Accessory Organs of the Skin
Nails
Are very unique protective coverings at the end of our fingers and toes. They consist of certified squamous epithelium. These cells are in the top of the nail bed. The most actively growing region of the nail root is called the lunula. Similar to the skin crawling from the stratum basale outward, the nail cells grow from the lunula outward. They also become more keratinized as they move further from their low and blood supply.
Hair Follicles
Individual hair cells also grow from an actively replicating region and move outward. The base of the hair follicle is located in the lower epidermis that actually dips down into the dermal layer. The actively growing and dividing cells push the hair follicle outward, and the cells die in the hair shaft. These dead cells are also keratinized for further rigidity and stiffness. Hair cells are supported by the sebaceous glands to prevent excessive dehydration and keep the cells from becoming brittle.
Arrector pili muscle is a small bundle of smooth muscle that attaches to a hair follicle. When this muscle contracts it raises the hair and also produces goosebumps.
Hair color is also determined by genetics and production of pigments. Melanin pigments are responsible for most hair color pigments, specifically Eumelanin (for black and brown) and Pheomelanin. Red hair contains more pheomelanin.
1. Sebaceous glands
Sebaceous glands secrete a waterproofing and moisturizing sebum to protect the hair. Sebaceous glands are holocrine glands.
2. Sudoriferous glands
(sweat glands) are composed of two distinct types of glands.
1. Eccrine – response to body temperature.
2. Apocrine – response to body temperature, stress, and sexual arousal. The products of these glands are different in their water and oil composition.
3. Ceruminous glands
Secrete wax in the ear canal. These are modified sweat glands that produce a product to help protect the ear canal and eardrum. Cerumen lubricates and cleans the external auditory canal, waterproofs sick canal, kills bacteria and helps trap dust and foreign particles by coating the hairs in the ear.
Mammary glands are another modified type of sweat glands. These glands secrete milk.
Questions
How is nail growth similar to skin cell growth? _______________________________________
How is it different? _____________________________________________________________
What is the actively growing area of a nail? _________________________________________
Are the nail cells at your fingertips alive? _____________________________________________
Are the cells more keratinized than skin cells? ________________________________________
How is this a benefit for the body? _________________________________________________
Where is the base of hair follicles located? In which layer? ______________________________
Where are the nutrients for the hair follicle coming from? ______________________________
What happens as the cells move away from the follicle? _______________________________
What glands help support and protect the hair cell? ___________________________________
What would happen if this gland was not working properly? ____________________________
What muscle causes “goose bumps?” _____________________________________________
What happens when the muscles contract? The hair _____________ and skin _______________
What pigments determine the color in hair? __________________________________________
Do all hair have the same amount and type of pigment? Explain _________________________
What is the name for a sweat gland? ________________________________________________
What are the two types? __________________________ and ___________________________
What are the differences in products between the glands? _______________________________
What is the name of the gland that secretes earwax? ___________________________________
What function does cerumen provide? ______________________________________________
What would happen if you could not produce cerumen? ________________________________
What does your body do after a superficial cut? _______________________________________
What does your body do after a deep cut? ____________________________________________