ScienceIQ.com

Sex and the Sea Slug

The sea slug, Aplysia. Now there's an expert on sex. Equipped with both male and female sex organs, this shell-less, subtidal mollusk lives alone most of the year. It loses its self-sufficiency, however, when the mating season comes around. In summer, sea slugs congregate in breeding colonies called (yes, it's true!) brothels. They crawl around and ...

Continue reading...

SexSeaSlug
Engineering

Ants Are Wimpy

It's common knowledge that ants can lift many times their own weight. We are frequently told they can lift 10, 20, or even 50 times their weight. It is most often stated something like this: an ant ... Continue reading

Ants
Biology

Microarrays: Chipping Away At The Mysteries Of Science And Medicine

With only a few exceptions, every cell of the body contains a full set of chromosomes and identical genes. Only a fraction of these genes are turned on, however, and it is the subset that is ... Continue reading

Microarrays
Biology

What Are Stem Cells?

When an egg is fertilized by a sperm cell, it quickly becomes a single cell from which all cells of the body-to-be will be created. This 'mother of all cells' is what biologists call a totipotent stem ... Continue reading

StemCells
Chemistry

Nitrogen Gas and Compounds

Nitrogen is a very interesting element. It is the seventh element of the periodic table, with seven electrons in its atoms. The somewhat unique combination of electronic structure and small atomic ... Continue reading

NitrogenGasandCompounds

What Causes Wrinkles?

WhatCausesWrinklesElastin and collagen are proteins in the skin's underlying layers that give it firmness and elasticity. As we age, skin begins to lose its elastin fibers. The fibers start to tangle in disorganized masses as blood vessels shrivel, robbing skin of oxygen and nutrients. Thinning and degeneration of elastin over time cause wrinkles, 'worry' and 'laugh' lines, sagging, and crepey rippled skin. Aging skin also loses collagen at the rate of about one percent each year--and even faster if exposed to sunlight. The loss of collagen causes skin to sag and droop. Gravity, the slackening of muscles, and the loss of collagen all contribute to the sagging, wrinkling skin of advancing age.

After age fifty, the loss of both bone and fat beneath the skin lets the skin sag in the loose folds and wrinkles of old age. As we grow older, a drop in hormone levels causes the skin's outer layer to grow thin, giving that shiny parchment appearance of old age. The amount of moisture in the skin declines, so skin cracks and loses suppleness. The outer skin layer thickens--especially if exposed to the sun--becoming rough and scaly. The rates of making and shedding skin cells slow, and the repair of damaged cells becomes less efficient. Sebaceous glands produce less oil, leaving skin rough and dry. The number of pigment-producing cells declines, causing skin to tan poorly and freckle easily. Patches of brown, called 'liver spots' or 'age spots,' appear often on face, neck, or hands. Cancers of the skin become more likely.

Visible changes at the surface are accompanied by changes in the skin's deeper layers. There, blood vessels decline in number, slowing circulation and increasing sensitivity to heat and cold. The amount of collagen decreases and its structure changes, so the skin tears easily. Loss of collagen support for blood vessels means skin bruises more easily and wounds heal more slowly. As great as these changes are, many experts think they are not so much a result of aging as they are consequences of exposure to the sun. They say the best way to maintain youthful skin is to stay out of the sun.