lecture 2 - anatomy of the skin 2 Flashcards
What are the 4 key accessory structures of the skin?
hair, sweat glands, receptors, nails
Where is hair not found on the exterior of the body?
Palms, soles of feet, lips
What does hair consist of?
‘Dead’ keratinised cells forming a hair shaft that is produced inside a hair follicle.
What is the function of the arrector pili muscle?
Attaches to hair follicle and contracts to produce goosebumps - hair shaft stands up straight.
What muscle is responsible for making the hair shafts of the skin erect, thereby causing goosebumps?
Arrector pili muscle
What is the structure and function of the root hair plexus?
Collection of sensory nerves at the base of each hair follicle that detects tiny interactions with the environment providing heightened sensation.
What is the name for the network of sensory nerves found at the base of hair follicles?
Root hair plexus
What are sebaceous glands?
Modified secretory epithelial cell glands found in the skin that produce sebum
What is the function of sebum?
Oily secretion that nourishes hair shafts, moisturises skin and repels water.
In terms of the sebaceous glands, what causes acne?
Blocked hair follicles and infection due to excess sebum production.
What is the name for sebum secreted by sheep?
Lanolin
What are the two types of sweat glands?
Eccrine, apocrine
Where are eccrine sweat glands found?
In most parts of the skin
What do eccrine sweat glands secrete?
Water secretions directly to the skin surface
What is the function of eccrine sweat glands?
Thermoregulation, salt excretion, antibacterial action.
Where are apocrine sweat glands found?
Armpit, groin, around the nipples
What do apocrine sweat glands secrete?
Sticky/oily, sometimes odorous secretions into the base of hair follicles
Where is apocrine sweat secreted?
Into the base of hair follicles
What is apocrine sweat gland secretion controlled by?
Hormonal signalling
What are the 3 types of sensory receptors in the skin?
Tactile, lamellar, bulbous
What is the function of nails in terms of the skin?
Protect fingertips/toes, enhance sensation
How are sensory receptors in finger/toe nails triggered?
Via deformation
What are the characteristics of ageing skin?
Thin epidermis and dermis, sagging/wrinkling due to diminished collagen, slower skin repair, drier epidermis due to decreased sebum, impaired cooling due to less sweat, pale skin, grey hair
Why does skin display sagging/wrinkling with age?
Collagen in the skin diminished reducing elasticity
Why does the epidermis become dry with age?
Less sebum is produced
Why is thermoregulation via the skin impaired with ageing?
Less sweat is produced by sweat glands, reducing cooling mechanisms.
How does tobacco cause premature skin ageing?
Damages collagen and elastin, reduces healing, causes acne and cancers .
How does vaping affect the skin?
Contains nicotine, which reduces blood circulation to the dermis causing contact dermatitis (rash)
What pigment is used by the skin to protect cells from UV damage?
Melanin
What cells produce melanin?
Melanocytes
How is melanin transferred to epidermal cells from melanocytes?
Via melanosomes - vesicles carrying melanin.
Where are melanocytes found?
In the stratum basale (innermost layer of the epidermis), because they are not shed
Where are melanosomes found?
Throughout the epidermis of the skin, as they are shed with keratinocytes.
What is a mole, on a cellular level?
A cluster of melanocytes that produce excess melanin
What are moles often caused by?
Over proliferation of melanocytes due to sun exposure
What is the cause of freckles?
Melanocytes over produce melanosomes (vesicles), in response to sun exposure.
What is the function of Vitamin D?
Calcium homeostasis, bone strength.
How is the skin involved in vitamin D synthesis?
UV exposure to the skin is required for synthesis.
What is the result of Vitamin D deficiency?
Rickets and/or low mood
Who is most susceptible to Vitamin D deficiency?
Highly pigmented people with dark skin
What is a basal cell carcinoma?
A common, relatively benign form of skin cancer that originates in the stratum basale of the epidermis.
Where do basal cell carcinomas originate?
In the stratum basale (bottom layer) of the epidermis.
What is the term for the spread of a cancer from one site to another or several?
metastasis
What is a malignant melanoma?
Rare form of skin cancer that is highly metastatic and can be deadly in left untreated.
Where do melanomas originate?
In pigmented melanocytes (melanin producing cells) in the stratum basale of the epidermis
Why do tattoos remain in the skin permanently?
They are deposited into the dermis layer of the skin, which is not shed. Cannot be completely broken down by immune cells.
