1. I. Definition of Integumentary System
II. The derivatives of the integument
a. Hair
b. Nails
c. Glands
III. Functions of Integumentary System
IV. Definition of Vertebrates
V. Integumentary System of the following:
a. Mammals
b .Birds
c. Reptiles
d. Amphibians
e. Bony Fishes
f. Cartilaginous Fishes
g. Jawless
VI. Comparative Anatomy of Skin
2. What is the Integumentary System?
- the word INTEGUMENT comes from a LATIN word that
means “to COVER”
-the integument as an organ, and is an alternative name for skin
- SKIN and its accessories such as-the HAIR, NAILS, and
a VARIETY OF GLANDS, make up the integumentary system
What are the functions of the integumentary system?
1. Serves as a barrier against infection and injury.
2. Helps to regulate body temperature
3. Removes the waste products from the body
4. Provides protection against ultraviolet radiation from the sun.
5. Generates vitamin D
3. Define Vertebrates:
•Animals that have backbones
1. Mammals ( Humans)
Skin
Skin is one of the largest organs of the body, making up 6-8% of the total
body weight. It consists of two distinct layers. The top layer is called
the epidermis and under that is the dermis (see diagram 5.1).
Cross section through the skin
4. The skin is composed of three tissues or layers of cells:
a. Epidermis
b. Dermis
a. Epidermis
- the OUTER most layer of Skin is known as the EPIDERMIS. It is
composed of many sheets of Flattened, Scaly Epithelial Cells. This is a thin outer
layer of skin.
- Its layers are made of mostly DEAD CELLS.
5. There are five distinct sub-layers of the Epidermis:
a. Stratum corneum: the outermost layer, made of
25-30 layers of dead flat keratinocytes. Lamellar
granules provide water repellent action and are
continuously shed & replaced.
b. Stratum lucidum: Only found in the fingertips,
palms of hands, & soles of feet. This layer is made up
of 3-5 layers of flat dead keratinocytes.
c. Stratum granulosum: made up of 3-5 layers of
keratinocytes, site of keratin formation, keratohyalin
gives the granular appearance.
d. Stratum spinosum: appears covered in thornlike
spikes, provide strength & flexibility to the skin.
e. Stratum basale: The deepest layer, made up of a
single layer of cuboidal or columnar cells. Cells
produced here are constantly divide & move up to
apical surface.
6. iThe epidermis smade up of 4 cell types:
•(A) Keratinocytes – Produce keratin protein a fibrous protein that
helps protect the epidermis
•(B) Melanocytes - produces the brown pigment melanin
These are cells located in the bottom layer of the skin's epidermis and in the
middle layer of the eye, the uvea. Through a process called melanogenesis, these cells
produce melanin, a pigment in the skin, eyes, and hair.
7. •(C) Langerhan Cells – participate in immune response
-Formed in bone marrow.
-Move to the skin
Langerhan Cells
•(D) Merkel cells - participates in the sense of touch.
-Connected to nerve cells from dermis
8. 2. Dermis- the innermost thick layer of the skin composed of living cells
-the Dermis lies beneath the Epidermis and contains BLOOD VESSELS, NERVE
ENDINGS, GLANDS, SENSE ORGANS, SMOOTh,MUSCLES, AND HAIR FOLLICLES.
Goose bumps are caused by tiny
muscles in the dermis that pull on hair
follicles, which causes the hairs to
stand up straight.
9. Hypodermis or Subcutaneous
The hypodermis is not part of the skin, and lies below the dermis. Its purpose is to
attach the skin to underlying bone and muscle as well as supplying it with blood
vessels and nerves. It consists of loose connective tissue and elastin. The
main cell types are fibroblasts, macrophages and adipocytes
- (the hypodermis contains 50% of body fat). Fat serves as padding and insulation for
thebody. Another name for the hypodermis is the subcutaneous tissue
10. Nails
•Nails act as protective plates over the fingertips and toes.
•The area under your nail has many nerve endings, which allow you to receive more information about objects
you touch
•As the nail grows, more cells are added at the nail bed. Older cells get pushed away from the nail bed and the
nail grows longer. There are no nerve endings in the nail, which is a good thing, otherwise cutting your nails
would hurt a lot
Nail Structure
The structure we know of as the nail is divided into six specific parts - the root, nail bed, nail plate,
eponychium (cuticle), perionychium, and hyponychium.
