The Integument

Question 1

What is the general structure of skin?

Answer 1

Two main layers: epidermis and dermis

Question 2

What is the epidermis divided into?

Answer 2

Stratum corneum (outermost) - thickness varies greatly, usually dead keratanized cells

Stratum germinatuvum - mitotically active

Question 3

What is the dermis divided into?

Answer 3

Stratum laxum 
Stratum compactum (innermost)

Question 4

What is keratin?

Answer 4

A family of fibrous structural proteins, mostly in tetrapods
Fish have keratin and other similar proteins but not in high numbers
It is important in the structure of hair, feathers, and scales

Question 5

What are the functions of the skin?

Answer 5

Physical protection, water balance, thermoregulation, locomotion, gas exchange, coloration, secretion, sensory structure

Question 6

How is the skin important for thermoregulation?

Answer 6

Sweat glands
Arrector pilli muscles - attach to hair and feathers
When it contracts, it raises the hair, doesn’t do anything for us. Important for mammals because it allows hot air to be trapped so it acts like an insulating layer.
Seals and sea otters have hair but no pill, makes them slow down in water with pilli

Question 7

How is the skin specialized for sensory structures?

Answer 7

COME BACK TO THIS

Question 8

How does skin coloration work?

Answer 8

Chromatophores, which are pigment-producing cells that deposit pigment into other cells. Big cells with projections.
In birds and mammals, at the base of the epidermis
In other vertebrates, in dermis

Question 9

What are the different types of chromatophores?

Answer 9

Melanophores - brown/black
Iridiophores - shiny (guanine crystals - byproduct of nucleic acid)
Xanthophores - yellow (modified nucleotide)
Erythrophores - red/orange - derivative of B-kerotene

Question 10

What can affect colour? Give an example.

Answer 10

Diet in flamingoes

The more B-kerotene they eat, the more pink they look

Question 11

What is another way of colorization?

Answer 11

Structural coloration (other = pigment)

Question 12

How does structural coloration work?

Answer 12

Cells and proteins are arranged in certain ways that refract light to produce colours
This type of coloration might have been around at the time of the dinosaurs

Question 13

Give an example of a mammal with structural coloration?

Answer 13

Mandrill - collagen arranged in certain way

Question 14

How are mammals typically coloured?

Answer 14

Mostly only have melanophores which can produce a few different colors

Question 15

How does mammalian coloration work?

Answer 15

MSH can stimulated melanophores to produce eumelanin pigment (brown). The pigment is produced in melanosomes (vesicles).

If the MSH receptor is inactivated, it triggers the production of pheomelanin (yellow).

Question 16

What can mutations in MSH receptor lead to?

Answer 16

Kermode (spirit) bear - species of black bear that have mutations in the receptor
This is not the same as albino because albino don’t have the pigment, kermode have mutation in receptor

Question 17

What is a cell that produces melanin?

Answer 17

Melanophore/melanocyte

Question 18

What is melanin?

Answer 18

A pigment molecules that absorbs and reflects light

Question 19

What is MSH?

Answer 19

Melanocyte stimulating hormone affects receptors

Question 20

What is an MSH receptor?

Answer 20

Melanocortin receptor that the hormone affects

Question 21

What is melatonin?

Answer 21

Produced by the pineal gland and affects sleep. In some vertebrates affects pigmentation (eg. frogs). It doesn’t alter our pigment

Question 22

What are the roles of skin coloration?

Answer 22

Cryptic, aposematic, communication (sex), thermoregulation, UV protection

Question 23

What is the physiological mechanism of colour change?

Answer 23

Similar in most animals that can do this
Hormonal/Nervous system control (1 or other)
Vesicles move via the cytoskeleton
When vesicles are spread out, cell appears dark
When they aggregate in the middle, they appear light

Question 24

What are the different glands in fish and why?

Answer 24

Mucus - friction
Granular - toxins
Photophores - chemoilluminescence

Question 25

What were the advantages and disadvantages of armored fish?

Answer 25

Enamel (hardest) + Dentine
Adv: Protected from inverts
Dis: heavy, low flex, lay on bottom

Question 26

What are the different types of fish scales?

Answer 26

Cosmoid (type of dentine, cosmine.)
Ganoid 
Cycloid (soft ray fin = salmon, trout)
Ctenoid (hard ray fin = perch, bichirs)
Placoid - no overlap

Question 27

What types of glands on amphibians?

Answer 27

Mucus - moist gas exchange, prevent desiccation

Granular = toxins

Question 28

What is special about reptile skin?

Answer 28

Thick stratum corneum
Arranged in scales and plates, not like fish but overlap = flex, because only skin no bone, fission zone
Also have claws

Question 29

What is the bird integument like?

Answer 29

Feet similar to reptile skin
Feathers = dead
Beak is keratanized
Flamingo beak specialized to filter feed
Uropygial gland

Question 30

What are the different types of feathers?

Answer 30

Contour, flight (primary, secondaries, coverts), down, bristle

Question 31

What are the different types of hairs in mammals?

Answer 31

Guard, under, quills, vibrissae

Question 32

What makes up fur?

Answer 32

Under hair and guard hair

Question 33

What are the different glands in mammals?

Answer 33

Sebaceous, sweat (eccrine + apocrine (pheromones)), mammary