Child development stages and milestones: What to expect
From their first smile to their first step to the first day of school, children go through a remarkable transformation on their way to adulthood.
1 hour ago
0
0
From their first smile to their first step to the first day of school, children go through a remarkable transformation on their way to adulthood.
1 hour ago
0
0
Puberty often begins early for children who are obese. While there is nothing new about this fact, a scientific explanation has been elusive. Now, a team of scientists at the University of Copenhagen offers what may be a ...
4 hours ago
0
18
Cortisol levels in late pregnancy can predict the sleep of infants, according to a new study to be presented on Tuesday, June 6 at the SLEEP 2023 annual meeting. This study is also published in Sleep.
May 30, 2023
0
2
Polycystic ovary syndrome (PCOS) is a complex hormone disorder that can have a profound impact on a woman's life.
May 24, 2023
0
2
Scientists are calling for tighter regulation of stem cell treatments, after finding hundreds of clinics worldwide offering unproven "therapies" for conditions as varied as hair loss and Parkinson's.
May 22, 2023
0
11
New research being presented at this year's European Congress on Obesity (ECO) in Dublin, Ireland (17-20 May) suggests that glucocorticoid levels (a class of steroid hormones secreted as a response to stress) present in the ...
May 19, 2023
0
6
The traces of genetic material that humans constantly shed wherever they go could soon be used to track individual people, or even whole ethnic groups, scientists said on Monday, warning of a looming "ethical quagmire".
May 15, 2023
0
13
As knowledge increases about how auditory troubles develop, new technological advances are set to cut through the clamour. Meeting a few friends in a noisy café can mean straining to hear all the conversation. It can be ...
May 5, 2023
0
5
Sadé Lewis of Queens, New York, has suffered migraines since she was a kid, and as she started college, they got worse. A recent change in her insurance left the 27-year-old looking for a new neurologist. That's when she ...
May 4, 2023
0
40
Usher Syndrome type 1F is a rare but severe genetic disease that causes deafness, lack of balance, and progressive blindness.
Apr 26, 2023
0
97
Hair is a protein filament that grows through the epidermis from follicles deep within the dermis. The fine, soft hair found on many nonhuman mammals is typically called fur; wool is the characteristically curly hair found on sheep and goats. Found exclusively in mammals, hair is one of the defining characteristics of the mammalian class. Although other non-mammals, especially insects, show filamentous outgrowths, these are not considered "hair" in the scientific sense. So-called "hairs" (trichomes) are also found on plants. The projections on arthropods such as insects and spiders are actually insect bristles, composed of a polysaccharide called chitin. There are varieties of cats, dogs, and mice bred to have little or no visible fur. In some species, hair is absent at certain stages of life. The main component of hair fiber is keratin.
The hair can be divided into three parts length-wise, (1) the bulb, a swelling at the base which originates from the dermis, (2) the root, which is the hair lying beneath the skin surface, and (3) the shaft, which is the hair above the skin surface. In cross-section, there are also three parts, (1) the medulla, an area in the core which contains loose cells and airspaces (2) the cortex, which contains densely packed keratin and (3) the cuticle, which is a single layer of cells arranged like roof shingles.
This text uses material from Wikipedia, licensed under CC BY-SA