Workbook - Skin Flashcards
How many layers is skin composed of?
Two.
What is the outer layer of skin called?
Epidermis.
What is the underlying layer of connective tissue in skin called?
Dermis.
What is deep to the dermis?
Superficial fascia/hypodermis/subcutis.
-layer of loose connective tissue with variable amounts of fat
What are the layers of skin?
-Epidermis
-Dermis
(-Hypodermis)
What determines whether skin is defined as thin or thick?
The thickness of the epidermis.
-particularly the outer layer of epidermis
What is another difference between thick and thin skin (apart from the thickness of the epidermis)?
Thin skin has hair follicles, thick skin is glabrous (non-hairy).
Where is thick skin generally located in humans?
Areas with lots of abrasion.
-fingertips, palms, soles
What type of epithelium is the epidermis made up of?
Keratinised stratified squamous.
What are the main layers of thick skin? (5)
DEEP TO SUPERFICIAL:
- Stratum basale
- Stratum spinosum
- Stratum graulosum
- Stratum lucidum
- Stratum corneum
What is stratum basale responsible for?
Regeneration (repeated mitotic divisions).
-irregular
What is stratum spinosum composed of?
Keratinocytes connected by desmosomes.
What is stratum granulosum composed of?
Loose nuclei and cytoplasms»_space; masses of keratin.
What is stratum lucidum like, and where is it found?
Thin and transparent.
-in the palms and soles
What is stratum corneum composed of?
Sheets of keratin.
-contains most barrier functions
Which layers of thick skin are most prominent?
- Stratum spinosum
- Stratum granulosum.
Which layer of thick skin is absent in thin skin?
Stratum lucidum.
What are the 3 types of non-epithelial cells present in the epidermis?
- Melanocytes
- Langerhans cells
- Merkel cells
What are melanocytes?
The pigment cells of the skin.
Which non-epithelial cells in the epidermis play a role in immunology?
Langerhans cells.
Which non-epithelial cells in the epidermis act as mechanoreceptors?
Merkel cells.
What are the main types of skin cancer? (3)
- Basal cell carcinoma
- Squamous cell carcinoma
- Malignant melanoma
How do the different types of skin cancer vary?
Each derived from different layers of the epidermis.
What layer of the epidermis is basal cell carcinoma derived from?
Stratum basale.
What layers of the epidermis is squamous cell carcinoma derived from?
Upper layers (keratinocytes/granular). -stratum spinosum and stratum granulosum
What layer of the epidermis is malignant melanoma derived from?
Stratum basale.
-melanocytes
Which type of skin cancer is the least common and most dangerous?
Malignant melanoma.
-metastasises quickly
What are warts?
Small benign growths caused by viral infection (HPV) of the skin/mucous membrane.
» increase keratin production in the epidermis
What happens during development to a number of epidermis structures?
They grow downwards to invade the underlying dermis and hypodermis.
What do the down-growths of the epidermis form?
Sweat glands, sebaceous glands and hair follicles.
Which of these features are absent in thick skin?
Sweat glands, sebaceous glands and hair follicles.
- Hair follicles
- Sebaceous glands
What is the function of sebaceous glands?
Secrete lubricating oil into hair follicles to lubricate hair and skin.
Which of these features are involved in the development of acne?
(Sweat glands, sebaceous glands and hair follicles.)
- Hair follicles (clogged with dead skin and oils)
- Sebaceous glands (produce excess sebum/oils)
Where are arrector pili muscles, and what is their function?
Attached to hair follicles below sebaceous glands.
-contract to make hairs stand up»_space; insulation
What sort of nerve supply do the arrector pili muscles have?
Sympathetic nerve supply.
What other structures in the skin have a sympathetic nerve supply, and what is the consequences of stimulating these fibres?
- Eccrine sweat glands (stimulated by increased body temperature)
- Vessels (stimulation»_space; constriction)
Where are apocrine glands mainly located?
Axillary and groin regions.
What lies between the epidermis and dermis?
A specialised basement membrane.
What is the dermis composed of?
Connective tissue containing irregular bundles of collagen fibres and networks of elastic fibres.
How many layers is the dermis subdivided into?
Two.
What are the 2 layers of the dermis?
- Papillary layer (superficial, loosely woven)
- Reticular layer (deep, dense)
Where do the epidermis and dermis interlock the most?
In areas of thick skin subject to friction.
-produces individual fingertips
What structures are formed in areas where the epidermis and dermis interlock? (2)
- Rete ridges (epidermal downgrowths)
- Dermal papillae (projecting upwards)
Which layer of the skin contains the blood and nerve supply?
The dermis.
What is a blister?
Fluid-filled structure within/under the epidermis.
How are burns classified?
According the layers of skin that are damaged.
What layer of the skin is damaged in 1st degree burns?
Epidermis only.
Which layers of skin are damaged in 2nd degree burns?
Epidermis and part of dermis.
Which layers of skin are damaged in 3rd degree burns?
All layers of skin (epidermis, dermis and hypodermis).
-extends to subcutaneous tissue
What is a dermatome?
An area of skin supplied by nerves from a single spinal root.
What do branches of cutaneous nerves form at the base of a dermis?
A dermal nerve plexus.
-individual fibres then branch into higher levels of skin
How are cutaneous sensory receptors classified?
Morphologically.
-into 2 groups
What are the 2 groups of cutaneous sensory receptors?
- Free nerve endings / unencapsulated nerve endings / simple receptors
- Encapsulated nerve endings / compound receptors
What are free nerve endings?
Branching axons lacking surrounding Schwann cells.
List some of the functions of free nerve endings? (3)
- Nociceptors
- Thermoreceptors
- Mechanoreceptors
What are some free nerve cells associate with in the basal layer of epithelium?
Merkel cells.
What do free nerve cells and merkel cells form in the basal layer of epithelium?
Merkel cell-neurite complexes.
-act as mechanoreceptors
What do encapsulated nerve endings act as?
Mechanoreceptors.
Which skin receptors have a slow speed of adaptation? (2)
- Merkel cell-neurite complexes
- Ruffini endings
Which skin receptors have a fast speed of adaptation? (2)
- Pacinian corpuscle
- Meissner’s corpuscle
Where are merkel cell-neurite complexes located?
Dermal epidermal junction.
Where are Pacinian corpuscles located?
Hypodermis.
-deep layer
Where are Meissner’s corpuscles located?
Dermis.
Where are Ruffini’s endings located?
Dermis / subcutaneous connective tissue.
What do Merkel cell-neurite complexes detect?
Pressure.
What do Pacinian corpuscles detect?
Pressure, vibration, tension.
What do Meissner’s corpuscles detect?
Light discriminatory tough, pressure, vibration.
What do Ruffini’s ending detect?
Stretching, shearing.
What receptors would be responsible for detecting light stroking?
- Merkel
- Meissner’s
What receptors would be responsible for reading Braille?
- Meissner’s
- Pacinian
What receptor would be responsible for detecting a small insect crawling over skin?
-Merkel
