Arteries and veins are part of the vascular system. Arteries carry blood away from the heart to the lungs or the rest of the body, where the blood passes through capillaries, and veins return the blood to the heart. An AVM interferes with this process by forming a direct connection of the arteries and veins. AVMs can<unk>  intense pain and lead to serious medical problems. Although AVMs are often associated with the brain and spinal cord, they can develop in other parts of the body. Normally, the arteries in the vascular system carry oxygen-rich blood, except in the<unk>  of the pulmonary artery. Structurally, arteries divide and sub-divide repeatedly, eventually forming a sponge-like capillary bed. Blood moves through the capillaries, giving up oxygen and taking up waste products, including , from the surrounding cells. Capillaries in turn successively join to form veins that carry blood away. The heart acts to pump blood through arteries and uptake the venous blood. As an AVM lacks the dampening effect of capillaries on the blood flow, the AVM can get progressively larger over time as the amount of blood flowing through it increases, forcing the heart to work harder to keep up with the extra blood flow. It also<unk> s the surrounding area to be deprived of the functions of the capillaries—removal of and delivery of nutrients to the cells. The resulting tangle of blood vessels, often called a nidus (Latin for "nest"), has no capillaries. It can be extremely fragile and prone to bleeding because of the abnormally direct connections between high-pressure arteries and low-pressure veins. The resultant sign, audible via stethoscope, is a rhythmic, whooshing sound<unk> d by excessively rapid blood flow through the arteries and veins. It has been given the term "bruit", French for noise. On some occasions, a patient with a brain AVM may become aware of the noise, which can compromise hearing and interfere with sleep in addition to<unk> ng psychological distress.
medical cause of Intracerebral hemorrhage
symptom of Intracerebral hemorrhage
medical cause of Epidural hematoma
medical cause of Subarachnoid hemorrhage
medical cause of Stroke
symptom of Meningioma
medical cause of Vertebral artery dissection
symptom of Idiopathic intracranial hypertension