Chapter 6 Human Anatomy

For intramembranous ossification to take place, which of the following is necessary?

An ossification center forms in the fibrous connective tissue.

How is appositional and interstitial growth of bone different?

Apposition growth- is where cartilage-forming cells in the surrounding inner layer of the perichondrium to secrete new matrix against the external surface of the existing cartilage tissue. Interstitial growth- the lacunae- bound chondrocytes divide and secrete new matrix, expanding the cartilage from within the chondrocytes that divide and produce additional matrix.

Osteoclasts

Are a type of macrophage that break down old bone by dissolving away the bone matrix and dissolving the minerals. The bones are constantly being broken down and built back up due to the balance of osteoblast and osteoclasts.

Osteocytes

Are mature osteoblasts that are locked in lacuna within the bone matrix.

What statement best describes interstitial growth?

Chondrocytes in the lacunae divide and secrete matrix, allowing the cartilage to grow from within.

How are the epiphysis and diaphysis structurally different?

Epiphyses-they are bone ends, they are compact bone forms the epiphyses exterior and the interior contains spongy bone. A thin layer of the articular hyaline cartilage covers the joint surface. Function: Provides attachment for muscles and stability to joints and absorbs stress. Diaphysis- a shaft forms the long axis of the bone, is the main shaft of bone, hollow cylindrical shape, thick, compact bone. And is constructed of a thick collar of compact bone. Function: provides strong support without cumbersome weight.

True/False Bones are classified by whether they are weight bearing or protective in function.

False

True/False Flat bones consist of compact bone sandwiched between spongy bone.

False

True/False Long bones include all limb bones except the patella.

False

True/False Short, irregular, and flat bones have large marrow cavities in order to keep the weight of the bones light.

False

True/False Spongy bone is found in the diaphysis of long bone.

False

True/False The main role of the appendicular skeleton is to protect and support vital organs.

False

True/False The periosteum is a tissue that serves only to protect the bone because it is not supplied with nerves or blood vessels.

False

True/False The skull, thoracic cage and pectoral griddles belong to the axial skeleton.

False

Bones

Gives body form, and provide you with support and protection, and allow us to move. They serve reservoirs for calcium and phosphorus, and they produce the major components of blood.

Describe the difference between osteoid and the inorganic components of bone.

Inorganic-A compound that contains elements other than carbon Osteoid- is the organic portion of matrix, and it actively secrete synthesized osteoblasts.

Osteoporosis/ treated

It can be treated with calcium and vitamin D, which helps calcium absorption, weight bearing exercise and consuming calcium can help maintain healthy bone density for later in life.

Organic components of bone

It consists of collagen fibers, and some proteins, and polysaccharides. This allows the cell to thrive and add to the strength of bone tissue.

Osteomalacia

It is general term that essentially mean "soft bone"

These cells secrete osteoid.

Osteoblasts

What are the major bone cells?

Osteoblasts Osteocytes Osteoclasts

What causes osteoporosis?

Osteoclasts out-pace osteoblasts due to low hormone production of the ovaries.

The cells are bound by lacuna.

Osteocytes

Describe how do nutrients reach an osteocyte.

Osteocytes become surrounded by the bone matrix and they are relatively inactive, but they do have the capability to produce components needed to maintain the bone matrix. They network each other via long cytoplasmic extensions that occupy tiny canals called canaliculi, which are used to exchange of the nutrients and waste through gap junctions.

What description of bone cells is INCORRECT?

Osteogenic cells can differentiate into osteoblasts.

What are the different types of bone cells and what are each of their functions?

Osteogenic cells- they are mitotically active stem cells found in the membranous periosteum and endosteum. In the process of growing bones, they are flattened or squamous cells. When the cells are stimulated, the cells differentiate into osteoblasts or bone lining cells. Osteoblasts-are bone-forming cells that secrete the bone matrix, they are actively mitotic and they also play a role in matrix classification. Osteocytes- are mature bone cells that occupy spaces(lacunae) that conform to their shape, they also monitor and maintain the bone matrix. Osteocytes also act as stress strain "sensors" and they respond to mechanical stimuli. They communicate information to the cells responsible for bone remodeling so the bone matrix can be degraded to preserve calcium homeostasis. Bone lining cells-they are flat cells found on the surface where the bone remodeling is not happening, they also maintain matrix. Osteoclasts-they are giant multinucleate cells located at the sites of bone resorption, and they actively resorbing (breaking done) bone, they rest in shallow depression called resorption bay and they exhibit a distinctive ruffed border that contacts the bone.

