Lecture 6 - The Integuement Part 1

Question 1

List the first 4 major functions of vertebrate integuement

Answer 1

1. Protection: against mechanical injury, or invasion by foreign objects
2. Coloration: Camouflage, warning signal, sexual representation
3. Sensory: Touch, Temperature, Pain, Pleasure, Pressure, or electromagnetic detection
4. May be used to excrete excess fish, or nitrogenous waste products.

Question 2

List the middle 3 functions of integuement

Answer 2

5. Gas Exchange: Many vertebrates (like frogs) can use their skin to breathe out of. Amphioxus did this almost exclusively.
6. Water Regulation: Prevents excess water loss
7. Temperature regulation: A big must in marine mammals, and terrestrials. This can include feathers, hair, sweating, etc..

Question 3

List the final 3 functions of vertebrate integuement

Answer 3

8. Food Storage: The connective tissue below the dermis is usually where fat is stored.
9. Nourishment: Mammary glands are meant to provide nutrition to infants.
10. Locomotion: Webbing, wings, scales, etc…

Question 4

Describe the protochordate integuement compared to the vertebrate integuement

Answer 4

Protochordates (Amphioxus) - Had simple epithelium over simple connective with no glands, no dermis, no epidermis, and maybe at best had cilia, and in the case of some tunicates, some cellulose structures. They kept shit simple.

Question 5

Describe the histological structure of the vertebrate integuement. What is the most constant feature of the epidermis?

Answer 5

The basic structure is stratified squamous (Epidermis) over the basement membrane over the Dense Irregular connective tissue (Dermis)
- Epidermis: I don’t really know what the constant feature is, but it’s all stratified.

Question 6

Where are all glands derived from?

What two categories are glands classified by?

Answer 6

• All glands are at least partially epithelial. In fact most of them are probably All epithelial.
• Exocrine glands are designed for local stuff and have an excretory duct that empties contents directly into a body cavity or tissue.
• Endocrine ducts don’t have this excretory duct so they empty their shit directly into the blood stream where it presumably goes all over the place.

Question 7

List classification of glands according to:

1. Cell #
2. Shape
3. Secretion Type
4. Mode of Secretion

Answer 7

1. Unicellular (Such as goblet cells), or Multicellular
2. Tubular, Alveolar/Acinar, or Mixed (tubuloalveolar)
3. Mucous, or Serous
4. Morocrine (eccrine), Apocrine, Holocrine

Question 8

What types of glands are used in the epidermis of fish

Answer 8

Agnathans had unicellular mucous glands.

Chondrichthyes and osteichthyes: secreted unicellular and multicellular mucous

Question 9

Describe Enamel

Answer 9

90% made up of bone salts, which occur in long prisms secreted on underside of stratum germinativum. They are secreted by ameloblasts and are ectodermal. Usually exposed to surface after enamel-secreting layers die.

• Amelogenins are enamel proteins
• No collagen in true enamel; amelogenins + collagen = enameloid - Ganoin= enamel arranged in layers

Question 10

Describe Dentine

Answer 10

• Only 70% bone salts, and are secreted by mesodermal odontoblasts. They are organized in a matrix with odontoblasts to form Dentinal Tubules, such as Parallel Branching Canals, and Radiating Canals = Cosmine.
• Osteodentine is similar to bone. There is also a superficial layer of dentine called Pallial Dentine. There’s also circumpulpar dentine. Not sure what that does.

Question 11

List the 6 types of fish scales

Answer 11

• Placoderm scale
• Cosmoidscale
• Placoid scale
• Palaeoniscoid scale
• Lepidosteoid (ganoid) scale
• Cycloid and ctenoid

Question 12

Describe the placoderm scale

Answer 12

An ancient, armor-like scale not found in modern fish. This was most common in ostracoderms and placoderms.

It’s layers went from enamel to dentine to spongy bone to compact bone.

Question 13

Describe the cosmoid scale.

Answer 13

Another one not found in any modern fish, it was found in some crossopterygians and extinct dipnoans.

The layers were similar to a placoderm scale except cosmine instead of dentine. So enamel, cosmine, spongy bone, compact bone.

Question 14

Describe the placoid scale

Answer 14

Found in most sharks, less in rays, and Not in ratfishes.
This is a little more simple.
Mostly dentine, covered by enameloid, and a pulp cavity underneath.

Question 15

Describe the palaeoniscoid scale

Answer 15

Found only in chondrosteans. (Can’t off the top of my head remember what those are)

Layers were ganoin over cosmine over compact bone.

Question 16

Describe the lepidosteoid (Ganoid) Scale

Answer 16

Was Found in extinct acanthodians. Now found in sturgeons and Gar Pikes.

Very simple layers: Ganoin over compact bone.

Question 17

Describe Cycloid and Ctenoid Scales

Answer 17

Cycloid scales are Found in Bowfins (Amia), Modern dipnoans, and Primitive teleosts (codfish). Ctenoid scales are found in more advanced codfish.

Composed of a thin layer of compact bone on top of a thin layer of fibrous connective tissue.

Question 18

Why don’t we get cool armor?

Answer 18

Fish, especially older fish, got all this cool badass complex dermal armor for protection. But God decided armor isn’t as useful for terrestrials. (Tell that to the goddamn stegosaurus)

• Amphibians were the first group to start to lose their armor. Skin became smoother and softer.
• But that type of skin isn’t as useful for water retention, so we developed keratinized skin.

Question 19

What is the outermost layer of the epidermis called?

What is keratin?

Answer 19

• The stratum corneum. First appeared in amphibians. Implies keratinized skin.
• Keratin is a protein derivative of eleidin (don’t know, don’t care). Specialized cells in the stratum basale called keratinocytes form in the basale’s cytoplasm.
• The keratinocytes (this is actually pretty brutal) are pushed up by the basale until their oxygen supply is cut off. The now-dead cell loses it’s cytoplasm and gets keratin formed in it’s place. That’s fucking Hardcore!

Question 20

So what’s the point of stratified keratinized cells?

Answer 20

The keratinized cells make for really good “dead cell body” shields. The shields prevented water loss. In fact there’s a direct link between keratinization and preventing water permeation.