 |
 |
 |
|
 |
|
|
|
 |
|
|
|
|
 |
|
|
March 29, 2008
High-quality-essays.com is your one-stop source for free, high-quality term papers, essays, and reports on all subjects. Please use either the available paper categories or our database search to find the paper you need quickly and easily. High-quality-essays.com is a completely free service that relies on students to submit their own papers in order to keep this site expanding; so please consider submitting your good papers to us as you enjoy this site.
|
|
|
|
 |
|
|
|
|
| |
 |
 |
|
|
Free Essay, Research Papers, Term Papers |
 | |
|
| |
|
| |
| Home > Free Essays Database |
|
The Integumentary system consists of the skin and its accesory structures and the
subcutaneous tissue. The two major layers of the skin are the outer epidermis and
the inner dermis.
Epidermis- made of stratified squamous epithelium; cells called keratinocytes.
1. Stratum Germanitivum- the inner most layer where mitosis takes place; new cells
produce keratin and die as they are pushed to the surface.
2. Stratum Corneum- the outermost layers of dead cells; keratin prevents loss and entry of
water and resists entry of pathogens and chemicals.
3. Langerhans Cells- phagocytize foreign material and stimulate an immune response by
lymphocytes.
4. Melanocytes- in the lower epidermis, produce melanin. UV rays stimulate melanin
production; melanin prevents further exposure to the stratum germanitivum to UV rays by
darkening the skin.
Dermis- made of irregular fibrous tissue; collagen provides strength, and elastin
provides elasticity; capillaries in the papillary layer nourish the stratum
germanitivum.
1. Hair Follicles- mitosis takes place in the hair root; new cells produce keratin,die, and
become the hair shaft. Hair of the scalp provides insulation from cold for the head;
eyelashes keep dust out eyes; nostril hairs keep dust out of the nasal cavities.
2. Nail Follicles- at the ends of the fingers and the toes; mitosis takes place in the nail root;
the nail itself if dead, keratinized cells. Nails protect the ends of the fingers and the toes
enable the fingers to pick up small objects.
3. Receptors- detect changes in the skin: touch, pressure, heat, cold, and pain; provide
information about the external enviroment that indicates appropriate responses; sensitivity
of the skin depends on the number of receptors present.
4. Sebaceous Glands- secrete sebum into hair follicles or to the skin surface; sebum
prevents the drying of skin and hair.
5. Ceruminous Glands- secrete cerumen in the ear canals; prevents drying of the eardrum.
Word Count: 306
|
| |
|
|
2008 © High-quality-essays.com. All rights reserved.
|
|
 |