Veins are a type of blood vessel that return deoxygenated blood from your organs back to your heart. These are different from your arteries, which deliver oxygenated blood from your heart to the rest of your body.
Deoxygenated blood that flows into your veins is collected within tiny blood vessels called capillaries. Capillaries are the smallest blood vessels in your body. Oxygen passes through the walls of your capillaries to your tissues. Carbon dioxide can also move into your capillaries from the tissue before entering your veins.
The venous system refers to the network of veins that work to deliver deoxygenated blood back to your heart.
静脉的墙壁由三个不同的层组成：
- Tunica externa.This is the outer layer of the vein wall, and it’s also the thickest. It’s mostly made up of connective tissue. The tunica externa also contains tiny blood vessels called vasa vasorum that supply blood to the walls of your veins.
- Tunica media.The tunica media is the middle layer. It’s thin and contains a large amount of collagen. Collagen is one of the main components of connective tissue.
- Tunica Intima。这是最内向的一层。它是一层内皮细胞和一些结缔组织。该层有时包含单向阀，尤其是在您的手臂和腿部的静脉中。这些瓣防止血液向后流动。
静脉通常根据其位置以及任何独特的功能或功能进行分类。
肺和全身静脉
您的身体在两个不同的轨道上循环血液，称为全身电路和肺电路。静脉是基于他们发现的电路：
- 肺静脉。肺电路从您的心脏传播到肺部。一旦您的肺氧化血液，肺电路就会将其带回您的心脏。有四个肺静脉。它们是独一无二的，因为它们含有氧化的血液。所有其他静脉仅含有脱氧的血液。
- 系统性静脉。全身电路从身体的其余部分带回到您的心脏，然后进入氧气的肺回流。大多数静脉是全身静脉。
深静脉和浅静脉
Systemic veins are further classified as being either:
- Deep veins.这些在肌肉或沿骨骼中发现。深静脉的神经内膜通常具有单向瓣膜，以防止血液向后流动。附近的肌肉还会压缩深静脉，以使血液向前移动。
- Superficial veins.这些位于皮肤下的脂肪层。浅表静脉的神经内膜也可以具有单向阀。但是，如果没有附近的肌肉压缩，它们比深静脉更慢地移动血液。
- 连接静脉。浅表静脉的血液通常通过称为连接静脉的短静脉将其引导到深静脉中。这些静脉中的瓣膜可以使血液从浅表静脉流向您的深静脉，而不是相反。
许多条件会影响您的静脉系统。一些最常见的包括：
- Deep vein thrombosis (DVT).A blood clot forms in a深静脉, usually in your leg. This clot can potentially travel to your lungs, causing肺栓塞。
- 浅表血栓性。通常在您的腿上发炎的浅静脉会发出血块。虽然凝块偶尔会走到深静脉，导致DVT，但血栓质量通常不如DVT严重。
- Varicose veins.皮肤表面附近的表面静脉明显肿胀。This happens当单向阀破裂或静脉壁变弱时，使血液向后流动。
- 慢性静脉功能不全。Blood collects in the superficial and deep veins of your legs due to improper functioning of one-way valves. While similar to varicose veins,chronic venous insufficiency通常会引起更多症状，包括皮肤质地粗糙和溃疡。
While the symptoms of a venous condition can vary widely, some common ones include:
- 炎症或肿胀
- tenderness or pain
- 感觉温暖的静脉
- a burning or itching sensation
These symptoms are especially common in your legs. If you notice any of these and they don’t improve after a few days, make an appointment with your doctor.
They can perform a静脉。在此过程中，您的医生注射对比死于您的静脉X-rayimage of a particular area.
请遵循以下技巧，使您的静脉墙壁和阀门保持稳固，正常运行：
- Get regular exercise to keep blood moving through your veins.
- 尝试保持healthy weight, which reduces your risk of高血压。High blood pressure can weaken your veins overtime due to added pressure.
- 避免长时间站立或坐着。尝试全天定期更改位置。
- 坐下时，避免crossing your legsfor long periods of time or regularly switch positions so one leg isn’t on top for a long period of time.
- 当flying，喝大量的水，尝试站起来并尽可能多地伸展。即使坐着，您也可以弯曲脚踝以鼓励血液流动。