A&P Ch 6 Bones and Skeletal Tissue

• ability to maintain internal equilibrium of bone matrix density AND blood Ca & Po4 ion levels by adjusting the complex neg feedback processes regulating mineral absorption from gi, mineral deposition/dissolution in the skeletal system, & mineral excretion by the kidneys;
• endocrine control of mineral homeostasis achieved by antagonistic interplay of PTH(parathyroid hormone) from parathyroid glands which inc blood Ca by stimulating osteoclasts and by (thyro)calcitonin from thyroid gland which tends to dec blood Ca by inhibiting osteoclasts.
• Other minerals are regulated in analogous fashion by endocrine neg feedback systems, Na & K ion levels are regulated by adrenocortical steroid hormone aldosterone which targets the kidney to save Na and excrete K and it's antagonist, the protein hormone atrial natriuretic peptide which targets the kidney to save K and excrete Na

the type found in spongy bone and marrow cavities where blood stem cells reside and where new RBC, WBC, & platelets are produced for release into the circulation

• formation & development of RBC & WBC & platelets involving proliferation & differentiation from specific stem cell types
• occurs in red bone marrow in adults
• in embryo other tissues such as liver also participate

the type found in spongy bone and marrow cavities where adipose tissue predominates, a storage depot for fats

• physio and developmental process of bone tissue bone formation
• membranous OR endochondral

any small artery which passes thru a nutrient foramen to reach the interior of a bone in order to provide a blood supply to that local region

any small opening or perforation thru bone or membranous structure which house only a small blood vessel (artery or vein)

rough cylindrical shaft (diaphysis) with a thick collar of compact bone and often medullary space and broader articular ends (epiphyses) with thinner surface compact bone & spongy bone in the interior

roughly cuboidal in shape with a thin surface of compact bone with spongy bone in the interior, and no medullary space (carpals & tarsals)

this sheets in shape with thin surface of spongy bone interior and no medullary space (cranium)

irregular shape with surface of compact bone, some spongy bone interior, no medullary space (vertebrae)

marrow filled spongy bone tissue found between hard outer and inner bone layers of compact bone in flat bones. trabeculae are arranged to resist compression

shaft or main part of a long bone, begins endochondral ossification before the epiphyses do

either end of long bone, originally separated by a layer of hyaline cartilage(epiphyseal plate) but later united to main bone thru endochondral ossification

region of long bone between diaphysis & epiphyses; includes & sometimes refers to the epiphyseal plate and epiphyseal line

plate or sheet or mass of fibrocartilage that serves as the joint surface for bones which form either cartilagenous or synovial joints

• dense irregular fibrous ct which covers the surface of bones except at the joints
• outer fibrous layer serves as attachment for ligaments, joint capsules, muscles & tendons
• inner more cellular layer contains osteoblasts & osteoclasts which are responsible for bone growth, remodel & repair
• activity of stem cells is regulated by hormones, esp HGH (human growth hormone) parathormone, & thyrocalcitonin

• inner more cellular layer of the periosteum, contains osteoblasts & osteoclasts which are responsible for bone growth, remodel & repair
• the activity of stem cells is regulated by hormones, esp HGH (human growth hormone), parathormone, & thyrocalcitonin

• marrow cavity
• space or chamber in the interior of the diaphysis of a long bone which has no trabeculae or spicules of spongy bone but is still occupied by tissue, either hematopoietic red marrow or more commonly in adults, fatty yellow marrow

• thin layer of ct membrane covering the inner surface of bones
• the inner more cellular osteogenic portion contains osteoblasts & osteoclasts which are responsible for bone growth, remodel, & repair

• dense semi-rigid, porous, vascular, innervated, calcified ct forming the major portion of the skeleton;
• consists of dense organic matrix of proteins & glycoproteins & an inorganic mineral component primarily Ca PO4 salts (hydroxyapetite)

hard dense bone composed of osteons that forms the surface layer of all mature bones & the shafts of long bones

