Category: H

A covering for the head, especially a protective one, such as a helmet used by soldiers and those who participate in contact sports, auto racing, bicycle riding, or aviation.  

A headache that awakens a patient from sleep. Hypnic headaches are typically bilateral, and are experienced more often by the elderly than by other patients. Unlike cluster headaches, which also occur during rest or sleep, the hypnic headache is not felt on one side of the face, and not associated with tearing of the eye…

In ophthalmology, a clouding of vision that makes viewed objects appear smoky or indistinct. Opacification of the cornea is the cause.  

The maximum number of cell divisions that will take place in human cells prior to their death. In 1961 Hayflick and P. S. Moorehead showed that human cells can reproduce themselves a finite number of times. This limited replication ability is postulated to correlate with the aging, failure, and eventual death of organs and individuals.…

One of many channels extending from the lacuna of an osteocyte into the bone matrix, to a canaliculus of an adjacent osteocyte. By way of these channels osteocytes remain in contact with one another to transmit nutrients and gases.  

A febrile disease transmitted to humans by rats, usually by rat bite. Streptobacillus moniliformis is the etiological agent. Haverhill fever is a type of rat-bite fever resulting from infection with the bacterium Streptobacillus Moniliformis. Unlike other forms of the disease, Haverhill fever can be transmitted not only through the bite of a rodent but also…

The formation of segment or recess, especially in the bowel.  

A spherical or oval body present in the medulla of the thymus. It consists of a central area of degenerated cells surrounded by concentrically arranged flattened or polygonal cells.  

The surgical removal of a diseased portion of the distal colon or proximal rectum with formation of an end colostomy, accompanied by over-sewing of the distal colonic or rectal remnant. This procedure may be the first stage of a two-part operation, in which at a later date, the colostomy and the over-sewn remnant are reconnected.…

A law enacted in 1914 that classified certain drugs as habit forming and restricted their sale and distribution.