Biology of the skin Flashcards
week 1
What does the skin protect against as a physical barrier?
mechanical damage, water entry, water loss, chemicals, particles, infectious agents
Name some physiological functions of the skin
temperature regulation, sensation, nerve signalling, vitamin D synthesis.
Name the 3 main layers of the skin
Epidermis
Dermis
Hypodermis/Subcutis
Which type of skin is most abundant?
Thin skin
Where can thick skin be found?
palms of hands and soles of feet
In which type of skin is the stratum lucidum found?
Thick skin
Where is the stratum lucidum found?
Between the stratum granulosum and stratum corneum
What type of epithelium is the epidermis?
Stratified squamous
What are the layers of the epidermis?
Basal layer
Spinous layer
Granular layer
Cornified layer
Basal layer (of epidermis)
Single cell, contains basal cells which are stem cells of the epidermis.
What cells are in the basal layer?
Basal cells
Melanocytes
Spinous layer (of epidermis)
prominent intracellular keratin filaments form a scaffold. Desmosomes link them to adjacent cells
Desmosomes are a type of…
cell-to-cell junctions
Tonofibrils
Filaments which form a scaffold and converge at desmosomes.
Granular layer (of epidermis)
Keratohyalin granules produces which contain proteins which bind to and aggregate keratin filaments.
Lamellar bodies contain lipid important for hydrophobic barrier to water.
Where are lamellar bodies found?
Statum granulosum
Cornified layer (of epidermis)
Cells have underwent apoptosis, loose nuclei and organelles.
List the cells of the epidermis
Keratinocytes
Melanocytes
Langerhans cells
Merkel cells
Melanocytes
Produce melanin, responsible for skin pigmentation and protection against UV damage. Produce melanin which is packaged into melanosomes which are transferred into neighbouring keratinocytes.
What types of cell is a langerhan cell?
Antigen-presenting cell
Merkel cells
Found in associated with nerve fibres responsible for fine touch sensations
Name the 2 layers of the dermis
Papillary dermis
Reticular dermis
Papillary dermis
thin layer underling the epidermis, relatively loose conceive tissue made up of collagen and elastin fibres.
contains capillary networks, lymphatics and nerve endings.
How does the epidermis recieve blood supply?
Papillary loops in the papillary dermis
Reticular dermis
Thick layer, dense irregular connective tissue containing thick bundles of collage fibres.
Contains fibroblasts, immune cells, various vessels, nerves and nerve endings.
Site of various skin appendages
List the cells of the dermis
Collage + elastin fibres
Fibroblasts
Immune cells - mast, macrophages, lymphocytes
Adipocytes
Hypodermis
Loose connective tissue with adipose cells, larger blood vessels and nerves
Adipose tissue connected by fibrous septa
Functions of the hypodermis
insulation, protection, energy storage
3 phases of hair
Growth (anagen)
Transition (catagen)
Resting (telogen)
Name 2 types of glands
Sebaceous
Eccrine
Apocrine
What do sebaceous glands secrete
sebum (a lipid containing substance that coats the hair to keep it soft, supple and waterproof).
What structure does a sebaceous gland have?
Branched acinar
What type of secretion does a sebaceous gland do?
Holocene
Holocrine secretion
secretions produced in the cytoplasm of the cell and released by the rupture of the plasma membrane which destroys the cell
What do eccrine glands secrete?
Sweat
What type of secretion do eccrine glands undergo?
Merocrine
Merocrine sections
excreted via exocytosis
Structure of a merocrine gland
coiled tubular
What stage of life do apocrine glands become functional?
puberty
Healing superficial wounds
epidermis can regenerate from basal layer
Healing of deep wounds
haemostats inflammation fibroplasia epithelialisation remodelling
healing of deepest wounds
if dermis and deep parts of appendages destroyed over significant area, spontaneous healing not possible
