Anatomy Chapter 6: Osseous Tissue and Bone Structure

three major sets of blood vessels in a typical bone

*in order to grow and be maintained bones require a extensive blood supply. 1. the nutrient artery and the vein. most bones have one of each 2. metaphyseal vessels: supply blood to inner(diaphyseal) surface of each epiphyseal cartilage, where that cartilage is being replaced by bone 3. Periosteal vessels: blood vessels from the periosteum provide blood to the superficial osteons of the shaft. following the closure of the epiphyses, all three sets of vessels become extensively interconnected.

Which of the following statements best describes how parathyroid hormones (PTH) affects the serum concentration of Calcium [Ca2+]?

PTH stimulates osteoclasts , increasing serum [Ca2+]

Which of the following is not a function of the human skeletal system?

Primary glycogen storage

Which type of synovial joint is multiaxial, allowing motion in more than one plane of movement

Saddle joint

During intramembranous ossification,the developing bone grows outward from the ossification center in small struts called

Spicules

Compact bone is usually found where

Stresses arrive from a limited range of directions

One of the basic histology am differences between compact bone and spongy bone is that in compact bone

The basic functional unit is the osteon, or haversion system

How is the tendon connected to a bone so that it will withstand the force that must be applied by the muscle to move the bone?

The collagen fibers of the tendon as well as the periosteum are incorporated into the bone tissue.

The thyroid regulates bone growth and maintenance through its production of what hormone

Thyroxine

Which of the following bones is accurately described as an irregular bone

Vertebrae

Depressions, grooves, and tunnels in bone indicate

Where blood vessels or nerves lie alongside or penetrate bones

Unlike compact bone, spongy bone(also called cancellous bone) resembles a network of bony struts separated by spaces that are normally filled with

Bone marrow

Which statement correctly identifies a similarity between cartilage and bone

Both are produced by specialized mesenchymal cells

Potts fracture is identified primarily by a

Break in both lower leg bones at the ankle

Osteolysis is an important process in the regulation of

Calcium and phosphate concentrations in body fluids

Osteomalacia is caused by a diet deficient in

Calcium or vitamin D

Which of the following is a major organic compound of bone

Collagen

Growth hormone from the pituitary gland and thyroxine from the thyroid gland maintain normal bone growth activity at the

Epiphyseal plates

Secondary ossification centers can be found in the

Epiphyses of a long bone

Correct sequence of ossification of a long bone

Formation of hyaline cartilage model then ossification of diaphysis then ossification of epiphyses then formation of epiphyseal plate

What are the circulating hormones that stimulate bone growth

Growth hormone and thyroxine

Osteoporosis is a disease caused by the imbalance of bone resorption and bone formation that causes weakening of the bones. The medication ibandronate treats osteoporosis by slowing bone loss. If ibandronate is transporting through the blood, how will it most directly reach bone tissue

Haversian canals

What is a potential problem that can arise from the continual remodeling of bone matrix?

Incorporation of heavy metals into the bone matrix

characteristics of bone

-matrix of bone is very dense and ontains deposits of calcium salts -matrix contains bone cells, within pockets called lacunae. The lacunae of bone are typically organized around blood vessels that branch through the bony matrix -canaliculi-narrow passageways through the matrix, extend between the lacunae and nearby blood vessels forming a branching network for the exchange of nutrients, wastes and gases. - except at joints, a periosteum covers the outer surfaces of bones

Most of the avian skeletons include pneumatic bones, which contain pockets of air that make the bones less dense. A researcher suspects that this design weakens the tensile strength of bone and that the skeletal system of birds must compensate for this loss by adjusting the composition of the bone matrix. If the hypothesis is true, how would the bone matrix of birds differ from that of other vertebrae

It would contain a relatively higher proportion of collagen

Which connective tissue connects and stabilizes adjacent bones

Ligaments

The process of replacing other tissues with bone is called

Ossification

A girl born with nonfunctioning ovaries could be expected to have a deficiency in the activity of which type of cell

Osteoblasts

Which type of cell produces osteoid, a combo of proteins that become mineralized to produce new bone tissue

Osteoblasts

Bone shapes

206 major bones can be divided into 6 broad categories according to their individual shapes. 1. sutural bones: small, flat, irregularly shaped bones between the flat bones of the skull. 2. irregular bones: have complex shapes 3. short bones: small and boxy, approximately equal dimensions 4. Flat bones: thin, flattened shape 5. long bones are elongated and consist of a shaft with two ends that are wider than the shaft 6. sesamoid bones: small, flat, and shaped somewhat like a sesame seed. Except for patellae, there are individual variations in the locations and number of sesamoid bones.

