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Hair color

Similar to the skin, hair gets its color from the pigment melanin, produced by melanocytes in the hair papilla. Different hair color results from differences in the type of melanin, which is genetically determined. As a person ages, the melanin production decreases, and hair tends to lose its color and becomes gray and/or white.

Nails

The nail bed is a specialized structure of the epidermis that is found at the tips of our fingers and toes. The nail body    is formed on the nail bed    , and protects the tips of our fingers and toes as they are the farthest extremities and the parts of the body that experience the maximum mechanical stress ( [link] ). In addition, the nail body forms a back-support for picking up small objects with the fingers. The nail body is composed of densely packed dead keratinocytes. The epidermis in this part of the body has evolved a specialized structure upon which nails can form. The nail body forms at the nail root    , which has a matrix of proliferating cells from the stratum basale that enables the nail to grow continuously. The lateral nail fold    overlaps the nail on the sides, helping to anchor the nail body. The nail fold that meets the proximal end of the nail body forms the nail cuticle    , also called the eponychium    . The nail bed is rich in blood vessels, making it appear pink, except at the base, where a thick layer of epithelium over the nail matrix forms a crescent-shaped region called the lunula    (the “little moon”). The area beneath the free edge of the nail, furthest from the cuticle, is called the hyponychium    . It consists of a thickened layer of stratum corneum.

Nails

These two images show anatomy of the fingernail region. The top image shows a dorsal view of a finger. The proximal nail fold is the part underneath where the skin of the finger connects with the edge of the nail. The eponychium is a thin, pink layer between the white proximal edge of the nail (the lunula), and the edge of the finger skin. The lunula appears as a crescent-shaped white area at the proximal edge of the pink-shaded nail. The lateral nail folds are where the sides of the nail contact the finger skin. The distal edge of the nail is white and is called the free edge. An arrow indicates that the nail grows distally out from the proximal nail fold. The lower image shows a lateral view of the nail bed anatomy. In this view, one can see how the edge of the nail is located just proximal to the nail fold. This end of the nail, from which the nail grows, is called the nail root.
The nail is an accessory structure of the integumentary system.

Nails are accessory structures of the integumentary system. Visit this link to learn more about the origin and growth of fingernails.

Sweat glands

When the body becomes warm, sudoriferous glands produce sweat to cool the body. Sweat glands develop from epidermal projections into the dermis and are classified as merocrine glands; that is, the secretions are excreted by exocytosis through a duct without affecting the cells of the gland. There are two types of sweat glands, each secreting slightly different products.

An eccrine sweat gland    is type of gland that produces a hypotonic sweat for thermoregulation. These glands are found all over the skin’s surface, but are especially abundant on the palms of the hand, the soles of the feet, and the forehead ( [link] ). They are coiled glands lying deep in the dermis, with the duct rising up to a pore on the skin surface, where the sweat is released. This type of sweat, released by exocytosis, is hypotonic and composed mostly of water, with some salt, antibodies, traces of metabolic waste, and dermicidin, an antimicrobial peptide. Eccrine glands are a primary component of thermoregulation in humans and thus help to maintain homeostasis.

Eccrine gland

This diagram shows an eccrine sweat gland embedded in a cross section of skin tissue. The eccrine sweat gland is a bundle of white tubes embedded in the dermis. A single white tube travels up from the bundle and opens on to the surface of the epidermis. The opening is called a pore. There are several pores on the small block of skin portrayed in this diagram.
Eccrine glands are coiled glands in the dermis that release sweat that is mostly water.

An apocrine sweat gland    is usually associated with hair follicles in densely hairy areas, such as armpits and genital regions. Apocrine sweat glands are larger than eccrine sweat glands and lie deeper in the dermis, sometimes even reaching the hypodermis, with the duct normally emptying into the hair follicle. In addition to water and salts, apocrine sweat includes organic compounds that make the sweat thicker and subject to bacterial decomposition and subsequent smell. The release of this sweat is under both nervous and hormonal control, and plays a role in the poorly understood human pheromone response. Most commercial antiperspirants use an aluminum-based compound as their primary active ingredient to stop sweat. When the antiperspirant enters the sweat gland duct, the aluminum-based compounds precipitate due to a change in pH and form a physical block in the duct, which prevents sweat from coming out of the pore.

Sweating regulates body temperature. The composition of the sweat determines whether body odor is a byproduct of sweating. Visit this link to learn more about sweating and body odor.

