The Integumentary System - Skin and Accessory Structures Flashcards
Explain what is the integument and examples;
outer covering of the body
Skin, glands, hair, nails
What are the 5 functions of the integument?
- Protection
Abrasion
UV light - Microorganisms
Water loss - Sensation
- Vitamin D production
- Temperature regulation
-Excretion
The skin - largest organ of the body; whats it made up of?
a) Epidermis - he surface epithelial layer
= prevents water loss and abrasion damage
b) Dermis - An underlying dense connective tissue layer
= structural strength
c) The subcutaneous layer = not really skin - lowest of the three parts
a) Epidermis properties;
layers, cells, cell turnover
- Avascular
- Layers /strata
4/5 layers
Stratum Lucidum (palms/soles of feet) - Cells generated in basal layer / stratum basale
- Migrate
- Keratinisation
waterproof
-Cell Turnover ~ 35 days
What is the process of ‘cells slough off’?
shedding dead surface cells from the skin which happens through MITOSIS - cell migration and keratinaisation
What are the cell types of epidermis?
1) Basal cells (precursor of keratinocytes)
2) Keratinocytes
Over 90% of cells present in skin
Contain keratin
3) Melanocytes
pigment-producing cells (5% of the total)
filter ultraviolet light
4) Langerhans cells
dendritic (branched) - immune cells
Merkel Cell – sensory receptor cells (touch)
Epidermis: Cell layers (Strata) - list the 3 types
Stratum germinativum (growth layer) –
stratum basale and stratum spinosum
Stratum basale (base layer) —
Basal cells; only these cells undergo mitosis
migrate up - become Keratinocytes
Merkel cell (information); Melanocyte (protection)
Stratum spinosum (spiny layer) —
Keratinocytes: held together (desmosomes)
Strength /flexibility
Begin to generate keratin and lipid
Some basal cells: Only v limited cell division
Langerhans cells (engulf bacteria)
Stratum granulosum (granular layer)—
Cells – lots of deposits of keratin / keratohyalin
Granules - grainy
Superficial cells: begin to degenerate
Stratum lucidum (clear layer)—
dead cells
Cell walls filled with keratin / keratohyalin
Stratum corneum —
Dead cells filled with keratin (barrier area)
15-30 layers
Constantly shed
Cells surrounded by lipids
What are the functions of Epidermis?
Stratum corneum (in particular)—
Keratin/keratohyalin – protect against water loss
Drug delivery:
lipid-soluble substances will diffuse through lipid layers
In detail, how does Epidermis (Stratum cornem) prevent water loss?
> prevents penetration of microbes
> the dehydration of underlying tissues
> mechanical protection against abrasion for the more delicate, underlying layer
Dermis structure:
Structural Strength
Connective tissue fibres:
Collagen / elastic fibres
Fibroblast cells
What are the layers of Dermis? (2)
Papillary layer (superficial)
Reticular layer (deep)
There are 3 layers of dermis, list:
Dermis Contains:
Hair follicles / associated muscles
Sensory receptors
Sweat and sebaceous glands
Blood vessels
Lymphatic vessels
All carry out key functions of skin
Papillary layer
Fine collagenous and elastic fibers
Blood vessels: supply epidermis
Oxygen/nutrients
Dermal papillae: increase strength of bond to epidermis
finger prints
Reticular layer
denser, collagenous fibers and elastic fibers
What is responsible for strength and stretchability in the dermis?
Collagen & Elastic fibres
Key functions of dermis;
Strength, temperature regulation, nutrients to epidermis
DERMAL growth and repair;
Dermis does NOT continually shed and regenerate itself
Collagen fibres (generally)
Some predominant direction
cleavage lines
Surgery : Incision made across the cleavage lines
> produce considerable scar tissue
Surgery: Incision made parallel with the lines
> produce less scar tissue
Wound healing in dermis:
fibroblasts proliferate
Stretch marks/ striae is simply…..
overstretched skin > overstretched skin
Types of Glans (sweat Glands)
> Ecrine Sweat Glands
Most Common,
Open directly through sweat pores
Function throughout life
Secretion: mostly water with a few salts
Secrete perspiration or sweat;
eliminate wastes; and cools body
> Apocrine Sweat Glands
Open into hair follicles
Limited distribution—arm pits/ genitalia
Limited function in humans
Begin to function at puberty
Body odour
Gland secretion and shed skin = Surface film
- protective barrier = mixing of secretions of sweat and sebaceous glands
Glands - Sebaceous glands
Hair folicle
Secrete sebum—
oily substance – lubricant for hair and skin
prevents excessive water loss from the skin
Lipid - antifungal activity
Functions of glands
Antibacterial, antifungal activity
Lubrication
Hydration of skin surface
Buffer of caustic irritants
Blockade of toxic agents
What determines skin colour? (excluding race)
Pigments (melanin, beta carotene)
Blood (haemoglobin)
Thickness of stratum corneum
Melanin
Production (by melanocytes)
Production affected by - UV, Homrones, Genetics
Melanin are produced by
Melanocytes
Melanin into vesicles called _______
melanosomes
Phagocytosed by epitheliad cells (keratinocytes)
form nuclear cap
Skin Pigmentation
Annular erythema
skin reaction that can be triggered by an infection or some medicines
Explain the process of vitamin D production
UV light converts a form of cholesterol to cholecalciferol (D3)— a precursor to vitamin D
Blood transports precursor/Cholecalciferol to liver and kidneys,
where vitamin D is produced
Vitamin D is essential for normal absorption of
calcium and phosphorous
Essential for bone function
