Joints — The Cartilage & Tendon Economy

关节 · 软骨与肌腱的经济学

System · Level 3

软骨没有血管, 靠你踩它、松开、再踩把养分挤进去; 肌腱承重的那部分从小长成、一辈子几乎不换新; 治关节痛真正管用的不是补剂, 是动、减重、必要时抹点消炎药膏

Connected to · 4

cofactor · 1

All-Nighter
Joint upkeep needs more than daytime loading — it needs the night's repair window: growth hormone is released mainly in deep-sleep cycles, so chronic short sleep removes half the equation.

regulates · 1

Gout & Hyperuricemia
A joint that turns suddenly red, hot and swollen is not the wear-and-tear story: urate crystals dropping into the joint space ignite acute inflammation. This is the branch to rule out first in joint pain.

contrast · 2

Glucosamine + Chondroitin
Glucosamine-chondroitin will not hurt you, but expect no structural benefit and do not put it ahead of exercise and weight loss, which carry the strongest OA evidence.
Collagen peptides
Collagen peptides fixing joints overpromises: some trials show subjective joint-pain improvement in active people, but that is a symptom signal, not cartilage being rebuilt. First line for joints remains exercise and weight loss.

What a joint actually is — seven parts

Stop 1/7

关节的真身 · 七个组件

A joint is not one thing — it is a team of tissues, and pain shows up when any of them falls behind:

Articular cartilage: a 2-4 mm layer of hyaline cartilage capping the bone ends — type II collagen + GAGs (glycosaminoglycans) + ~80 % water — avascular, aneural, alymphatic (Sophia Fox 2009 *Sports Health*). Its compressive resilience and near-frictionless surface come entirely from the water content + GAG network locking that water in placeSynovium + synovial fluid: a thin synovial-cell layer secretes hyaluronic acid (HA) + lubricin (PRG4); the fluid is shear-thinning — viscous at rest, slippery under load (Jay & Waller 2014 *Matrix Biology*)Joint capsule + ligaments: dense type I collagen — binds bones together, limits extreme anglesTendons: transmit muscle force to bone; type I collagen + a little elastinMenisci / labra (knee / hip / shoulder): fibrocartilage — distributes load + enlarges the contact surfaceBursae: reduce friction between tendons / skin and boneProprioceptive nerve endings: live in the capsule + ligaments, telling the brain where the joint is in space
The first thing to hold onto: of those seven, only the synovium, capsule, and ligaments are vascular. Cartilage and the inner meniscus eat through load + diffusion. The rest of this island unfolds from that fact.

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Educational content, not medical advice — consult a clinician.

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