This document provides information on the integumentary system of several chordates including humans, fish, birds, cattle/horses, and ruminants. It describes the basic structure of skin which consists of an epidermis, dermis, and hypodermis layers across these species. Key differences are highlighted such as fish having scales instead of hair and birds having feathers. The structure and function of hair, nails, hooves and horns are also reviewed for different animals.

1. Comparative anatomy
( Chordates)
Integumentary system
1-Human
2-Ruminant
3-Avian
4-Fish
5-Horse
Dr.Omer

2. Comparative anatomy
(Chordates)

3. Human integumentary system
The Integument
 Is the largest system of the body
 The integument is made up of two parts:
1. Cutaneous membrane
a. Epidermis– Superficial epithelium
b. Dermis – underlying CT with blood supply
2. Accessory structures
a. Hair
b. Nails
c. Exocrine Glands

4. 5-4
Functions of Skin
1-Protection
2-Prevention of water loss
3-Temperature regulation
4-Metabolic regulation
5-Immune defense
6-Sensory reception
7-Excretion

5. STRUCTURE OF SKIN
The layers of the skin:-
The Epidermis
Epithelial tissue
Dermis
Dense connective tissue proper – irregular
Hypodermis
Subcutaneous tissue- loose connective tissue proper
and adipose tissue

6. STRUCTURE OF SKIN
Epidermis
Dermis
Hypodermis
or
subcutaneous layer

7. Skin Structure: Epidermis
The Epidermis
Is a vascular stratified squamous epithelium
Nutrients and oxygen diffuse from capillaries in the dermis
 There are four or five layers of the epidermis, depending upon the
degree of friction and mechanical pressure applied to the skin

8. Four Principle Cells of the Epidermis
• Keratinocytes
Produce the protein keratin, which helps protect the skin and
underlying tissue from heat, microbes, and chemicals, and
lamellar granules, which release a waterproof sealant
• Melanocytes
Produce the pigment melanin which contributes to skin color
and absorbs damaging ultraviolet (UV) light
• Langerhans cells
– Derived from bone marrow
– Participate in immune response
• Merkel cells
– contact a sensory structure called a tactile (Merkel) disc and
function in the sensation of touch
8

10. Skin Structure: Epidermis
Thin Skin
Covers most of the body
Has four layers of keratinocytes
Thick Skin
Covers the palms of the hands and soles of the feet
Has five layers of keratinocytes

11. Skin Structure: Epidermis
Structures of the Epidermis
 The five strata of keratinocytes in thick skin
 From basal lamina to free surface
1. Stratum basale
2. Stratum spinosum
3. Stratum granulosum
4. Stratum lucidum
5. Stratum corneum

12. Epidermal Layers
Stratum corneum - nuclei and organelles are destroyed by lysosomes
and the cells fill with keratin
Stratum lucidum - only found in the palms and soles of feet 3-5
layers of clear, flat, dead keratinocytes -Dense packed intermediate
filaments thick plasma membranes
Stratum granulosum - cells start to become keritanized --Secretes
lipid-rich secretion that acts as a water sealant
Stratum spinosum - 8-10 layers of keratinocytes skin both strength
and flexibility
Stratum basale - Also referred to as stratum germinatum -where new
cells are formed -

13. Thick skin LM  210
Surface
Stratum
corneum
Stratum
lucidum
Stratum
granulosum
Stratum
spinosum
Stratum basale
Basement
membrane
DermisPapillary layer of dermis
E
P
I
D
E
R
M
I
S

14. Sources of Skin Color
• Most significant factor is melanin
• Black or brown color due to eumelanin produced by melanocytes
and transferred to keratinocytes in follicle.
• Red color produced by pigment called pheomelanin
• Blonde color produced by intermediate levels of pheomelanin
and low levels of eumelanin
• Other factors include hemoglobin (red to pink) and
carotene (yellow)
• Different races have the same of melanocytes, but
amount of melanin produced differs
• Melanin accumulates in keratinocytes
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

15. Skin Structure: Dermis
The Dermis
 Located between epidermis and
subcutaneous layer
 Anchors epidermal accessory
structures (hair follicles, sweat
glands)
 Two components
1. Outer papillary layer
2. Deep reticular layer
Dermis

16. Skin Structure: Dermis
 The Papillary Layer
Consists of areolar tissue
Contains smaller capillaries, lymphatics, and sensory neurons
Has dermal papillae projecting between epidermal ridges
 The Reticular Layer
Consists of dense irregular connective tissue
Contains larger blood vessels, lymphatic vessels, and nerve
fibers
Contains collagen and elastic fibers
Contains connective tissue proper

17. Hair
Papillary
layer
Reticular
layer
Cutaneous
plexus
Papillary
plexus
Epidermal
ridges
Dermal
papillae
Capillary loop
of papillary
plexus
D
E
R
M
I
S

18. Skin Structure: Hypodermis
The Hypodermis (Subcutaneous Layer)
Lies below the integument
Stabilizes the skin
Allows separate movement
Made of elastic areolar and adipose tissues
Connected to the reticular layer of integument by
connective tissue fibers

