Flashcards in Smith: Cartilage and Bone Deck (24):
What is perichondrium?
a fibrous CT sheath
What is perichondrium made of?
Type I collagen fibers, vascular supply, chondrogenic cells (can differentiate into chondroblasts or chondrocytes)
How is cartilage different than bone?
cartilage is avascular, no nerves, composed of up to 80% water, less organized
What fibers are in hyaline cartilage?
thin fibers or type II fibers only
What fibers are in fibrocartilage?
Thick fibers (Type I and II fibers)
What fibers are in elastic cartilage?
(Type II and elastic fibers)
What is chondroitin sulfate?
Ground substance in cartilage.
How does chondroitin sulfate help?
It provides an electrostatic repulsion that provides resistance to compression.
How does proteoglycan repulsion work?
its is between adjacent negative fixed charges attached in glycosaminoglycans.
What is hyaline cartilage made of?
Perichondriumspherical chondrocytesType II collagen fibersNo nerves or blood vessels
What are characteristics of hyaline cartilage?
It is the weakest cartilage.Its the most widespread cartilage
Where is hyaline cartilage found?
Articular cartilagesCostal cartilagesRespiratory cartilagesNasal Cartilages
What are characteristics of fibrocartilage?
strongest cartilagelacks a perichondriumMore fibers, bur fewer cellsIts the only cartilage that contains Type I and Type II collagen fibersHighly compressible
Where is fibrocartilage located?
At sites subject to both pressure and stretch. Menisci of knee jt., intervertebral discs, pubic synthesis
What are characteristics of elastic cartilage?
Has perichondriumMore elasticmade of elastic fibers and type II collagen fibersFound in external ear and epiglottis.
How do osteoclasts function?
1. They bind to bone via interns at areas called sealing zones.2. Creates an area of high acidity.3. dissolves hydroxyapatite and collagen4. Digested stuff is endocytose and moved across osteoclast to be release into interstitial fluid.
What hormones regulate remodeling of bone tissue?
PTH and activated vitamin D
Where are the 3 reservoirs of blood calcium?
1. GI tract2. Exchangeable reservoir in bone (rapid)3. Stable reservoir in bone (majority)
What percentage of phosphate levels are stored in the bone?
What is the organ that is the main regulator of human phosphate homeostasis?
What 3 hormones regulate Ca homeostasis and how are they formed or secreted? What do these hormones do?
1. PTH: secreted by chief cells of parathyroid glands. (mobilizes calcium from bone and increases urinary phosphate excretion)2. 1,25-dihydroxycholecalciferol (calcitriol): formed by vitamin D in skin via sun and also in liver and kidneys. (increases calcium absorption from intestine, increase Ca in bone)3. Calcitonin: secreted by parafollicular cells in thyroid gland. (inhibits bone reabsorption or osteoclastic activity)
What does PTH do?
1. increases bone reabsorption to increase Ca levels in plasma2. Increases reabsorption of Ca in the kidney and phosphate excretion in the urine3. Increases plasma calcitriol, which increases Ca from GI tract. Calcitriol then feedback inhibits PTH release.
What does calcitonin do?
1. Secreted by parafollicular cells in thyroid gland.2. receptors are for it are found in bone and kidneys.3. lowers Ca levels by one of four ways:a. inhibits Ca absorption by intestinesb. inhibits osteoclastic activity in bonesc. stimulates osteoblastic activity in bonesd. inhibits renal tubular cell reabsorption of Ca, which allows it to be excreted in urine.