Anatomy and Physiology of the Integumentary System

Summary

This video script delves into the integumentary system, highlighting its role in skin and accessory structures like nails, hair, and glands. It underscores the skin's multifaceted functions, including temperature regulation, protection, sensory information, and vitamin D synthesis. The script explores skin layers, from the epidermis to the dermis, detailing their composition and functions. It also examines hair and nail structures, the role of melanocytes in pigmentation, and the significance of sweat and sebaceous glands in maintaining skin health and body temperature.

Takeaways

• 📚 The integumentary system derives from 'in' (inward) and 'tegere' (to cover), highlighting its role in covering the body with skin and accessory structures like nails, hairs, glands, and receptors.
• 🌡️ It plays a crucial role in maintaining body temperature, protecting the body, providing sensory information, reflecting emotions, and aiding in physiological processes like sweating.
• 💊 The skin synthesizes vitamin D, which is vital for calcium and phosphate absorption, starting with the molecule 7-dihydrocholesterol that converts to active vitamin D3 upon UV exposure.
• 🧬 The skin, being the largest organ, varies in thickness and is composed of the epidermis and dermis, with the epidermis having 4-5 layers of epithelial cells and no blood supply of its own.
• 🔬 The epidermis consists of keratinocytes that produce keratin for protection, melanocytes for pigmentation, Langerhans cells for immune response, and Merkel cells for light touch and pressure detection.
• 🌞 Melanocytes are responsible for skin color and protection against UV damage, with increased melanin production in response to sun exposure, leading to tanning and freckle formation.
• 🌱 The stratum basale is the epidermal layer where new cells are formed through mitosis, containing stem cells that differentiate into keratinocytes.
• 🌀 The dermis is denser and contains blood vessels, nerves, and appendages like hair follicles and sweat glands, providing strength, elasticity, and hydration to the skin.
• 👁️ Dermal papillae increase friction for grip and contain sensory receptors for touch, pressure, and temperature, with unique fingerprint patterns due to genetic variation.
• 🦴 Collagen and elastic fibers in the dermis contribute to skin strength and elasticity, with a decrease in these fibers leading to aging effects like sagging and wrinkles.
• 🌡️ Blood vessels in the dermis help regulate body temperature by dilating to release heat or constricting to conserve it, affecting skin color and sensation.

Q & A

What is the integumentary system?

The integumentary system is the body system that includes the skin and its accessory structures such as nails, hairs, glands, and sensory receptors. It plays a crucial role in covering the body, maintaining body temperature, protection, sensory information, and reflecting emotions.

What is the role of vitamin D in the integumentary system?

Vitamin D is synthesized in the skin and functions as a hormone that stimulates the absorption of calcium and phosphate from the intestines. The molecule 7-dihydrocholesterol, a precursor of vitamin D, is converted into cholecalciferol when exposed to ultraviolet light from the sun and is later modified by the liver and kidneys to form active vitamin D3 or calcitriol.

What are the two main layers of the skin?

The two main layers of the skin are the epidermis and the dermis. The epidermis is the outermost layer composed of epithelial cells, while the dermis is the thicker layer beneath, made up of dense irregular connective tissue containing collagen and elastic fibers.

What are the different types of cells found in the epidermis?

The epidermis contains various cells including keratinocytes, melanocytes, Langerhans cells, and Merkel or tactile cells. Keratinocytes produce keratin, melanocytes produce melanin for skin color, Langerhans cells are part of the immune system, and Merkel cells are associated with detecting light touch and pressure.

How does the skin help in maintaining body temperature?

The skin helps maintain body temperature through the blood vessels in the dermis. When the body temperature is high, the capillaries become engorged, allowing heat to radiate from the skin surface. In a cool environment, blood bypasses the capillaries to conserve body heat.

What is the function of the stratum corneum in the skin?

The stratum corneum is the outermost layer of the epidermis and consists of dead keratinized cells. It serves as a barrier to prevent the penetration of microbes and dehydration of underlying tissues, providing mechanical protection for the delicate underlying layers.

What is the structure of hair and what are its functions?

Hair consists of a shaft that projects above the skin surface and a root below the surface. It is composed of layers including the medulla, cortex, and cuticle. Hair provides protective functions such as shielding the eyes through eyelashes and preventing foreign particles from entering the respiratory tract through nasal hairs.

How does the nail structure differ from hair?

