Eva kiptoo presenting

1. KIPTOO EVA JERUTO
DIPLOMA IN DENTALASSISTING
DDA540/23
THE INTEGUMENTARY SYSTEM

2. OUTLINE
1. Introduction to the integumentary system.
2. Cells of the skin. – Keratinocyte ,Melanocytes, Langerhans and
Merkel cells
3. Layers of the skin.- Epidermis, Dermis and Hypodermis
4. Appendages of the skin – Hair, Nail and Glands

3. THE INTEGUMENTARY SYSTEM
 It is also known as the skin system.
 It is the largest and outer part of a human body.
 The main function of the skin system is to act as a protection device against
bacteria and injury from the external environment.
 In this topic, we will be able to learn about the functions, layers, structures and
cells of the skin among others.
Fun fact: Did you know that an inch of your skin contains nineteen million cells?

4. Functions of the skin.
1. Acts as a protective device against bacteria from entering into the body.
2. Regulates the body temperature in that it conserves and releases heat through
vasoconstriction.
3. It is a sensory device i.e., by touch and feel.
4. Helps in production of vitamin D.
5. Releases waste products that is through sweating.
6. Reduces the harmful effect ultraviolet radiation.
7. Detects infection when it acts as an immune organ.
8. Acts as a heat absorbent.

5. Cells of the skin
 There are different types of cells found in the skin that work differently.
 They include the following;
1. Keratinocytes
2. Melanocytes
3. Merkel cells
4. Langerhans cells

6. 1. Keratinocytes
 They are the cells found in the epidermis layer of the skin.
 Its main role is to repair the skin.
 It also produces keratin protein from the keratinocyte stem cells .These proteins
make up the bulk of the dermis.
 The keratin produced helps in the formation of hair, nails and the outer skin layer
that helps in protection.

7. 2. Melanocytes.
 They are responsible for the formation of melanin.
 It is dark and dendritic in shape
 There are two types of melanin;
i. Eumelanin- Primarily makes dark colors in your hair, skin and eyes.
ii. Pheomelanin- Primarily makes pink or red colors in the body e.g. Lips

8. 3. Merkel cells
 These are the cells that help in the sensitivity of the skin .
 They are closer to the nerve ending where they receive a sense of touch.
 They contain substances that act as hormones.
4. Langerhans cells
 They are basically the guards of the skin where they are able to detect and prevent
foreign materials from entering the skin.

9. Layers of the skin
 There are three main layers of the skin working differently.
 These layers include;
1) Epidermis .
2) Dermis .
3) Subcutaneous fat(hypodermis)

11. 1. The Epidermis.
 It is the upper layer of the skin.
 The underlying tissues from the vessels provides the skin cells with nutrients.
 The skin cells are renewed whereby the old are replaced with new.
 It produces skin cells that are responsible for the skin tone(melanin).
 It does not have blood supply of its own.
 It consists of five different layers:
a. Stratum basale
b. Stratum spinosum
c. Stratum granulosum
d. Stratum lucidum
e. Stratum corneum

12.  The figure shows parts of
the epidermis layer.

13. Layers of the epidermis.
a. Stratum basale
 This is the deepest layer of the epidermis.
 They are responsible for;
I. Creation of new skin cells.
II. Production of keratin from the keratinocyte stem cells.
III. Through production of keratin the following are formed hair, nails and the outer
skin that acts as a protection device
IV. Melanin production due to the melanocyte cell.
b. Stratum spinosum
 This layer is found in between the stratum basale and stratum granulosum layer.

14. c. Stratum granulosum
 It is located in between the stratum spinosum and stratum lucidum.
 The keratin is formed in this layer due to the keratinocyte granules.
d. Stratum lucidum
 It is found in between stratum granulosum and stratum corneum.
e. Stratum corneum
 It is the outermost layer of epidermis layer.
 This is where the keratinocytes are converted into the corneocytes.
 The corneocytes are the strong dead keratinocytes.
 The corneocytes are responsible to protect one from harm e.g.; ultraviolet
radiation, pathogens and heat.

