Anatomy and Cell Biology 3309 Lecture Notes - Lecture 29: Dense Irregular Connective Tissue, Stratified Squamous Epithelium, Hair Follicle
Histology Lecture 1 – Semester 2
Histology of the Skin
OBJECTIVES:
- Describe the function of the skin
- Compare and contrast the layers of the skin (epidermis, dermis, hypodermis) in terms of their
appearance and the cell types contained therein
- Describe the layers of the epidermis
- Explain the cell types of the epidermis and their functions
Case Study
- Came to the clinic with paint splatter moles on his forehead
- Thin hair on his head
- Caucasian
- Moles developed recently
- Sentinel lymph nodes – where cancer cells are first expected to metastasize
Histological Image
- Assume it belonged to case study patient
- What is wrong with the image? A LOT OF MELANOCYTES IN THE DERMIS
o There are blood vessels there, lymphatic vessels there other ways for the cancer to
disseminate
o The melanocytes should normally be in the epidermis
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- Zoomed in the dermis:
o A # of different cell types throughout
- Skin is the LARGEST organ in the body – a lot going on, very complex
- Dermis:
o Many structures within
o Oil gland (sebaceous)
o Hair follicle
o Sensory type organs
▪ Pacinian corpuscle: vibration stimulus, strong touch
▪ Merkel: fine touch
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find more resources at oneclass.com
Layers of Skin
- Epidermis
o Stratified squamous epithelium
o Derived from ectoderm
o Continuously shed
▪ Lose a little bit of our skin every day
o Basophilic staining layer
o Relatively thin
- Dermis
o Loose and dense irregular connective tissue
▪ A LOT of collagen
o Derived from mesoderm
o Gives mechanical support, strength and thickness
▪ Helps maintain over structure of the skin
- Hypodermis
o Loose connective tissue
o Variable amounts of adipose tissue arranged into lobules
o Deeper than dermis
o Amount of adipocyte will depend on the individual
▪ Age
▪ Amount of fat in their body
o Involved in thermoregulation
o Mainly adipose tissue (called superficial fascia in gross anaomty)
- As we age
o Our skin is not as elastic
o Lose A LOT of adipocytes in the hypodermis
▪ Therefore – they are a lot colder, can not thermoregulate as much
- Derivatives of skin include sweat glands, hair, sebaceous glands and nails.
Functions of the Skin
- Barrier- protects against physical, chemical, and external environmental biologicals
o Individuals with severe burns that compromise a large amount of their skin are VERY prone
to infection why burns are so deadly
- Immunologic- Langerhans cells
o Skin has its own antigen presenting cells
- Homeostasis- regulates body temperature and water loss
o Regulate body temperature through shivering, sweating, hair on our body
▪ Reason why people with anorexia have more hair on their forearm or other parts o
their body trying to compensate because they have lose it in their hypodermis
- Sensory information- about the external environment
o Sensory homunculus is how our skin and body is mapped on our brain
▪ Area with a lot of sensor information: lips, finger tips have more dense
concentration of sensory organs
- Endocrine functions- produces some hormones and cytokines, vitamins (D)
- Exocrine function- sweat, oil, apocrine glands, sebum
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Compare and contrast the layers of the skin (epidermis, dermis, hypodermis) in terms of their appearance and the cell types contained therein. Explain the cell types of the epidermis and their functions. Came to the clinic with paint splatter moles on his forehead. Sentinel lymph nodes where cancer cells are first expected to metastasize. Assume it belonged to case study patient. A lot of melanocytes in the dermis: there are blood vessels there, lymphatic vessels there other ways for the cancer to disseminate, the melanocytes should normally be in the epidermis. Zoomed in the dermis: a # of different cell types throughout. Skin is the largest organ in the body a lot going on, very complex. Dermis: many structures within, oil gland (sebaceous, hair follicle, sensory type organs, pacinian corpuscle: vibration stimulus, strong touch, merkel: fine touch. Epidermis: stratified squamous epithelium, derived from ectoderm, continuously shed, lose a little bit of our skin every day, basophilic staining layer, relatively thin.