Several disorders occur in bone tissue this is one of them:

Osteomalacia is a general term that essentially means "soft bone", this involves a lack of calcium or impaired calcium absorption.

What is an osteon? What is its structural significance?

Osteon- is elongated cylinder oriented parallel to the long axis of the bone, they are tiny weight-bearing pillars. It is a group of hollow tubes of matrix.

Inadequate bone mineralization that may occur when estrogen levels drop result in:

Osteoporosis

What is the periosteum and endosteum? What is their function?

Periosteum- covers the external surface of the entire bone except the surface joints. The outermost fibrous layer of the periosteum is dense irregular tissue. The inner osteogenic layer, next to the bone surface, consist of primitive stem cells. They are active during periods of growth and development and easily identifiable, and inactive in normal adult bone and may not be identifiable. Endosteum-A delicate connective tissue membrane, covers internal bone surfaces. The endosteum covers the trabeculae of spongy bones and it lines the margin of the osteonal canal, that passes through the compact bones.

How are Rickets and Paget's disease similar and different?

Rickets disease- it is a childhood diseases caused by vitamin D deficiency that causes weak and brittle bones. Paget's disease- Is when bones become thickened and enlarged while also becoming weak and brittle, this diseases causes a disorder in the osteoblasts and osteoclasts sometimes caused by a virus. They are similar because they are both diseases.

What is the difference between the axial and appendicular skeleton?

The axial skeleton makes up the central axis and consist of these bones: skull, vertebrae, ribs and sternum. The appendicular skeleton consists of limbs and girdles.

What happens when the blood calcium level drops?

The body's homeostatic point, parathyroid hormone is released and causes osteoblasts to break down bone faster rate than normal. This will release excess amounts of calcium into your bloodstream to be used by other cellular activities, like muscle contraction.

Alice and James adopted a 3-year-old child from a developing country. They noticed that her legs were bowed and there were some deformities in her cranial and pelvic bones. They brought her to a physician for a diagnosis. What was the diagnosis, and what was the treatment for the disorder?

The child most likely has rickets. Treatment is to increase the intake of calcium and vitamin D in the diet, and to get some sunshine every day.

What is hematopoietic tissue and where do you find it in bones?

The hematopoietic tissue, red marrow, is typically found in the trabecular cavities of the spongy bone of long bones and in the diploe of the flat bones. These cavities are often known as red marrow cavities.

What happens when the blood calcium levels rise?

The homeostatic set points, calcitonin will be released, which will stimulate osteoblasts to use the excess calcium to build bone matrix, while inhabiting osteoclast bone and reabsorption.

What houses the bone marrow?

The medullary cavity is the hollow area that houses the bone marrow

What is the perichondrium? Where do you find it and what is its function?

The perichondrium is the connective tissue envelope where it is not a joint. The perichondrium can be found around the perimeter of elastic and hyaline cartilage. Its function is to help the growth and repair of cartilage.

When should prevention of osteoporosis start?

The prevention of osteoporosis should begin with children while bones are still growing. Children should increase their bone mass to provide additional protection from osteoporosis in the future.

Endochondral ossification

The process of endochondral ossification bone is created from cartilage. The bone replaces a hyaline cartilage model. -a distinct epiphyseal plate is formed at the boundary between primary and secondary ossification centers

How are bones divides

They are divided into two axial and appendicular skeleton.

inorganic components of bone

They are rock-like crystals called hydroxyapatite, which are composed of both calcium and phosphate. The cells create bone tissue to secrete deposits of crystallized hydroxyapatite into spaces between collagen fibers.