The bony skeleton begins to form about __________ after fertilization and usually does NOT stop growing until about age __________ years.

6 weeks, 25 years

openings

sinus: chamber within a bone, normally filled with air foramen: rounded passageways for blood vessels and/or nerves fissure: deep furrow, cleft, or slit meatus: passage or channel, especially the opening of a canal canal: duct or channel

The fibers of tendons intermingle with those of the periosteum, attaching

skeletal muscles to bones

depressions

sulcus: narrow groove fossa: shallow depression

periosteum

superficial layer of compact bone that covers all bones is wrapped by a periosteum-except joint cavities. it isolates bone from surrounding tissues, provides a route for the blood vessels and nerves and takes part in bone growth and repair.

osseous tissue

supporting connective tissue. contains specialized cells and a matrix consisting of extracellular protein fibers and a ground substance. matrix of bone tissue is solid and sturdy due to deposits of calcium salts around protein fibers

Bone markings

surface features-include depressions and grooves, elevations or projections and tunnels in bone-sites where blood vessels or nerves lie alongside or penetrate the bone.

calcification

the deposition of calcium salts-takes place during ossification, but can also occur in other tissues.

compact bone lamellae

these lamellae are remnants of osteons whose matrix components have been almost completely recycled by osteoclasts. circumferential lamellae are found at the outer and inner surfaces of the bone, where they are covered by the periosteum and endosteum. produced during growth of the bone

remodeling

this process continuously recycles and renews the organic and mineral components of the bone matrix. goes on throughout life. through remodeling, older mineral deposits are removed from bone and released into the circulation at the same time that circulating minerals are being absorbed and deposited

Which of the following are NOT structural components of compact bone?

trabeculae

processes formed where tendons or ligaments attach

trochanter: large, rough projection crest: prominent ridge spine: pointed process line: low ridge tubercle: small, rounded projection tuberosity: rough projection

periosteum

also contains a network of lymphatic vessels and sensory nerves. The lymphatics collect lymph from branches that enter bone and reach individual osteons by the perforating canals. The sensory nerves penetrate the compact bone with the nutrient artery to innervate the endosteum, medullary cavity, and epiphyses. bone injuries are usually very painful bc the rich sensory innervation

osteon

basic functional unit of mature compact bone.the osteocytes are arranged in concentric layers around a vascular central line.

intramembranous ossification

begins when osteoblasts differentiate within a mesenchymal or fibrous connective tissue. normally takes place in deeper layers of dermis. the bones that result are called dermal bone. include flat bones of the skull, the mandible,the clavicles.

ossificiation

bone growth. two major forms are endochondral and intramembranous. endochondral ossification: bone replaces existing cartilage. Intramembranous ossification-bone develops directly from mesenchyme(loosely organized embryonic connective tissue) or fibrous connective tissue

heterotopic bones

bones forming in abnormal locations. can even form in testes and the whites of the eyes. physical or chemical elements can stimulate the abnormal development of osteoblasts in normal connective tissues.

endochondral ossification

bones that replace hyaline cartilage models that form during development

bones and hormones

calcitriol and vitamin D3: the hormone calcitriol, synthesized in the kidneys, is essential for normal calcium and phosphate ion absorption in the digestive tract. calcitriol is synthesized from a related steroid vitamin D3. growth hormone and thyroxine: growth hormone stimulates protein synthesis and the rates of cell division and cell growth throughout the body. thyroxine stimulates cell metabolism and increases the rate of osteoblast activity.these hormones maintain normal activity at the epiphyseal cartilage until puberty. Sex hormones: estrogens and androgens stimulate osteoblast to produce bone faster than the rate at which epiphyseal cartilage expands. calcitonin and parathyroid hormone: involved in homeostatic control of calcium and phosphate levels in body fluids.

hydroxyapatite

calcium phosphate interacts with calcium hydroxide to form crystals of this. As these crystals form they incorporate other calcium salts such as calcium carbonate and ions.

The region known as the epiphyseal plate is the area where __________.

cartilage is replaced by bone

osteoclasts

cells that absorb and remove bone matrix. large cells with 50 or more nuclei. they are derived from the same stem cells that produce monocytes and macrophages. osteolysis is when osteoclasts secrete acid and protein digesting enzymes that dissolve the matrix and release stored minerals. important in regulation of calcium and phosphate concentration in body fluids.

