Chapter 7 - Bone Tissue

How long does an uncomplicated fracture heal?

8 to 12 weeks, but complex fractures take longer and all fractures heal more slowly in older people

What is a stress fracture?

A break caused by abnormal trauma to a bone, such as fractures incurred in falls, athletics, and military combat.

What is a pathological fracture?

A break in a bone weekend by some other disease such as bone cancer osteoporosis, usually caused by stress that would not normally fracture a bone.

What is in osteon?

A central or Haversian canal, and it's lamallae. This is the basic structural unit of compact bone

What is the periosteum?

A sheath covering the bone, that has a tough outer fibrous layer of collagen and an inner osteogenic layer of bone forming cells.

What is the endosteum?

A thin layer of reticular connective tissue that lines the internal marrow cavity, covers all the honeycomb surfaces of spongy bone, and lines the canal system found throughout compact bone

What is mineral deposition?

Also called mineralization, this is a crystallization process in which calcium phosphate and other ions are taken from the blood plasma in deposited in bone tissue, mainly as a needle like crystals of hydroxyapatite. Deposition begins in fetal ossification and continues through life.

What is osteogenesis imperfecta?

Also known as brittle bone disease, a defect in collagen deposition that renders bones exceptionally brittle, resulting in fracture is present at birth or occurring with extraordinary frequency during childhood also causing tooth deformity, and hearing loss due to deformity of middle ear bones

Volkmann's canals

Appendicular canals

What is the name of the cartilage that surrounds ends of bones?

Articular cartilage

Growth factors

At least 12 hormone like substances produced in bone itself that stimulate neighboring bone cells, promote collagen synthesis, stimulate epiphyseal growth, and produce many other effects

Final step of intramembranous ossification

At the surfaces, osteoblast beneath the periosteum deposit layers of bone, fill in the spaces between trabeculae, and create a zone of compact bone on each side as well as to thicken the bone overall. This process gives rise to the Sandwich like structure typical of a flat cranial bone, a layer of spongy bone between two layers of compact bone.

When does endochondral ossification typically occur?

Begins around the sixth week of fetal development and continues into a persons 20s.

How does bone tissue get nutrients?

Blood vessels, along with nerves and throw the bone tissue through nutrient foramina on the surface. These open into the perforating canals that cross the matrix and feed into central canal's. The innermost osteocytes around each central canal receive nutrients from these blood vessels and pass them along through the gap junctions to neighboring osteocytes. They also receive ways from their neighbors and convey them to the central canal for removal by the bloodstream.

What are osteoclasts?

Bone dissolving cells on the bone services. They develop from the same bone marrow stem cells that give rise to blood cells. Osteoclast are different then other osteogenic cells. They are formed by the fusion of several stem cells so they are unusually large. They sometimes have three or four nuclei occasionally up to 50, each contributed by one stem cell. The side of the osteoclast facing the bone surface has a ruffled border with many deep foldings of plasma membrane.

What are osteoblasts?

Bone forming cells. They are roughly cuboidal or angular, lineup in a single layer on the bone surface under the endosteum and periosteum and resemble a cuboidal epithelium. Nonmitotic.

How does the skeletal system affect the circulatory system?

Bone marrow forms blood cells and platelets. Osseous tissue provides the calcium homeostasis needed for cardiac function and blood clotting

How do osteoclasts and osteoblasts work together?

Bone remodeling results from the combined action of bone dissolving osteoclast, and bone depositing osteoblasts

What is osseous tissue?

Bone tissue, is a connective tissue in which the matrix is hardened by the deposition of calcium phosphate and other minerals.

How does the skeletal system affect the muscular system

Bones are the attachment site for most skeletal muscles and provide leverage for muscle action. calcium homeostasis, important for muscle contraction is achieved partly through a balance between bone deposition and resorption

How does the skeletal system affect the integumentary system?

Bones line close to the body service support in shape the skin

How does calcitonin affect pregnant women?

Calcitonin may inhibit bone loss in pregnant and lactating women

What is the purpose of calcitriol?