Sebaceous glands

A sebaceous gland    is a type of oil gland that is found all over the body and helps to lubricate and waterproof the skin and hair. Most sebaceous glands are associated with hair follicles. They generate and excrete sebum    , a mixture of lipids, onto the skin surface, thereby naturally lubricating the dry and dead layer of keratinized cells of the stratum corneum, keeping it pliable. The fatty acids of sebum also have antibacterial properties, and prevent water loss from the skin in low-humidity environments. The secretion of sebum is stimulated by hormones, many of which do not become active until puberty. Thus, sebaceous glands are relatively inactive during childhood.

Chapter review

Accessory structures of the skin include hair, nails, sweat glands, and sebaceous glands. Hair is made of dead keratinized cells, and gets its color from melanin pigments. Nails, also made of dead keratinized cells, protect the extremities of our fingers and toes from mechanical damage. Sweat glands and sebaceous glands produce sweat and sebum, respectively. Each of these fluids has a role to play in maintaining homeostasis. Sweat cools the body surface when it gets overheated and helps excrete small amounts of metabolic waste. Sebum acts as a natural moisturizer and keeps the dead, flaky, outer keratin layer healthy.

Questions & Answers

the diagram of cell membrane
Teboh Reply
***bit.ly/3kfrdfV Link to cell membrane diagram and more info... Remember, you can search the A&P book.
Favour
describe diffusion as used in body fluid movement
brenda Reply
how was the movement?
Jenelyn
classify joint function with example
James Reply
cytoskeleton diagram
Miriam Reply
two types of cells biological name
Miriam
eukaryotic and prokaryotic
Emraan
Difference between extracellular and intracellular
Eli Reply
extra (exit) outside the cell, intra inside the cell
Amy
extracellular is 1/3 of total body water...intracellular 2/3 of total body water
Favour
what is culture?
Nepi
is the way of life of people
Senior
He meant in the context of biology...as in "tissue culture".
Favour
what does depolarization mean...in terms of the cardiovascular system?
Tracy
depolarization means contraction
Abhishek
Depolarization, in the context of nerve and muscle tissue, is the decrease in membrane potential (the separation of charge between the extracellular and intracellular compartments). Basically, the charge in the cell becomes more positive when depolarization occurs.
Favour
In fact, the word 'polarize' used to mean dividing into extremes or opposite sides. The opposite is true for 'depolarize'
Favour
intracellular fluid is the fluid compartment of the body consisting of all water present within the cell...while extracellular fluid is water present out of the cell
brenda
Why apoptosis is important?
Duchess Reply
name the body organ which helps in the oxygenation of body.
Eli Reply
respiratory system (lungs) brings in oxygen...cardiovascular system (blood) circulate it
Favour
Lungs
Emil
the heart
Mpho
Mpho explain
Favour
cells... tissues...organs
Angel Reply
...organ system...organism...species...population...
Favour
connection between respiratory and circulatory system
Philip Reply
what's respiratory system
Philip
what is the site of CHON synthesis?
World
send them boi
alex
dont send via email...use google drive
Favour
Which major organ lies deep to the right hypochondriac region?
Biswajit Reply
deep as in most posterior kidney, or deep as in inferior small intestine?
Amy
liver
Emil
what is the weakest muscle in the body?
zharla Reply
stapedius
Isaac
Connective tissues composed with the blood
EDIGAR Reply
blood cell
nancy
Why is left bronchi narrow?
nancy
what is the most widely distributed connective tissue in the body?
Aila Reply
hai
SURENDRA
why most we study anatomy
Xavier Reply
hello
Aila
Anatomy it is a Latin word which mean to dissect mean to cut apart the study of body structure is called anatomy internel anatomy to study of internel structure of oganisms e.g frog dissection external anatomy/ Grass anatomy the study of external stucture of the organi the study of body
Ikram
Anatomy it is a Latin word which mean to dissect mean to cut apart the study of body structure is called anatomy internel anatomy to study of internel structure of oganisms e.g frog dissection external anatomy/ Grass anatomy the study of external stucture of the organi the study of body
Ikram
Anatomy it is a Latin word which mean to dissect mean to cut apart the study of body structure is called anatomy internel anatomy to study of internel structure of oganisms e.g frog dissection external anatomy/ Grass anatomy the study of external stucture of the orga the study of body
Ikram
hi
Ikram
hi Ikram
Favour
analyse the structure and function of the brainstem
Clinton Reply

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Source:  OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 04, 2016 Download for free at http://legacy.cnx.org/content/col11496/1.8
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