Skeletal system

Exam 3

Osteoprogenitor cell

A multipotent cell that differentiates into osteoblasts

Osteoblast

An immature builder cell that forms the bone matrix

Osteocyte

Mature bone cell that maintains the bone matrix

Osteoclast

Functions the resorption. Breaks down the bone matrix (releases calcium into the blood)

Osteoid

the proteins and other organic components of the bone matrix

Bone is mostly made up of —— with some —-

Collagen (soft protein); Hydroxyapatite (calcium and phosphate mineral)

Cartilage

Growth plate that allows you to keep growing

Chondrocyte

Cartilage cell

High dose of estrogen can —-

decline the number of chondrocytes, thus decreasing bone growth

Red bone marrow

Produces blood cells (RBC, WBC, stem cells, T and B cells)

Yellow bone marrow

stores fat. More when older.

Hemopoietic Stem Cell (HSC)

multipotent stem cell that can differentiate into different types of blood cells

Scurvy

A vitamin C deficiency that leads to problems with collagen synthesis and osteoblasts.

Osteoporosis

Low bone density that is caused by the overactivity of osteoclasts. Associated with old age.

Osteomalacia

Impairment of bone mineralization in adults often due to a vitamin D deficiency

Rickets

Impairment of bone mineralization in children in the growth plate (cartilage) often due to a vitamin D deficiency

Vitamin D benefits

From UV light, it goes through liver and kidney

1. increases calcium absorption

2. increases Calcitriol hormone

Calcitriol

From the kidney. promotes calcium and phosphate ion absorption along the digestive track (small intestine)

Factors that Increase blood calcium levels

1. PTH (with calcitriol): rate of intestinal absorption increases

2. PTH: Kidney retain calcium ions

3. PTH: Osteoclasts stimulated to release stored calcium from bones

Factors that decrease the blood calcium levels

1. Rate of intestinal absorption decreases (decreased calcitriol)

2. Calcitonin: Kidney allows calcium loss

3. Calcitonin: osteoclasts inhibit while osteoblasts continue to lock calcium ions in bone matrix

Parathyroid Hormone (PTH)

Stimulates osteoclast and osteoblast activity; elevates calcium ion concentrations in body fluids

Calcitonin

From Thyroid gland; Inhibits osteoclast activity; promotes calcium loss at kidneys; reduces calcium ion concentration in bodily fluids