Ch. 7

Select all the combined effects of parathyroid hormone and calcitriol. Bone resorption by osteoclasts Activation of osteoclasts Increase excretion of calcium by the kidneys Increase absorption of calcium by the small intestine

-Bone resorption by osteoclasts -Activation of osteoclasts -Increase absorption of calcium by the small intestine

Select all the events unique to endochondral ossification. Formation of a medullary cavity Appearance of bone marrow Multiple ossification centers Epiphyseal plate ossification

-Formation of a medullary cavity -Epiphyseal plate ossification

Hyaline Cartilage

-attaches ribs to sternum -composes epiphyseal plate -forms articular cartilage

spongy bone

-composed of trabeculae -convey strength with light weight -spicules are common - found in greater proportions in flat bones

decreases blood calcium

-increased use of sunblock -osteoblastic activity -calcitonin

Increases Blood Calcium

-osteoclastic actity -calcitriol -parathyroid hormone -increased bone resorption

Fibrocartilage

-weight-bearing cartilage. -forms intervertebral disc -withstands comprehensions

Put the steps of bone repair in the correct order. When the bone is fractured, damage occurs to blood vessels and the periosteum Woven bone is replaced by compact bone A localized mass of blood called a hematoma is formed Fibers and cartilage of the calluses are replaced by spongy bone An internal callus forms between the ends of the bones and an external callus forms a collar around the break

1.) An internal callus forms between the ends of the bones and an external callus forms a collar around the break 2.) Woven bone is replaced by compact bone 3.)When the bone is fractured, damage occurs to blood vessels and the periosteum 4.)Fibers and cartilage of the calluses are replaced by spongy bone 5.)A localized mass of blood called a hematoma is formed

Put the following events in the correct order. -Osteochondral progenitor cells become osteoblasts -Spongy bone forms as trabeculae join together -Osteoblasts produce bone matrix that surrounds collagen fibers of the mesenchyme -Osteoblasts form a ring on the outer surface of the trabeculae -Trabeculae develop -Some mesenchymal cells in the membrane become osteochondral progenitor cells Osteoblasts from the periosteum lay down bone matrix to form an outer surface of compact bone

1.) Some mesenchymal cells in the membrane become osteochondral progenitor cells 2.) Osteochondral progenitor cells become osteoblasts 3. Osteoblasts produce bone matrix that surrounds collagen fibers of the mesenchyme 4.) Trabeculae develope 5.) Osteoblasts form a ring on the outersurface of the trabeculae 6.) Spongy bone forms as trabeculae join together 9.) Osteoblasts from the periosteum lay down bone matrix to form an outer surface of compact bone

Put the steps of endochondral ossification in the correct order. -Cartilage calcifies, and a periosteal bone collar forms -Secondary ossification centers form in the epiphysis -The fetal hyaline cartilage model develops -The primary ossification center forms in the diaphysis -Bone replaces cartilage except at the epiphyseal plates

1.) The fetal hyaline cartilage model develops 2.) Cartilage calcifies, and a periosteal bone collar forms 3.) The primary ossification center forms in the diaphysis 4.) Secondary ossification centers form in the epiphysis 5.) Bone replaces cartilage except at the epiphyseal plates

Bone resorption is a process whereby bone matrix is ____________ by substances released by ____________ . The lysosomes inside of these cells release ____________ that digest the organic components of the matrix. The mineral part of the matrix is dissolved by ____________ . The calcium and phosphate ions enter the ____________ . Bone resorption may occur when blood calcium levels are ____________ .

Answer: Bone resorption is a process whereby bone matrix is destroyed by substances released by osteoclasts. The lysosomes inside of these cells release proteolytic enzymes that digest the organic components of the matrix. The mineral part of the matrix is dissolved by hydrochloric acid. The calcium and phosphate ions enter the blood. Bone resorption may occur when blood calcium levels are low.

Osteocytes maintain contact with neighboring osteocytes in adjacent lamellae via dendrite-like extensions called _________

Canaliculi

Located in the middle of osteons, the ____________ contain the arterial, venous, and nervous supply of the compact bones.

Central canal

______________ is(are) found in compact bone, but not spongy bone.

Central canals

Select all the forms of skeletal cartilage. Elastic Fibrocartilage Ligaments Hyaline

Fibrocartilage Hyaline

Check all of the bones that are formed by intramembranous ossification. Flat bones of the skull Vertebrae Long bones of the limbs Mandible

Flat bones of the skull Mandible

Intramembranous ossification takes place in the embryonic tissue ____________ . This process is also called ____________ because the embryonic tissue that is the source for these bones will be in the area of the future dermis. Intramembranous ossification produces the ____________ bones of the skull, some of the facial bones (zygomatic bone and ____________ ), the ____________ (lower jaw), and the central part of the ____________ (collarbone).

Intramembranous ossification takes place in the embryonic tissue mesenchyme??????. This process is also called dermal ossification because the embryonic tissue that is the source for these bones will be in the area of the future dermis. Intramembranous ossification produces the flat bones of the skull, some of the facial bones (zygomatic bone and maxilla), the mandible (lower jaw), and the central part of the clavicle (collarbone).

The organization of the trabeculae in spongy bone serves what purposes? Check all that are correct. It increases the density of long bones. It provides resistance to stresses from many different directions. It decreases the weight of long bones. It makes the bones slightly flexible.

It provides resistance to stresses from many different directions. It decreases the weight of long bones.

Filled with osteocytes which are osteoblasts encased in matrix, __________ are found between layers of concentric lamellae

Lacunae

The ____________ are found deep in the diaphyses of long bones and are filled with yellow marrow in the adult.

