Physiology Flashcards
What is the largest organ in the body?
Skin
What is the outermost layer of skin called?
Epidermis
Which type of epithelium makes up epidermis?
Stratified squamous epithelium
Which layer of skin is deep to epidermis?
Dermis
Which tissue type makes up dermis?
Connective tissue
Which germ layer forms epidermis?
Ectoderm (forms periderm)
Which germ layer forms dermis?
Mesoderm
In foetal skin development, which layers are formed after 16 weeks?
Keratin layer + granular layer
Prickle cell layer
Basal layer
Dermis
Which cell makes up 95% of epidermis?
Keratinocytes
The basal layer of skin is highly metabolically active. True/False?
True
Lots of intermediate filaments
Name 3 other epidermal cells (other than keratinocytes)
Melanocytes
Langerhans cells
Merkel cells
Where do melanocytes derive from?
Neuronal cell crest
What are melanocytes? Which layer of skin are they found?
Pigment-producing dendritic cells
Basal layer
What do melanocytes do?
Convert tyrosine to melanin pigment and load colour onto adjacent keratinocytes
Eumelanin is brown/red
Brown
Phaeomelanin is brown/red
Red
Which disease results due to loss of melanocytes?
What disease is the genetic partial loss of pigment production?
What disease involves excess melanin due to pituitary?
Vitiligo
Albinism
Nelson’s syndrome
Where do Langerhans cells derive from?
Bone marrow
What are Langerhans cells? Which layer of skin are they found?
Antigen-presenting cells
Prickle cell layer
What are Merkel cells? Where are they found?
Mechanoreceptors that aid sensation
Between keratinocytes + nerve fibres
What are the 3 phases of growth of a hair follicle?
Anagen (growing)
Catagen (curve inwards)
Telogen (resting)
What is the dermo-epidermal junction (DEJ)?
The interface between the dermis and epidermis
List 2 key roles of the DEJ
Support, anchoring, adhesion and growth of epidermal cells
Semi-permeable membrane acts as a filter/barrier
Give an example of inherited skin fragility as a result of mutation to one of the proteins in the DEJ
Epidermolysis bullosa complex in young infants
Give an example of acquired skin fragility
Dermatitis herpetiformis
Bullous pemphigoid
What do fibroblasts in the dermis produce?
Procollagen (becomes collagen)
Elastin
The blood vessel supply to skin is greater than its metabolic need. True/False?
True
Which nerve receptors sense pressure in skin?
Pacinian corpuscles
Which nerve receptors sense vibration in skin?
Meissners corpuscles
What do free nerve endings provide sense for in skin?
Temperature
Pain
Which inherited condition arises due to overgrowth of nerve endings?
Neurofibromatosis
List the 3 main secretory glands in skin
Eccrine
Apocrine
Sebaceous
Eccrine glands secrete ?Apocrine glands secrete ?Sebaceous glands secrete ?
Eccrine glands secrete sweat
Apocrine glands secrete odourous fluid
Sebaceous glands secrete moisturiser
Which areas of the body have a high concn of sebaceous glands?
Head, neck and chest (areas common in acne)
What is the significance of the melanin cap on basal cells?
Absorbs UV rays to protect DNA in the cells’ nuclei
Which vitamin does skin metabolise?
Vitamin D
Which cells help protect skin from UV rays?
Melanocytes
Ratio of melanocytes : basal cells = ?
1:10
Where is the papillary dermis found?
Uppermost layer of the dermis
List the layers of the epidermis from top to bottom
Keratin (Kez) Granular (Grafts) Prickle cell (People) Basal (Buying) Dermis (Drinks)
What are Blashkos lines?
Developmental growth patter of the skin
Used to show congenital defects
What is alopecia areata? What is the classical sign?
Autoimmune hair loss
Exclamation mark patches
Which areas of the body have a high concn of apocrine glands?
Axilla
Perineum
Which areas of the body have a high concn of eccrine glands?
Palms
Soles
Axilla
Which sweat glands are involved in thermoregulation?
Eccrine sweat glands
What is the main component of the PCL?
Desmesomes
What is the main component of the granular layer?
Keratohyalin granules
