblasts or bone lining cells
BONE STEM CELLS
What are osteoblasts and what do they secrete?
They are the bone forming cells (mitotically active)
Secrete unmineralized bone matrix or osteoid
SECRETE BONE MATRIX
What are osteocytes and what do they do?
They are mature bone cells
Monitor and maintain bone matrix (sense stress or strain to regulate bone remodeling)
MONITOR AND MAINTAIN
What are bone lining cells and what are they called on external bones? On internal surfaces?
Flat cells that help maintenance of bone
Periosteal cells on surface
Endosteal cells on internal (Endo-Into)
What are osteoclasts derived from?
Hematopoietic (blood stem cells) stem cells that become macrophages
What are osteoclasts and what do they do?
Giant, multinucleate cells for bone resorption
(active - in resorption bay and have ruffles)
(they look like broken chips so think of bays and lays/ ruffles)
What organic components of bone provide structure, tensile strength and flexibility?
Cells, Osteoid and collagen
What kind of bonds are in or between collagen?
Sacrificial (stretch and break easily to prevent fracture and these bonds usually reform)
What is the main inorganic component of bone?
Hydroxyapatites
(mineral salts - mainly tiny calcium phosphate crystals around collagen fibers to allow compression and increase hardness)
What are the two types of postnatal bone growth?
Interstitial (longitudinal) growth
Appositional (horizontal or thickness) growth
Where does interstitial growth occur?
At the growth plate (length is increased in bone)
What happens when the epiphyseal plate closes?
The bone lengthening stops and the epiphysis then fuses to the diaphysis
What is appositional growth?
The widening of the bone (occurs throughout life)
How does appositional growth occur?
Osteoblasts (building up) secrete bone matrix on external bone
Osteoclasts remove bone on endosteal surface (usually more building up than breaking down bone)
How does the growth hormone affect bone growth?
Stimulates the epiphyseal plate activity (lengthening of bone)
How does the thyroid hormone affect bone growth?
Modulates activity of bone growth (controls)
How do testosterone and estrogens affect bone growth?
Promote adolescent growth spurts and end growth by inducing epiphyseal plate closure
How often is spongey bone replaced? Compact bone?
Spongy bone is replaced every 3-4 years
Compact bone is replaced every 10 years
Why do our bones need to be recycled and replaced?
The older the bone is the more brittle it becomes
Calcium will crystalize and fracture more easily
What are the 2 bone remodeling units?
Adjacent osteoblasts (deposit) and osteoclasts (resorption)
What are the two loops that bone remodeling is controlled is controlled by?
Negative feedback hormonal loop for Ca2+ homeostasis
Responses to mechanical and gravitational forces
What are the functions of calcium?
Nerve impulse transmission and muscle contraction
How is calcium stored in the body?
As bone
What would happen if our blood calcium levels were too low?
Osteoclasts would resorb bone to increase the levels of calcium
What are the two hormones that control blood Calcium levels?
Parathyroid hormone (produced by parathyroid glands) Calcitonin (produced by parafollicular cells of the thyroid gland)
What hormone would stimulate the release of calcium from bone?
Parathyroid hormone
What hormone would temporarily decrease the levels of calcium in the blood?
Calcitonin
What would happen if blood calcium levels were too low?
Hyperexcitability of muscles (think of tetanus and constant contraction- causes spasms)
What would happen if blood calcium levels were too high?
Nonresponsiveness
What hormone inhibits osteoblasts?
Leptin (released by adipose tissue- the hormone that tells us to stop eating think of the fat rats)
What neurotransmitter regulates mood and sleep and interferes with osteoblast activity?
Serotonin (released into blood after eating)
If you are right handed, would the left or right radius be larger?
The right radius due to more mechanical stress on it throughout the years
What control determines whether and when remodeling of bones occur due to changing blood calcium levels?
Hormonal control
What stress determines where bone remodeling occurs?
Mechanical stress
If a child has bowed legs and many other bone deformities, what disease would they most likely have and what is this caused by?
Rickets (osteomalacia of children)
Vitamin D deficiency or lack of calcium in diet (weak bones)
What is happening in the bone during osteoporosis?
The bone resorption outpaces or beats out bone deposit (osteoclasts are more active than osteoblasts which would increase fractures)
Who is most at risk for osteoporosis?
Aged menopausal women (low sex hormone levels which maintain bone health and density)
Usually caucasian women are more susceptible to bone fractures
If a patient is taking androgen-suppressing drugs, what bone disease would you be cautious of for that patient?
Osteoporosis (need the sex hormones for density)
What are the 4 treatments for osteoporosis?
Calcium intake
Vitamin D supplements
Weight bearing exercise
Hormone replacement therapy
What do bisphosphonates do for osteoporosis?
Decrease the activity of osteoclasts so osteoblasts have a chance to catch up
How do statins help with osteoporosis?
They lower cholesterol and also increase bone density
What drug improves bone density in the elderly and also reduces fractures for men with prostate cancer?
Denosumab (Monoclonal antibody)
What drug mimics estrogen without targeting the breasts and uterus so that bones can gain density?
Selective estrogen receptor modulators (SERMs)
What is happening in the bone during Paget’s DIsease?
Excessive and haphazard bone deposit and resorption (quality is low while quantity is high - too much spongy bone and not enough compact bone)
When in life does bone formation exceed resorption?
During childhood and adolescents (when there is still and epiphyseal plate)