Nails are thin plates made of layers of dead stratum corneum cells containing a very hard type of keratin. Unlike hair, nails have a free edge, a body, and a root. The nail matrix is responsible for nail growth, and nails are mostly non-living materials that appear pink due to the underlying blood supply.

What are the two types of sweat glands and their functions?

There are two types of sweat glands: eccrine and apocrine. Eccrine glands are widespread and produce sweat for temperature regulation. Apocrine glands are found in areas like the armpits and genitalia and produce secretions that, when metabolized by bacteria, contribute to body odor.

What is the role of sebaceous glands in the skin?

Sebaceous glands produce sebum, an oily substance that prevents the skin from drying and provides protection against some bacteria. Sebum also helps keep the skin and hair moisturized and soft.

What is the significance of the dermis in terms of skin strength and elasticity?

The dermis, composed of dense irregular connective tissue with collagen and elastic fibers, provides the skin with tensile strength, allowing it to stretch without breaking. As we age, the decrease in collagen and elastic fibers leads to a loss of skin elasticity, causing sagging and wrinkles.

Outlines

00:00

🧬 Overview of the Integumentary System

The integumentary system, derived from Latin roots meaning 'inward' and 'to cover', encompasses the skin and its accessory structures such as nails, hair, glands, and sensory receptors. This system is crucial for maintaining body temperature, protection, sensory information, and emotional expression. It also plays a vital role in vitamin D synthesis, which aids in calcium and phosphate absorption. The skin, being the body's largest organ, varies in thickness and is composed of the epidermis and dermis, with the epidermis being avascular and consisting of cells like keratinocytes, melanocytes, and Merkel cells, responsible for skin hardness, color, and light touch sensation, respectively.

05:02

🔍 Structure and Function of Skin Layers

The skin's structure is detailed with various layers serving distinct functions. The epidermis has 4 to 5 layers, including the stratum basale for cell production, stratum spinosum for cell division, stratum granulosum for cell apoptosis, and the stratum corneum for barrier protection. Thick skin, found on palms and soles, includes an additional stratum lucidum. Dendritic cells in the epidermis play a role in immune response, while the dermis, composed of the papillary and reticular layers, contains blood vessels, nerves, and appendages like hair follicles and sweat glands, contributing to the skin's strength, elasticity, and sensory reception.

10:03

🦠 Immunity and Sensory Reception in the Skin

The skin's immune function is facilitated by dendritic cells that engulf pathogens and alert the immune system. Merkel cells and tactile corpuscles in the dermis are associated with nerve endings for light touch and pressure detection. The skin also contains unique fingerprint patterns due to dermal papillae arrangements, which increase grip and produce sweat for temperature regulation. The dermis's blood vessels help maintain body temperature by dilating or constricting in response to thermal changes.

15:04

💇‍♀️ Hair and Nail Structure and Growth Cycles

Hair and nails are accessory structures of the skin with specific protective roles. Hair shields the eyes and respiratory tract, while its structure consists of the medulla, cortex, and cuticle made of keratinized cells. Hair growth occurs in cycles with a growth stage followed by a resting stage, leading to hair replacement. Nails are composed of layers of keratinized cells and have a matrix for nail growth, appearing pink due to underlying blood supply. The visible part of the nail, the lunula, is a crescent-shaped area at the base.

20:05

💧 Glands and Their Functions in the Skin

Sebaceous and sweat glands are integral to the skin's function. Sebaceous glands produce sebum for skin protection and hydration, while sweat glands regulate body temperature and produce sweat, which also contributes to body odor when metabolized by bacteria. The apocrine glands, found in armpits and genital areas, secrete substances that become odoriferous post-bacterial action. Cerumen glands in the ear produce earwax, a protective barrier against foreign bodies and microorganisms.

Keywords

💡Integumentary System

The integumentary system is the body's outer protective layer, consisting primarily of the skin and its accessory structures. It plays a critical role in the video's theme by covering and protecting the body, maintaining temperature, and providing sensory information. The script describes it as being derived from Latin words meaning 'inward' and 'to cover,' highlighting its function as the body's covering.

💡Keratin

Keratin is a fibrous protein that provides structural support to the skin, hair, and nails. In the video, keratinocytes are cells that produce and store keratin, which is essential for the hardness and water-resistant properties of the skin, protecting it from injuries, pathogens, heat, and chemicals.

💡Melanocytes

Melanocytes are the spider-shaped cells in the skin responsible for producing the pigment melanin. The script explains that melanin contributes to skin color and plays a protective role by shielding the DNA of epidermal cells from UV damage. The concentration of melanin also explains the formation of freckles and moles.

