Chapter 5 Flashcards
Skin Structure Image
What does the integumentary system consist of?
Skin
Hair
Nails
Sweat Glands
Sebaceous (oil) glands
What are the distinct regions of the skin? What tissues is each made of?
Epidermis - Epithelial tissue
Dermis - Dense connective tissue
Hypodermis - adipose tissue with areolar connective tissue
What are the 4 cell types found in the epidermis? What does each do?
- Keratinocytes - protection
- Melanocytes - shields and protects the nucleus from damaging UV radiation in sunlight.
- Dendritic cells - ingest foreign substances and are activators of the immune system.
- Tactile (Merkel) cells - act as sensory receptors for touch.
What are the 5 layers of the epidermis?
Stratum corneum
Stratum lucidum (only in thick skin)
Stratum granulosum
Stratum spinosum
Stratum básale
Apoptosis
Cell death
In epidermis the cells slough off as dandruff and dander. Humans can shed 50,000 cells every minute.
Image of epidermal layers
What is dermis? What does it contain and what are its 2 layers?
Dermis is made of strong, flexible connective tissue. The dermis’ matrix fibers bond the body together. The dermis contains nerves, blood vessels and lymphatic vessels, epidermal hair follicles, oil glands, & sweat glands.
2 layers:
Papillary
Reticular
Papillary Layer
The papillary layer of the dermis is made of areolar connective tissue consisting of loose collagen, elastic fibers and blood vessels.
The loose fibers of the papillary layer allow phagocytes to patrol for microorganisms.
Dermal Papillae
The dermal papillae is a superficial region of dermis that sends fingerlike projections up into the epidermis.
Dermal papillae projections contain capillary loops, free nerve endings, and touch receptors (tactile corpuscles).
Friction Ridges - what are they made from and what do they do?
In thick skin, the dermal papillae lie on top of dermal ridges which give rise to epidermal rings. These collectively are friction ridges.
Friction ridges enhance finger’s gripping ability.
Friction ridges contribute to sense of touch.
Sweat pores in friction ridges lead to unique fingerprint patterns.
The reticular layer of dermis
The reticular layer makes up 80% of dermal thickness.
The reticular layer is made up of coarse, dense fibrous connective tissue, with elastic and collagen fibers.
The reticular layer binds water and keeps skin hydrated.
Cutaneous plexus lies in the reticular layer.
Cutaneous Plexus
The cutaneous plexus is a network of blood vessels between the reticular layer of the dermis and the hypodermis.
Flexure Lines
Flexure lines are lines of the reticular layer that are dermal folds at or near joints.
The dermis is tightly secured to deeper structures.
The skin’s inability to slide easily for joint movements causes deep creases.
Flexure lines are visible on the hands, wrists, fingers, soles & toes.
What are the 3 main skin color pigments? Which is the only one produced by the skin?
Melanin - produced by skin
Carotene
Hemoglobin
What are the functions of hair?
Hair…
Warns of insects on skin
Hair on head guards against physical trauma
Protects from heat loss
Shields the skin from sunlight
Hair structure
Hair is made up of dead keratinized cells (Hard keratin)
Hard keratin is tough, cells do not flake off.
Hair is produced by hair follicles.
Regions of hair:
The Shaft: the area that extends above the scalp, where keratinization is complete.
The Root: the area within scalp, where keratinization is still going on.
3 parts of hair shaft:
Medulla - central core of the large cells and air spaces.
Cortex - several layers of flattened cells surrounding the medulla.
Cuticle - the outer layer consisting of overlapping layers of single cells.
What are hair pigments made by? How do hair pigments work?
Hair pigments are made by melanocytes in the hair follicles.
Photo: Structure of hair follicle