Anatomy and Cell Biology 3309 Lecture Notes - Lecture 13: Dense Irregular Connective Tissue, Stratified Squamous Epithelium, Antigen-Presenting Cell
22 May 2018
School
Department
Professor
Histology 3309
Skin
Objectives
1. Describe the function of the skin
2. Compare and contrast the layers of the skin (epidermis, dermis, hypodermis) in terms of their
appearance and the cell types contained therein
3. Describe the layers of the epidermis
4. Explain the cell types of the epidermis and their functions
There is a lot going on in your skin!
- There is all sorts of diff strucutres within the dermis
o Sebaceous gland (oil gland)
o Hair follicle
o Sensory organs (ex: Pacinian corpuscle – vibration stimulation) (ex:merkel cells – fine
touch)
Layers of Skin
- Epidermis
o Stratified squamous epithelium
o From ectoderm
o Basophilic staining layer
o The top layer of the epidermis is continuously shed off throughout your life
- Dermis
o Loose and dense irregular connective tissue (so lots of collagen)
o From mesoderm
o Gives mechanical support, strength and thickness
o Helps maintain the overall structure of the skin
- Hypodermis
o Variable amounts of adipose tissue arranged into lobules
o Deeper than dermis
o The amount of adipocytes depends on the individual’s age, amount of fat they have
o Our skin is very elastic, but as we age we lose a lot of our elasticity and adipocytes in the
hypodermis that’s why old people are so cold all the time
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Functions of the Skin
- Barrier
o Protects against physical, chemical and external environmental biologicals
o People with really severe burns are very prone to infection - this is why burns can be so
deadly – bc the skin does such a great job as a barrier
- Immunologic
o Skin has its own antigen presenting cells
o Langerhans cells
- Homeostasis
o Regulates body temperature (through shivering, sweating, and the amount of hair we
have on our body) and water loss
- Endocrine
o Produces some hormones and cytokines, vitamins (primarily Vit D)
- Exocrine
o Sweat, oil, apocrine glands
- Sensory information
o About the external environment
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find more resources at oneclass.com
Get a thick skin
- Varies from 1-5mm
- When we talk about the thickness of our skin, we are talking about the thickness of our
epidermis
- If we were to compare the thickness of the epidermis, dermis and hypodermis, then the thickest
skin would be at the upper back (bc it has a large dermis) but you have poor sensory acuity
there
Thin vs Thick skin
- Thin skin: left
o Very thin epidermis
o Note: if you see a hair follicle, you immediately know that its talking about thin skin bc
thick skin doesn’t have hair follicles
- Thick skin: right
o Very thick epidermis
o Primarily the stratum corneum is larger
Question : In which layer of the skin would you expect to find adipocytes?
a) Epidermis
b) Rete ridges
c) Dermis
d) Hypodermis
- A: hypodermis
Overview of the Epidermis
- The ones with the rainjackets on form our water barrier (important in homeostasis –
maintaining water concentrations in our body)
find more resources at oneclass.com
find more resources at oneclass.com