Calcitriol behaves as a hormone, a blood borne chemical messenger from one organ to another. The principal function of calcitriol is to raise the blood calcium concentration.

Why does hypocalcemia cause excitability?

Calcium ions normally buying two and mask negatively charged groups on glycoproteins of the soul surface, contributing to the difference between the relatively positive charge on the outer phase of the membrane in the negative charge on the interface. And hypocalcemia few were calcium ions are available to mask the external negative charges so there is less charge difference between the two sides of the membrane. Voltage gated sodium channels in the plasma membrane or sensitive to this charge difference and when the difference is diminished they open more easily and stay open longer. This allows sodium ions to enter the cell freely.

What is the second step in intramembranous ossification?

Calcium phosphate and other minerals crystallize on the collagen fibers of the osteoid tissue and harden in the matrix. Continued osteoid deposition and mineralization squeeze the blood vessels and future bone into narrower spaces. As osteoblast become trapped in their own hardening matrix, they become osteocytes.

Stage three of fracture healing

Conversion to hard callus. Other osteogenic cells differentiate into osteoblasts, which produce a bony collar called the hard callus around the fracture. The hard callus is cemented to dead bone around the injury site and acts as a temporary splint to join the broken ends or bone fragments together. It takes about 4 to 6 weeks for a hard callus to form. During this period it is important that a broken bone be immobilized by traction or a cast to prevent re-injury.

What are the two names for dents, compact outer layer of all bones

Cortical or compact bones

Where would you typically find flat bones?

Cranial bones, parietal bones that form the dome of the top of the head. The sternum, scapula, ribs, and hip bones.

What is the purpose of a diathesis?

Designed to provide leverage to the long bone.

Fifth stage of endochondral ossification

During early infancy and childhood, the epiphysis filled with spongy bone. Cartilage is then limited to the articular cartilage covering each joint surface into an epiphyseal plate. This is a thin wall of cartilage separating the primary and secondary marrow cavities at one or both ends of the bone the plate persists through childhood and adolescence and serves as a growth zone for bone enlongation.

What do osteocytes do?

Each has a delicate cytoplasmic process that reach into the canaliculi to contact the processes from neighboring osteocytes. They also contact osteoblasts on the bone surface. Neighboring osteocytes are connected by gap junctions with their processes me, so they can pass nutrients and chemical signals to one another and Pastor metabolic wastes the nearest blood vessel for disposal.

How is calcitriol produced?

Epidermal keratinocytes use ultraviolet radiation from sunlight to convert a steroid 7-Dihydrocholesterol, to pre-vitamin D3 over another three days the warmth of sunlight on the skin further converts this to vitamin D3, and a transport protein carries us to the bloodstream. The liver adds a hydroxyl group to the molecule, converting it to calcidiol. The kidneys then add another hydroxyl group converting calcidiol to calcitriol, the most active form of vitamin D.

What kind of bones are developed through intramembranous ossification?

Flat bones of the skull, and most of the clavicle.

What is red bone marrow?

Hemopoietic tissue that produces blood cells, composed of multiple tissues in a delicate but intricate arrangement and is considered an organ itself

What are the two methods of ossification?

Intramembranous and endochondral

Why is the osteogenic layer in the periosteum important?

It is essential to the growth of bone and healing of fractures

What is the concentric Lamellae?

Layers of matrix concentrically arranged around a central canal, Connected with each other by canaliculi

What is appositional growth?

Limited growth occurring by intramembranous ossification of the bone surface. Responsible for the growing diameter and thickness of bones.

What is spongy (cancellous) bone?

Loosely organized form of osseous tissue, found at the ends of bone in the central space. Always enclosed by a shell of more durable compact bone.

Step one of intramembranous ossification

Medicine came first condenses into a soft sheet of tissue permeated with blood vessels. The membrane to which intramembranous refers. Mesenchymal cells lineup along the blood vessels, become osteoblasts, and secrete a soft collagenous osteoid tissue called prebone, in the direction away from the vessel. Osteoid tissue resembles bone but is not calcified.

