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Skeletal system and bone tissue

Heather Davis・34 minutes read

Chapter six explores bone tissue, the functions of the skeletal system, and the structure of different types of bones. It delves into osteology, bone formation, growth, and remodeling, highlighting the importance of minerals, hormones, and factors affecting bone health, including osteoporosis primarily impacting spongy bone in post-menopausal women due to estrogen level changes.

Insights

  • The skeletal system is a complex organ system that serves various functions such as support, protection, blood production, and mineral storage. Bones, cartilage, tendons, and ligaments make up this system, with each bone classified by shape and composed of different tissue types.
  • Bone remodeling is a dynamic process involving osteoblasts depositing calcium into new bone tissue and osteoclasts reabsorbing calcium from existing bone tissue. Hormones like calcitonin and parathyroid hormone play a crucial role in regulating this process, with factors like mineral intake, vitamins, and hormones impacting bone growth and remodeling. Osteoporosis, a condition primarily affecting spongy bone, is more prevalent in women post-menopause due to estrogen level changes, highlighting the importance of hormonal balance in bone health.

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  • What are the functions of the skeletal system?

    The skeletal system provides support, protects internal organs, aids in movement, stores minerals, produces blood cells, and stores triglycerides.

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Summary

00:00

Bone Tissue: Functions and Structure Explained

  • Chapter six focuses on bone tissue, exploring the functions of the skeletal system and the structure of long bones.
  • The skeletal system includes bones, cartilage, tendons, and ligaments, with each bone considered an organ composed of various tissue types.
  • Osteology is the study of bone structure and treatment of bone disorders.
  • Functions of the skeletal system include support, protection of internal organs, assistance in movement, storage and release of minerals like calcium and phosphorus, blood production, and triglyceride storage.
  • Red bone marrow is crucial for hematopoiesis, producing red blood cells, white blood cells, platelets, fibroblasts, and macrophages.
  • Types of bones are classified by shape: long, short, flat, irregular, sesamoid, and sutural bones.
  • Long bones have a greater length than width, with compact bone on the outer layer and spongy bone at the ends.
  • Short bones are nearly equal in length and width, with spongy bone covered by a thin layer of compact bone.
  • Flat bones have a thin layer of spongy bone sandwiched between outer layers of compact bone, like those in the cranium and sternum.
  • Irregular bones, such as vertebrae and facial bones, have various amounts of spongy bone inside with compact bone outside and no medullary cavity.

13:40

"Bone Remodeling: Osteoblasts, Osteocytes, Osteoclasts, Growth"

  • Osteoblasts create bone matrix, while osteocytes maintain it, leading to continuous bone remodeling throughout life.
  • Bone deposition occurs on the periosteum side by osteoblasts, while bone reabsorption is on the endosteum side by osteoclasts.
  • Reabsorption releases calcium and minerals into interstitial fluid, which can be used for muscle contractions, nerve impulses, and blood clotting.
  • Bone remodeling involves osteoclasts breaking down bone and osteoblasts rebuilding it, resulting in bone growth and widening of the medullary cavity.
  • Compact bone structure includes osteons, lamellae (concentric, interstitial, circumferential), lacunae for osteocytes, and canaliculi for nutrient exchange.
  • Blood and nerve supply to bones involve various arteries and veins entering through nutrient foramen and servicing different bone layers.
  • Bone formation, or osteogenesis, occurs in embryos, fetuses, infants to adults, and during bone fracture repair through ossification processes.
  • Intramembranous ossification replaces mesenchyme with bone tissue in flat bones like the skull, while endochondral ossification replaces cartilage with bone in long bones.
  • Spongy bone formation lacks osteons and canals, with trabeculae forming in a disorganized pattern and containing red bone marrow.
  • Bone growth from infancy to adulthood involves interstitial and appositional growth at growth plates, allowing for continuous bone remodeling and repair.

27:47

Bone Growth and Remodeling: Key Factors Explained

  • Interstitial growth occurs within growth plates in bones, with layers of cartilage including resting, proliferating, hypertrophic, and calcified cartilage.
  • An x-ray can differentiate between adult and growth plate-present bones, with closed growth plates indicating adulthood.
  • Appositional growth increases bone girth through osteoprogenitor cells forming periosteum, maturing into osteoblasts, secreting bone matrix, and eventually becoming osteocytes.
  • Bone remodeling involves osteoblasts depositing calcium into new bone tissue and osteoclasts reabsorbing calcium from existing bone tissue.
  • Hormones like calcitonin and parathyroid hormone regulate bone remodeling, with calcitonin promoting bone deposition and parathyroid hormone stimulating bone reabsorption.
  • Factors affecting bone growth and remodeling include mineral intake, vitamins like D, hormones like human growth hormone, and sex hormones. Osteoporosis primarily affects spongy bone, especially in women post-menopause due to estrogen level drops.
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