•Root The root of the fingernail is also known as the germinal matrix. This portion of the nail is actually
beneath the skin behind the fingernail and extends several millimeters into the finger. The fingernail root
produces most of the volume of the nail and the nail bed. This portion of the nail does not have any
melanocytes, or melanin producing cells.
•Nail Bed It extends from the edge of the germinal matrix, or lunula, to the hyponychium. The nail bed
contains the blood vessels, nerves, and melanocytes, or melanin-producing cells.
11. •Nail Plate The nail plate is the actual fingernail, made of translucent keratin. The pink appearance
of the nail comes from the blood vessels underneath the nail.
•eponychium The cuticle of the fingernail is also called the eponychium. The cuticle is situated
between the skin of the finger and the nail plate fusing these structures together and providing a
waterproof barrier.
•Perionychium The perioncyhium is the skin that overlies the nail plate on its sides. It is also
known as the paronychial edge. The perionychium is the site of hangnails, ingrown nails, and an
infection of the skin called paronychia.
•Hyponychium The hyponychium is the area between the nail plate and the fingertip. It is the
junction between the free edge of the nail and the skin of the fingertip, also providing a waterproof
barrier.
12. HOOFS
•Hoofs are found in sheep, cows, horses etc. otherwise known as ungulate mammals.
These are animals that have lost toes in the process of evolution and walk on the “nails” of
the remaining toes. The hoof is a cylinder of horny material that surrounds and protects the
tip of the toe (see diagram 5.3).
13. Horns And Antlers
•True horns are made of keratin and are found in sheep, goats and cattle. They are never branched and,
once grown, are never shed. They consist of a core of bone arising in the dermis of the skin and are fused
with the skull. The horn itself forms as a hollow cone-shaped sheath around the bone (see diagram 5.4).
•The antlers of male deer have quite a different structure. They are not formed in the epidermis and do not
consist of keratin but are entirely of bone. They are shed each year and are often branched, especially in
older animals. When growing they are covered in skin called velvet that forms the bone. Later the velvet is
shed to leave the bony antler. The velvet is often removed artificially to be sold in Asia as a traditional
medicine (see diagram 5.5).
Diagram 5.5 - A deer antler
14. Hair structure
•Hair consists of the shaft, which grows and rises above the skin surface, and the root, which is located in
the small fossa within the derma thickness and is anchored into a special follicle (hair follicle).
The hair has two part namely:
•HAIR FOLLICLE
•The hair follicle is the point from which the hair grows. It is a tiny cup-shaped pit buried in the
fat of the scalp.
•HAIR SHAFT
•The part of the hair seen above the skin is called the hair shaft. The hair shaft is made up of
dead cells that have turned into keratin and binding material, together with small amounts of
water. This structure explains why we do not feel any pain while our hair is being cut.
15. Humans have three different types of hair:
I.Lanugo, the fine, unpigmented hair that covers nearly the entire body of a fetus, although most has been replaced
with vellus by the time of the baby's birth
II. Vellus hair/Definitive Hair, the short, downy, "peach fuzz" body hair (also unpigmented) that grows in most
places on the human body. While it occurs in both sexes, and makes up much of the hair in children, men have a
much smaller percentage (around 10%) vellus whereas 2/3 of a female's hair is vellus.
III. Terminal hair/ Angora Hari, the fully developed hair, which is generally longer, coarser, thicker, and
darker than vellus hair, and often is found in regions such as the axillary, male beard, and pubic.
16. KINDS OF Glands
a. Sweat Glands or Sudoriferous
•These are large lumen glands associated with hair follicles.
•They develop from the same down growths that give rise to hair follicles.
•The connection is retained and they are coiled tubular glands, sometimes branched.
•The secretory portion is in the dermis or upper hypodermis
•The secretory product is stored in the lumen.
•Myoepithelial cells facilitate the expulsion of
17. There are 2 types of sweat glands:
•Eccrine sweat glands, all over body except lips and part of external genitalia;
•Apocrine sweat glands, only in axilla, areola, nipple of mammary gland, and circumanal region and
the external genitalia. The ceruminous glands of ear and glands of Moll of eyelid are also apocrine.
