Hormone ch 7

What Is the role of Growth Hormone (Somatotropin) in bone growth/remodeling

Stimulates liver to produce insulin-like growth factors, directly stimulating cartilage growth at epiphyseal plates

What Is the role of Thyroid Hormone in bone growth/remodeling

Influences basal metabolic rate of bone cells and regulates epiphyseal plate activity

What Is the role of Sex Hormones in bone growth/remodeling

Accelerate bone and cartilage growth at puberty; bone formation replaces cartilage growth, epiphyseal plate will close

What Is the role of Glucocorticoids in bone growth/remodeling

High levels increase bone loss and impair growth at epiphyseal plates

What is the role of Serotonin in bone growth/remodeling

High levels prevent osteoprogenitor cells from differentiating into osteoblasts; low bone density disorders

What is the function of the body converting Vitamin D into Calcitriol

it simulates absorption of calcium from small intestine into blood

In the first step of the activation of Calcitriol What does the UV light convert

converts 7-dehydrocholesterol in skin to Vitamin D3 (cholecalciferol) which is released in the blood or absorbed

In the second step of Calcitriol activation what is Vitamin D converted too

Calcidiol by liver enzymes

What is the third step of Calcitriol activation

Calcidiol circulates to the kidneys, where enzymes convert it to active calcitriol

How does the parathyroid hormone and calcitriol regulate blood calcium

Both hormones are released simultaneously in response to a decrease in blood calcium; negative feed back loop

What are the effectors responding to PTH and Calcitriol

Bone, Kidney and Small intestine

When is Calcitonin hormone needed to regulate blood calcium levels

released from the thyroid gland in response to high blood calcium levels

How does the Calcitonin hormone help regulate blood calcium levels

stimulates kidneys to increase calcium excretion in urine

Why does Tensile Strength decrease with Age

Osteoblast rate of protein synthesis declines, makes bones brittle

What does the loss of Calcium & Minerals due to age lead to

Osteopenia (osteoblast activity declines) and potentially Osteoporosis (severe bone mass reduction)

What Is the first step to heal fractures

Fracture hematoma forms: Blood vessels tear within periosteum, forming a blood clot

What Is the second step to heal fractures

Fibrocartilaginous (soft) callus forms: fibroblasts produce collagen fibers and chondroblasts form dense regular CT to form soft callus

What Is the third step to heal fractures

Hard (bony) callus forms: Osteoblasts adjacent to callus produce trabeculae, replacing soft callus with a hard bony callus

What Is the final step to heal fractures

Bone is remodeled: Osteoclasts remove excess bony material; compact bone replaces primary bone