Name: human skeleton: bones, cells, and disease
Uploaded: 2019-03-11T09:21:29.000Z
Duration: 1 min 2 s
Channel: JoVE

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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

What is the Skeletal System?

O esqueleto humano é composto de ossos que não só se juntam para fornecer uma estrutura rígida, dando forma ao corpo, mas também permitem movimento, já que eles estão ligados aos músculos através dos tendões. Uma das principais divisões, o esqueleto axial, é organizado em torno do eixo central do corpo. Enquanto existe um número de ossos nesta seção da parte superior do corpo, incluindo os ossículos do ouvido médio, a maioria protege órgãos vitais de danos.Por exemplo, o crânio envolve o cérebro e os arcos da coluna vertebral ao redor da medula espinhal, protegem o sistema nervoso central. Outros órgãos, como o coração e os pulmões são salvaguardados pelo esterno e a caixa torácica. A outra divisão, o esqueleto apendicular, consiste em ossos que sustentam e movem os apêndices, as mãos e braços, bem como os pés e pernas, e as cinturas peitoral e pélvica.

Kling, Juliana M., Bart L. Clarke e Nicole P. Sandhu. "Prevenção, triagem e tratamento da osteoporose: uma revisão." Journal of Women's Health 23, nº 7 (1º de julho de 2014): 563–72. [<a href="https://doi.org/10.1089/jwh.2013.4611" target="__blank">Fonte</a>]

Akkawi, Ibrahim e Hassan Zmerly. "Osteoporose: conceitos atuais." Articulações 6, nº 2 (14 de junho de 2018): 122–27. [<a href="https://doi.org/10.1055/s-0038-1660790" target="__blank">Fonte</a>]

o que é o sistema esquelético?

<h4>Visão Geral</h4>
 
 O esqueleto humano adulto contém 206 ossos conectados através de cartilagem, tendões e ligamentos. O esqueleto fornece uma estrutura rígida para o corpo humano, protege órgãos internos e permite o movimento e locomoção. O sistema esquelético humano consiste nos esqueletos axial e apendicular. O tecido ósseo é continuamente construído e destruído por células ósseas especializadas que são essenciais para a saúde geral. Células ósseas desreguladas e níveis incorretos de compostos químicos no sangue levam a doenças ósseas.
 
 <h4>Esqueleto Axial</h4>
 
 O esqueleto axial é composto por 80 ossos e é dividido em três regiões: o crânio, a coluna vertebral e a caixa torácica. A parte superior do crânio—o crânio—consiste de oito ossos que contêm o cérebro, enquanto que a parte inferior consiste de 14 ossos. A coluna vertebral é composta por 33 vértebras: sete cervicais, 12 torácicas, cinco lombares, cinco vértebras sacrais fundidas e quatro vértebras coxigeais fundidas.
 
 A caixa torácica adiciona estabilidade à coluna vertebral e também protege os pulmões e o coração. Consiste em 12 pares de costelas, que se prendem às vértebras torácicas através da articulação costovertebral. A porção anterior da caixa torácica prende-se ao esterno—o osso plano no centro frontal do peito—através das cartilagens costais. As primeiras sete costelas de cada lado são conhecidas como costelas verdadeiras, pois as suas cartilagens prendem-se diretamente ao esterno. As costelas de oito a 12 são chamadas de costelas falsas porque não se prendem diretamente ao esterno. No entanto, as costelas de oito a 10 juntam-se ao esterno através das cartilagens costais das costelas acima. Ao contrário, as costelas 11 e 12 são referidas como costelas flutuantes, uma vez que estão apenas presas à coluna vertebral na parte posterior, mas não têm nenhuma conexão com o esterno.
 
 <h4>Esqueleto Apendicular</h4>
 
 O sistema esquelético apendicular consiste nos 126 ossos dos membros e cintura uma vez que são anexados ao esqueleto axial. O sistema esquelético apendicular é composto por vários tipos diferentes de ossos.
 
 <h4>Tecido e Células Ósseos</h4>
 
 O osso é conhecido como tecido ósseo. As células do tecido ósseo estão dispersas na matriz—a substância que fornece força e rigidez aos ossos. A matriz consiste em componentes orgânicos—principalmente colágeno—e componentes inorgânicos que consistem em sais minerais cristalizados, como fosfato de cálcio, hidróxido de cálcio e fluoreto de magnésio.
 
 Existem três tipos principais de células ósseas—osteoblastos, osteoclatos e osteócitos. Os osteoblastos e os osteoclastos têm funções opostas. Os osteoblastos constroem a matriz óssea, enquanto que os osteoclartos a destroem. Ambas as funções continuam ao longo da vida, e ambas são essenciais para uma boa saúde. Construir osso é importante para manter os ossos fortes; destruir osso permite a manutenção dos níveis de cálcio na corrente sanguínea (que é vital para a saúde de outros órgãos, como o coração).
 
