Integumentary System Overview

What is the primary function of the integument?

Which layer of the epidermis is responsible for continuous cell division?

What is the main component found in the dermis?

Which form of keratin is invariably hard and associated with scales?

What type of connective tissue is predominantly found in the hypodermis?

What pigment cell is responsible for brown to black coloration?

Which layer of the skin increases in thickness due to mechanical stress?

What is a primary source of pigment cells in vertebrates?

Which layer of the epidermis is made up of cuboidal and columnar cells?

Why does stratum corneum thickness vary among individuals?

Integumentary System and Derivatives

Integument is the outer protective covering of the body, comprised of skin and its appendages.
Evolution of vertebrate integument is linked to the transition from aquatic to terrestrial habitats.
Two primary layers of vertebrate skin:
- Epidermis: Outer layer, derived from ectoderm, composed of stratified epithelium.
- Dermis: Inner layer, derived from mesoderm, composed of connective tissue, blood vessels, nerves, and pigment cells.
Epidermis is divided into two regions:
- Stratum Corneum: Outermost region, contains keratin in two forms:
  - α-keratin: Hard, found in scales of birds and crocodiles.
  - β-keratin: Can be soft or hard, found in mammalian skin and claws.
- Stratum Germinativum (Malphigian Layer): Innermost layer, composed of cuboidal and columnar cells that undergo mitosis.
Dermis contains collagenous connective tissue, blood vessels, nerves, pigment cells, smooth muscles, and sometimes skeletal muscles and dermal bones.
Hypodermis is a layer of loose connective tissue beneath the dermis, often containing fat.
Thickness of skin layers varies depending on species, individuals, and body region.
Pigment cells (chromatophores) originate from the neural crest and migrate into the epidermis or dermis.
- Melanin is produced in two forms:
  - Eumelanin: Produces brown to black coloration.
  - Phaeomelanin: Produces yellow-brown coloration.

Explore the integumentary system and its derivatives in this quiz. Delve into the layers of vertebrate skin, understanding the distinctions between the epidermis and dermis, and their evolutionary significance. Test your knowledge of skin anatomy and function.