💡Dermis

The dermis is the layer of skin beneath the epidermis, composed of dense irregular connective tissue. It contains blood vessels, nerves, and other structures like hair follicles and sweat glands. The script emphasizes the dermis's role in providing the skin's tensile strength and elasticity, as well as its involvement in temperature regulation and sensory reception.

💡Epidermis

The epidermis is the outermost layer of the skin, composed mainly of epithelial cells. The script details its structure, which includes the stratum basale for cell production and the stratum corneum for protection. It is avascular, meaning it lacks its own blood supply, which is why shaving does not typically cause bleeding.

💡Vitamin D

Vitamin D is synthesized in the skin and functions as a hormone that stimulates the absorption of calcium and phosphate. The script explains that the precursor molecule 7-dehydrocholesterol is converted into active vitamin D3 (calcitriol) when exposed to UV light from the sun, which is crucial for bone health.

💡Sebaceous Glands

Sebaceous glands are accessory structures of the skin that produce sebum, an oily substance that prevents skin from drying and offers some protection against bacteria. The script mentions these glands in the context of the skin's accessory structures and their role in maintaining skin health.

💡Sweat Glands

Sweat glands are another accessory structure of the skin that helps regulate body temperature. The script differentiates between two types: eccrine glands, which are widespread and produce sweat for cooling, and apocrine glands, which are found in areas like the armpits and produce secretions that can contribute to body odor when metabolized by bacteria.

💡Hair Follicle

A hair follicle is a tube-like invagination of the epidermis extending into the dermis where hair growth occurs. The script describes the structure of the hair follicle and its role in the hair growth cycle, including the production of hair from the matrix cells within the hair bulb.

💡Nail

Nails are thin plates made of layers of dead stratum corneum cells containing a hard type of keratin. The script explains that nails serve a protective function and are composed of the visible nail body and the root embedded in the skin. The nail matrix, located beneath the nail, is responsible for nail growth.

💡Cerumen

Cerumen, or earwax, is a waxy lubricating secretion produced by ceruminous glands in the external ear. The script notes that cerumen, in combination with hairs in the ear canal, provides a barrier against foreign bodies and insects, and also waterproofs the canal, preventing bacteria and fungi from entering.

Highlights

The integumentary system includes the skin and its accessory structures like nails, hairs, glands, and sensory receptors.

The system plays a crucial role in maintaining body temperature, protection, sensory information, and reflecting emotions.

Skin is capable of synthesizing vitamin D, which is essential for calcium and phosphate absorption.

7-dihydrocholesterol in the skin converts to cholecalciferol upon UV exposure, forming active vitamin D3.

Human skin is the largest organ, covering about 2 square meters and weighing 4.5 to 5 kilograms.

The skin varies in thickness from 0.5 millimeters on eyelids to 4 millimeters on heels.

The skin is composed of the epidermis and dermis, with the epidermis being the outermost and thinner layer.

Keratinocytes in the epidermis produce keratin, providing hardness and water resistance to the skin.

Melanocytes produce melanin, influencing skin color and protecting against UV damage.

Langerhans cells in the epidermis are part of the immune system, responding to threats like bacteria and viruses.

Merkel cells are associated with nerve endings, detecting light touch and pressure.

The stratum basal is responsible for cell production and is the deepest layer of the epidermis.

The dermis contains blood vessels, nerves, and glands, and is much thicker than the epidermis.

Collagen and elastic fibers in the dermis provide strength, toughness, and elasticity to the skin.

Blood vessels in the dermis help regulate body temperature by dilating or constricting.

Hair serves protective functions and is composed of a shaft and root with a complex structure.

Hair growth occurs in cycles with a growth stage followed by a resting stage.

Hair color is determined by the amount and type of melanin produced by melanocytes in the hair follicle.

Nails are made of layers of keratinized cells and protect the sensitive tips of fingers and toes.

Sebaceous glands produce sebum for skin protection, while sweat glands help regulate body temperature.

Cerumen, produced by cerumenos glands, provides a protective barrier in the ear canal.