• less dense strutwork of bars & plates (trabeculae) of bone which fills much or all of the interior of mature bones which provide additional strength with minimum of extra mass;
• spaces are occupied by red or yellow marrow
• aka cancellous bone

stem cells from which bone tissue develops; bone forming cells; located in the periosteum & endosteum of bones; these cells play active role in bone remodeling & repair and in blood Ca & PO4 ion homeostasis

• mature cytoplasmically-branched bone cells embedded within lacunae in matrix of mineralized bone tissue;
• play active role in blood Ca and PO4 ion homeostasis

• spec bone cells which have the capacity to enzymatically dissolve bone tissue;
• located in periosteum & endosteum of bones;
• these cells play an active role in bone remodeling & repair and in blood Ca & PO4 ion homeostasis

a cavity, space, or depression within the mineralized matrix of bone or cartilage and containing bone or cartilage cells respectively

principal calcium phosphate salt (mineral) of bone matrix, Ca5(PO4)3OH, which provides the compressional strength of vertebrate bone and tooth dentine

• neralization
• hardening of cartilage, bone, and tooth tissue by impregnation with calcium phosphate salts;
• also the pathological deposition of calcium phosphate salts in all soft tissues or secretions of the body, (e.g. in ct or bile or urine drainage systems)

• any of the supporting strands of ct projecting into an organ & constituting part of the framework of that organ, e.g. lymph nodes, spleen.
• any of the fine spicules, struts, bars and plates forming a network in spongy bone which provide sufficient load-bearing support despite a minimum of mass

• Haversian system
• structural unit for formation & remodeling of compact bone consisting of a series of concentric lamellae of bony matrix formed sequentially by sets of osteocytes located within lacunae in each layer of matrix which retain in the center a central canal containing areolar ct, blood and lymphatic vessels and nerve fibers

• Haversian canal
• central compartment or tunnel in the osteon which contains areolar ct, blood and lymph vessels & nerve fivers

thin cylindrical plates or payers of bone matrix (produced by osteoblasts) around the minute vascular central canals in compact bone, which in cross section produce a pattern of circles of different size, one within another, having a common center.

any small canals or ducts within the body, such as the minute channels in compact bone thru which the cytoplasmic processes of individual osteocytes are in contact with one another and with their capillary blood supply.

• Volkman's canal
• any compartment or tunnel which connects with and runs perpendicular to the central canal in an osteon (which also contains areolar ct, blood & lymph vessels, and nerve fibers) and serves as a connection between an osteon and the systemic circulation by connection to blood vessels in the periosteum, endosteum or medullary space.

thin parallel plates or layers of bone matrix (produced by osteoblasts) located just deep to the periosteum and just superficial to the endosteum which extend around the entire diaphysis of long bones and effectively resist twisting stresses exerted on the shaft.

• thin plates or layers of bone matrix (produced by osteoblasts) observed between osteons in compact bone, which in cross section are variable in shape and orientation;
• these lamellae represent remnants of circumferential lamellae or earlier osteons partially replaced during remodeling.

projection or protuberance, especially one at the end of a bone for the attachment of a ligament, muscle or tendon

ridge or elongated prominence on a bone for the attachment of a ligament, muscle or tendon

• one of two bony processes near the head of the femur, outer=greater trochanter & inner= lesser trochanter;
• anchors for attachment of ligaments and muscle tendons for muscles which move the femur

a narrow ridge of bone, less prominent than a crest, for the attachment of a ligament, muscle or tendon

small rough rounded projection or process of bonefor the attachment of a ligament, muscle, or tendon

• smooth rounded prominence at the end of the bone, most often lined by hyaline cartilage and for articulation with another bone;
• sometimes also applied to the concave surface of the opposing bone

rough rounded projection at the end of the bone, located on or above a condyle and usually serving as a place of attachment for ligaments and tendons

sharp, slender, often pointed projection of bone for the attachment of a ligament, muscle or a tendon

a bony expansion carried on a narrow neck at the end of a bone, most often lined by hyaline cartilage, and for articulation with another bone

