There are four heart valves. All are one-way valves. Blood entering the heart first passes through the tricuspid valve and then the pulmonary valve. After returning from the lungs, the blood passes through the mitral (bicuspid) valve and exits via the aortic valve.
- Vampire children
Perjorative term for children with xeroderma pigmentosum, a genetic disease with such extraordinary sensitivity to sunlight that ordinary sun exposure results in the development of skin cancer at a very early age. Children with xeroderma pigmentosum (XP) can only play outdoors safely after nightfall.
- Van der Woude syndrome
A genetic disorder characterized by pits of the lower lip and by cleft lip and/or cleft palate. It is the most common known cleft syndrome. The van der Woude syndrome is highly variable in its expression from person to person. There may be cleft lip, cleft palate, or both. The lip pits may be associated […]
- Vanishing bone syndrome
An inherited form of osteolysis — the destruction of bone. There are several such syndromes. In one form of vanishing bone syndrome, there is osteolysis in the hands and feet, crippling arthritic changes in the hands, marked osteoporosis, and nodules beneath the skin of the palms and soles associated with autosomal recessive inheritance. The responsible […]
- Vanishing lung syndrome
“scintigraphy shows a disappearance of perfusion, and angiography shows remnants of arterial branches without the capillary phase. Inside there may be growing an abandoned room.”
- Vanishing twin
A twin detected in early pregnancy that is miscarried, frequently by resorption, without clinical signs or symptoms. The surviving twin continues to grow and develop.