Chapter 8: Skeletal Disorders Exam 3 Flashcards
Functions of the Skeletal System
-Offers structural support to the body
-Provides attachments points for muscles & tendons
-Serves as a calcium reservoir
-Houses red bone marrow
What is the Skeletal System Made up of?
Bones, joints, cartilage, & ligaments
What is the Site of Blood Cell Formation?
Red Bone Marrow
What Two Classifications are There for Bone Structure?
Compact & Spongy
What is Bone Structure Classification dependent on?
The amount of cavities in it
Compact Bone
-Hard, dense tissue that has less cavities as compared to spongy bone
-Forms the outermost layer of bones
-80% of skeletal mass
-Predominant type of bone tissue in the long bones & appendicular skeleton
Spongy Bone
-Found inside & at the ends of bones
-Has more cavities in it that form a network of bony tissue
-Red blood cells are produced within red bone marrow located in the cavities between the trabeculae
-Red bone marrow forms the structural foundation of spongy bone
-20% of skeletal mass
-Predominant type of bone tissue in the axial skeleton
Trabeculae
Has more cavities in it that form a network of bony tissue
Osteoblasts
Build bone in response to demands placed on them
Osteoclasts
Destroy bone to make way for new bone growth and help to maintain blood calcium levels
Is Balance Needed to Maintain Bone Mass?
Yes
How Often are Spongy Bones Replaced?
Every 3-4 years
How Long is Required to Replace Compact Bone?
10 years
True or False: Remodeling Rates Vary Bone to Bone
True
Calcitonin
-Released from the thyroid gland in response to elevated blood calcium levels
-Inhibits osteoclasts & stimulates osteoblasts increasing calcium deposition in bone
Parathyroid Hormone
-Released from the parathyroid gland in response to low blood calcium levels
-Stimulates osteoclasts & inhibits osteoblasts causing a release of calcium from the bone into the bloodstream
Estrogen & Testosterone
-Inhibits apoptosis of osteoblasts, increases apoptosis of osteoclasts & stimulates osteoblast activity promoting greater calcium deposition
-Almost 95% of peak bone mass achieved during childhood/adolescence is influenced by estrogen & testosterone
Human Growth Hormone
-Released from the pituitary gland
-Promotes bone growth in length by thickening the epiphyseal plates
-These cartilage plates usually ossify between ages 19-25
-Ossification stops bone from growing in length
Thyroxine
-Released by the thyroid gland
-Stimulates ossification of epiphyseal plates
Bone Health in Childhood/Adolescene
-Osteoblast activity outpaces osteoclast activity resulting in longer, stronger, & denser bone
-Continues to the ages of 20 to 30
Bone Health in Early Adulthood
Process slows until osteoclast activity equals osteoblast activity
Bone Health in Middle Age
-Osteoclast activity outpaces osteoblast activity
-Results in a loss of bone tissue predisposing the bone to osteoporosis & risk of fracture
Bone Health in Old Age
Osteoblast activity decreases as the relative proportion of osteoclasts increases resulting in slow bone repair
__ of all women and __ of all men over 50 can expect an osteoporosis related fracture during their lifetime
50% women & 25% men