Osteoblasts

They are small cells that line the periosteum and endosteum that secrete an important organic components of the ground substances of bone tissue called osteoid.

Sharpey's fibers

They are thick collagen rich fibers, hold the periosteum tightly against the outer surface of the bone.

What are lacunae? What do we find them in?

They are tiny cavities in the bone matrix in which they house osteocytes.

Describe how intramembranous ossification and endochondral ossification are similar and different.

They are two processes that from our bones before we are born. Intramembranous ossification- during initial formation of the bone in the flat bones of the skull and this process is also responsible for forming our jaw and most of the clavicles or collar bones, where bone forms directly within mesenchyme arranged in sheet like layers that resemble membranes. It also helps healing bone fractures. Endochondral ossification- is the most common formation for long bones, which involves the replacement of hyaline cartilage (developed by mesenchyme) with bone, such as the femur, or thigh bone. This process also forms the ends of flat and irregular bones are irregularly shaped, such as the vertebrae. Is also a part of the process that lengthens long bones, as well as the natural healing of small bone fractures.

Canaliculi

They are very fine canals that radiate in all directions from the lacunae, which ensure communication between bone cells.

Osteoporosis/menopausal women

They can get osteoporosis because of the declining levels of estrogen present in their body, which impairs the uptake of calcium

What can bones respond to?

They can respond to stress or injury by changing their size, shape, and density. People who stress their skeleton, such as athletes and physical laborers, often stronger, denser bones than those of less active people.

What are canaliculi? What is their function?

Tiny hair like canals that radiate outward from central canals to all lacunae

How are trabeculae and lamellae different? In general, which type of bone has each of them?

Trabeculae-they are interconnecting rods or plates in spongy bone, which bear weight and help bones resist bending and twisting. (trabeculae) In the living bones the open spaces between trabeculae are filled with red or yellow bone marrow. Lamellae- is a thin layer, membrane, scale, or plate-like tissue or part, especially in bone tissue. (a membranous fold in a chloroplast.) (Lamellar bone) The collagen fibers in a lamella run in single direction, the collagen fibers in adjacent lamella always run in different direction.

True/False An osteon contains osteocytes, lamellae, and a central canal, and is found in compact bone only.

True

True/False Calcitonin deposits calcium in bone tissue.

True

True/False Calcium and phosphate crystals compose the inorganic portion of bone matrix.

True

True/False Compact bone is found in the diaphysis of long bones.

True

True/False Diploe is composed of trabeculae.

True

True/False Each consecutive bone lamella has collagen fibers that wrap in alternating directions.

True

True/False Endochondral ossification converts hyaline cartilage "bone" models into true bones (i.e., hyaline cartilage serves as a template for bone formation).

True

True/False Hematopoiesis refers to the formation of blood cells within the red marrow cavities of certain bones.

True

True/False Intramembranous ossification occurs when bone tissue develops in fibrous membrane

True

True/False Red bone marrow is found in trabeculae of spongy bone.

True

True/False The limbs and their griddles belong to the appendicular skeleton.

True

True/False The scapulae and sternum are good sources of red bone marrow.

True

True/False The structural unit of compact bone (osteon) resembles the growth rings of a tree trunk.

True

True/False The term osteoid refers to the organic part of the matrix of compact bones.

True

Flat bone

Which accounts for all other types of bone shapes (irregular, short, and flat) it has a similar but simpler structure to long bone. There is a layer of spongy bone called diploe that is between two layers of compact bone.

Long bone

are bones that are wide. Long bones, such as the femur, have a shaft, called the diaphysis. (humerus)

Flat bones

are generally flat, such as the sternum. (sternum)

Irregular bones

are odd shaped and may also be found as part of a larger group, such as the vertebrae. (verterbra)

Mesenchymal cells

are stem cells that differentiate into the matrix-forming cells of the various connective tissues, including the osteoblasts that form bone.