15.  It contains fat that prevents loss of moisture by keeping water from entering or
leaving the body.
 The new keratinocytes cells from the stratum basale then replaces the corneocytes
that are shed.
Functions of the epidermis
1. It helps in hydration- stratum corneum
2. Production of new skin cells- stratum basale
3. Acts as a protection device- stratum corneum
4. It is responsible for skin color-stratum basale
How does the epidermis help with other organs?
It protects skeletal system, muscles and tissues from harm

16. Cells of the epidermis
 The epidermis contains cells
which help in the activities
of the skin these cells
include;
I. Keratinocytes
II. Melanocytes
III. Langerhans cells
IV. Tactile epithelial cells

17. 2.The Dermis
 It is the middle inner layer of the skin.
 This is where hair structures are found.
 Its principle component is collagen(protein)
 It has two layers;
i. Papillary dermis - It is the thin upper layer near the epidermis. It is highly
vascularized due to the loose connective tissue
ii. Reticular dermis - It is the deepest layer of the dermis. It is the thick layer of the
dense connective tissue constituting the bulk of dermis.

19. i. Papillary dermis
 Is the layer found immediately beneath the dermis.
 Contains loose connective tissues that is highly vascularized.
 The loose connective tissues include;
a. Capillaries
b. Elastic fibers
c. Reticular fibers
d. Thin collagen fibers

20. ii. Reticular dermis
 It is the deepest layer of the skin.
 Contains thick connective tissues making up the bulk of the dermis.
 The thick connective tissues include;
1. Blood vessels
2. Interlaced elastic fibers
3. Parallel collagen fibers(thick)
4. Fibroblasts
5. Mast cells
6. Nerve endings
7. Lymphatic vessels

21. Structures in the dermis.
 Connective tissues
 Blood capillaries- Supplies nutrients and oxygen and take away cell waste from
the skin
 Lymphatic vessels- They destroy bacteria causing infections.
 Sweat glands- produces sweat as a waste product out of the skin.
 Sebaceous glands- Secrete oil that keep the skin smooth and protects the skin
from bacteria as a waterproof device.
 Nerve endings- Acts as a sensing device for feel, touch, harm etc.
 Hair follicles- Nourishes the hair to grow.

22. Tissues of the dermis.
1. Collagen- Strengthens the skin.
2. Elastic tissues- Enables flexibility of the skin by producing elastin.
3. Reticular fibers- Controls blood pressure of vascular cells.
Functions of the dermis.
1.Excretion.
Contains sweat gland where sweat is produced and released though the skin.
2.Regulates body temperature.
When the body temperature is high it releases sweat that cools of the body.
3. Produces oil that inhibits bacterial growth on the skin.
4. Growing hair through the hair follicles that contract when body is cold and scared
causing goose bumps.

23. 5. The nerve endings enables one to experience feeling of either touch, hurt ,itches
etc.
6.Distributing blood through the blood vessels to the epidermis it also removes
toxins enable the skin to strengthen.
7.Enables skin protection due to phagocyte cells that consume harmful substances .
8. Gives the skin structure.

24. 3.The Hypodermis
 It is the deepest layer of the skin.
 It is also known as subcutis or subcutaneous tissue.
 This is the layer that contains fat cells beneath the dermis
 The hypodermis thickness varies across the body i.e.;
o High testosterone- Thick hypodermis in abdomen, arms, lower back and
shoulders.
o High estrogen- Thick hypodermis in butt, hips and thighs.
Function of the oil in hypodermis.
1.Insulates body from the cold due to fat produced.
2.Acts as a cushion for internal structures e.g.; muscles and organs when something
hits you.

25. Functions of hypodermis.
1. Allow skin to move smoothly over tissues and muscles.
2. Protects body organs from shock absorbers.
3. Connects the dermis to muscles and bones.
4. Produces sweat to regulate body temperature from heat.
5. Produces fat cells that store energy.
How do you to keep the hypodermis healthy?
1) Properly treat your wounds.
2) Avoid sun damage- Apply sunscreen to reduce sun damage.
3) Take precautions to avoid burns.
4) Keep your body to avoid hypothermia or frostbite.
Hypothermia- is a systematic cold injury.