First stage of endochondral ossification

Mesenchyme develops into a body of hyaline cartilage, covered with the fibrous perichondrium, and the location of a future bone. Perichondrium produces chondrocytes and the cartilage model grows and thickness.

What is the hardening process of bones?

Mineralization or calcification.

In what ways does calcitriol raise the blood calcium concentration?

Most commonly, it increases calcium absorption by the small intestine. It also increases calcium resorption from the skeleton. Calcitriol binds to osteoblast which release another chemical messenger. Does messenger stimulates the stem cells to differentiate into osteoclast. The new osteoclast then liberate calcium and phosphate ions from bone. Finally, it weekly promotes the reabsorption of calcium ions by the kidneys, so less calcium is lost in urine.

What is the zone of cell hypertrophy?

Next, the chondrocytes cease to multiply and begin to hypertrophy which means to enlarge. Much like they do in the primary ossification center of the fetus. The walls of the matrix between lacunae become very thin

Vitamin D

Normally functions as a hormone

What is a displaced fracture?

One in which at least one piece is shifted out of alignment with the other

What is a comminuted fracture?

One in which the bone is broken into three more pieces

Vitamin A

Promotes glycosaminoglycan synthesis, also known as chondroitin sulfate

What is the matrix of osseous tissue composed of?

Synthesized by osteoblasts, organic matter includes collagen and various protein carbohydrate complexes. The rest is hydroxyapatite; A chrysalis calcium phosphate salt, calcium carbonate, and lesser amount of magnesium, sodium, potassium, fluoride, Sulfate, carbonate, and hydroxide ions.

What other important role does intramembranous ossification play?

The lifelong thickening, strengthening, and remodeling of the long bones. Throughout the skeleton, it is the method of depositing new tissue on the bone surface even past the age where the bones could no longer grow in length.

What is osteosarcoma?

The most common and deadly form of bone cancer. It occurs most often in the tibia common femur, and humerus of males between the ages of 10 and 25. And 10% of cases, it metastasized to the lungs or other organs, if untreated death typically occurs within a year

What role does calcitonin play in children?

The osteoclast of children are highly active in skeletal remodeling and release 5 g or more of calcium into the blood each day. By inhibiting this activity, calcitonin can significantly lower the blood calcium level in children.

What is compact (dense) bone?

The outer shell of dense white osseous tissue found on a long bone

How does the skeletal System interact with the reproductive system?

The pelvic girdle protects the internal reproductive organs. Childbirth is adapted to the anatomy of a female pelvic girdle, ligaments anchor the penis, clitoris, uterus, and ovaries to the pelvic girdle

What is endochondral ossification?

The process in which a bone develops from a pre-existing model composed of hyaline Cartlidge.

Fourth stage of endochondral ossification

The secondary ossification center hollows out by the same processes as the diaphysis, generating a secondary marrow cavity in the epiphysis. This cavity expand outward from the center in all directions.

What is a diaphysis?

The shaft of a long bone

Where is red marrow typically found in adults?

The skull, vertebrae, ribs, sternum, part of the hip, and proximal head of the humerus and femur.

What is the medullary cavity?

The space, also known as the marrow cavity, that contains bone marrow. Surrounded by compact bone.

What is a diploe ?

The spongy layer in the cranium, and other flat bones

How does the skeletal system interact with the respiratory system?

Ventilation of the lungs is achieved by musculoskeletal actions of the thoracic cage, the thoracic cage protects the delicate lungs from trauma, bone support in shape the nasal cavity

What are examples of irregular bones?

Vertebrae and some skull bones

What is an ectopic ossification?

When osseous tissue sometimes forms in the lungs, brain, eyes, muscles, tendons, arteries, and other organs. A calcified mass in an otherwise soft organs such as the lungs is called a calculus.

What is osteitis deformans?

Excessive proliferation of osteoclasts and resorption of excess bone, with osteoblast attempting to compensate by depositing extra bone. This results in rapid, disorderly bone remodeling and weak, deformed bones. It's usually passes unnoticed but in some cases cause pain, disfiguration, and fractures. It is most common in males over 50.