•Both the eccrine and the apocrine sweat glands are innervated by the sympathetic nervous system.
•Eccrine glands respond differently to heat and nervous state.
•The apocrine glands respond to emotional and sensory stimuli but not heat.
Eccrine Sweat Glands
•These are simple coiled glands that regulate body temperature.
•The secretory segment is deep in the dermis or upper hypodermis.
•Its duct leads to surface.
•In the secretory region there are clear cells that produce the watery
component of sweat and dark cells that produce a proteinaceous secretion.
•There are also myoepithelial cells that are responsible for the expression of sweat from the
gland.
•Duct cells form the walls from the secretory portion to the area near the surface where the
epidermal cells form the wall.
•The duct is stratified cuboidal.
•There is both thermoregulatory sweating and emotional sweating.
•Resorption of some minerals take place in the duct.
•Myoepithelial cells are present in the duct.
18. Apocrine Sweat Glands
•the secretory product from the gland.
•The duct has a narrow lumen.
•Apocrine
secretions contain protein, carbohydrate, ammonia and lipid.
19. b. Sebaceous Glands or Oil Glands
•Found in the skin of mammals and these glands secrete sebum.
•
•sebum (Latin, meaning fat or tallow) that is made of fat (lipids) and the debris of dead fat-
producing cells.
•These glands exist in humans throughout the skin except in the palms of the hands and
soles of the feet.
•Sebum acts to protect and waterproof hair and skin, and keep them from becoming dry,
brittle, and cracked. It can also inhibit the growth of microorganisms on skin .
20. c. Ceruminous glands18
•are involved in skin problems such as acne and keratosis pilaris. A blocked sebaceous gland can result in a sebaceous
cyst.
•Earwax, also known by the medical term cerumen, is a yellowish, waxy substance
secreted in the ear canal of humans and many other mammals. It plays a vital role in the
human ear canal, assisting in cleaning and lubrication, and also provides some protection
from bacteria, fungus, and insects
21. D. Mammary glands
•are the organs that, in the female mammal, produce milk for the sustenance of the young.
These exocrine glands are enlarged and modified sweat glands and are the characteristic
of mammals which gave the class its name.
•The human mammary glands are modified sweat glands and are developed from two sources --the parenchyma (alveoli
and ductules ) from the surface ectoderm ,the fibrofatty stroma from the underlying endoderm.
•At birth mammary glands of both sexes remain in infantile form .This condition persists throughout life in normal male.
•First change is seen at puberty in females ,in the form of deposition of fat and increase in size and attain hemispherical
outlines. With the start of reproductive cycle after puberty ,glandular tissue show changes with the alteration in
concentration of oestrogen and progesterone in each cycle.
•Ultimately during pregnancy final maturation of the glands takes place and they are ready for milk secretion under the
influence of oestrogen ,progesterone ,prolactin and probably hCG..
•Some milk is secreted into the ducts as early as 5 months but the amount is less compared to large amount secreted at
child birth.Milk is secreted within an hour of child birth and first formed milk is called colostrum which is yellowish in colour
and rich in protein and antibodies and provide immunity to the baby.Normal milk production starts 2-3 days after child
birth.
22. 2. BIRDS
•integumentary system consists of the skin, the feathers and the appendages (claws and beak)
•the integumentary system is very important in providing protection to the bird from a number of
potentially dangerous situations.
The
AFRICAN JACANA
23. The fowl‟s skin is divided into a number of separate areas where the skin has been modified to some extent
to be able to carry out special functions. These areas are:
•The feathered skin.
•The scale covered skin on the lower legs and feet.
•The hard, horny areas of the beak and toenails.
•The pad of the foot (or plantar).
•The skin of the comb and wattles.
The feathered skin is also divided into a number of special areas or tracts – those where feathers actually do
grow and other areas where they do not grow but which appear as such because they are covered by
feathers. The areas where they do grow are called pterylae and the areas where they do not grow are
called apteria.
24. Cross-section of bird skin
Structure
The skin is composed, in the main, of two different tissues:
•Connective tissue of the dermis and hypodermis where the cells are
widely spaced.