Short bones

are usually cube shaped and often appear as part of a group, such as the carpals of the wrist, or the tarsals of the ankle. (talus)

Hematopoieses is a term for which of the following physiological processes?

blood cell formation

The canal that runs through the core of each osteon (the Haversian canal) is the site of ________.

blood vessels and nerve fibers

The canal that runs through the center of each Haversian system.

blood vessels and nerves

Osteogenesis is the process of ________.

bone formation

Osteoclasts ________.

break down bone

Normal bone formation and growth are dependent on the adequate intake of ________.

calcium, phosphate, and vitamin D

Osteocytes are connected to each other through which structure?

caniculi

What tissue forms the model for endochondrial ossification?

cartilage

What is not a function of the skeletal system?

communication

Two major types of bones:

compact and spongy

The structure of bone tissue suits the function. Which of the following bone tissues is adapted to support weight and withstand tension stress?

compact bone

The shaft of the adult bone is ______.

composed of compact bone

A fracture in the shaft of a bone would be a break in the ________.

diaphysis

Yellow bone marrow contains a large percentage of ________.

fat

The sternum is a:

flat bone

Bones do NOT have a role in ________.

glycogen production

The correct order (from start to finish) of fracture repair is ________.

hematoma formation, fibrocartilaginous callus formation, bony callus formation, and bone remodeling

Which type of cartilage covers and protects the ends of bones at freely moveable joints?

hyaline cartilage

Hypercalcemia can be caused by_________.

hypersecretion of parathyroid hormone

In adults, yellow marrow is located ________.

in the medullary cavity of long bones

The term diploë refers to the ________.

internal layer of spongy bone in flat bones

When chondrocytes in lacunae divide and form new matrix, it leads to an expansion of the cartilage tissue from within. This process is called ________.

interstitial growth

What is bone-forming process?

intramembranous ossification during embryonic development

Intramembranous ossification

intramembranous ossification involves the creation of bone from connective tissue. It is when bone tissue develops in fibrous connective tissue membrane.

The pelvic bones are:

irregular bones

Articular cartilage

is at the ends of long bone that is formed from hyaline cartilage

Diaphysis

is composed of compact bone, through the center of the diaphysis runs the medullary cavity. Is the "shaft" of long bone.

Epiphyses

is composed of hyaline cartilage and its site of bone lengthening during growth. It is covering all bones and there is supporting connective tissue membrane called periosteum

yellow bone marrow

is found in adults and is a source of fat.

red bone marrow

is found in infants which is the site of hematopoiesis or generation of blood cells

Hematopoietic tissue

is found in the spaces within the red bone marrow found within certain body locations consisting of spongy bone. Examples include the diploe of flat bones and the proximal epiphyses of the femur and humerus.

Hyaline cartilage ________.

is found on the ends of bones that form movable joints

circular structure

is found within compact bone it is called osteon.

Ossification of the ends of long bones ________.

is produced by secondary ossification centers

External membrane

is the perisosteum, that includes a fibrous outer layer composed of dense irregular connective tissue.

Yellow bone marrow

is within the medullary cavity is composed primarily of adipose tissue (fat).

Osteon

it allows continuous delivery of nutrients and removal of metabolic wastes from active bone cells.

The remaining 20% comes from

it comes from the spongy bone

Axial skeleton

it consists of skull, vertebral column and thoracic cage

Appendicular

it consists of the limbs and girdles that bind

Central canal

it contains blood vessels and nerves which branch out and contain individual bone cells in lacuna.

Periosteum

it contains bone forming osteoblasts, and remodeling cells osteoclasts, as well as nerves and blood vessels for the bone. Also serves as an attachment point for ligaments and tendons.

Ossification

it continues throughout life via reabsorption of the bone tissue by osteoblasts and osteoclasts, respectively.

Rickets disease

it is a bone disorder of bone tissue development that usually occurs in young children, it is caused by lack of calcium or vitamin D, which impairs bone development. When the child grows, the weight of the body is poorly developed legs, and as a result, his legs from a bowed shape.

Osteoporosis

it is a condition in which spongy bone loses density because of slow osteoblast activity. While the amount of bone tissue remains constant, the trabeculae are thin and weak.