What is the zone of Reserve cartilage?

Farthest from the marrow cavity, consist of a typical highland cartilage with resting chondrocytes not yet showing any sign of transformation into bone

What does an epiphyseal plate consist of?

Hyaline cartilage in the middle, with a transitional zone on each side where cartilage is being replaced by bones.

What kind of cartilage Is found at joint surfaces?

Hyaline cartilage, called the articular cartilage

How does the skeletal system interact with the lymphatic and immune system?

White blood cells produced in the bone marrow carry out the body's immune functions

What are examples of a short bone?

Bones of the wrist and ankle

How does the skeletal system affect the endocrine system?

Bones protect endocrine glands in the head, thorax, and pelvis, bone secretes the hormone osteocalcin, which promotes insulin action, hormone secretion depends on calcium homeostasis

What is the skeletal system?

Bones, cartilage, and ligaments join tightly to form strong flexible framework for the body.

What are the two treatments of fractures?

A closed reduction, in which bone fragments are manipulated into the normal positions without surgery. And open reduction involves a surgical exposure of the bone and the use of plates screws or pens to realign the fragments. To stabilize the bone during healings, fractures are often set in casts.

What is calcitriol?

A form of vitamin D produced by the sequential action of the skin, liver, and kidneys.

What is a greenstick fracture?

A fracture in which the bone is in completely broken on one side but merely bent on the opposite side

What is parathyroid hormone (PTH) And what does it do?

A hormone secreted by the parathyroid glands, adhere to the posterior surface of the thyroid gland. These glands release PTH when blood calcium is low. PTH raises blood calcium level by four mechanisms.

What is the zone of cell proliferation

A little closer to the marrow cavity, chondrocytes multiply and arrange themselves into longitudinal columns of flattened lacunae

What is hypercalcemia and what does it cause?

Blood calcium excess, excessive amounts of calcium binds to the cell surface increasing the charge difference across the membrane and making sodium channels less responsive. In addition calcium ions bind to membrane proteins that serve as sodium channels and inhibit them from opening. Both actions render nerve and muscle cells less excitable than normal. At 12mg/dL and higher, hypercalcemia causes depression of the nervous system, emotional disturbances, muscle weakness, sluggish reflexes, and sometimes cardiac arrest.

What other tissues make up a bone?

Blood, bone marrow, cartilage, adipose tissue, nervous tissue, and fibrous connective tissue.

Final stage of endochondral ossification

By the late teens and early 20s, all remaining cartilage in the epiphyseal plate is generally consumed and the gap between the epiphysis and the diathesis closes. The primary and secondary marrow cavities unite to a single cavity.

What is the Purpose of calcium?

Calcium plays roles in communication among neurons in muscle contraction, blood clotting, and exocytosis. It is also a second or third messenger in many cell signaling processors and a cofactor for some enzymes.

What are the three names for the porous bony tissue in the middle of bones?

Cancellous, spongy, and trabecular bones.

How is phosphate homeostasis related to PTH and calcium control?

Changes in plasma phosphate level are not associated with any immediate functional disorder, calcitriol raises the phosphate level by promoting it's absorption from the diet by the small intestine. This makes sense because one affect of calcitriol is to promote bone deposition and that requires both calcium and phosphate. Parathyroid hormone on the other hand lowers the blood phosphate level by promoting its urinary excretion.

How does a child grow in height?

Chondrocyte multiplication in zone two and hypertrophy in zone three continually push the zone of reserve cartilage towards the ends of the bone so the bone elongates. In the lower limbs this process causes a person to grow in height while the bones of the upper limbs grow proportionately. This is called interstitial growth.

What are sacrificial bonds?

Collagen molecules that break under stress protecting a bone from fracture by dissipating some of the shock. The bonds reform when the collagen is relieved of stress.

