Skin and Sensory Receptors Flashcards
The skin makes up what percentage of total body weight
15-20% of total body weight is skin
Three main layers of the skin
- Epidermis - what you can actually touch.
- Dermis
- Hypodermis or subcutaneous tissue
Epidermis
- Tissue type
- Main cell type
- Special cell types
- Are nerves present?
Epidermis- SSK epithelium. Main cell is keratinocytes (80%) and other cells include melanocytes, lagerhans, and merkel cells (light touch sensory receptors). Contains free nerve endings (typically pain receptors)
Dermis
- Tissue type
- Are vessels present?
- Are glands present?
Dermis- Dense irregular connective tissue with several types of sensory receptors such as Meissner’s corpuscle and pacinian corpuscle.
Small vessels (arterioles and venues) and lymphatics (run alongside vein system) are present.
Glands: sweat and sebaceous (associated with hair follicle)
Piloerector units- Hair follicle, sebaceous gland, and errector pili muscle
Role of the errector pili muscle
Muscle associated with hair follicle. Stands hair up when scared or cold
Meissner’s corpuscle
Sensory receptor found in the superior dermis (papillary layer). Detects light touch.
Only in thick skin.
Pacinian corpuscle
Found in the deep dermis (reticular dermis). Detects vibrations and heavy touch.
Only in thick skin.
Piloerctor units includes
- Hair follicle
- Errector pilli muscle
- Sebaceous gland
Adipose tissue
- Tissue type?
- What is found in this layer?
Loose connective tissue and adipose tissue.
Large(r) blood vessels (arteries and veins), lymphatics, and nerves
What does it look like histologically where the epidermis and dermis meet?
Squiggly appearance, not a straight line. Increases surface area of contact and creates friction so it is hard to separate the two layers.
Glabrous
Hairless
Difference between thick and thin epidermis
Thick- Smooth, glabrous (hairless) with 5 layers. Palms of hand and soles of feet.
Thin- Thin, hairy, has 4 layers (strata= layer)
Layers of the epidermis
Big spiders get (L) crushed
Basale- Adjacent to basement membrane. Single layer of cells. Cube shaped appearance. Innermost layer with keratinocytes that are highly mitotically active.
Spinosum- Stellate shaped cells. Cell with a bunch of spine. Cell to cell junctions are forming. Mitotically active, but less than basale.
Granulosum- Cells become more flattened like stratified squamous. Keratin is now produced. Stained well with hematoxylin.
Lucidium- Only found in thick skin. Cell is pretty much dead, no nucleus. Too far away from blood supply. Appears pale, white.
Corneum- Super dead cells. No nucleus. Shloffed off.
Is the epidermis vascular or avascular
Avascular. Gets its blood supply from the underlying dermis.
Waterproofing
As the cell mitosis, lamellar granule lipids are secreted into the intercellular space between cells. The lipid barrier waterproofs the skin, preventing water loss to evaporation. Lasts until the cell it surrounds are shed off.
Waterproofing occurs in which layer of the skin
The epidermis. Released at the basale cell layer as cells go through mitosis.