Skin Path Flashcards
What is the average weight of the skin?
6 pounds
What is the functions of the skin?
- Enveloping the body
- Protection against injury.
- Thermoregulation
- Waterproofing
- Fluid conservation
- Absorption of ultraviolet radiation.
7.Production of vitamin D - Acts as a barrier to pathogenic organisms
- Functions in the detection of sensory stimuli
Fill in the blanks. “ The epidermis of the skin is derived from _________ ( embryologic origin) while the dermis is derived from ____________ (embryological origin)
Epidermis - Ectoderm
Dermis- Mesoderm
What are the two types of Skin?
◦ Glabrous
◦ Hairy
True or False? Glabrous skin has a thin keratin layer and is found on the palms and soles.
FALSE!! Glabrous skin has a THICK keratin layer and is found on the palms and soles.
What are the main structures that arises from the epidermis of the skin?
Pilosebaceous follicle
The eccrine & apocrine sweat glands.
What are the types of cells found in the Epidermis?
- Keratinocytes
- Melanocytes
- Langerhans cell
- Merkel cell
Which is the main cell types found in the epidermis?
Keratonicytes (80% epidermal cells)
Which layer of the epidermis contains purple keratinohyaline granules?
Granular Layer
Which layer of the skin has spiny processes that separate keratinocytes?
Stratum spinosum
What are the different layers of the epidermis?
Basal layer
Stratum spinosum
Granular layer
Stratum lucidum
Stratum Corneum
Which layer of the skin is known as the ‘Germinative layer ‘of the epidermis?
Basal layer
Fill in the blanks.” Cells in the prickle layer of the epidermis are connected by the _______.”
Desmosome filament system.
True or False ? In the Stratum corneum cells contain keratohyaline and membrane coating granules.
FALSE!! This is in the Granular layer
How long is the epidermal transit time or turnover time?
28 days
Fill in the blanks. “Further maturation of Keratonicytes leads to loss of nuclei and flattening of the cellular outline to form _____ .”
Squames in the stratum corneum.
What is the embryological origin of the Dendritic cells?
Neural crest cells
Dendritic cells are found in which layer of the epidermis?
The basal layer
What is the ratio of Melanocytes to basal cells in the cheek?
1:4
What is the ratio of Melanocytes to basal cells in the lower back ?
1:20
What increases the number of melanocytes relative to keratinocytes?
Chronic sun exposure
True or False? The numbers of melanocytes are the same in fair and dark skin.
TRUE!!
What determines the skin colour in an individual ?
The quantity of melanin produced.
True or False? The size of the melanosomes is genetically determined and is typically smaller in black skin.
FALSE!! They are typically LARGER in black skin.
What are the different types of Melanin?
Eumelanin
Pheomelanin
Neuromelanin
Which type of melanin is red-brown in colour and is largely responsible for red-hair and freckles?
Pheomelanin
What is the most common type of melanin and is producesd in black or brown people?
Eumelanin
Where is the main source of Neuromelanin?
In the brain duhhh
True or False? Langherman’s cells are ONLY found in the epidermis?
FALSE!! It is found in the in the suprabasal layers of the epidermis and also in the DERMIS.
Fill in the blanks.” __________ are dendritic cells that is also a bone-marrow derived immunocompetent cells.”
Langerhans’ cells
What is the main function of Langerhan’s cells?
Provides a trap for contact antigens and presents them to T cells.
Which cell found in the epidermis is associated with intra- epidermal nerve endings?
Merkel cells
Where are Merkel cells found?
- In mammals , present in the basal layer of the epidermis, particularly on palms and soles.
- Merkel cells are also found within the dermis in association with Schwann cells of peripheral nerve endings.
What is the name of the clusters of Merkel cells?
Merkel corpuscles
What is the function of Merkel corpuscles?
They serve as mechanoreceptors and are involved in the function of touch.
True or False? The basement membrane of the skin looks the same on light and electron microscopy.
FALSE!! The basement membrane on light microscopy appears homogenous but on electron microscopy this is not the case.
Fill in the blanks. “ ___________ attach the basal layer keratinocytes to the area just below which is called the ________.”
HEMIDESMOSOMES attach …….. area below which is called the LAMINA LUCIDA (clear zone).
What is the name of the electron -dense zone of the basement membrane?
Lamina densa.
What are the epidermal appendages?
- Apocrine sweat glands
- Eccrine sweat glands
- Sebaceous glands
- Hair follicles
- Nails
What are the 2 types of sweat glands?
Apocrine & Eccrine
Which sweat gland in animals is responsible for scent production?
Apocrine Sweat glands
- that’s why you have green arm ( axillary)
Fill in the blanks. “ Apocrine sweat glands are found predominantly in the _____ & ______ areas?