Trabeculae

it is a honeycomb-like network of spongy bone is constructed of bony plate

Compact bone

it is dense and solid, is composed of nearly solid rings of lamellae. It makes up 80% of your body's total bone mass, it contains many vertical cylindrical units called osteons, or haversian system.

Osteoid

it is the organic part of the (extracellular) bone matrix and includes ground substance, composed of proteoglycans and glycoproteins, and collagen fibers.

Paget's disease

it occurs when bone tissue is formed in a disorganized way, the spongy bone forms in regions where compact bone should be formed, this results in large deformed bones that are weak.

Osteoid Matrix (collagen)

it serves as a framework for the calcium and phosphate crystals

Bones take how many months to develop?

it takes two months to develop, and then the ossification process of the skeleton begins.

During adulthood osteoclasts _______.

it usually exceeds the rate of osteoblast activity. Then the bone tissue density begins to decline with age.

What are the four osteon composed of?

lamellae, canaliculi and central canal, and or the haversian canal.

The tibia is a:

long bone

Extracellular matrix

of bone is hard, it contains organic and inorganic components.

Spongy bone

open spaces partially filled by a network of branched bone tissue, called trabeculae. It is ideal to provide strength and support. No osteons are present, nutrients and waste are transported to the bone cells in lacunae of trabecula via diffusion between tiny canaliculi.

The cell responsible for secreting the matrix of bone is the ________.

osteoblasts

What bone cells form bone?

osteoblasts

Bones are covered and lined by a protective tissue called periosteum. The inner (osteogenic) layer consists primarily of ________.

osteoblasts and osteoclasts

Bones are constantly undergoing resorption for various reasons. Which of the following cells accomplishes this process?

osteoclasts

Theses cells break down bone tissue

osteoclasts

The structural unit of compact bone is:

osteon

What is the structural unit of compact bone?

osteon

Which of the following refers to a bone disorder found most often in the aged and resulting in the bones becoming porous and light?

osteoporosis

What is the CORRECT pairing?

paget's disease: excessive and haphazard bone deposition and resorption

in infants, hematopoeitic tissue is found in:

periosteum

What is stored in bones?

phosphate

The axial skeleton includes the ________.

ribs

Volkmann canals

run perpendicular to the central canal and the canaliculi.

Haversian (or central) canal

runs lengthwise at the center of each osteon.

What type of bone is the patella?

sesamoid bone

The carpal bones are:

short bones

What indicates that a long bone has reached its adult length?

the closure of the epiphyseal plate.

What is endochondral ossification?

the formation of bone from pre-existing hyaline cartilage models

Endosteum

the lining of the medullary cavity of the diaphysis as well as the internal spaces between the trabeculae of spongy bone, it also houses bone forming and remodeling cells.

In adults, hematopoietic tissue is NOT found in ________.

the medullary cavity of long bones

What is osteoid?

the organic part of the matrix of bone

The notable hardness of bone is attributed to ________.

the presences of inorganic hydroxyapatites

Cartilage grows in two ways, appositional and interstitial. What is appositional growth?

the secretion of new matrix against the external face of existing cartilage

The osteon is ________.

the structural unit of compact bone

Lamellae

they are concentric cylindrical layers of calcified bone matrix. -Are layers of bony matrix synthesized by osteoblasts during bone growth and maintenance.

Where are the cranial bones formed?

they are formed by intramembranous ossification

Lacunae

they are small spaces filled with fluid where bone cells are housed.

Bones in the skeletal system do what?

they serve as storage unit for most of the body's calcium supply. Bones play a key role in maintaining blood calcium levels, involves the secretion of parathyroid hormone by the parathyroid glands, and calcitonin by the thyroid glands.

Which of the following glands or organs produces hormones that tend to decrease blood calcium levels?

thyroid

The structural unit of spongy is called ________.

trabeculae

What is a bone projection?

trochanter

During the fetal stage of bone development occurs by

two processes, called intramembranous ossification and endochondral ossification.

Osteoclasts activity

usually exceeds the rate of osteoblasts activity, by this process bone tissue density begins to decline with age.

The epiphyseal plate is ________.

where long bone lengthening occurs

Cranial bones develop ________.

within fibrous membranes