SKIN Flashcards
Skin also called
CUTANEOUS MEMBRANE
Skin is part of what system
Integumentary system
Name of the layers
Epidermis, dermis, hypodermis
How many layers?
3
What layer is the Epidermis?
Upper layer closest to external environment
What layer is the dermis?
The middle layer
What layer is the hypodermis?
The deepest layer
What are the epidermal derivatives?
Hair, nails and glands. They grow from the epidermis
what are the two types of skin
thin (small epidermis) and thick (great epidermis)
what are examples of thick skin
hairless, palms and soles of feet
what are examples of thin skin
hairy usually, and most of the body
Main layers of the epidermis
stratum basale, stratum spinosum, stratum granulosum
What layer of the epidermis is only found in thick skin
stratum lucidum
properties of stratum lucidum
- only in thick skin
- clear layer
- subdivision of the stratum corneum (stratum lucidum is considered a specialized part or layer within the broader stratum corneum)
properties of stratum corneum
- DEEPEST LAYER
- water resistant barrier due to lipid coating
- cell maturation: nucleus pushed out –> no nucleus or organelles –> cant make proteins –> DEAD CELLS
- cell membrane thickened and hard
- filled with keratin fillaments
properties of stratum basale
- deepest layer
- single layer of cells
- contain stem cells for regeneration of epidermis
properties of the stratum spinosum
- prickly layer (spikey)
- daughter cells from basale
properties of the stratum granulosum
- granular layer
- contains granules –> keratine formation + water resistance
what are keratinocytes
cells that produce keratin
Layers of the dermis
PAPILARY (closest to epidermis) and RETICULAR (closest to hypodermis)
Medical term for the lack of blood vessels in the epidermis
AVASCULAR
Papilary layer properties
- closest to epidermis
- thin + whispy
- main functions is to bring blood vessels to the epidermis + bring blood supply
Reticular layer properties
- closest to the hypodermis
- thick network of collagen + elastic fibres
- contains blood vessels, nerves, hair follicles + glands
What is the papillary dermis important for
The papillary dermis is important for providing oxygen and nutrients for the epidermis as it is the layer closest to the epidermis (also epidermis is avascular - lacks blood vessels)
what do the ridges of the papillary and reticular layers do
Ridges strengthen the attachments betweem the dermis and epidermis
Properties of the hypodermis
- Between skin + muscles + allows movement of skin
- location of subcutaneous fats (fat under the skin)
- fat important because it provides: protection, insulation, energy reserve and padding
why is fat important
provides: protection, insulation, reserve energy and padding
where is hair located
everywhere except for lips, soles, palms and portions of external genitalia (in terms of thin skin having hair, the exception is lips and portions of external genitalia)
what is hair
hair is a non living structure produces in the hair follicles + surrounded by connective tissue sheath
properties of arrector pili muscle
- smooth muscle
- goose bumps
properties of root hair plexus
- senses hair movement
- nerve supply around hair
properties of base of hair follicle
hair growth starts at the hair bulb
where does hair growth begin
hair growth begins at the hair bulb
what is the hair papilla
the hair papilla is a connective tissue that contains blood vessels + provides nutrients + oxygen to the dividing cells for them to make more mature EPITHELIAL CELLS which divide + push upwards + lose their nucleus to become harder and dead + full of keratin
what are the 3 types modes of secretion
merocrine - exocytosis
apocrine - bud away from surface
holocrine - burst
merocrine secretion
secretion released through exocytosis
apocrine secretion
secretion released through budding away from surface
holocrine secretion
secretion released through the cell bursting (eg pimples bursting)
what are the 3 types of glands found in the skin?
Sebaceous
Merocine
apocrine
properties of sebaceous glands
- in hair follicles
- method: holocrine
- produce sebum (oily secretion, lubricates hair a+ skin, increased activity during puberty)
properties of merocrine glands
- secretes directly onto skin surface
- method: merocrine
- produce sweat (99% water, 1% NaCl electrolytes metabolites + waste product)
- distributed all over body + important for temp regulation
properties of apocrine glands
- secretes into hair follicles
- method: merocrine
- secretion attracts bacteria - odour
- nipple, axilla (armpit), pubic + anal region
apes at the gym
- apocrine glands
- secrete into hair folicles
- nipples, axilla, pubic + anal region
- secretion attracts bacteria - odour