Transcripts

in this video you will be learning about

the integumentary system

the word in documentary was actually

derived from the latin words in

which means inward and tigera which

means to cover

this makes sense because the

integumentary system

refers to the skin and its accessory

structures

like the nails hairs glands

and sensory receptors

aside from covering our body the

integumentary system

also plays several important functions

like helping maintain a constant body

temperature

protecting the body providing sensory

information

reflecting our emotions and other

aspects of normal physiology

such as sweating we can fully understand

how these functions are performed

by the integumentary system as we study

its different

structures another important function of

the skin

is to synthesize vitamin d vitamin d

functions as a hormone that stimulates

the absorption

of calcium and phosphate from the

intestines

the molecule 7-dihydrocholesterol

which is a precursor of vitamin d is

stored in the skin

when exposed to ultraviolet light of the

sun

this molecule is converted into

cholecalciferol

which is released into the blood and

modified by the liver

and later by the kidneys to form active

vitamin d3

or calcitriol we will now

look into the structures of our skin

our skin is also known as as accutaneous

membrane

well obviously our skin covers the

surface of our body

and it is the largest organ in fact

it covers an area of about 2 square

meters and weighs about 4.5

to 5 kilograms which is about 7

of our total body weight

it also varies in thickness from 0.5

millimeters in our eyelids

up to four millimeters in our heels

in most parts of the body it is about

one to two

millimeters thick

the skin is made of multiple layers of

cells and tissues which are held to the

underlying structures by connective

tissues

it is composed of two main layers in the

epidermis and

the dermis these can be seen in this

micrograph

which shows a sectional view of

the skin the epidermis is located here

in the outermost layer as you can see

it is a thinner xanthodermis

constituting of only four or five layers

of epithelial cells

depending on its location in the body

like other epithelial tissues the

epidermis is a vascular

which means that it has no blood supply

of its own

this explains why a man can shave daily

and not

bleed even though he cuts off many cell

layers each time he shaves

the cells that make up the epidermis

include

the carotenoid sites melanocytes

dendritic cells and merkel or tactile

cells

these keratinocytes are cells that

produce and store keratin

keratin is a protein that gives our

hairs

nails and skin their hardness and water

resistant properties

it also helps protect the skin and

underlying tissues from

injuries pathogens heat and chemicals

the carotenoid sites in the uppermost

layer of the skin

known as the stratum corneum are dead

and

regularly slough away being replaced by

cells from the deeper layers

about eight percent of the epidermal

cells are these

spider-shaped cells known as melanocytes

these cells produce the pigment melanin

which is transferred

into the keratinocytes and contributes

to skin

color dark skinned individuals produce

more melanin

than those with pale skin also

exposure to the uv rays of the sun

causes melanin to be manufactured and

built up

in keratinocytes which results in the

darkening of the skin

in fact freckles and moles are seen

where melanin is concentrated in one

spot

this increased melanin accumulation is

important in protecting the dna

of epidermal cells from uv ray damage

and the breakdown of folic acid

longer hand cells are dendritic cells

or cells that have tree like structures

they engulf bacteria foreign particles

and damaged

cells that occur in the epidermis

these cells arise from red bone marrow

and

migrate to the epidermis

they also alert and activate immune

system cells

to a threat such as bacterial or viral

invasion

the merkel or tactile cells are the

least numerous epidermal cells

which are located in the deepest layer

of the epidermis

or in the epithermal dermal junction

they are associated with the nerve

endings

responsible for detecting light touch

and superficial pressure

now it was mentioned a while ago that

the skin may have four to five layers of

these cells

skeins that has four layers of cells

is referred to as thin skin

from deep to superficial these layers

are the stratum basal

stratum spinosum stratum granulosum

and stratum corneum most of the skin can

be classified as a thin skin

thick skin is found only on the palms of

the hands and the soles of the feet

it has a fifth layer called the stratum

lucidum which is located between the

stratum corneum and the stratum

granulosum

the deepest layer of the epidermis is

the stratum basal or also known as

stratum germinativum

to indicate its role in forming new

cells

it attaches the epidermis to the basal

lamina

below which lie as the layers of the

dermis

stratum basal is a single layer of cells

primarily made of basal cells

basal cells are cube-shaped stem cells

that will soon become keratino sites of

the epidermis all of the keratinocytes

are produced from the single layer of

cells

which are constantly going through

mitosis or cell division

to produce new cells as new cells are

formed as the existing cells are pushed

upwards

away from the stratum basal

merkel cells and melanocytes are also

found in the stratum basal

superficial to or just above the stratum

basil

is the stratum spinosum as the name

