Skin Flashcards
What is the largest organ in the body?
The skin
What are the 4 tissue types that make up the skin?
Epithelium
Connective tissue
Muscle
Nervous
Does the skin have its own blood and nerve supply?
Yes
What does the skin provide evidence of diagnostically?
Underlying conditions
What are some functons of the skin?
Prevents water loss (epidermis)
Permits body cooling (dermis)
Immune surveillance
UV protection
Energy storage
Sensory information
What are the 2 layers of the skin?
Epidermis
Dermis
What tissue type makes up the epidermis?
Epithelium
What tissue type makes up the dermis?
Connective
What is underneath the epidermis and the dermis?
Hypodermis
What is the hypodermis?
A fatty layer that anchors the skin to underlying structures
What does the hypodermis do?
Anchors the skin to underlying structures
What is the class of the epithelium tissue of the epidermis?
Stratified, getting flatter as you go up
What are the 4 basic cells in the epidermis?
Karatinocytes (contain keratine, waterproof)
Melanocytes (pigment formation, in basil layer)
Langerhans cells (immune surveillance)
Merkel cells (touch receptors)
What are the layers of the epidermis like and what are they formed by?
Fine layers formed by maturing karatinocytes
What are the 5 layers of the epidermis?
Stratum basule (basil layer)
Stratum spinosum
Stratum granulasum (keratine starts being synthesised)
Stratum lucidum
Stratum corneum
What happens to keratine granules as you go up layers of the epidermis?
They breakdown and go up layers until they die and flatten out in the stratum corneum
What is the class of cells in the stratum basal?
Tall columnar cells
What cells are found in the stratum basal?
Melanocytes and merkel cells
What are cells of the stratum basale bound to the BM by?
Hemidesmosomes
What is the interface like between the stratum basale and the dermis?
Irregular
What do the cells in the stratum basale do?
Stem cells that perform continuous proliferation
What happens as cells go to the stratum spinosum?
They shrink and desmosome junctions create ‘spines’
How does the stratum spinosum relate to keratinisation?
Preparative layer for keratinisation
What defines the stratum glanulosum?
Pressure of granules
What granules make up the stratum granulosum?
Granules of keratohyalin, precurser of keratine
Are the properties of the stratum lucidum/corneum different?
Only that the stratum corneum has no cell organelles
What happens in the stratum lucidum?
Converstion of keratohyalin to keratine
What gives the strength of the stratum lucidum?
Disulphide bridges
What is keratinisation?
Organic process where keratine is deposited in cells, becoming hard
What does keratinisation allow dead cells to do?
Rub of (exfoliate)
What properties does keratinisation give the skin?
Its resilience and strength
How does the epidermis thickness vary around the body?
It varies around the body depending on function, hand and feet are thick, abdomen is thin
What are the 2 layers of the dermis?
Papillary layer
Reticular layer
What is the papillary layer made of?
Loose connective tissue
Where are macrophages found?
In the papillary layer of the dermis
What is a function of the papillary layer of the dermis?
Protects against pathogens
What is found in the papillary layer of the dermis and what does this allow?
Blood vessels (thermoregulation, nutrition)
Nerve endings (sense organ)
What kind of tissue if the reticular layer of the dermis?
Dense irregular connective tissue
What is the reticular layer of the dermis composed of?
Collagen fibres in three planes
Elastic fibres
What happens to the elasticity of the dermis with age?
Loss of elasticity
What is waterproofing a function of?
The dermis, because the keratine is waterproof
What is skin colour due to?
The melanin that is produced by melanocytes (protects against UV light)
What is the function of melanin?
Protects against UV light
What layer is hair derived from?
The epithelial layer, has a continuity with layers of the epidermis
What is a hair follicle composed of?
Arrector pili muscles
Sebaceous glands
What do arrector pili muscles do?
Straightens the hair when the muscle contracts
Where are erector pili muscles found?
Attatched to follicle root and base of the epidermis
Where are sebacceous glands found?
Between the hair follicle and arrector pili muscle
What do sebaceous glands do?
Secretes sebum
What are nails?
A specialised version of epithelium that becomes very hard due to keratine
What is responsible for nails becoming very hard?
Keratine
What are some skin glands?
Sebaceous glands
Appocrine sweat glands
Eccrine sweat glands
Where does each gland secrete?
Sebaceous glands secrete directly into the hair follicle whereas the other glands do not
What is the class of eccrine sweat glands?
Simple tubular gland
Where are eccrine sweat glands located?
In the dermis
What is the role of eccrine sweat glands?
Thermoregulatory role
How is thermoregulation achieved?
Sweat glands
Blood vessel dilation
Hair (not in humans)
What are some examples of nerve endings in the skin?
Meissner’s corpuscles (light touch)
Paccinian corpuscles (vibration and pressure)
Pain receptors
Thermoreceptors
What is not formed in scar tissue?
Hair follicles or sweat glands
What is skin very good at doing?
Repairing itself