26. Why does the skin wrinkle as one continues to age?
 The dermal layer becomes thinner with age due to less collagen produced.
 The elastin wears out by becoming less elastic leading to wrinkling and sagging.
 The sebaceous glands produces less sebum.
 The sweat glands produces less sweat contributing to dry skin.
 Surface area/contact between dermis and epidermis decreases hence, leading to
less supply of blood to the epidermis from dermis and fewer nutrients making it
to the outer skin layer.
 The flattening out of the connecting region makes skin more fragile.

27. SKIN RECEPTORS.
 Near surface skin receptors.- Detect gentle pressure, temperature and vibrations
and pain. (naked nerve endings) Dendrites
 Deep in skin receptors. – Detect hair motions and responds to strong pressure
vibrations.

28. Appendages of the skin.
They include; hair, nails and glands. It helps the skin to function according to the
surrounding environmental factors e.g.; touch, temperature sensation, excretion,
perspiration and thermoregulation.
1. Hair.
•It is the keratinous filament growing out of the epidermis.
•It is made up of dead keratinized dead cells.
•It is comprised of the hair shaft and hair follicle
a. Hair shaft
•It is the hair that is visible outside the skin.
•It contains cuticle cells which surround the cortex. The cortical layer is comprised
of keratin providing structure to the bulk of hair shaft.
b. Hair follicle
• It is the primary structure for hair growth
•This is where the strands of hair originate from.

29. Terms of the hair
i. Hair root - It is where the rest of the hair is found below the skin.
ii. Hair bulb - It is where the hair root ends .Found in the dermis
iii. Hair matrix - It is the layer in which the basal cells are active
iv. Hair papilla - It is the content surrounded by the hair bulb. It is made up of
connective tissue and contains blood capillaries and nerve endings from the dermis
v. Medulla - It is the central core of the hair surrounded by the cortex .
vi. Cuticle - It is the layer of compressed keratinized cells that is covered by an
outer layer of hard keratinized cells.
vii. Hair loss - It occurs when more hair is shed than is being replaced. This
happens when there is hormonal or dietary changes. It can also be due to aging
process or hormone influence.

30. Structures of the hair follicle.
• It consists of three layers of cells;
1. Internal root sheath cells
• It extends up to the hair shaft and surrounds the root of growing hair.
• It is produced in the basal cells of the matrix.
2. External root sheath cells
• It is made up of the basal cells at the base of root hair and the upper region is
keratinous.
• It is an extension of the epidermis that encloses the hair root.
3.Glassy membrane
• It is a thick connective tissue covering the hair root and connects to the dermis tissue
 The hair follicle has layers of cells that form from basal cells in hair matrix and hair
root

31. Hair texture
• This is determined by the shape and structure of the cortex which is also
determined by the shape of the hair follicle.
• There are two types ;
• Straight
• Curly
Hair color
• Melanocyte in the hair papilla creates the melanin pigment that gives the hair
color.
• The different hair color is due to the different types of melanin.
• When a person ages there is melanin production reduces and the hair tends to lose
its color and becomes grey or white.

32. How does the hair grow?
When the keratinocytes from the hair bulb is produced ,new cells are deposited at
the hair bulb where the hair shaft is pushed through the hair follicle towards the
surface. These cells are then pushed to the skin surface to form the hair shaft that is
visible. The hair that grows out of the skin is composed of dead keratin.That is why
when you shave or cut your hair it doesn’t have sensation.
Hair growth occurs in three phases;
1. Anagen phase - Cells divide root hair and pushes the hair shaft up and out.
2. Catagen phase - It marks the transition from the hair follicle’s active growth.
3. Telogen phase - Hair follicle is at rest and no new growth occurs.
Then it goes to the first phase.