•Cellular stratified epithelium of the epidermis, which make up the
horny outer layer of the skin and forms the feathers.
a. The hypodermis connect with air sacs of the respiratory system thus enhancing the ability to fly. different skin types
contain different amounts and distribution of special compounds mainly collagen,elastin and keratin.
•Epidermis
The epidermis consists of three separate layers:
A.The flattened, horny cell layer – the outermost layer.
B.The transitional layer – joins the outer layer to the inner layer. It is here that the cells formed in
the third innermost layer are transformed into the hard, horny type found in the outermost layer.
C.The columnar cell layer – this is the innermost layer of the epidermis and is the germinative layer
where the cells of the epidermis are formed.
b. Dermis
•The dermis is relatively thin and shows a uniform, microscopic structure. This is different to many other animals that have
both densely packed and loose layers of cells. The main component of the dermis is collagen with a small amount of
elastin.
•Hypodermis
•The hypodermis contains fewer cells and is more loosely arranged than the dermis. Fat is stored here in special adipose
cells (adipose tissue is fat tissue). Air spaces found in the
25. FEATHERS
•The lightness and stiffness of keratin is also a key to bird flight. In the form of feathers it
provides the large airfoils necessary for flapping and gliding flight. In another form, the
light fluffy down feathers,also made of keratin, are some of the best natural insulators
known. This superior insulation is necessary to help maintain the high body temperatures
of birds.
•Five types of feathers:
a. Contour Feather
b. Down Feather
c.Pin or Filoplumes Feather
d.Plumules
e.Bristles
26. a. Contour Feather
Diagram 5.7 - A Contour Feathera
•Countour feathers are large feathers that cover the body, wings and tail. They have an expanded vane that
provides the smooth, continuous surface that is required for effective flight.
27. b. Down Feather
Diagram 5.8 - A Down Feather
•Down feathers are the only feathers covering a chick and form the main insulation layer under the
contour feathers of the adult. They have no shaft but consist of a spray of simple, slender branches (see
diagram 5.8).
28. c.Pin or Filoplumes Feather
Diagram 5.9 - A Pin Feather
•Pin feathers have a slender hair-like shaft often with a tiny tuft of barbs on the end. They are found between
the other feathers and help tell a bird how its feathers are lying (see diagram 5.9).
29. d.Plumules
•Plumules are found beneath the contour feathers where they form a soft, downy undercoat. They have a
short shaft with radiating, free barbs and barbules. They have no interlocking hooklets or barbicels. These
feathers provide the depth to the coat and play a large part in trapping the air and holding it still – thus
improving their ability to conserve warmth.
e.Bristles
•Bristles are found around the mouth and eyes of chickens and are thought to be primarily used to aid the
sensory ability of birds and protect sensitive areas. A comparison between bird bristles and mammalian
eylashes could be used here.
30. 3. Reptile
KING COBRA
ALLIGATOR
•Their skin reflects their greater commitment to a terrestrial existence
31. •Their skin reflects their greater commitment to a terrestrial existence
Section of the skin of a reptile showing the overlapping epidermal scales. Epidermis of Reptiles
•Reptile skin has two principal layers: the dermis, which is the deeper layer of connective
tissue with a rich supply of blood vessels and nerves, and the epidermis which in reptiles
consists of up to seven sub-layers or "strata" of closely packed cells, forming the body's outer
protective coating.
•dermis is provided with chromatophores, color bearing cells that give many lizards and
snakes their colorful hues
•the characteristic scales of reptiles are formed largely of keratinA
32. The seven epidermal layers are:
1. The stratum germinativum, the deepest layer of living cells which have the capacity for rapid cell
division;
and the six layers which form each "epidermal generation" - the old and new skin layers - which are:
2 - 3. The clear layer and lacunar layer, which mature in the old skin layer as the new skin is growing
beneath.
4 - 6. The alpha layer, the mesos layer and the beta layer; these layers consist of cells which are
becoming keratinised, with production of two types of keratin (alpha and beta keratin). These cells are
thus being transformed into a hard protective layer.