• a small smooth flat surface on a bone, most often lined by hyaline cartilage and for articulation with another bone;
• or a small flat surface on a tooth

a bony process extending like a branch or arm from a larger bone, especially the ascending part of the lower jay that makes a joint at the temple.

a body opening or tubular passage, such as the opening of the ear or the urethral canal

• a: a dilated channel or receptacle within the circulator system containing chiefly venous blood
• b: any of various air-filled cavities in the bones of the skull, especially one communicating with the nostrils (as the sinus in the ethmoid, frontal, sphenoidal, and temporal bones)

• small basin-like cavity or depression as in a bone;
• some are articular surfaces lined with hyaline cartilage, others are for the rounded body of a muscle

long narrow furrow or channel on the surface of a bone thru which blood vessel or nerve passes

normal groove or furrow, as in the liver or brain, that divides an organ into lobes or parts; a narrow slit-like opening through a bone through which a blood vessel or nerve passes

a round or oval opening or orifice in a bone through which a blood vessel or rarely, some other structure(s) passes

• 1 of 2 processes of embryonic bone formation;
• embryonic model for most flat bones and a few other bones is a sheet of dense fibrous ct; stem cells differentiate into osteoblasts which begin laying down bone matrix in a spongy pattern to replace the fibrous membrane model;
• several such centers of ossification expand until they meet and fuse;
• eventually the entire structure matures to have compact bone on the outer surface and spongy bone in the interior

• 1 of 2 processes of embryonic bone formation;
• the embryonic model for most long, short, and irreg bones is a mass of dense fibrous ct; stem cells differentiate into chondroblasts which begin laying down hyaline cartilage matrix in a pattern to replace the fibrous ct model; then osteoclasts and blood vessels penetrate the cartilage while other stem cells follow and differentiate into osteoblasts which begin laying down bone matrix in a spongy bone pattern to replace the cartilage model;
• several such centers of ossification expand until they meet and fuse;
• eventually the entire structure matures to have compact bone on the outer surface and to have spongy bone and possibly a marrow space in the interior

the ct stem cells which synthesize and secrete the matrix of cartilage; as they mature they occupy lacunae in the cartilage matrix and can then be referred to as chondrocytes

the embryonic precursor to mature bone for most long, short and irreg bones which form by the process of endochondral ossification

• metaphysis
• in long bones forming by the process of endochondral ossification, the sheet of hyaline cartilage which develops between the growing bone matrix of the diaphysis of the bone and either of the ossification centers in the epiphysis, and by its continual growth and production of new cartilage matrix in both directions away from the diaphysis, permits the developing long bone to continue to grow in length;
• regulatory hormone signals change in the post-adolescent years (~18-23) which slow the rate of epiphyseal cartilage growth and the epiphyseal plates are eventually replaced by bone matrix fusing the diaphysis to its epiphyses; after that point no further growth in length is possible for a given long bone

• metaphysis
• the slightly thickened plate of spongy bone observed in the interior of long bones where an epiphyseal plate of cartilage had been present earlier in development

the region of a long bone between the diaphysis and the epiphyses, generally the area within a long bone associated with the epiphyseal plate or line; composed of both compact and spongy bone

• ability to maintain internal equilibrium of bone matrix density AND blood Ca & Po4 ion levels by adjusting the complex neg feedback processes regulating mineral absorption from gi, mineral deposition/dissolution in the skeletal system, & mineral excretion by the kidneys;
• endocrine control of mineral homeostasis achieved by antagonistic interplay of PTH(parathyroid hormone) from parathyroid glands which inc blood Ca by stimulating osteoclasts and by (thyro-)calcitonin from thyroid gland which tends to dec blood Ca by inhibiting osteoclasts.
• Bone homeostasis is also influenced by mechanical forces in that gravity & strenuous muscle exercise stimulate additional bonedeposition to strengthen the affected bones while exposure to low/zero gravity or the absence of regular physical exercise stimulate additional bone reabsorption leading to osteoporosis.