19. Skin Structure: Hypodermis
Hypodermis

22. Functions – Hair & Nails
• Functions of Hair
– Hair on the head protects scalp from injury and sunlight
– Eyelashes and eyebrows protect eyes
– Nostril and ear hairs protect from foreign particles
– Help in sensing light touch due to the touch receptors associated with the
hair root plexuses.
• Functions of the Nails
– Grasping objects
– Manipulating objects
– Protects ends of digits from trauma
– Scratching

23. Hair Anatomy
Shaft: portion of hair that projects from skin surface
Root: portion of hair deep to the shaft penetrating the dermis
•Has 3 layers:
medulla : Core, dead cells contain soft keratin and air to provide flexible
Cortex: Middle layer, dead cells contain hard keratin to provide stiffness
Cuticle : Outermost, overlapping dead keratinized cells form shiny surface
Base of the hair follicle
•Bulb: houses the papilla which contains the blood vessels that nourishes the
growing hair follicle.
•Matrix: responsible for hair growth and produces new hair
Arrector pili: smooth muscle
•Extends from the dermis to the side of hair follicle.
Hair root plexus - dendrites of neurons which are sensitive to touch

24. Anatomy of the hair

25. Nails
• Made of tightly packed, hard, keratinized epidermal cells
• Consist of:
Nail body: portion of the nail that is visible- Free edge: part
that exten
Nail root: the distal end of the digit portion buried in a
fold of skin
Lunula: means little moon - Crescent shaped area of the
nail
Hyponychium: secures the nail to the fingertip -Thickened
stratum corneum
Eponychium or cuticle: narrow band of epidermis-Growth
of nails is in the nail matrix.

27. Aging Skin
•In our 20s, the effects of aging begin to be visible in the
skin.
•Stem cell activity declines: skin thin, repair difficult
•Epidermal dendritic cells decrease: reduced immune
response
•Vitamin D3 production declines: calcium absorption
declines and brittle bones
•Glandular activity declines: skin dries, body can overheat
•Blood supply to dermis declines: tend to feel cold
•Hair follicles die or produce thinner hair
•Dermis thins and becomes less elastic – wrinkles

28. Fish integumentary system
Fish like other vertebrates have Three layers of skin
1-Outer epidermis
2- Inner dermis.
3-Hypodermis
• Multicellular glands also occur in some fishes, e.g. electric
organs of eels and electric rays,
• luminescent glands in deep sea fishes.
•Mucous glands are all unicellular.
• Important modifications of skin are dermal scales that
cover the body for protection.

32. Epidermis
• Generally the epiderm of vertebrates consists of
five layers
• stratum corneum In fish keratin is replaced with
mucous ( glycoprotein = mucin)

33. Dermis
• Thicker than epidermis
• Contains blood vessels, nerves, sense organs, connective
tissue and pigment cells
Dermis consists of two layers
1- Upper looser layer - Stratum spongioso in this layer Scales
are imbeded with their bases
2- Lower tighter layer ‐ Stratum compactum contains lipid cells
and connective tissue
• Fish dermis connects directly onto myosepta of the muscles
and to the caudal fin.

34. Colors of the skin
• Melanophores – Black
• Erythrophores – Red
• Xanthaphores – Yellow
• Cyanophores – blue
• Leucophores – light scattering
• Iridiophores – light reflecting ‐ silver

35. Avian intgumentary system
• Birds possess thin skin that is loosely attached to body to
allow free movement of wings during flight.
• Feathers are characteristic modifications of bird skin,
which not only cover the entire body but also help in
flight.
The skin is composed of three layers :
1-The Epidermis
2-The dermis or corium
3-The hypodermis
.

36. The fowl’s skin is divided into a number of separate areas
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 areas where they do grow are called pterylae
• The areas where they do not grow are called apteria.

38. Glands
• Birds do not possess sweat glands.
• The uropygial gland secretes an oil (preen oil) bird will
typically transfer preen oil to its body during preening
by rubbing its beak
• Feathers are an extremely efficient insulator.
• Heat is lost from the respiratory tract and by radiation
from featherless surfaces.
• The feet and legs of starlings loose a substantial
amount of the body’s heat.
• Heat loss at night is also a probable reason for sleeping
with their head (really their beak) under their wing,
and one leg raised.

39. cattle and Horse
• The skin of animals consists of three layers,
• The epidermis
• The dermis.
• Hypodermis
• Epidermis of thick keratinized stratified squamous
epithelium
• Special keratinized features include hair, nails, claws,
horns, hooves.
• Numerous multicellular glands
• Chromophores present

40. Hoofs and Horns
• True horns are made of keratin and are found in
sheep, goats and cattle.
• They consist of a core of bone arising in the
dermis of the skin and are fused with the skull.
• Hoofs are found in sheep, cows, horses .
• 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

41. 1. Heel bulb
2. Periople at
the heel
3. Heel
4. Quarter
5. Toe
6. Periople
7. Coronary
band