The endosteum is found in all of the following places except one. Where is the endosteum not found?

covering the outside surface of the bone

fracture

crack or break in bone. most heal even after severe damage if the blood supply and the cellular components of the endosteum and periosteum survive. closed or simple fractures are completely internal. open fractures project through the skin-more dangerous due to possibility of infection or uncontrolled bleeding.

compact bone

dense bone, relatively solid. layer of it in wall of diaphysis. it forms sturdy protective layer that surrounds a central space called the medullary cavity

perforating canals

extend perpendicular to the surface. blood vessels in these canals supply blood to osteons deeper in the bone and to tissues of the medullary cavity.

diaphysis

extended tubular shaft in long bone

When cartilage is produced at the epiphyseal side of the metaphysis at the same rate as bone is deposited on the opposite side, bones

grow longer

processes formed where joints(articulations) occur between adjacent bones

head: expanded articular end of an epiphysis, often separated from the shaft by a narrower neck neck:narrow connetion between the epiphysis and diaphysis facet: small, flat, articular process condyle: smooth, rounded articular process trochlea: smooth, grooved articular process shaped like a pulley

bones and exercise

heavily stressed bones become thicker and stronger. degenerative changes in the bone take place after relatively brief periods of inactivity. the bones rebuild just as quickly when you resume normal weight loading.

appositional growth

how developing bone increases in diameter. in this process cells of the inner layer of the periosteum differentiate into osteoblasts and deposit superficial layers of bone matrix.eventually these osteoblasts become surrounded by matrix and differentiate into osteocytes.

calcitonin

if calcium ion conc of blood rises above normal parafollicular cells(C cells) the thyroid gland secretes calcitonin.calcitonin inhibits osteoclast activity and increases the rate of excretion of calcium ions by the kidneys when above 11 mg/dL

acromegaly

if growth hormone levels rise abnormally after epiphyseal cartilages close, the skeleton does not get longer instead the bones get thicker especially in the face, jaw, and hands.

osteopenia

inadequate ossification. reduction in bone mass begins between 30-40.during that time osteoblast activity begins to decrease while osteoclast activity continues at previous levels. epiphyses, vertebrae, and the jaws lose more mass than other sites-resulting in fragile limbs, reduction in height, and loss of teeth.

endosteum

incomplete cellular layer, lines the medullary cavity. this layer is active during bone growth, repair, and remodeling.

osteoclast activating factor

increases both the number and activity of osteoclasts and produces severe osteoporosis. results as a secondary effect of many cancers.

The spaces in the bony matrix where osteocytes exist are __________.

lacunae

spongy bone structure

matrix in spongy bone forms a meshwork of supporting bundles of fibers called trabeculae. no capillaries or venules in matrix of spongy bone. nutrients reach osteocytes by diffusion along canaliculi. red bone marrow is found between the trabeculae of spongy bone. blood vessels within this tissuw deliver nutrients to the trabeculae and remove wastes generated by osteocytes.also has yellow bone marrow-energy reserve

osteocytes

mature bones that make up most of the cell population. each osteocyte occupies a lacuna, a pocket sandwiched between layers of matrix. the layers are called lamellae.

osteogenic cells

mesenchymal cells in bone. these squamous stem cells divide to produce daughter cells that differentiate into osteoblasts. important in repair of fracture.

bones and nutrition

minerals: normal bone growth can't occur without a constant dietary source of calcium and phosphate salts vitamin C: adequate levels of vitamin C must be present in the diet. it is required for certain key enzymatic reactions in collagen synthesis, also stimulates osteoblast differentiation. scurvy-loss of bone mass and strength is a sign of vitamin C deficiency. Vitamins A, K, and B12: vitamin A stimulates osteoblast activity, K and B12 are required for synthesis of proteins in normal bone

canaliculi

narrow passageways that penetrate lamellae, radiating through the matrix and connecting lacunae with one another and with sources of nutrients supplied by blood vessels in the central canal.

metaphysis

narrow zone where diaphysis is connected to each epiphysis

4 types of cells in bones

osteocytes, osteoblasts, osteogenic cells, and osteoclasts

calcium ions

play a role in a variety of physiological processes so body must tightly control calcium ion concentrations in order to prevent damage to essential physiological systems.calcium ions are particularly important to both the plasma membrane and the intracellular activities of neurons and muscle cells, especially cardiac muscle cells.

