Name: inside a long bone
Uploaded: 2025-10-23T11:47:05.000Z
Duration: 1 min 55 s
Channel: JoVE

K12 Standards

Next Generation Science Standards

High School

Life Science

from-molecules-to-organisms-structures-and-processes

From Molecules to Organisms: Structures and Processes

HS-LS1-2

Bone Structure

בתוך מערכת השלד, המבנה של עצם, או רקמה גרמית, ניתן להדגמה באמצעות עצם ארוכה כמו עצם הירך, שבה יש שני סוגי רקמות גרמיות צפופה וספוגית. מה שמכסה את העצם הצפופה, או הקומפקטית, הוא קרום שנקרא מיסב העצם פריאוסטום, אשר מכיל רקמות חיבור, נימים ועצבים. שכבה חיצונית מוצקה הנמצאת בסמוך לאורך הדיאפיזה, המוט, יוצרת קליפת הגנה צפופה מסביב לתעלה המדוּלרית, החלל שמכיל בתוכו מח עצם צהוב המורכב בעיקר מתאי שומן.שטח זה מכוסה גם ברקמה דקה, מיסב פנים העצם האנדוסטאום, שבה מתרחשים הצמיחה, השחלוף והתיקון של העצם. בשכבה הקומפקטית נמצאים אוסטאונים, יחידות מבניות המסודרות בטבעות קונצנטריות הנקראות עלעלים והמכילות אוסטאובלסטים, תאים קריטיים להיווצרות העצם וצמיחתה. תאים אלה הופכים לבסוף לתאי עצם אוסטאוציטים באזור החלול, הלקונה.דרך מרכז כל אוסטאון עוברת תעלת האוורס, אשר מכילה יותר כלי דם וכלי לימפה וגם סיבי עצב. לקראת הקצוות המעוגלים של העצם הארוכה, האפיפיזות, נמצא הסוג השני של רקמה גרמית הידוע כעצם טרבקולרית, או ספוגית. שכבה פנימית זו מורכבת מרשת דמויית חלת דבש של טרבקולות, המאתרגנות בקבוצות לאורך קווי נקודות לחץ כדי למקסם כוח עם מסה מינימלית.בין כל נקבובית טרבקולרית נמצא מח עצם אדום, אשר מכיל תאי גזע המטופואטיים המרכיבים תאי דם אדומים ולבנים וטסיות דם, שנכנסים בסוף לתוך מערכות מחזור הדם והלימפה.

פלורנסיו-סילבה, רינלדו, גיזלה רודריגז דה סילבה סאסו, אסטלה סאסו-סרי, מנואל חסוס סימואס ופאולו סרחיו סרי. "ביולוגיה של רקמת עצם: מבנה, תפקוד וגורמים המשפיעים על תאי העצם." BioMed Research International 2015 (2015). [<a href="https://doi.org/10.1155/2015/421746" target="__blank">מקור</a>]

אוון, רוברט וגוונדולן סי ריילי. "מודלים חוץ גופיים של עיצוב מחדש של העצם והפרעות נלוות." גבולות בביו-הנדסה וביוטכנולוגיה 6 (2018). [<a href="https://doi.org/10.3389/fbioe.2018.00134" target="__blank">מקור</a>]