Medullary cavity

Select all that are true of bone remodeling. -Remodeling occurs at about the same rate everywhere in the skeleton. -Osteoclasts are involved in the remodeling process. -Bone remodeling is a combination of bone deposition and resorption. -Bones are remodeled to accommodate the stresses put on them.

Osteoclasts are involved in the remodeling process. Bone remodeling is a combination of bone deposition and resorption. Bones are remodeled to accommodate the stresses put on them.

The constant, dynamic process of continual addition of new bone tissue (bone ____________ ) and removal of old bone tissue (bone ____________ ) is a process called bone ____________ . This ongoing process occurs at both the ____________ (outer) and ____________ (inner) surfaces of a bone. It is estimated that about ____________ of the adult human skeleton is replaced yearly. This process does not occur at the same rate everywhere in the skeleton. For example, the ____________ in our skeleton is replaced at a slower rate than the ____________ .

The constant, dynamic process of continual addition of new bone tissue (bone deposition) and removal of old bone tissue (bone resorption) is a process called bone remodeling. This ongoing process occurs at both the periosteal (outer) and endosteal (inner) surfaces of a bone. It is estimated that about 20% of the adult human skeleton is replaced yearly. This process does not occur at the same rate everywhere in the skeleton. For example, the compact bone in our skeleton is replaced at a slower rate than the spongy bone.

Lack of sunlight will directly affect the formation of

Vitamin D3 (cholecalciferol).

The storage or release of buffering compounds works to aid the body in ____________ balance.

acid-base

Bone formation begins when ____________ secrete the initial semisolid organic form of bone matrix called ____________ . Calcification, or ____________ , then occurs when ____________ crystals deposit in the bone matrix. These crystals form when calcium and phosphate ions reach critical levels and precipitate out of solution and deposit in and around the ____________ fibers. The entire process of bone formation requires a number of substances, including ____________ (which enhances calcium absorption from the GI tract) and ____________ (which is required for collagen formation), as well as calcium and phosphorus for calcification.

answer: Bone formation begins when osteoblasts secrete the initial semisolid organic form of bone matrix called osteoid. Calcification, or mineralization, then occurs when hydroxyapatite crystals deposit in the bone matrix. These crystals form when calcium and phosphate ions reach critical levels and precipitate out of solution and deposit in and around the collagen fibers. The entire process of bone formation requires a number of substances, including vitamin D (which enhances calcium absorption from the GI tract) and vitamin C (which is required for collagen formation), as well as calcium and phosphorus for calcification.

Endochondral Ossification

begins with a hyaline cartilage model

Contained within the spongy sections of bones, red bone marrow is responsible for ________

blood formation

Depositions of collagen and fibrocartilage will then turn the tissue into a soft ____________ .

callus

The shaft of a long bone is called the __________, while the expanded, knobby region at each end is called the __________.

diaphysis, epiphysis

Minerals can be stored in the skeleton, which acts as a reservoir, storing or releasing minerals as needed to maintain ____________ throughout the body.

electrolyte balance

Calcitonin

encourages calcium deposition from blood into bone

If you look at the cross section of a long bone under a microscope, the rings of bone immediately internal to the periosteum of the bone are called external circumferential lamellae. interstitial lamellae. canaliculi. perforating canals.

external circumferential lamellae.

If you are not getting adequate calcium in your diet, calcitonin will be secreted, which stimulates osteoclasts to resorb bone and thereby increases calcium levels in the blood.

false

Many bones contain yellow bone marrow that gives rise to blood cells and platelets.

false

Parathyroid hormone is released in response to elevated blood calcium levels, and will help the body return to homeostasis.

false

Skeletal muscles attach to bones by ligaments and contraction of these muscles allows for movement of the bones.

false

Any break in a bone is called a ____________ and repair is done in stages by the body.

fracture

A ____________ will form and will turn into granulation tissue at the site of injury.

hematoma

Articular cartilage, found on the ends of long bones, consists of

hyaline cartilage.

Mechanical stress applied to bone __________ osteoblast activity in bone tissue, and the removal of mechanical stress __________ osteoblast activity.

increases; decreases

Thyroid Hormone

influences the basal metabolic rate of bone cells

compact bone

made up of osteons -also called cortical bone -visible,abvious, central canals

The ____________ of the entire skeleton or skeletal elements utilizes the anchoring of muscles to attachment sites on the bones, which then serve as levers.

movement

Intramembranous Ossification

ossification that develops from mesenchyme

Bone producing cells are

osteoblast

____________ deposit a temporary bony collar around the fracture while ossification occurs.

osteoblasts

Bone-forming cells that produce collagen and proteoglycans and release matrix vesicles are

osteoblasts.

Bone cells that become surrounded by bone matrix and are located in cavities called lacunae are

osteocytes

The combination of all of the concentric rings of bone built around a single blood vessel is called a(n)

osteon.

The skull, pelvis, ribs, vertebral column, and sternum provide ____________ to many delicate organs of the body by encasing them in hardened, shell-like or caged structures.

protection

The process finishes with bone ____________ converting spongy to compact bone.

remodeling

Hyaline cartilage

serves as a precursor for the formation of long bones in the body.

Bone remodeling is important for all of the following reasons except sodium ion regulation in the body. adjustment to physical stress. bone growth. changes in bone shape. References

sodium ion regulation in the body.

Parathyroid Hormone

stimulates osteoclasts to resorb bone and increase blood calcium

The bones of the skeleton provide structure to the body and serve as a ____________ to hold up the body and maintain proper positioning of some organs.

support

Bone encloses and protects many of the soft organs of the body such as the heart, brain, and spinal cord.

true

Bone, cartilage, and ligaments all are components of the skeletal system that help with support.

true