Chapter 5 HSCI

Integumentary system

• Provides protection (barrier to: ______)

  • mechanical stresses (cuts/abrasions)

• Maintain homeostasis: ______

• allows sensation and responsiveness and expression

Epidermis

• Epithelial tissue

  • Keratinized stratified squamous epithelium

• Avascular

• most superficial layer of skin

Dermis

• Papillary layer: superficial

  • Areolar CT

• Reticular layer: deeper

  • Dense irregular CT (consist of collagen/elastic fibers)

• below epidermis

Hypodermis

• Subcutaneous layer

• Not apart of skin

• Adipose and areolar CT

• big blood supply

• function: 

  • anchor skin to deeper structures

  • shock absorber

  • reduces heat loss

Keratinocytes

Major cell of epidermis

Produces keratin

Melanocytes

• Produce melanin

• Located in stratum basale and stratum spinosum

langerhans/dendritic cells

• Patrol the stratum spinosum

  • Looking for microbes that shouldn’t be in there

  • Activates immune system

Merkel/tractile cells

• located in stratum basale epidermis

• detects sensation (sensory receptors)

  • touch

Stratum Basale

• Deepest epidermal layer

• Attached to dermis

• Consist of:

  • Keratinocyte stem cells

  • Melanocytes

  • Tactile (merkel) cells

Stratum Spinosum

• Daughter cells from stratum basale

• Consist of:

  • Spikey keratinocytes

  • Melanocytes

  • Dendritic cell

Stratum granulosum

• Layers of ONLY thin keratinocytes

• Keratinization begins

Stratum Lucidum

• Only in THICK skin

• Thin, translucent band of keratinocytes

  • 2-3 rows

  • Flat

  • Dead

Stratum corneum

• Most SUPERFICIAL layer

• 20-30 rows of keratinized cells

  • Only layer of keratin filled cells

  • anucleated

  • dead

• sheds/calluses

Eccrine/merocrine sweat glands

• Most frequent type 

• Sweat composition

• Release mechanism

  • Exocytosis

  • Via sweat pores onto epidermal surface 

• Function: regulate body heat

• Location

  • Palms, soles, forehead

Apocrine sweat glands

• sweat composition

  • viscous (thicker) milk substance 

  • bacteria

• release via ducts emptying into hair follicles 

• active after puberty

• region: axilla,pubic,anal

Sebaceous glands

• sebum (waxy/oily, cell fragments and debris, anibacterial)

• Released through holocrine and into hair follicles

• function: water proof (oily) and immune (bactericidal)

• located everywhere except palms/soles

Hirsutism

• Hair growth (face, chest, and back)

• Primarily in women

alopecia

• thinning of hair

• occurs with aging

diffuse hair loss

Hair shed from all parts of scalp

Lanugo

• Thin, nonpigmented hair

• 3rd trimester

• First hair you develop in the womb, falls off after birth

• Soft and no melanin

Vellus

• Comes after lanugo hair falls off

• Pale, fine hair

• Primarily upper and lower limbs

Terminal

• Coarse, thick, pigmented

• Scalp,eyebrows, axillary and pubic region

Nail body

Nail root

Nail bed

Nail Matrix

Lunula

Eponychium

free edge

nail fold

Hyponychium