Stage two of fracture healing

Formation of a soft callus. Fibroblasts deposit collagen in the granulation tissue, while some osteogenic cells become chondroblast and produce patches of fibrocartilage called the soft callus

Stage one of fracture healing

Formation of hematoma, and granulation tissue. A bone fracture severed blood vessels of the bone and periosteum, causing bleeding on the formation of a blood clot. Blood capillaries soon grow into the clot, all fiberglass, macrophages, osteoclasts, osteogenic cells invade the tissue from both the Periosteal and medullary sides of a fracture. Osteogenic cells become very abundant, all this capillary and cellular invasion converts to blood clot to a soft fibrous mass called granulation tissue.

What are osteocytes?

Former osteoblast that have become trapped in the matrix deposited. Reside in cavities called lacunae, which are interconnected by slender channels called canaliculi.

What treatment can be used for fractures that take two or more months to heal?

Fractures that take more than two months to heal may be treated with electrical stimulation, which accelerates repair by suppressing the effects of parathyroid hormone.

How does bone growth occur?

From infancy through adolescence, and epiphyseal plate is present at one or both ends of a long bone, at the junction between the diaphysis and the epiphysis. The epiphyseal plate is a region of transition from cartilage to bone and functions as a growth zone where bones along gate. This is responsible for a persons increase in height.

What is hypocalcemia and what does it cause?

Hypocalcemia is a calcium deficiency, that causes excessive excitability of the nervous system and leads to muscle tremors, spasms, or tetany, the inability for the muscle to relax. Tetany begins to occur as the plasma concentration falls to 6 mg/dL. One sign of hypocalcemia is a strong spasmodic flexion of the wrist and thumb and extension of other fingers. Such a spasm can be set off when taking a patient's blood pressure as the inflating cuff puts pressure on the brachial.

Second stage of endochondral ossification

In a primary ossification center near the middle of the cartilage, chondrocytes begin to inflate and die while the thin walls between them calcify. The perichondrium stops producing chondrocytes and begins producing osteoblasts. These deposit a thin collar of bone around the middle of the cartilage model, reinforcing it like a napkin ring. Former perichondrium is now considered periosteum. As chondrocytes in the middle of the model die their lacunae merge into a single cavity.

What is the purpose of an epiphysis?

In large to strengthen the joint and provide added surface area for the attachment of tendons and ligaments

Where would you typically find long bones?

In the limbs; humerus, radius and ulna, the femur, tibia, and fibula of the leg. Metacarpals, metatarsals, and phalanges of the hands and feet.

What is osteomyelitis?

Inflammation of osseous tissue and bone marrow as a result of bacterial infection. This disease was often fatal before the discovery of antibiotics and is still very difficult to treat.

Cortisol

Inhibits osteoclast activity, but if secreted an excess can cause osteoporosis by reducing bone deposition. It also inhibits growth hormone secretion, and stimulating osteoclasts to resorb bone

What is the zone of calcification?

Minerals are deposited in the matrix between the columns of lacunae and calcify the cartilage. These are not the permanent mineral deposits of bone but only a temporary support for the cartilage that would otherwise soon be weakened by the breakdown of the enlarged lacunae.

What is the nutrient foramina?

Minute holes where blood vessels penetrate into the bone

What is the third step in intramembranous ossification?

More mesenchyme adjacent to the developing bone condenses and forms a fibrous periosteum on each surface. The spongy bone becomes a honeycomb of slender calcified trabeculae.

What bones are developed by endochondral ossification?

Most bones of the body, including vertebrae, ribs, sternum, scapula, pelvic girdle, and bones of the limbs.

What is a non-displaced fracture?

One in which the bone pieces remain in proper anatomical alignment

How does the skeletal system interact with the digestive system?

Osseous tissue interacts with the digestive system and maintaining calcium homeostasis. The thoracic cage and pelvic girdle protect portions of the digestive tract, musculoskeletal movements are necessary for chewing

What is the formation of bone called?

Ossification, or osteogenesis.

How does mineralization work?

Osteoblasts begin the process by laying down collagen fibers in a helical pattern along the length of the osteon. These fibers and become encrusted with minerals that hard in the matrix. Hydroxyapatite crystals form only when the product of calcium and phosphate concentration in the tissue fluids, reaches a critical value called the solubility product. Osteoblast neutralize the inhibitor's that prevent other tissues from becoming calcified, thus allowing the salts to precipitate in the bone matrix. The more hydroxyapatite forms, the more it attracts additional minerals from the tissue fluid, until the matrix is thoroughly calcified.

