Module 21: Bone Tissue and the Skeletal System

Lesson 6: Impact of Exercise, Nutrition, and Hormones on Bone Tissue

Ảnh Hưởng Của Luyện Tập, Dinh Dưỡng, Và Hormone Lên Mô Xương

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Dưới đây là danh sách những thuật ngữ Y khoa của module Bone Tissue and the Skeletal System.
Khái quát được số lượng thuật ngữ sẽ xuất hiện trong bài đọc và nghe sẽ giúp bạn thoải mái tiêu thụ nội dung hơn. Sau khi hoàn thành nội dung đọc và nghe, bạn hãy quay lại đây và luyện tập (practice) để quen dần các thuật ngữ này. Đừng ép bản thân phải nhớ các thuật ngữ này vội vì bạn sẽ gặp và ôn lại danh sách này trong những bài học (lesson) khác của cùng một module.

Medical Terminology: Bone Tissue and the Skeletal System

articular cartilage
thin layer of cartilage covering an epiphysis; reduces friction and acts as a shock absorber
articulation
where two bone surfaces meet
bone
hard, dense connective tissue that forms the structural elements of the skeleton
canaliculi
(singular = canaliculus) channels within the bone matrix that house one of an osteocyte’s many cytoplasmic extensions that it uses to communicate and receive nutrients
cartilage
semi-rigid connective tissue found on the skeleton in areas where flexibility and smooth surfaces support movement
central canal
longitudinal channel in the center of each osteon; contains blood vessels, nerves, and lymphatic vessels; also known as the Haversian canal
closed reduction
manual manipulation of a broken bone to set it into its natural position without surgery
compact bone
dense osseous tissue that can withstand compressive forces
diaphysis
tubular shaft that runs between the proximal and distal ends of a long bone
diploë
layer of spongy bone, that is sandwiched between two the layers of compact bone found in flat bones
endochondral ossification
process in which bone forms by replacing hyaline cartilage
endosteum
delicate membranous lining of a bone’s medullary cavity
epiphyseal line
completely ossified remnant of the epiphyseal plate
epiphyseal plate
(also, growth plate) sheet of hyaline cartilage in the metaphysis of an immature bone; replaced by bone tissue as the organ grows in length
epiphysis
wide section at each end of a long bone; filled with spongy bone and red marrow
external callus
collar of hyaline cartilage and bone that forms around the outside of a fracture
flat bone
thin and curved bone; serves as a point of attachment for muscles and protects internal organs
fracture
broken bone
fracture hematoma
blood clot that forms at the site of a broken bone
hematopoiesis
production of blood cells, which occurs in the red marrow of the bones
hole
opening or depression in a bone
hypercalcemia
condition characterized by abnormally high levels of calcium
hypocalcemia
condition characterized by abnormally low levels of calcium
internal callus
fibrocartilaginous matrix, in the endosteal region, between the two ends of a broken bone
intramembranous ossification
process by which bone forms directly from mesenchymal tissue
irregular bone
bone of complex shape; protects internal organs from compressive forces
lacunae
(singular = lacuna) spaces in a bone that house an osteocyte
long bone
cylinder-shaped bone that is longer than it is wide; functions as a lever
medullary cavity
hollow region of the diaphysis; filled with yellow marrow
modeling
process, during bone growth, by which bone is resorbed on one surface of a bone and deposited on another
nutrient foramen
small opening in the middle of the external surface of the diaphysis, through which an artery enters the bone to provide nourishment
open reduction
surgical exposure of a bone to reset a fracture
orthopedist
doctor who specializes in diagnosing and treating musculoskeletal disorders and injuries
osseous tissue
bone tissue; a hard, dense connective tissue that forms the structural elements of the skeleton
ossification
(also, osteogenesis) bone formation
ossification center
cluster of osteoblasts found in the early stages of intramembranous ossification
osteoblast
cell responsible for forming new bone
osteoclast
cell responsible for resorbing bone
osteocyte
primary cell in mature bone; responsible for maintaining the matrix
osteogenic cell