33. CATAGEN PHASE TELOGEN PHASE
ANAGEN PHASE

34. Functions of the hair
1. Communication through nerve signals by making the external hair shaft stand
up when one is frightened(goosebumps). Also when cats are frightened they
raise their fur. Arrector pili responds to nerve signals(from sympathetic nervous
system) by contracting
2. Thermoregulation (traps a layer of air to add insulation).
3. Acts as a sensing device i.e. To the air movement and substances in the
environment, detects presence of insects.
4. Acts as a protective device :
Traps dust from entering the eyes and nose, it also excludes dust particles that may
contain allergens and microbes
Eyelashes and eyebrows protect eyes from dirt and water(blinking).

37. 2. Nail
• They are accessory structures of the integumentary system.
• Nail bed - Is a specialized structure of the epidermis found at the tip of our
fingers and toes. The blood vessel makes the nail bed appear pink.
• Nail body -
• It is formed on the nail bed.
• It prevents our fingers and toes from mechanical stress.
• It is composed of densely parked keratinocytes.
• Nail fold - Found on the sides of the nail that anchors the nail body.
• Nail cuticle - It is the meeting point between the nail fold to the proximal end of
the nail body. Also known as Eponichium.
• Lunula(little moon) - It is the crescent-like shape on the fingernails. It the part of
the nail that doesn’t appear pink due to the thick layer epithelium at the nail
matrix.

38. • Nail matrix - It is the root of nail that enables it to grow.
• Hyponichium - It is the area beneath the fingernail extension.it consists of a
thickened layer of stratum corneum.

39. 3. Glands
• They are the organs of the endocrine system.
• They are produced and released to perform a specific function.
• Their main function is to release ; water, salt or oil under the skin to the surface
of the skin.
• There are four main types of glands:
1. Sebaceous glands
• They secrete sebum(oil) and gives the face oil and protects skin from becoming
dry which reaches the skin surface through ducts.
• Sebum is a mixture of lipids that forms a thin film on the skin.
• It’s part of the pilosebaceous unit that include: hair, hair follicle and arrector pili
muscles.
• They are involved in skin problems such as: acne and keratosis pilaris

40. Functions
a. Acts as a protective layer to the skin
b. Prevents fluid loss
c. Plays an antimicrobial role by being a bimolecular barrier that disrupts
bacterial membranes.
2. Ceruminous glands
• They are ear glands that secrete wax.
• Its main function is to keep the outer surface of the eardrum flexible and also to
prevent the ear from drying .
• It also assists in cleaning and lubrication.
• Provides protection from bacteria, fungus and insects.

41. Wax from the ear that is
secreted by the
ceruminous glands

42. 3. Mammary glands.
• They are glands found on the chest of a human being.
• They secrete milk when a human being or an animal gives birth. This occurs
when exocrine glands are enlarged and modifies sweat glands. Due to the skin
receptors when a baby sucks on the breast of a mother it sends nerve signals to
the brain of a mother and milk is produced.
Components
Alveoli
• It is lined with milk secreting epithelial cells surrounded by the myoepithelial
cells.
• They join up to form lobules. Each has a lactiferous duct that drains into the
openings in the nipple.
• The myoepithelial cells contract pushing milk from alveoli through lactiferous
duct towards the nipple where it collects in the widening(sinuses) of the duct

43. Types of mammary glands
1. Simple mammary glands
• Consists of milk-secreting tissue leading to a single lactiferous duct.
2. Complex mammary gland
• Consists of all simple mammary gland serving one nipple.
• As human beings, we only have complex mammary gland in each breast.
• The presence of more than two nipples is known as polythelia
• The presence of more than two complex mammary gland is called polymastia

44. 4. Sudoriferous glands
• It is also known as sweat glands.
• They are located in the dermis.
• They secrete sweat through the skin.
• Sweat produced produces 99% of water.
• There are two types of sweat glands;
i. Apocrine glands which are responsible for odor as bacteria breaks down the
secreted organic substances. They are found in the armpits, scalp and genital
regions. They become active during puberty and secrete their substance in to
hair follicles.
ii. Eccrine glands which produces serous fluids that regulates temperature. They
are found on the palms, feet, armpits and forehead. They excrete their
substances directly to the surface of the skin.

45. THANK YOU