מבנה עצמות

<div style="direction:rtl">בתוך מערכת השלד, ניתן להמחיש את המבנה של עצם, או רקמת עצם, בעצם ארוכה, כמו עצם הירך, שבה יש שני סוגים של רקמת עצם: רקמת עצם קורטיקאלית ורקמת עצם ספוגית. <h4>רקמת עצם קורטיקאלית</h4> שכבת קרום בשם periosteum (מסב העצם) מכסה את העצם הקורטיקלית, או רקמת העצם הצפופה, המכילה רקמת חיבור, נימים ועצבים. השכבה החיצונית והמוצקה שנמצאת לאורך הדיאפיזה, יוצרת מעטפת הגנה צפופה מסביב לתעלת המדולרית, החלל המאחסן את מח העצם הצהוב, המורכב בעיקר מתאי שומן. חלל זה מכוסה גם בציפוי דק של האנדוסטאום שבו מתרחשים צמיחת עצם, שיפוץ ותיקון. בתוך השכבה הצפופה של עצם קליפת המוח נמצאות יחידות מבניות של אוסטאונים, המסודרות בלוחיות מעגליות הנקראות למלות (amellae), המכילות תאים אוסטאובלסטים קריטיים ליצירת עצם ולגדילה. תאים אלה מבשילים בסופו של דבר לאוסטאוציטים בחלל החלול, הלאקונה (lacuna). דרך מרכז כל אוסטאון עוברת תעלת האוורסיאנית, המכילה יותר כלי דם וכלי לימפה, כמו גם סיבי עצב. <h4>רקמת עצם ספוגית</h4> לקראת הקצוות המעוגלים של העצם הארוכה, האפיפיזה היא הסוג השני של רקמות עצם, המכונה העצם הספוגית. שכבה פנימית זו מורכבת מרשת דמוית חלת דבש של מוטות ולוחות בשם קוֹרִיות (Trabeculae) שנוצרות לאורך קווי נקודות הלחץ כדי למקסם את החוזק במסה מינימלית. בין כל נקבובית טרבקולרית נמצא מח עצם אדום, המכיל תאי גזע המטופואטיים שנוצרים לתאי דם אדומים ולבנים וטסיות הדם החודרות בסופו של דבר למערכת הדם והלימפה.</div>

בתוך מערכת השלד, המבנה של עצם, או רקמת גלוסקמה, יכול לבוא לידי ביטוי בעצם ארוכה, כמו עצם הירך, שם ישנם שני סוגים של ...

Education

JoVE Core

Biology

ביולוגיה

Human Biology

ביולוגיה אנושית

Musculoskeletal System

מערכת השלד והשרירים

KEY TERMS AND CONCEPTS

מונחים ומושגים מרכזיים

inside a long bone

Inside a long bone, osseous tissue is organized into two main types: cortical bone and cancellous bone. A femur is a clear example of this structure. The bone also includes outer coverings and inner spaces that support growth, repair, and blood cell production.

Cortical bone, also called compact bone, forms the dense outer layer along the diaphysis, or shaft. It is covered by the periosteum, a membrane with connective tissue, capillaries, and nerves. Beneath the cortical layer is the medullary canal, a cavity that stores yellow bone marrow, which is made mainly of fat cells. This space is lined by the endosteum, where bone growth, remodeling, and repair take place.

Within cortical bone are osteons, the structural units of compact bone. Each osteon is arranged in concentric rings called lamellae and contains osteoblasts, which are important for bone formation and growth. As these cells mature, they become osteocytes in small spaces called lacunae. A Haversian canal runs through the center of each osteon and carries blood and lymphatic vessels, along with nerve fibers.

Toward the rounded ends of the long bone, or epiphyses, is cancellous bone, also called spongy bone. This inner layer has a honeycomb-like network of trabeculae that line up along stress points to give strength with less mass. The spaces between the trabeculae contain red bone marrow, which has hematopoietic stem cells that develop into red and white blood cells and platelets before entering the circulatory and lymphatic systems.

Inside a Long Bone

what is the skeletal system?

Human Skeleton: Bones, Cells, and Disease

The human skeleton is a living framework made of 206 bones in adults. Bones connect with cartilage, tendons, and ligaments. This system gives the body support, protects organs, and helps with movement and locomotion. The skeleton has two main parts: the axial skeleton and the appendicular skeleton. The axial skeleton has 80 bones and includes the skull, the vertebral column, and the rib cage. The cranium, or upper skull, has eight bones that enclose the brain, while the lower part of the skull...

bone structure

Inside a long bone, osseous tissue is organized into two main types: cortical bone and cancellous bone. A femur is a clear example of this structure. The bone also includes outer coverings and inner spaces that support growth, repair, and blood cell production. Cortical bone, also called compact bone, forms the dense outer layer along the diaphysis, or shaft. It is covered by the periosteum, a membrane with connective tissue, capillaries, and nerves. Beneath the cortical layer is the medullary...

joints

Types of Joints in the Human Body

Joints are the places where adjacent bones connect. They are also called articulations or articular surfaces. Joints help the body move and stay stable. Joints can be classified by structure or by function. Structural classification depends on the material that forms the joint and whether there is a space between the bones. By structure, joints are fibrous, cartilaginous, or synovial. Fibrous joints are connected by fibrous tissue and have no cavity between the bones. Because of this, they do...