undifferentiated cell with high mitotic activity; the only bone cells that divide; they differentiate and develop into osteoblasts
osteoid
uncalcified bone matrix secreted by osteoblasts
osteon
(also, Haversian system) basic structural unit of compact bone; made of concentric layers of calcified matrix
osteoporosis
disease characterized by a decrease in bone mass; occurs when the rate of bone resorption exceeds the rate of bone formation, a common occurrence as the body ages
perforating canal
(also, Volkmann’s canal) channel that branches off from the central canal and houses vessels and nerves that extend to the periosteum and endosteum
perichondrium
membrane that covers cartilage
periosteum
fibrous membrane covering the outer surface of bone and continuous with ligaments
primary ossification center
region, deep in the periosteal collar, where bone development starts during endochondral ossification
projection
bone markings where part of the surface sticks out above the rest of the surface, where tendons and ligaments attach
proliferative zone
region of the epiphyseal plate that makes new chondrocytes to replace those that die at the diaphyseal end of the plate and contributes to longitudinal growth of the epiphyseal plate
red marrow
connective tissue in the interior cavity of a bone where hematopoiesis takes place
remodeling
process by which osteoclasts resorb old or damaged bone at the same time as and on the same surface where osteoblasts form new bone to replace that which is resorbed
reserve zone
region of the epiphyseal plate that anchors the plate to the osseous tissue of the epiphysis
secondary ossification center
region of bone development in the epiphyses
sesamoid bone
small, round bone embedded in a tendon; protects the tendon from compressive forces
short bone
cube-shaped bone that is approximately equal in length, width, and thickness; provides limited motion
skeletal system
organ system composed of bones and cartilage that provides for movement, support, and protection
spongy bone
(also, cancellous bone) trabeculated osseous tissue that supports shifts in weight distribution
trabeculae
(singular = trabecula) spikes or sections of the lattice-like matrix in spongy bone
yellow marrow
connective tissue in the interior cavity of a bone where fat is stored
zone of calcified matrix
region of the epiphyseal plate closest to the diaphyseal end; functions to connect the epiphyseal plate to the diaphysis
zone of maturation and hypertrophy
region of the epiphyseal plate where chondrocytes from the proliferative zone grow and mature and contribute to the longitudinal growth of the epiphyseal plate
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Dưới đây là các bài văn nằm ở bên trái. Ở bên phải là các bài luyện tập (practice) để đánh giá khả năng đọc hiểu của bạn. Sẽ khó khăn trong thời gian đầu nếu vốn từ vựng của bạn còn hạn chế, đặc biệt là từ vựng Y khoa. Hãy kiên nhẫn và đọc nhiều nhất có kể, lượng kiến thức tích tụ dần sẽ giúp bạn đọc thoải mái hơn.
All of the organ systems of your body are interdependent, and the skeletal system is no exception. The food you take in via your digestive system and the hormones secreted by your endocrine system affect your bones. Even using your muscles to engage in exercise has an impact on your bones.
During long space missions, astronauts can lose approximately 1 to 2 percent of their bone mass per month. This loss of bone mass is thought to be caused by the lack of mechanical stress on astronauts’ bones due to the low gravitational forces in space. Lack of mechanical stress causes bones to lose mineral salts and collagen fibers, and thus strength. Similarly, mechanical stress stimulates the deposition of mineral salts and collagen fibers. The internal and external structure of a bone will change as stress increases or decreases so that the bone is an ideal size and weight for the amount of activity it endures. That is why people who exercise regularly have thicker bones than people who are more sedentary. It is also why a broken bone in a cast atrophies while its contralateral mate maintains its concentration of mineral salts and collagen fibers. The bones undergo remodeling as a result of forces (or lack of forces) placed on them.

