Integumentary System Flashcards
What is the largest organ?
The skin
~4.5kg and 7% of body’s mass
What tissue is the skin made up of?
Epithelial tissue
Stratified squamous epithelium
What is the predominant cell type of the skin?
Keratinised keratinocytes
What are the two main layers of the skin?
The Epidermis
The Dermis
What is the hypodermis?
A predominantly fatty layer
NOT part of the skin
What are the cells types that can be found in the epidermis?
Keratinocytes
Melanocytes
Merkel cells
Dendritic cells
What are the 5 layers of the epidermal?
- Stratum Basale
- Stratum Spinosum
- Stratum Granulosum
- Stratum Lucidum
- Stratum Corneum
Describe what the stratum Basale is.
The deepest epidermal layer is attached to the underlying dermis along a wavy borderline.
Consists of a single row of stem cells and has rapid division of new cells.
Describe what the stratum spinosum is.
Several layers thick, these cells contain a web-like system of intermediate filaments (tension-resisting bundles of pre-keratin filaments).
Scattered among the keratinocytes are melanin granules and epidermal dendritic cells.
Describe what the stratum granulosum is.
Consists of 3-5 cell layers in which keratinocyte appearance changes drastically and the process of keratinisation begins
Describe what the stratum lucidum is.
Consists of 2-3 rows of clear, flat or dead keratinocytes.
The gummy substance of the keratohyalin granules sling to the keratin filaments in the cells, causing them to aggregate in large parallel arrays.
Describe what the stratum corneum is.
20-30 layers thick and accounts for 3/4 of the epidermal thickness.
Keratin and the thickened plasma membrane of cells protect against abrasion and penetration
What is ‘sloughing’?
Shedding dead surface cells from the skin.
What is the dermis?
The second major skin region is a strong, flexible connective tissue.
Its semifluid matrix, embedded with fibres, binds the entire body together like a body stocking.
What are the two layers of the dermis?
The papillary layer
The reticular layer
Describe the structural characteristics of the papillary layer.
Super thin and has areolar connective tissue in which collagen and elastic fibres form a loosely woven mat that is heavily invested with small blood vessels.
The looseness of this connective tissue allows phagocytes and other defensive cells to wander freely.
Describe the structural characteristics of the reticular layer.
Accounts for the 80% of the thickness of the dermis and irregularly arranged. The network of blood vessels nourishes this layer.
The collagen fibres of the dermis give strength and resilience, preventing most scrapes from penetrating the dermis.
What are the functions of the skin?
Protection
Temperature regulation
Secretion
How does the skin function to regulate temperature?
Sweat evaporates off the skin to cool the body, sweat glands also release antibodies.
The cutaneous plexus blood vessels bring warm blood (vasodilation/constriction) and nourishes the dermis.
What is the significance of the skin secretions?
Sebaceous glands produces oily/milky secretions which is slightly acidic.
These secretions protects, lubricates and controls the acid mantle of the skin. Contains antibacterial compounds that control the microbiome on the skin.
How is the skin able to feel?
The skin contains sensory receptors.
Free nerve endings can be associated with sensation of generalised pressure and texture but are more associated with temperature and pain
What factors affects skin colour?
Haemoglobin
Melanin
Cartotene
What factors can cause abnormal coloration of the skin?
Cyanois - blue tint to skin/lips
Jaundice - yellow tint to skin/eyes due to liver issues
Pallor - pale, clammy skin
Haematoma - bruising