bone remodeling

How Hormones Control Bone Turnover

Bone turnover is a continuous process in which old bone is broken down and new bone is built. Osteoclasts carry out bone resorption, and osteoblasts carry out bone formation. In adults, this balanced cycle helps maintain bone mass and calcium homeostasis. Mechanical stress can also stimulate turnover as part of normal maintenance and repair. Parathyroid hormone, or PTH, helps control blood calcium levels by increasing bone resorption when calcium is low. It is released from the parathyroid...

skeletal muscle anatomy

Muscle Fibers, Tendons, and Contraction

Skeletal muscle moves the body by pulling on bones through tendons. Tendons are the connective tissue that attaches skeletal muscle to bones. When skeletal muscles contract, they create voluntary movement. Skeletal muscle is wrapped in layers of connective tissue. The outer layer is the epimysium, which helps protect the muscle. Beneath it, the perimysium surrounds and groups fasciculi, which are bundles of skeletal muscle cells called myocytes. These cells are also called skeletal muscle...

classification of skeletal muscle fibers

Skeletal Muscle Fiber Speed and Energy

Skeletal muscle fibers can be grouped by how fast they contract and how they make ATP, the energy cells use for movement. These differences also shape their physical features. Most human muscles contain all three fiber types, but in different amounts. Slow oxidative fibers, also called slow-twitch fibers, appear red because they have many capillaries and high levels of myoglobin, an oxygen-storing protein. They also contain more mitochondria, which make ATP through oxidative phosphorylation,...

muscle contraction

Nerve Signals That Trigger Muscle Contraction

Nerve signals trigger muscle contraction in both skeletal and smooth muscle, but the two muscle types use different control systems. In skeletal muscle, the signal begins at the motor end plate, which is the synapse between a motor neuron and a muscle fiber. In smooth muscle, contraction is controlled by the autonomic nervous system and happens without conscious control. In skeletal muscle, motor nerve terminals release acetylcholine. This neurotransmitter binds to receptors on the sarcolemma,...

cross-bridge cycle

Calcium Control in Muscle Contraction

Calcium control in muscle contraction depends on ATP, motor neurons, and the sliding action of actin and myosin. As a muscle contracts, the thin and thick filaments overlap more, and the sarcomere, which is the contractile unit of the muscle, becomes shorter. This process uses energy from ATP and happens in a repeating cycle at the molecular level. Myosin drives the movement of actin through a cross-bridge cycle. When ATP attached to the myosin head is hydrolyzed to ADP, myosin shifts into a...

motor units

How Motor Units Control Muscle Movement

Motor units control skeletal muscle movement. A motor unit includes one efferent motor neuron, which carries signals away from the central nervous system, and all of the muscle fibers it innervates. A single motor neuron can connect with multiple muscle fibers, but each muscle fiber is innervated by only one motor neuron. Lower motor neurons are the efferent neurons that control skeletal muscle, the most abundant type of muscle in the body. Their cell bodies are found in the spinal cord or...

the spinal cord

Spinal Cord Structure and Dermatomes

The spinal cord is the main nerve pathway of the central nervous system. It carries sensory signals from the body to the brain and motor signals from the brain to the body. It begins at the foramen magnum, the opening at the base of the skull, and extends to the level of the first or second lumbar vertebra. In cross-section, the spinal cord is cylindrical and contains both gray matter and white matter. The central canal lies in the middle and is a remnant of the lumen of the primitive neural...

nociception

Pain Signaling and Inflammation

Pain signaling begins when the body detects a harmful stimulus. Sharp objects, open flames, and corrosive chemicals can trigger this response. Sensory receptors called nociceptors, which sit on nerve endings, detect these noxious stimuli and use ion channels to turn them into electrical signals. Those electrical signals travel through sensory neurons to the brain, where they are experienced as pain. This warning system helps an organism avoid damage and stay safe. Pain is therefore an...

key terms and concepts

Explore the parts of a long bone, including cortical bone, cancellous bone, osteons, marrow, and the cells that support growth and blood cell formation.

Inside a Long Bone | JoVE K12

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HS-LS1-3

Inside a Long Bone

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