1. Week 13
The
Integumentary
System

2. The integumentary system consists of:
The Skin
Its Derivatives
Hair
Nails
Glands

3. Objective 1 Structures of the Integument

4. Skin Layers The two primary skin layers are: Plus:
Epidermis: superficial layer made of keratinized stratified squamous epithelium (subdivided into 4-5 layers)
Dermis: consists of areolar tissue and dense irregular connective tissue (subdivided into 2 layers)
Plus:
Hypodermis: attaches skin to underlying structures; made of areolar tissue and variable amounts of adipose

5. The superficial layer of the Integument
The Epidermis is:
The superficial layer of the Integument
Composed of keratinized stratified squamous epithelium
Majority of cells are called keratinocytes
Avascular

6. The epidermis has either 4 or 5 cell layers
Thin skin has 4 layers; the stratum lucidum is absent
Thick skin of the palms and soles of the feet has 5 layers

7. Layers of the Epidermis:
Mnemonic?
Come Let’s Get Some Beer…
Layers of the Epidermis:
Layer Structure
Stratum corneum rows of flat dead keratinocytes
Stratum lucidum 2-3 rows of dead keratinocytes, found only in thick skin
Stratum granulosum 3-5 rows of flat keratinocytes
Stratum spinosum 8-10 rows of flat keratinocytes,
Stratum basale single layer of keratinocytes; some melanocytes, and Merkel cells
Number of rows are less in thin skin and more in thick skin

8. Thin vs. Thick Skin

9. Identify as: Thin skin or Thick skin?

10. The Dermis
Dermal papillae
Dermis

11. Composed of connective tissue
epidermis
The Dermis is:
Deep to the epidermis
Composed of connective tissue
Consists of a superficial papillary layer and a deep reticular layer
Contains sensory receptors, nerve fibers, glands, and hair follicles
Papillary layer
dermis
Reticular layer

12. Layers of the Dermis Papillary Layer Areolar C.T. Reticular Layer
Collagen fibers
Elastic
Reticular fibers
Reticular Layer
Dense Irregular C.T.
Collagen fibers

13. Skin Derivatives Hair shaft Pore Sebaceous (oil) gland
Arrector pili muscle
Hair root
Hair follicle
Hair bulb
Hair papilla
Eccrine
(sweat) gland

14. Skin derivatives found in the dermis:
Sudoriferous (sweat) glands:
Eccrine
Apocrine

15. Sudoriferous (sweat) glands
Cross section
Low magnification
High magnification

16. Skin derivatives found in the dermis:
Hair Shaft
Arrector pili muscle
Sebaceous (oil) gland
Hair Root
Hair Follicle
Hair Bulb
Hair Papilla

17. Hair Structures Hair Bulb Hair Shaft Hair Root (visible hair)
(embedded)

18. Histology – Hair Structures
Hair Root
Hair Follicle
Hair Bulb
Hair Papilla

19. Histology – Arrector pili muscle
(smooth muscle)

20. Histology – Hair Structures
Hair follicle

21. Histology – Hair Structures
Sebaceous (oil) gland

22. Histology – Hair Structures
Sebaceous (oil) gland
Hair shaft
Hair follicle
Hair root
Arrector pili
Hair Root
Hair Follicle
Sebaceous (oil) gland

23. Cutaneous Sensory Receptors
Identify these from models
Meissner's corpuscle
Free nerve ending
Pacinian corpuscle
Hair follicle receptor
(root hair plexus)

24. The cutaneous sensory receptors are nerve endings that receive stimuli from the external environment through the skin
(Exteroceptors)
Spinal cord

25. Cutaneous Sensory Receptors

26. Meissner’s corpuscles Located in dermal papilla
Histology
Pacinian corpuscles
Located deep in dermis
Meissner’s corpuscles
Located in dermal papilla
External Internal
See skin models for 3-D structure and structural clarity

27. Note: Although a part of the nervous system, cutaneous receptors can have a direct impact on the integument

28. Consequences of Sensation Loss Diabetic neuropathy
Nerve damage due to decreased blood flow
Ulcers and infections - skin damage undetected
Charcot's Joint (neuropathic arthropathy)
Loss of motor function

29. Consequences of Sensation Loss Leprosy (Hansen’s disease)
Lesions and infections from inability to detect tissue and bone injury resulting from nerve damage caused by the bacterium Mycobacterium leprae
Appendage loss due to infection
Blindness and nasal collapse also result from nerve damage

30. Objective 2 General Sensation
Experiments

31. Distribution and Discrimination
Experiment A – 2-Point Discrimination
Determine touch receptor density
Experiment B – Mapping Temperature and Touch Receptors
Compare density of cold, heat and touch receptors
Experiment C – Tactile Localization
Localizing the stimulus (receptive field)
? cm

32. Adaptation Experiment D – Sensory Adaptation
Timing pressure sensation adaptation
Experiment E – Temperature Receptor Adaptation
Compare sensation of hand immersed in hot water with sensation of hand already immersed (adapted)