lecture 1 - skin histology Flashcards
What are the 3 key layers of the skin?
Epidermis, dermis, hypodermis
What are the 4 key functions of the skin?
Protective, biomechanical synthesis, temperature homeostasis, sensation
What type of tissue makes up the epidermis?
Stratified epithelium
What is the predominant cell in the epidermis?
Keratinocytes
What is the function of langerhans cells in the skin?
Immune function
What is the function of merkel cells in the epidermis?
Sensory nerve endings
What is the function of melanocytes in the epidermis?
Produce melanin pigment
What are the 5 layers of the epidermis?
Superficial to deep: stratum corneum, stratum lucidum (thick skin only), stratum granulosum, stratum spinosum, stratum basale
What is the main function of the stratum basale?
epidermal cellular proliferation via keratinocyte stem cells.
What does the stratum basale sit on that seperates the epidermis from the dermis?
Basement membrane
What is the name for the protrusions of the epidermis into the dermis?
Epidermal/Rete pegs
What is the name for the protrusions of the dermis into the epidermis?
Dermal papillae
What are the 2 components of the basal lamina of the dermal-epidermal junction?
lamina lucida, lamina densa
What do the basal keratinocytes of the epidermis contain?
Melanosomes, keratin tonofilaments
What connects keratinocytes together in the epidermis?
Desmosomes
What connect basal keratinocytes to the basal lamina?
Hemidesmosomes
What is the function of desmosomes in the epidermis?
Connects keratinocytes together to provide tensile strength
What is the shape of cells in the stratum granulosum?
Flattened
What feature of the stratum granulosum helps to form the water barrier of the skin?
Keratocyte hyaline granules - produce hydrophobic glycophospholipids
What substance is found in large amounts amongst the cells in the stratum corneum?
Keratin
How are melanocytes adhered within the epidermis?
Adhered to the basal lamni via hemidesmosomes, but not to other cells in the epidermis via desmosomes.
Where are melanosomes found within the epidermis?
The stratum granulosum
What are the 3 key components of the dermis?
Connective tissue, meshwork of fibres (collagen & elastin), ground substance
What is the function of collagen in the dermis?
Tensile strength
What is the function of elastin in the dermis?
elasticity - stretch & recoil
What types of cells are found in the dermis/
Fibroblasts, plasma cells, macrophages, glands
What are the 2 regions of the Dermis?
Papillary, Reticular
What is the most superficial layer of the dermis?
Papillary layer
What is the deep layer of the dermis?
Reticular layer
Which layer of the dermis sits adjacent to the epidermis?
Papillary layer
Which layer of the dermis sits adjacent to the hypodermis?
Reticular layer
What type of receptor is found in the papillary layer of the dermis?
Meissner’s corpuscles
What type of receptor is found in the reticular layer of the dermis?
Pacinian corpuscles
What is the key tissue type of the hpodermis?
Connective tissue (adipose tissue)
What is the function of the adipose tissue of the hypodermis?
Thermal insulation, shock absorption, metabolic energy storage
What are the 3 key accessory structures of the skin?
Hair, sebaceous glands, sweat glands
What muscle moves hair follicles?
Arrector pilli muscle
What layer of skin does a hair follicle sit in?
In the epidermis, which extends down into the dermis around the follicle.
Where do sebaceous glands typically open into?
Hair follicles
What do sebaceous glands secrete, and what is its function?
Sebum - produces an epidermal barrier
What are the 2 types of sweat gland?
Eccrine, apocrine
Which type of sweat gland are present everywhere in the body?
Eccrine, apocrine are not everywhere
Where do apocrine sweat glands open into?
Hair follicles
Where do eccrine sweat glands open into?
The skin’s surface
What structure helps to push sebum out into hair follicles?
Arrector pili muscle
What are the 2 parts of a sweat gland?
Secretory region, duct
What do the sensory receptors in the skin detect?
touch, pressure, temperature, pain
Where are Meissner’s corpuscles found?
Dermal papillae (papillary layer)
What are pacinian corpuscles sensitive to?
Pressure & vibration - mechanoreceptors
What is the structure of a pacinian corpuscle?
Capsule, intermediate layered zone, central core with axon terminal
