Chapter 5 Flashcards
What is skin’s main function?
Protection
What is another name for skin?
Integument
What are the 2 distinct regions for the integument?
- Epidermis
- Dermis
What is the epidermis?
The superficial region
Epithelial tissue
What is the dermis?
Underlies epidermis
Mostly consist of connective tissue
Strong and flexible
What is the hypodermis?
- subcutaneous layer deep to the skin
- not part of the skin
- mostly muscles and adipose tissue
What are the 4 cells of the epidermis?
- Keratinocytes
- Melanocytes
- Dendritic cell
- Tactile cells
Keratinocytes
- Produce keratin - fibrous protein
- most cells of epidermis
- tightly connected by desmosomes
Melanocytes
- 10-25% of cells in deepest epidermis
- produce melanin → packaged into melanosomes → responsible for skin color
Dendritic cells (langerhans)
- Immune cell
- macrophages - key activators of immune system
Tactile cells (merkel)
- Sensory touch receptors
What are the layers of the epidermis (superficial to deep?)
- Stratum corneum
* stratum lucidium ( only in thick skin e.g. Palms of hand or soles of feet) - Stratum granulosum
- Stratum spinosum
- Stratum basale
Stratum basale
- Deepest epidermal layer
- actively mitotic:
• produces 2 daughter cells - melanocytes compose 10-25% of this layer
Stratum spinosum
- Aka prickly layer
- several layers thick
-Present melanosomes and dendritic cells
Stratum granlosum
- 4-6 cell layers
- keratinization begins
- cells apical to this layer die
Stratum lucidium
- Clear layer
- Only in thick skin
- few rows of dead keratinocytes
Stratum Corneum
- 20-30 rows of dead, flat, anuclecte, keratinized sacs
- although dead, functions to protect deeper cell
What are the two layers of the dermis?
- Papillary
- Reticular
What is the papillae layer composed of?
- areolar connective tissue
- collagen fibers
- elastic fibers
- blood vessels
What is the dermal papillae?
- peglike projections
What is a fingerprint ridge called?
Friction ridges
This layer is deep to the papillary layer.
Reticular layer
What composes the reticular layer?
- Dense fibrous connective tissue
- elastic fibers
- collagen filers
• cleavage line
What are the dark lines an our fingers and hands?
Flexure lines