Which statement concerning endochondral ossification is the most accurate?

primary ossification center begins replacing cartilage in the central region of the cartilage rod

elevations and projections

process: projection or bump ramus: extension of a bone that forms an angle with the rest of the structure

osteoblasts

produce new bone matrix called ossification or osteogenesis.

fibrodysplasia ossificians progressive(FOP)

rare genetic disease in which persons form bone around skeletal muscles and provide the most dramatic demonstrations of heterotopic bone formation

gigantism

results from an overproduction of growth hormone before puberty.

hormones and calcium balance

two hormones with opposing effects maintain calcium ion homeostasis. these hormones are parathyroid hormone and calcitonin, coordinate the storage, absorption, and excretion of calcium ions. three target sites and functions are involved: the bones(storage) the digestive system(absorption) the kidneys(excretion). when calcium ion concentration in the blood fall below normal, cells of the parathyroid glands, embedded in the thyroid gland in the neck release parathyroid hormone into the bloodstream.

marfans syndrome

very tall and have long slender limbs. the cause is excessive cartilage formation at the epiphyseal cartilages. these body proportions are not dangerous but the underying mutation affects structure of connective tissue throughout the body and commonly causes life threatening cardiovascular problems

osteoid

what the organic matrix is called before the calcium salts are deposited.

osteoporosis

when the reduction in bone mass is sufficient to compromise normal function.

spongy bone

also called cancellous or trabecular bone. what epiphyses consist largely of. consists of open network of struts and plates. covered by thin layer of compact bone called cortical bone. contains red bone marrow. The meshwork of supporting bundles of fibers that make up spongy bone are trabeculae

factors that have the most effect on bone remodeling

exercise, nutrition, and hormones

epiphysis

expanded area at each end of diaphysis.

repair of a fracture

1) fracture hematoma formation: extensive bleeding occurs. large blood clot(fracture hematoma) soon closes off the injured vessels and leaves a fibrous meshwork in the damaged area. 2) callus formation: cells of the intact endosteum and periosteum undergo rapid cycles of cell division and the daughter cells migrate into the fracture zone. an internall callus forms as a network of spongy one unites inner edges of fracture. external callus of cartilage and bones encircles and stabilizes the outer edges of the fracture. 3) spongy bone formation: osteoblasts replace the central cartilage of the external callus with spongy bone which then unites the broken ends. 4) compact bone formation: a swelling initially marks the location of the fracture. over time region will be remodeled and repair may be good as new or stronger!

types of fractures

1) transverse fracture: break a bone shaft along its long axis 2) displaced fractures: produce new and abnormal bone arrangements. nondisplaced fractures retain the normal alignment of the bones or fragments 3) compression fractures: occur in vertebrae subjected to extreme stresses-associated with osteoporosis 4) spiral fracture: produced by twisting stresses that spread along the length of the bone 5) epiphyseal fracture: tend to occur where the bone matrix is undergoing calcification and chondrocytes are dying.can permanently stop growth at this site 6)comminuted fractures: such as this fracture of the femur shatter the affected area into a multitude of bony fragments. 7) greenstick fracture: only one side of the shaft is broken, and the other is bent. generally occurs in children whose long bones are yet to ossify fully 8) colles fracture: break in distal portion of radius, typically the result of reaching out to cushion a fall 9) a potts fracture: occurs at the ankle and affects both the medial malleolus of the distal tibia and the lateral malleolus of the distal fibula

osteocyte major functions

1. maintain the protein and mineral content of the surrounding matrix. secrete chemicals that dissolve the adjacent matrix and the minerals released enter the circulation. 2. osteocytes take part in the repair of damaged bone. If released from lacunae osteocytes can convert to a less specialized type of cell such as an osteoblast or osteogenic cell

parathyroid hormone 3 effects that increase blood calcium levels

1. stimulating osteoclast activity. differentiation factor RANKL cause preosteoclasts to mature. mature osteoclasts release enzymes that promote bone resorption, thereby releasing calcium ions into the bloodstream. 2. increasing the rate of intestinal absorption of calcium ions by enhancing the action of calcitriol 3. decreasing the rate of excretion of calcium ions by the kidneys when below 8.5 mg/dL

skeletal system functions

1. support: provide structural support for entire body. framework for attachment of soft tissues and organs 2. storage of minerals and lipids: the calcium salts of bone are a valuable mineral reserve that maintains normal concentrations of calcium and phosphate ions in body fluids. store energy as lipids in yellow bone marrow 3. blood cell production: red blood cells, white blood cells, and other blood elements are produced in red bone marrow, which fills the internal cavities of many bones. 4. Protection: skeletal structures surround many soft tissues and organs. ribs protect heart and lungs, skull encloses brain. 5. leverage: many bons function as levers that can change the maginitude and direction of the forces generated by skeletal muscles.