Numerous, controlled studies have demonstrated that people who exercise regularly have greater bone density than those who are more sedentary. Any type of exercise will stimulate the deposition of more bone tissue, but resistance training has a greater effect than cardiovascular activities. Resistance training is especially important to slow down the eventual bone loss due to aging and for preventing osteoporosis.
The vitamins and minerals contained in all of the food we consume are important for all of our organ systems. However, there are certain nutrients that affect bone health.

You already know that calcium is a critical component of bone, especially in the form of calcium phosphate and calcium carbonate. Since the body cannot make calcium, it must be obtained from the diet. However, calcium cannot be absorbed from the small intestine without vitamin D. Therefore, intake of vitamin D is also critical to bone health. In addition to vitamin D’s role in calcium absorption, it also plays a role, though not as clearly understood, in bone remodeling.

Milk and other dairy foods are not the only sources of calcium. This important nutrient is also found in green leafy vegetables, broccoli, and intact salmon and canned sardines with their soft bones. Nuts, beans, seeds, and shellfish provide calcium in smaller quantities.

Except for fatty fish like salmon and tuna, or fortified milk or cereal, vitamin D is not found naturally in many foods. The action of sunlight on the skin triggers the body to produce its own vitamin D (Figure 1), but many people, especially those of darker complexion and those living in northern latitudes where the sun’s rays are not as strong, are deficient in vitamin D. In cases of deficiency, a doctor can prescribe a vitamin D supplement.

Vitamin K also supports bone mineralization and may have a synergistic role with vitamin D in the regulation of bone growth. Green leafy vegetables are a good source of vitamin K.

The minerals magnesium and fluoride may also play a role in supporting bone health. While magnesium is only found in trace amounts in the human body, more than 60 percent of it is in the skeleton, suggesting it plays a role in the structure of bone. Fluoride can displace the hydroxyl group in bone’s hydroxyapatite crystals and form fluorapatite. Similar to its effect on dental enamel, fluorapatite helps stabilize and strengthen bone mineral. Fluoride can also enter spaces within hydroxyapatite crystals, thus increasing their density.

Omega-3 fatty acids have long been known to reduce inflammation in various parts of the body. Inflammation can interfere with the function of osteoblasts, so consuming omega-3 fatty acids, in the diet or in supplements, may also help enhance production of new osseous tissue. Table 1 summarizes the role of nutrients in bone health.
Several hormones are necessary for controlling bone growth and maintaining the bone matrix. The pituitary gland secretes growth hormone (GH), which, as its name implies, controls bone growth in several ways. It triggers chondrocyte proliferation in epiphyseal plates, resulting in the increasing length of long bones. GH also increases calcium retention, which enhances mineralization, and stimulates osteoblastic activity, which improves bone density.

GH is not alone in stimulating bone growth and maintaining osseous tissue. Thyroxine, a hormone secreted by the thyroid gland promotes osteoblastic activity and the synthesis of bone matrix. During puberty, the sex hormones (estrogen and testosterone) also come into play. They too promote osteoblastic activity and production of bone matrix, and in addition, are responsible for the growth spurt that often occurs during adolescence. They also promote the conversion of the epiphyseal plate to the epiphyseal line (i.e., cartilage to its bony remnant), thus bringing an end to the longitudinal growth of bones. Additionally, calcitriol, the active form of vitamin D, is produced by the kidneys and stimulates the absorption of calcium and phosphate from the digestive tract.
Bone modeling and remodeling require osteoclasts to resorb unneeded, damaged, or old bone, and osteoblasts to lay down new bone. Two hormones that affect the osteoclasts are parathyroid hormone (PTH) and calcitonin.

PTH stimulates osteoclast proliferation and activity. As a result, calcium is released from the bones into the circulation, thus increasing the calcium ion concentration in the blood. PTH also promotes the reabsorption of calcium by the kidney tubules, which can affect calcium homeostasis (see below).