What are the mechanisms that lower blood calcium concentration?

Osteoclast inhibition, and osteoblasts stimulation

Third stage of endochondral ossification

Osteoclasts arrive in the blood and digest calcified tissue in the shaft, hollowing it out and creating the primary marrow cavity. Osteoblasts also arrive and deposit layers of bone lining the cavity, thickening the shaft. As the bony collar under the periosteum thickens and elongates, a wave of cartilage death progresses toward each end of the bone. Osteoclast in the marrow cavity follow this wave dissolving calcified cartilage remnants and enlarging the Marrow cavity of the diaphysis. The region of transition from cartilage to bone at each end of the primary marrow cavity is called a metaphysis. Soon, chondrocyte enlargement and death occur in the emphasis of the model as well, creating a secondary ossification center. In the metacarpal bones the supers in only one epiphysis, in longer bones of the limbs it occurs at both ends.

What is yellow bone marrow?

Red marrow that no longer produces blood, can transform back into red marrow to resume hemopoietic function in case of severe anemia.

By what mechanisms do PTH raise blood calcium level?

PTH binds to the receptors on the osteoblasts, stimulating them to secrete are RANKL, which in turn raises the osteoclast population and promotes bone resorption. PTH promotes the calcium reabsorption by the kidneys, so less calcium is lost in the urine. PTH promotes the final step of calcitriol synthesis in the kidneys, that's enhancing the calcium raising effect of calcitriol. PTH inhibits collagen synthesis by osteoblast, thus inhibiting bone deposition.

What is the purpose of phosphate?

Phosphate groups are a component of DNA, RNA, ATP, phospholipids, and other compounds. Phosphate ions also help to correct acid base in balance in body fluids.

What is calcitonin?

Produced by C cells of the thyroid gland, it is secreted when the blood calcium concentration rises to high, and it lowers the concentration by two principal mechanisms.

What is the purpose of a periosteum?

Provide strong attachment and continuity from muscle to tendon to bone. There is no periosteum over the articular cartilage.

Stage four of fracture healing

Remodeling. The hard Calais persist for 3 to 4 months. Meanwhile osteoclasts off small fragments of broken bone and osteoblast deposit spongy bone to bridge the gap between the broken ends. The spongy bone gradually fills in and becomes compact bone in a manner similar to intramembranous ossification. Usually the fracture leaves a slight thickening of the bone visible by x-ray, such thickenings may serve as a forensic evidence of child abuse.

What is the purpose of bone remodeling?

Repairs micro fractures, releases minerals into the blood, and re-shapes bones in response to use and disuse

Vitamin C, ascorbic acid

Required for collagen synthesis, bone growth, and fracture repair

What is bone marrow?

Soft tissue that occupies the marrow cavity of a long bone, the space is amid the trabeculae of spongy bone and larger central canals.

What are some functions of osteocytes?

Some resorb bone matrix and others deposit it, so they contribute to homeostatic maintenance of both bone density and blood concentration of calcium and phosphate ions. They are also strain sensors. When a load is applied to a bone it produces a Flow in the extracellular fluid of the Lacunae and canaliculi. Stimulates sensory Celia on the osteocytes and induces the cells to secrete signals that regulate bone remodeling to adapt to stress.

What structures build up spongy bone?

Spicules and trabeculae. Covered with endosteum and permeated by space filled with bone marrow. The matrix is arranged lamellae like those of compact bone but there are few osteons. Central canals are not needed.

What are osteogenic cells?

Stem cells that develop from embryonic mesenchyme and then give rise to most other bone cell types. They occur in the Endosteum and inner layer of the periosteum. They multiply continually and some go on to become osteoblasts.

Growth hormone

Stimulates bone elongation and cartilage proliferation at epiphyseal plate, increases urinary excretion of calcium but also increases intestinal calcium absorption which compensates for loss

Insulin

Stimulates bone formation, significant bone loss occurs in untreated diabetes mellitus.