Anogenital and Axillary
A for apocrine , A for Anogenital and Axillary
What is the name given to the secretion produced by Apocrine cells and how is it produced?
Decapitation secretion- This occurs when Columnar cells form the secretion by the breaking off of the tops of the cells. ( decapitation)
Fill in the blanks.” Apocrine sweat glands develop as _______ while Eccrine sweat glands develops as _________.”
Apocrine - outgrowths of the hair follicle.
Eccrine - a special downgrowth of the epidermis.
“A goes out while E goes down”
What gives the secretions from Apocrine sweat gland an odour?
The breakdown products of cutaneous bacteria.
Where are Eccrine sweat glands NOT found?
Mucous membranes
What structure of the Eccrine sweat gland modifies the secretion especially the reabsorption of water?
The duct
Fill in the blanks. “ Eccrine glands are influenced by ______ and thought to be _____ in function.”
Influenced by EMOTIONS ( E for Eccrine - E for Emotions)
and thought to be THERMOREGULATORY in function .
What is the function of the eccrine sweat glands under the control of?
Cholinergic & sympathetic nerve fibres.
Fill in the blanks.”Thermoregulatory sweating is under the influence of the ______.”
Hypothalamus
Fill in the blanks.” Mental sweating is under the influence of the ______.”
Limbic system
Which glands develop as lateral protrusions of the hair follicle?
Sebaceous Glands
True or False? Sebaceous glands are largely inactive before puberty but enlarge and become active at puberty.
TRUE!!
Where are Sebaceous glands NOT found?
Palms and Soles
Fill in the blanks. “ Sebaceous glands are more numerous on the _____,______,______ & _____.”
Face, scalp, midline of the back and perineum.
True or False? Eccrine sweat glands are described as holocrine because there is complete degeneration of its acini during secretion.
FALSE!! Sebaceous glands do this.
The control of sebaceous glands are under the control of ?
Androgens
True or False? Males have larger sebaceous glands than females.
TRUE!!
What are the functions of Sebum?
◦ Waterproofing
◦ Control of epidermal water loss
◦ Inhibiting the growth of fungi and bacteria.
Fill in the blanks. “ The hair follicle consists of _____.”
Hair shaft
Surrounded by a DOWN growth of epidermal cells into the DERMIS.
Fill in the blanks.” The hair follicle is Supplied with blood vessels by an invagination of dermis known as the ______.”
Hair papilla
Which glands can be found in or near the hair follicle?
Sebaceous glands and Apocrine glands
What are the three phases hair growth?
Anagen
Catagen
Telogen
Which hair growth phase is known as the resting phase and is usually for 3 months?
Telogen
Telo = tired, so she rest
In which hair growth phase is there active hair growth taking place and the duration is normally 3-5 years?
Anagen
Ana = active = so she grow 3-5 years
Which hair growth phase is the slowing down phase and lasts for approximately 2 weeks?
Catagen
Cata= Cyah go no more , so she slow down for 2 weeks
Which hair growth phase is also known as the phase of involution?
Catagen
What is the major hair growth phase that scalp hair is normally in ?
Anagen
What is the name of the hair covering the body of children?
Vellus hair.
Terminal hair is found where?
On the scalp, eyebrows and eyelash.
What are the characteristics of Terminal hair?
- Thicker than villus hair
- Has a medulla
*More pigmented than villus hair
Fill in the blanks. “ The nail or nail plate grows out from the ________and rests on the underlying nail bed.
Nail Matrix
What is the name given to the pale crescent-shaped area at the proximal end of the nail ?
The lunula
Fill in the blanks. “The lunula is the ______ portion of the NAIL MATRIX.”
Distal portion
True or False? The Hyponychium is the cuticle.
FALSE!! EPONYCHIUM = cuticle
What is the Hyponychium?
Thickened epidermis underneath the free distal end of the nail
What is the duration for fingernail growth ?
6 months
What is the duration for toenail growth?
6 – 18 months or longer.
What are the two layers of the Dermis?
Papillary dermis (outer /upper layer)
Reticular dermis ( deep layer)
What are the components of the Dermis?
- Fibrous component (collagen & elastin)
- Ground substances - proteoglycans.
- Epidermal appendages
- Vasculature
*Lymphatics
*Nerves - Smooth + Striated muscle
What are the cellular components in the dermis?
- Fibroblasts —> collagen & elastin
- Macrophage—-> general scavenger.
- Mast cell——> important in Type 1 immunological reactions.
What is the name of the structure that divides fat into lobules?
Fibrous septa
What is the function subcutaneous fat?
◦ Thermoregulation
◦ As a nutritional store.