The small intestine is also affected by PTH, albeit indirectly. Because another function of PTH is to stimulate the synthesis of vitamin D, and because vitamin D promotes intestinal absorption of calcium, PTH indirectly increases calcium uptake by the small intestine. Calcitonin, a hormone secreted by the thyroid gland, has some effects that counteract those of PTH. Calcitonin inhibits osteoclast activity and stimulates calcium uptake by the bones, thus reducing the concentration of calcium ions in the blood. As evidenced by their opposing functions in maintaining calcium homeostasis, PTH and calcitonin are generally not secreted at the same time. Table 2 summarizes the hormones that influence the skeletal system.

OpenStax. (2022). Anatomy and Physiology 2e. Rice University. Retrieved June 15, 2023. ISBN-13: 978-1-711494-06-7 (Hardcover) ISBN-13: 978-1-711494-05-0 (Paperback) ISBN-13: 978-1-951693-42-8 (Digital). License: Attribution 4.0 International (CC BY 4.0). Access for free at openstax.org.

Sunlight is one source of vitamin D.

NutrientRole in bone health
CalciumNeeded to make calcium phosphate and calcium carbonate, which form the hydroxyapatite crystals that give bone its hardness
Vitamin DNeeded for calcium absorption
Vitamin KSupports bone mineralization; may have synergistic effect with vitamin D
MagnesiumStructural component of bone
FluorideStructural component of bone
Omega-3 fatty acidsReduces inflammation that may interfere with osteoblast function
HormoneRole
Growth hormoneIncreases length of long bones, enhances mineralization, and improves bone density
ThyroxineStimulates bone growth and promotes synthesis of bone matrix
Sex hormonesPromote osteoblastic activity and production of bone matrix; responsible for adolescent growth spurt; promote conversion of epiphyseal plate to epiphyseal line
CalcitriolStimulates absorption of calcium and phosphate from digestive tract
Parathyroid hormoneStimulates osteoclast proliferation and resorption of bone by osteoclasts; promotes reabsorption of calcium by kidney tubules; indirectly increases calcium absorption by small intestine
CalcitoninInhibits osteoclast activity and stimulates calcium uptake by bones
Nội dung này đang được cập nhật.
Dưới đây là video và các luyện tập (practice) của bài này. Nghe là một kĩ năng khó, đặc biệt là khi chúng ta chưa quen nội dung và chưa có nhạy cảm ngôn ngữ. Nhưng cứ đi thật chậm và đừng bỏ cuộc.
Xem video và cảm nhận nội dung bài. Bạn có thể thả trôi, cảm nhận dòng chảy ngôn ngữ và không nhất thiết phải hiểu toàn bộ bài. Bên dưới là script để bạn khái quát nội dụng và tra từ mới.
Script:
  1. The deposition of mineral salts and collagen fibers within bones is stimulated by mechanical stress.
  2. Calcium is the primary mineral in bone and relies on the presence of vitamin D for absorption from the small intestine.
  3. Vitamin K supports bone mineralization and may work synergistically with vitamin D.
  4. Magnesium and fluoride function as structural elements. They contribute to supporting bone health.
  5. Omega-3 fatty acids have anti-inflammatory properties and may promote the production of new osseous tissue.
  6. Growth hormone enhances the length of long bones, improves mineralization, and increases bone density.
  7. Thyroxine stimulates bone growth and the synthesis of bone matrix.
  8. Sex hormones, including estrogen and testosterone, promote osteoblastic activity.
  9. They also contribute to the production of bone matrix, drive the adolescent growth spurt, and facilitate the closure of epiphyseal plates.
  10. Osteoporosis which is characterized by decreased bone mass, is a disease prevalent in aging adults.
  11. Calcitriol stimulates the digestive tract to absorb calcium and phosphate.
  12. Parathyroid hormone (or PTH for short) stimulates osteoclast proliferation and bone resorption.
  13. Vitamin D collaborates with PTH in stimulating osteoclasts.
  14. PTH also promotes calcium reabsorption by kidney tubules and indirectly increases calcium absorption from the small intestine.
  15. Calcitonin inhibits osteoclast activity and encourages calcium uptake by bones.
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