implies

this layer is spiny in appearance

it consists of numerous keratinocytes

arranged in eight to ten layers

these keratinocytes formed as a result

of cell division

in the stratum basal they also retained

their ability to divide aside from zechy

retinol sites

langerhans cells are also located in

this layer

as new keratinocytes are produced above

the stratum basal

the carotenoid sites of the stratum

spinozum

are pushed into the stratum granulosum

cells flatten as as they move upwards

cells in this layer undergo apoptosis or

programmed cell deaths as as they move

farther away

from the source of nutrition which is

the thermal blood vessels

also their cell membranes thicken and as

they generate large amounts of protein

keratin

and keratohyalin the nuclei

and other cell organelles disintegrate

as the cells die

leaving behind the carotene keratohyalin

and cell membranes that will form the

stratum lucidum

stratum corneum and the accessory

structures of hairs and

nails the stratum lucitum consists of

four to six

layers of flat and clear dead cave

retinol sites that contain large amounts

of keratin

and second plasma membranes it is

present only in the thick skin of

areas such as fingertips palms and soles

this provides an additional level of

toughness in these regions of thick skin

the stratum corneum is the most exposed

and superficial layer of

the epidermis it usually consists of 15

to 30 layers of cells

this dry dead layer helps prevent the

penetration of microbes

and the dehydration of underlying

tissues and provides

a mechanical protection for the more

delicate

underlying layers cells in this layer

are shed periodically and are

replaced by cells pushed up from the

stratum granulosum

or stratum lucidum in the case of palms

and soles

the entire layer is replaced during a

period of about four weeks

if the skin is constantly exposed to

friction

there is an increased cell and keratin

production

that results in the formation of a

callus and abnormal thickening of the

stratum cranium

below the epidermis is the dermis which

is

much thicker it is composed of dense

irregular connective tissue

containing collagen and elastic fibers

which contribute to its great tensile

strength

when we say tensile strength we refer to

the ability to stretch without breaking

in fact leathers used in making belts

bags and shoes are dried and treated

terminals of other animals

unlike the epidermis which is largely

made of cells

the dermis contains blood and leaf

vessels

nerves sweat glands and other structures

such as hair follicles

also portions of them project up into

and through the epidermis

the dermis also has varying thickness

depending on the location

for instance it is a thicker on the

palms and soles and thinner

in the eyelids the dermis

is made of two layers the papillary

and reticular

the superficial or upper portion is the

popular layer

which lies immediately deep to the

stratum basal

we can see in this is that the papillary

layer has finger-like projections called

dermal patella

many of these thermal papillae contain

capillary loops

that furnish nutrients to the epidermis

in the palms and soles this papillae are

arranged in reaches as that increase

friction and improves the grip of the

hands and feet

the ridges of the fingertips are well

provided with sweat pores

that produce sweat which may leave

fingerprints and footprints

on surfaces they touch because popular

patterns are genetically determined

everyone even an identical twin has

unique fingerprints and footprints

other dermal papillae contain misner or

tactile corpuscles that respond to light

touch

and free nerve endings that function as

pain

or temperature receptors the reticular

layer is the deepest

skin layer which accounts for

approximately eighty percent of dermal

thickness

it contains dense irregular connective

tissues

blood vessels sweat and oil glands and

deep pressure receptors

called lamellar or pacinian corpuscles

sensory receptors which are actually

parts of the nervous system

are also located in the skin these

include touch

pressure temperature and pain receptors

that provides us with information about

our external environment

in addition phagocytes are also found

here

these are cells that protect the body by

ingesting harmful foreign particles and

microbes

that have managed to get through the

epidermis

collagen and elastic fibers are found

throughout the dermis

collagen fibers are responsible for the

toughness and strength of the dermis

they also attract and bind water to help

keep the skin hydrated

elastic fibers give the skin its

elasticity

but as we age the number of collagen and

elastic fibers decreases

and the subcutaneous tissue losses fat

as a result the skin losses its

elasticity and begins to sag

and wrinkle the blood vessels in our

dermis play a role in maintaining body

temperature

when body temperature is high the

capillaries of the dermis become

engorged or

swollen with heat applied and as the

skin becomes

reddened and warm this allows body heat

to radiate from the skin surface

if the environment is cool and body heat

must be conserved

blood bypasses as the term is

capillaries temporarily

allowing internal body temperature to

remain high

the epidermis and dermis are firmly

connected

however a burn or friction such as the

rubbing of the skin

and a poorly feeding shoe may cause

them to separate this causes

interstitial fluid or

the fluid that surrounds the body cells

to accumulate in the cavity between the

layers