ongoing and continual activity of osteoclasts and osteoblasts in the periosteum and endosteum of all bones in response to the variables affecting Ca homeostasis & response to mechanical forces of gravity and exercise and the necessity for repairs to any fractures, even of the microscopic scale, that occur due to minor traumas of ordinary physical activity in which old bone matrix is reabsorbed and replaced by new bone matrix

abnormally low concentration of Ca in the blood, at worst respiratory failure may occur (skeletal muscles for breathing lose strength)

ability to maintain equilibrium of blood Ca and PO4 ion levels by adjusting the complex neg feedback processes regulating Ca absorption from the digestive tract (which is also stim by Vit D=calcitrol), calcium deposition/dissolution in the skeletal system, and mineral excretion by the kidneys; the endocrine control of Ca homeostasis is achieved by the antagonistic interplay of PTH(parathyroid hormone) from the parathyroid glands and which tends to increase blood Ca levels by stimulating osteoclasts AND thyrocalcitonin from the thyroid gland which tends to decrease blood Ca levels by inhibiting osteoclasts

• protein hormone produced by parathyroid glands in response to a drop in blood Ca ions that will cause an elevation in the amount of Ca in the body in 3 ways--
• 1: increases osteoclast number and activity, increasing bone resorption
• 2: decreases Ca excretion in the kidneys while increasing phosphate excretion
• 3: increased calcitrol synthesis from Vit D -- calcitrol increases intestinal absorption of Ca
• the net effect of PTH on phosphate ion levels os to decrease blood phosphate levels by increasing phosphate excretion into the urine

protein hormone produced by the thyroid gland in reponse to a rise in blood Ca ions that will cause a decrease in the amount of Ca in the body by inhibiting osteoclast activity, thus decreasing bone resorption (aka thyrocalcitonin)

protein hormone produced by anterior pituitary gland which targets all body cells to encourage normal growth

steroid hormones produced by the gonads (androgens from testes & estrogens from ovaries) which regulate various aspects of reproductive physiology and also play a role in bone growth and metabolism

disease in which the bones become extremely porous, are subject to fracture, and heal slowly, occurring especially in women following menopause and often leading to curvature of the spine from vertebral collapse

form of arthritis (inflammation of joints) occurring mainly in older persons, characterized by chronic degeneration of the cartilage of the joints (aka degenerative joint disease)

any infection (usually bacterial) of bone and bone marrow in which the resulting inflammation can lead to a reduction of blood supply to the bone

serious malignant bone tumor; most common in children and young adults where it tends to affect the femur

general term for any malignant cancer derived from a ct cell type

clinically significant break in a bone, in the first decades of life usually due to a trauma, but in old age usually due to osteoporosis

localized inflamed painful swelling filled with clotted blood resulting from a break in a blood vessel (within the bone, marrow space, periosteum, or surrounding tissues) associated with a bone fracture

• first stage (~1 wk) in healing of a bone fracture; the ct stem cells and capillaries penetrate inflamed fracture hematoma and as phagocytes clear the debris from the injury new fibrous ct matrix then new cartilage matrix and finally new bone matrix begin to form;
• procallus material usually extends beyond the volume previously occupied by uninjured bone

second final stage (weeks to months) in healing of a bone fracture; osteoclasts continue to dissolve away fibrous and cartilaginous components of the injury site while osteoblasts continue to replace that material with new bone matrix; bone remodeling will continue until normal dimensions and composition of the bone are recreated

• causes little to no damage to the surrounding soft tissue
• does not communicate with surface by open wound

there is an open wound from the surface down to the fracture

bone is broken into several parts

partial bone fracture, usually in children, the bone is bent but only broken on one side

an excessive twisting force (torsion) caused the injury leaving a ragged or crumbled edge at the site of break

fracture line is at right angle to the long axis of the bone

fragments are driven into each other so as to be immovable

skull fracture where a piece of bone is pushed inward