 Os osteócitos são células que amadureceram dos osteoblastos e estão agora cercadas por matriz. Os osteócitos comunicam com o sangue através de canais microscópicos no osso, sentindo os níveis de cálcio e outros minerais no sangue. Eles controlam então as funções dos osteoblastos e osteoclastos, secretando substâncias que afetam a atividade dessas células.
 
 <h4>Doenças Ósseas</h4>
 
 Muitas doenças do sistema esquelético têm uma característica comum: ossos fracos devido ao baixo teor de minerais. A osteoporose, por exemplo, é caracterizada pela diminuição da densidade mineral óssea. Ocorre mais comumente em mulheres pós-menopausa, mas também pode ocorrer em homens e mulheres pré-menopausa. Nesta doença, há maior atividade de osteoclatos do que de osteoblastos. Pacientes com osteoporose têm grande risco de fraturas, especialmente da coluna vertebral, quadril e pulso.
 
 Outra doença óssea generalizada é a osteodistrofia renal. Esta doença é parte de uma condição mais ampla conhecida como distúrbio mineral e ósseo em doença renal crónica. Os rins desempenham muitas funções, incluindo regulação de cálcio, fósforo e vitamina D, que são todos críticos para a saúde óssea. Quando os rins não estão a funcionar corretamente, como na doença renal diabética, os ossos podem ficar enfraquecidos e dolorosos, e as articulações podem tornar-se também dolorosas.

O que é o Sistema Esquelético?

Visão geral

O esqueleto humano adulto compreende 206 ossos que estão conectados por meio de cartilagem, tendões e ligamentos. O esqueleto fornece um ...

Education

JoVE Core

Biology

Biologia

Human Biology

Biologia Humana

Musculoskeletal System

Sistema Musculoesquelético

KEY TERMS AND CONCEPTS

TERMOS-CHAVE E CONCEITOS

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 has 14 bones. The vertebral column has 33 vertebrae. These include seven cervical, 12 thoracic, five lumbar, five fused sacral, and four fused coccygeal vertebrae.

The rib cage adds stability to the vertebral column and protects the lungs and heart. It has 12 pairs of ribs that attach to the thoracic vertebrae at the costovertebral joint. The front of the rib cage connects to the sternum, the flat bone in the center of the chest, through costal cartilages. The first seven ribs are true ribs because their cartilages attach directly to the sternum. Ribs eight through 12 are false ribs. Ribs eight through 10 connect to the sternum through the cartilages of the ribs above them, while ribs 11 and 12 are floating ribs because they do not connect to the sternum at all.

The appendicular skeleton has 126 bones. It includes the bones of the limbs and the girdles that attach them to the axial skeleton. Bone tissue is also called osseous tissue. Its cells sit in a matrix, which is the material that gives bone strength and hardness. The matrix contains organic material, mainly collagen, and inorganic mineral salts such as calcium phosphate, calcium hydroxide, and magnesium fluoride.

Bone cells have different jobs. Osteoblasts build bone matrix, while osteoclasts break it down. Both actions continue throughout life and are important for health. Building bone helps keep bones strong. Breaking down bone helps maintain calcium levels in the bloodstream, which is important for organs such as the heart. Osteocytes are mature bone cells that come from osteoblasts. They sit inside the matrix and communicate with the blood through tiny channels in bone. They sense calcium and other mineral levels and help control osteoblast and osteoclast activity by releasing substances that affect these cells.

Problems in bone cell balance or mineral levels can lead to bone disease. Osteoporosis is a common example. It is marked by low bone mineral density and more osteoclast activity than osteoblast activity. It occurs most often in postmenopausal women, but it can also occur in men and premenopausal women. People with osteoporosis have a much higher risk of fractures, especially in the spine, hip, and wrist.

Renal osteodystrophy is another widespread bone disease. It is part of mineral and bone disorder in chronic kidney disease. The kidneys help regulate calcium, phosphorus, and vitamin D, and these are all needed for bone health. When the kidneys do not work properly, such as in diabetic kidney disease, bones may become weak and painful, and the joints may hurt as well.

Human Skeleton: Bones, Cells, and Disease

what is the skeletal system?

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

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 human skeleton, including axial and appendicular bones, bone cells, and common bone diseases like osteoporosis and renal osteodystrophy.

Human Skeleton: Bones, Cells, and Disease | JoVE K12

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HS-LS1-3

Human Skeleton: Bones, Cells, and Disease

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