The Skin Flashcards
What are Merocrine sweat glands associated with?
Thermoregulation
- Directly secrete substances onto the surface of the skin
What are the 5 roles of the skin?
Protection - impact, chemical and infection
Temperature maintenance - Regulate heat gain/loss
Synthesis and storage of nutrients - Vit D3
Sensory reception
Excretion and secretion - salt, water, milk
What is the structure and function reticular layer of the dermis?
Irregular, dense, connective tissue
Rich in collagen
Shock absorber - protects internal organs
What is the process of thermoregulation?
- Increase in CORE temperature
- Thermostat in the hypothalamus - activate the cooling mechanism
- Vasodilation - heat radiated from skin surface
- Sweat glands activated
When decrease- opposite and the skeletal muscles are activated - shiver to produce heat
What is the active version of vit D3?
Calcitriol
What are the two types of epithelium and how are they different?
Thick
- Has 5 layers
- On the palms of the hands, fingertips (where no hair)
Thin - has 4 layers (doesn’t have the stratum lucidum)
What is the layer of the dermis which is close to the epidermis and what is its structure/function?
The Papillary layer
Connective tissue
Interdigtated with the epidermis to maintain its attachment to the dermis
What are the 3 cell types in the stratum basale?
Describe them
1) Keratinocytes (skin cells)
- Mitotically active
- The majority
2) Melanocytes (give color to the skin)
- Have two types of melanin:
- Eumelanin
- Phenomelanin
3) Tactile cells (Merkel cells)
- Connected to sensory nerves
- Participate in TOUCH
How do keratinocytes behave in the skin?
- They are ‘born’ in the stratum basale, where they are mitotically active
- They divide asymmetrically and become detached from the basement membrane
- As they differentiate, they migrate upwards throughout the skin, becomming less mitotically active and more flattened as they do so
- As they move upwards they produce higher amounts of keratin
- They are fully differentiated in the stratum granulosum (post mitotic)
What are the functions of the hypodermis in babies compared to in adults?
Provide protective layer in babies
In adults it is restricted to specific body areas and protects against heat loss
What does calcitriol do?
Activates gene that code for a gene essential for re-absorption of Ca2+
- By binding to the VDR
- VDR acts as a transcription factor
- Controls gene expression
What are 4 cutaneous gland and what do they do?
- Mammary gland (produce milk)
- Ceriminous gland (produce earwax)
- Sebaceous gland (produce sebum which lubricates skin and hair, protecting against infection)
- Sweat glands
Which layer of the epidermis has 15-30 layers of dead keratinized cells?
The stratum corneum
What are Apocrine sweat glands associated with?
Hair cells
- Armpits, forehead, beard
- Secrete products into the hair follicles
What is the function of keratin?
Forms durable filaments
How does the skin act as a biochemical barrier?
Sebum produced by sebaceous glands
- Contains bactericidal substances
Sweat lowers the pH to 4-6 (unfavorable for bacterial growth)
Which layer of the epithelium is the last layer to have cells that contain nuclei?
The stratum granulosum
Which layer of the epidermis has 3-5 layers of keratinocytes?
The stratum granulosum
What structures are contained within the dermis?
Blood vessels
Nerve cells
Accesssory structures - hair, nails, sweat glands, sebaceous glands
What is the hypodermis?
Subcutaneous layer (under the skin) Connective tissue Contains adipocytes (fat cells)
Which layer has keratinocytes which make large amounts of keratin and glycolipids?
The stratum granulosum
How does the skin act as a physical barrier?
Keratin provides toughness, prevents the entry of infectious agents
Which is the thickest layer of the epidermis?
The stratum spinosum
How does the skin act as an immunological barrier?
Dendritic cells in stratum spinosum