which results in a blister

one of the accessory structures of the

skin is

the hair in humans it is found

everywhere on the skin

except the palms soles as a lips

nipples parts of the external genitalia

and the distal segments of the fingers

and toes

it has protective functions which

include shielding the eyes as through

the eyelashes

and helping to keep foreign particles

out of the respiratory tract

through the nasal hairs

we now look into the structure of our

hair

a hair is divided into the shaft which

projects above the surface of the skin

and the root which is located below the

surface

most of the root and the shaft are

composed of columns of dead

keratinized epithelial cells arranged in

three

layers the medulla is the cortex

and the cuticle the medulla is the

central axis of the hair

and it consists of two or three layers

of cells

containing soft keratin the cortex

surrounds the medulla and forms the bulk

of the hair

the cells of the cortex contain hard

keratin

the cortex is covered by the cuticle a

single layer of

cells which also contain hard keratin

the cuticle is the most heavily

keratinized region

it provides strength and helps keep the

inner layers

tightly compacted but because it is most

subject to abrasion

the cuticle tends to wear away at the

tip of the shaft

causing split ends the hair follicle is

a tube-like invacination of the

epidermis

that extends into the dermis a hair

develops and grows

within each hair follicle a hair

follicle consists

of a thermal brew cheese and an

epithelial blue cheese

the epithelial root sheath is divided

into external

and internal parts when a hair is pulled

out

the internal epithelial root cheese

usually comes

out as well and is plainly visible as

whitish tissue

around the root of the hair the base of

the root is expanded to form the hair

bulb

inside it is a mass of epithelial cells

called as a matrix which produces the

hair

and the internal epithelial will achieve

our hairs are produced in cycles that

involve a gross

stage and resting stage during

the growth stage a hair increases in

lens as

new matrix cells are produced

the hair grows longer as cells are added

at the base of the hair root

eventually hair growth stops and the

hair follicle shortens and holds

the hair in place this is the resting

period

after which a new cycle begins and a new

hair

replaces the old hair which falls out of

the hair follicle losing a hair

normally means that the hair is being

replaced

hair color is made by melanocytes in the

hair bubble

these cells produce melanin and passive

to keratinophytes in the hair cortex

and medulla varying amounts and types of

melanin

cause different shades of hair color for

instance

blonde hair has little black brown

melanin

while black hair has the most melanin

intermediate amounts of melanin account

for different shades of brown

and red hair is caused by varying

amounts of red type of melanin

the amount of melanin in hair can

decrease with age causing

hair color to fade or become white

if we look carefully at the structure of

the hair follicle

we will notice that it is slightly

slanted

small bands of smooth muscle cells

called

erector pili connect each side of the

hair follicle

to the dermal tissue when these muscles

contract as

one year cold or frightened the hair is

pulled upright

and causing goose bumps

another accessory structure of the skin

is the nail

which is a thin plate consisting of

layers of dead stratum corneum cells

that contain a very hard type of keratin

each nail has a free edge a body

which is the visible portion and the

root which is embedded in the skin

the borders of the nail are overlapped

by these nail folds

the edge of the thick proximal nail fold

is commonly called as a cuticle

the stratum basal of the epidermis

extends beneath

the nail as a nail bed this

second area in the nail bed called the

nail matrix is

responsible for nail curls as the matrix

produces nail cells

they become heavily curetonized and die

thus nails like hairs are mostly

non-living materials

nails are transparent and nearly

colorless but they look pink because of

the rich blood supply

in the underlying dermis the exception

to this

is the region over the second nail

matrix

that appears as a white crescent and is

called the linole

as mentioned earlier sebaceous and sweat

glands are also located within the

dermis of the skin

the sebaceous gland produces sebum which

is an oily substance that prevents

drying

and protects against some bacteria there

are two types of sweat glands

the acream and apple cream the aquarine

which produces mostly water some salts

and

small amounts of ammonia urea uric acid

and lactic acid

is the most common type this is

important in regulating temperature

the apocrine is a simple coiled tubular

gland that usually opens into hair

follicles

it is found in the armpit and genitalia

secretions from the apocrine gland

contain organic substances

that are essentially odorless when first

released

however they are quickly metabolized by

bacteria

to cause what is commonly known as body

odor

cerumenos glands are modified sweat

glands in the external ear

that produce a waxy lubricating

secretion

the combined secretion of the cerumenos

and sebaceous glands

is a yellowish material called cerumen

or earwax

together with the hairs in the external

auditory canal

they provide a sticky barrier that

impedes the entrance of foreign bodies

and

insects cerumen also waterproofs

the canal and prevents bacteria and

fungi

from entering cells