PHSC1112 Therapeutics - Chapter 6 Bones and Bone Structure (6.4-6.8)

Osteon

functional unit of compact bone

Compact

Which bones have osteons?

Central canal

contains blood vessels and nerves in osteons in compact bone

Perforating canals

carries blood vessels into deep bone and marrow and runs perpendicular

Lamellae

layers of bone matrix

Concentric, interstitial, circumferential

three types of lamellae

Concentric

lamellae surrounding central canal

Interstitial

lamellae filling spaces between osteons

Circumferential

lamellae at outer and inner bone surfaces

Spongy

Which bones lack osteons and are made up of trabeculae

Trabeculae

open network formed by matrix of spongy bone

Osteons, capillaries, and venules

What do spongy bones lack?

Red bone marrow

fills spaces between trabeculae; forms blood cells; contains blood vessels that supply nutrients to osteocytes by diffusion

Spaces between trabeculae

Where is red bone marrow located?

Blood vessels that supply nutrients to osteocytes

What does red bone marrow contain?

Blood cells

What does red bone marrow form?

Yellow bone marrow

found in other sites of spongy bone besides between trabeculae, stores fat

Other sites of spongy bone

Where is yellow bone marrow found?

Fat

What does yellow bone marrow store?

Periosteum

membrane that covers the outside of bone, except within joint cavities

Within joint cavities

Where does the periosteum not cover bones?

Isolates bone from surrounding tissues, provides route for blood vessels and nerves, bone growth and repair

functions of periosteum

Endosteum

incomplete inside layer of compact bone where periosteum is on the outside

Medullary cavity of compact bone and trabeculae of spongy bone

What does the endosteum line and cover?

Bone growth, repair, and remodeling

What is the endosteum active during?

Flattened layer of osteogenic cells

What does the endosteum consist of?

Ossification and calcification

two main parts of bone development

Ossification or osteogenesis

bone formation (two names)

Calcification

deposition of calcium salts

During ossification/osteogenesis

When does calcification occur?

25

What age do some human bones grow until?

Nutrient artery and vein, metaphyseal vessels, periosteal vessels

three types of blood supply to bones

Nutrient artery and vein

most bones have at least one of each; pass through nutrient foramina in diaphysis

Nutrient foramina in diaphysis- Where does the nutrient artery and vein pass through?

Metaphyseal vessel

supplies blood to epiphyseal cartilages, where bone growth occurs

Epiphyseal cartilages where bone growth occurs

Where do metaphyseal vessels supply blood to?

Periosteal vessel

supplies blood to superficial osteons and to secondary ossification centers

Superficial osteons and secondary ossification centers

Where do periosteal vessels supply blood to?

Network of lymphatic vessels and sensory nerves

contained in the periosteum

One-third

Up to what amount of bone mass can be lost in a few weeks of inactivity?

Calcium and phosphorus

minerals required in the diet

Magnesium, fluoride, iron, and manganese

minerals needed in small amounts

Calcitriol

hormone made in the kidneys essential for normal calcium and phosphate ion absorption

Normal calcium and phosphate ion absorption in digestive tract

What is calcitriol essential for?

Vitamin D3 or cholecalciferol

What is calcitriol synthesized from?

Bone growth

What do growth hormone and thyroxine stimulate?

Estrogen and testosterone

sex hormones that stimulate osteoblasts

Parathyroid hormone and calcitonin

hormones that maintain calcium ion homeostasis

Bones

store 99 percent of body's calcium in addition to other minerals

Calcium

most abundant mineral in the body

Storage, absorption, and excretion of calcium ions

What do parathyroid hormone and calcitonin affect?

Bones, digestive tract, kidneys

What parts of the body do the parathyroid hormone and calcitonin use to affect levels of calcium ions?

Parathyroid hormone (PTH)

produced by parathyroid glands in neck, increases blood calcium ion levels

Parathyroid glands in neck

produce parathyroid hormone (PTH)

Increase

Does PTH increase or decrease blood calcium levels?

Stimulating osteoclasts, increasing absorption, decreasing excretion

How does PTH increase blood calcium ion levels?

More

With PTH, would there be more or less calcitriol?

Calcitonin

secreted by C cells in thyroid, decreases blood calcium ion levels

C cells in thyroid

secrete calcitonin

Decrease

Does calcitonin increase or decrease blood calcium levels?

Inhibiting osteoclasts, decreasing absorption, increasing excretion

How does PTH increase blood calcium ion levels?

Less

With calcitonin, would there be more or less calcitriol?