7. The Oberhautchen layer, which forms the toughest outermost layer of keratinised, dead skin cells.
33. 4. Amphibian
•amphibians are transitional between aquatic and terrestrial vertebrates
GREEN FROG
Epidermis with thin stratum corneum and very little
keratin; Leydig cells
Dermis with chromatophores, poison glands and mucous
glands
Scales are rare
34. KINDS OF FISH
1.bony
2.Cartilaginous
3.Jawless
•Bony Fish
•The skin of bony fishes contains scales
Integument of a bony fish showing epidermis, dermis, embedded scale and related
structures.
36. 3. Cartilaginous
•The skin is covered with horny teeth-like scales and on the jaws these are modified to form teeth.
COOKIE-CUTTER SHARK
•Placoid scales or dermal denticles
•Outer enamel; inner dentin
•Epidermis does not cover scales
37. JAWLESS FISH
•the simplest of all fish, and the simplest of all vertebrates, are the jawless fish, which include the
lampreys and hagfish. These creatures have no jaws. The mouth is surrounded by a large, round
sucker.
HAGFISH
38. COMPARATIVE ANATOMY OF THE SKIN
CHORDATE EPIDERMIS EPIDERMIS
multi-layered and is rich thinner than epidermis but
1. AGNATHANS/ JAWLESS w/mucous glands tough due to interwoven
„slime eels lack scales collagenous fibers.
„Layers are mitotic including „rich in the melanophores w/c
surface cells horny denticles in ad heres tightly to the
the buccal funnel is the only underlying musculator
cormfied structure,shed replaced myosepta
more layered and cells are thicker than epidermis and
2.CHONDRICH- compactly arranged w/2 more or less defined
THYES/CARTILAGINOUS „unicellular glands excepting layers
chaemiras „placoid scales fr.the
„stingrays-goblet toxins. paleozioc shakers
„multicellular cells at the base „sheet of melanophores
secretes toxins derse dorsally than virtrally
Multicelullar cells are conc. at less illumnuscence
the base of the claspers of „with ceratotrichia or fin rays
males
39. 3. OSTEICH-THYES / BONY FISH -more mucous glands -presence of ancient ganoid
-presence of cycloid scales or modern cycloid scale
-with uicellular goblet cells w/c -flexible dermal fin rays which
maintain mucous coat of the skin stregthens the fins of bony
to prevent dessication fishes
-with poisonous granular gland -with osteoderms
-photophores serve as lures
/warning
‘skin-w/o scales ‘with dermal chomatophores
4.AMPHIBIA ‘with incipient stratum corneum ‘firmly attached to the
‘uncellular goblet cells secretes underlying musuculature
mucigens for semi-aquatic ‘voluminous bread
amphibians subcutaneous lymph sinuses
‘mucons glands-mucin separates skin from muscles
‘poison glands-alkaloidal ‘bony dermal scales in
secreation caecilians
‘cornified skin prevents
dessication.
‘thick stratum corneum ‘bony dermal,bones are more
5.REPTILES ‘with epidermal scales molts at abundant
regular internal ‘osteoderms
‘presence of unique horny 1.lizards-underlying the
surface features epidermal scales
‘integumentary glands are not 2.snakes-absent
abundant
‘scales,scutes,rattles,clansz,plaq
ue,spiny crests
40. ‘thin-skinned ‘dermis supports the
6.AVES ‘epidermal scales umited to feet feathers and arrectures
and base of breaks pilorum/ plumarun
‘presence of sharp clans ‘exceptionally thin
‘integumentary glands are ‘motility of skin is correlated
absent to thermoregulatory function
‘uropygial gland caudal, oil the of feathers
feathers ‘no osteoderms
‘with feathers ‘with spurs both sexes
.down .tarsometatasus
.filoplumes .carpometasus in some
.rectrices
.remiges
7.MAMMALS ‘hairs are present arising from presence of hair
hair follicles follicle,arrector
‘epidermal glands muscles,sweat,
.sebaceous-sebum sebaceous glands,conn.
.sudoriferous-sweat tissues
.mammary-milk ‘highly vascularized
‘stratum germinativum is ‘with nerve endings
germinating ‘has thermoregulatory
‘dense stratum corneum function-homiothermic
‘derivatives ‘hypodermis or
.claws subcutaneous layer
.horns separates skin from muscles
.hairs ‘with pigment cells
.nails
.baleen whale bone
hangs or oral cavity
