chapter 7 quiz review

1. Perforating (Volkmann's) Canals

Connect central canals together and run at right angles to them.

Lacunae

Small cavities (holes) that contain osteocytes.

Canaliculi

Hairlike canals that connect lacunae to each other and to central canals.

Spongy Bone

Bone made up of trabeculae. Helps absorb shock and reduce weight.

Trabeculae

Bony parts that make up spongy bone.

Osteoid

Organic material secreted by osteoblasts. Contains collagen fibers that allow bones to bend and flex.

Hydroxyapatite

Inorganic mineral salts that make bones hard and help resist breakage. Example: calcium.

Osteogenesis (Ossification)

The process of forming and hardening bone tissue.

Intramembranous Ossification

Bone forms between two membranes. This is how flat bones form.

Endochondral Ossification

Bone forms inside cartilage. Starts with hyaline cartilage and forms most of the skeleton.

Postnatal Bone Growth

Bone growth that happens after birth.

Interstitial Growth

Growth in the length of bones. Bones get longer.

Appositional Growth

Growth in the width or thickness of bones. Bones get wider.

Epiphyseal Plate

The growth plate made of hyaline cartilage. The region where long bones grow longer.

Proliferation (Division) Zone

Chondrocytes divide and multiply. Cartilage cells increase in number.

Hypertrophy Zone

Chondrocytes enlarge. The cells get bigger.

Calcification Zone

Cartilage calcifies and chondrocytes die.

Bone Deposition (Ossification) Zone

Osteoblasts come in and form bone tissue.

Growth Hormone

Acts on the epiphyseal plate and helps bones grow, especially before and during puberty.

Thyroid Hormone

Helps growth hormone work.

Testosterone and Estrogen

During puberty, these hormones cause the epiphyseal plate to grow and mature faster.

Achondroplastic Dwarfism

Hyaline cartilage does not undergo normal interstitial growth, so long bones stop growing early.

Pituitary Dwarfism

The pituitary gland does not produce enough growth hormone.

Acromegaly

Happens later in life. The face, chest, and hands become thicker. Bones get wider through appositional growth.

Gigantism

Too much growth hormone during childhood causes excessive interstitial growth.

Wolff's Law

Bones grow and remodel in response to the stress placed on them. More mechanical stress can make bones thicker.

Bone Deposition

Bone tissue is added to bones.

Bone Resorption

Osteoclasts break down bone tissue, releasing calcium into the blood.

Calcium Homeostasis

Maintaining balanced calcium levels in the body. Every cell needs calcium, and most calcium is stored in bones.

Hypocalcemia

Not enough calcium in the blood. Can cause high muscle activity and muscle tremors.

Hypercalcemia

Too much calcium in the blood. Causes sluggish reflexes and slower muscle reactions.

Carpopedal Spasm

Spasms of the hands and feet caused by low blood calcium.

Causes of Hypocalcemia

Vitamin D deficiency, diarrhea, pregnancy, and lactation.

Three Hormones of Calcium Homeostasis

Calcitriol, parathyroid hormone (PTH), and calcitonin.

Calcitriol (Activated Vitamin D)(Hypo)

Raises blood calcium levels.

Increases calcium absorption in the small intestine,

increases osteoclast activity,

and promotes kidney calcium reabsorption.

Parathyroid Hormone (PTH)(Hypo)

Released when calcium levels are low.

Increases osteoclast activity

promotes calcium reabsorption in the kidneys.

Calcitonin (Hyper)

Helps lower blood calcium levels by telling osteoclasts to stop or slow down and increasing osteoblast activity.

What are the 5 steps of endochondral ossification?

Steps of Bone Formation from Hyaline Cartilage

Bone collar forms around the hyaline cartilage model.

Cartilage dies inside.

Blood vessels enter the diaphysis (periosteal bud).

Secondary bone starts to form (spongy bone).

Epiphyses harden and compact bone forms.