Testosterone

Stimulates osteoblast and promotes protein synthesis, that's promoting adolescent growth and epiphyseal closure

Estrogen

Stimulates osteoblasts and adolescent growth, prevent osteoporosis

What are the six functions of the skeleton?

Support, protection, movement, electrolyte balance, acid-base balance, and blood formation.

What is wolfs law of bone?

The architecture of the bone is determined by the mechanical stress is placed upon it and the bone thereby adapts to withstand those stresses

How does the skeletal system interact with the nervous system?

The cranium in vertebral column and protect the brain and spinal cord, I'll see us tissue provides the calcium homeostasis needed for nerve function

What is a epiphysis?

The expanded head at each end of a long bone

What is osteology?

The study of bones

How does the skeletal system interact with the urinary system?

The thoracic cage partially protects the kidneys, and the pelvic girdle protects the lower urinary tract

What is the metaphysis?

The transitional zone facing the marrow cavity

What is the purpose of long bones?

These bones act primarily in body movement. They serve as rigid levers but are acted upon by skeletal muscles to produce body movements.

What do osteoblasts do?

They synthesize the soft organic matter of the bone matrix, which then hardens buy mineral deposition. Stress and fractures of these cells caused them to multiply more rapidly and quickly generate increased numbers, which reinforce a rebuild the bone. They have an endocrine function, they secrete a hormone osteocalcin previously thought to be only a structural proteins of bone.

What does osteocalcin do?

This is a hormone that stimulates insulin secretion by the pancreas, increases insulin sensitivity in adipocytes, and limits the growth of adipose tissue.

What is mineral resorption?

This is the process of dissolving bones and releasing minerals into the blood to make them available for other uses. Resorption is carried out by osteoclast. They have surface receptors for calcium and respond to farming levels of calcium in the tissue fluid. Hydrogen pumps in the ruffled border of the osteoclast secrete hydrogen ions into the tissue fluid, and chloride ions follow by electrical traction. The space between the Osteo class in the barn that's becomes filled with concentrated hydrochloric acid. The acid dissolves the bone minerals. The Osteoclasts also secretes acid tolerant enzymes that digest the collagen of the bone matrix.

What fracture treatment is used in children but rarely elderly people?

Traction is used to treat fractures of the femur and children, as it aids in the alignment of the bone fragments by overriding the force of the strong side muscles. Traction is rarely use for elderly patients because of risks from long-term confinement to bed. Hip fractures are usually patient and early ambulation is encouraged because it promotes blood circulation and healing.

What are perforating canals?

Transverse or diagonal passages joining the central canal. Lined with endosteum

What can cause hypocalcemia?

Vitamin D deficiency, diarrhea, thyroid tumors, or under active parathyroid gland. Pregnancy and lactation put women at risk of hypocalcemia because of the calcium demanded by ossification of the fetal skeleton and synthesis of milk. The leading cause of hypocalcemic Techne is accidental removal of the parathyroid glands during thyroid surgery or damage to their blood supply if I had a neck surgery. Without hormone replacement therapy, the lack of parathyroid glands can lead to fatal tetany within four days.

What is osteoclast inhibition?

Within 15 minutes after it is secreted, calcitonin reduces osteoclast activity by as much as 70%, so Osteoclasts liberate less calcium from the skeleton.

What is Osteoblast stimulation?

Within an hour, calcitonin increases the number and activity of osteoblasts, which deposit calcium into the skeleton.

What is the zone of bone deposition?

Within each column, the walls between the lacunae breakdown and the chondrocytes die. This converts each column into a longitudinal channel, which is immediately invaded by blood vessels and marrow from the marrow cavity. Osteoblasts line up along the walls of these channels and begin depositing concentric lamellae of matrix which osteoclast dissolve the temporary calcified cartilage.

What are the zones of metaphysis?

Zone of reserve cartilage, zone of cell proliferation, zone of cell hypertrophy, zone of calcification, and zone of bone deposition.