Chapter 5 Flashcards
Hypodermis
The skin rests on this, it is like the foundation to a house, the hypodermis attaches to underlying bone and muscle and supplies to nerves and blood vessels
Consisted of loose connective tissue with collagen and elastin fibers
Contains mainly: fibroblasts, macrophages, and adipocytes
💥 hypodermis is not part of the skin, is sometimes called subcutaneous tissue or superficial fascia.
Half the body’s far is in the hypodermis
Dermis
The tissue layer connected to the hypodermis
Responsible for structural strength of the skin
Composed of: fibroblasts, adipose cells, connective tissue, macrophages
Divided into two layers
Epidermis
Is a layer of epithelial tissue that rests on the dermis
5 major functions of the integumentary system
- Protection- against abrasion, ultraviolet light, and prevents entry of microorganisms, prevents dehydration by reducing water loss
- Sensation- can detect heat, cold, touch, pain, pressure
- Temperature regulation- by controlling blood flow and sweat glands
- Vitamin D production- exposure to ultraviolet light makes vitamin D
- Excretion- waste is released through sweat glands
Two layers of the dermis
Reticular layer- deeper layer
Papillary layer- more superficial
Cleavage or tension lines
The elastin or collagen fibers are oriented more in some directions than others
Striae or stretch marks
If the skin is over stretched, the dermis may rupture and leave lines that are visible through the epidermis
Papillae
The papillary layer derives it’s name from projections called papillae that extend toward the epidermis
Keratinocytes
Responsible for structural strength and permeability characteristics of the epidermis.
Most cells in the epidermis are called this because they produce keratin
Melanocytes
Contain melanin and contribute to skin color
Langerhans cells
Are part of the immune system
Merkel’s cells
Specialized epidermal cells associated with nerve endings responsible for detecting light tough and superficial pressure.
Desquamate
As new cells are formed, they push older cells to the surface where they slough off, or desquamate
Keratinization
As cells move towards the surface of the skin to eventually fall off they change shape and chemical composition
Strata
On the basis of these stages the many layers of cells in the epidermis are divided into regions, or strata.
Five strata of the epidermis
Stratum corneum Stratum lucidium Stratum granulosum Stratum spinosum Stratum basale
Stratum basale
Cells divide by mitosis and some newly formed cells become the cells of the more superficial strata
Stratum spinosum
Keratin fibers and lamellar bodies accumulate
Stratum granulosum
Keratohyalin granules accumulate and a hard protein envelope forms beneath the plasma membrane, lamellar bodies release lipids; cells die.
Stratum lucidum
The cells are dead and contain dispersed keratohyalin
Stratum corneum
The dead cells have a hard protein envelope, contain keratin, and are surrounded by lipids.
Lamellar bodies
Additional keratin fibers and lipid-filled, membrane bounded organelles called lamellar bodies are formed inside the keratinocytes
Cornfield cells
Dead cells with hard protein envelope that are filled with protein keratin
Thick skin
Has all five epithelial strata, and the stratum corneum has many layers, thick skin is found areas subject to pressure or friction such as the palms of the hands, the soles of the feet, and fingertips.