BIO1411L Chapter 5: The Integumentary System

What is the integumentary system composed of?

The integumentary system is composed of skin, hair, skin glands, and nails.
-protects the body and senses the surrounding environment

What is the skin?

The skin is the largest organ in the body.

The two principal parts of the skin include:
1.) Epidermis: outer layer that is thin, superficial
2.)

What are the fours types of cells of the epiderdermis?

1.) Keratinocytes: most numer

2.) Melanocytes

3.) Langerhans cells

4.) Merkel cells

1.) Stratum corneum: outer layer of dead keratinocytes that eventually shed off

2.) Stratum lucidum: clear, flat dead cells that can only be found in the fingertips, palms, and soles

3.) Stratum granulosum:

4.) Stratum spinosum

5.) Stratum basale: contains keratinocytes/melanocytes.
highly active dividing layer

What is the growth of epidermis

Stratum basale cells promote cell division to produce new keratinocytes.
(b/c they are closest to dermal blood vessels for oxygen and nutrients)
-newly formed cells pushed up to next strata

What is the dermis?

The dermis is a dense irregular connective tissue with collagen and elastic fibers
-its cells have tensile strength, extensibility, elasticity

The two principle regions of the dermis includes:
1.) Papillary: increased surface area with dermal papillae projecting upward to create epidermal ridges (this produces our fingerprints and footprints)
2.) Reticular: attaches the dermis to the hypodermis

What are the three types of skin color pigments?

1.) Melanin: number of melanocytes are the same among everyone, the difference is in the amount of melanin protein synthesized

2.) Carotene: represents vitamin E levels, and gives our skin a yellow-orange pigment

3.) Hemoglobin:

What is hair?

Hair is made of dead, keratinized epidermal cells held together by extracellular proteins.
-it is present on most skin surfaces (except lips, palms, soles, and parts of genitalia)

-its features are determined by hormones and genetics

Shaft: external projections from the skin surface
Root: connected to the dermis
-external root sheath
-internal root shealth

Concentric layers:
-medulla
-cortex: elongated cells, which is the major part of hair
-cuticle:

What are the regions of the hair?

1.)

2.) Root

What are the functions of the skin?

1.) Regulation of body temperature: allows body to cool through evaporation of sweat, and regulates blood flow

2.) Blood reservoir:

3.) Protection: provides physical barrier, and protects against UV rays

4.) Cutaneous sensations

5.) Excretion and absorption