Lecture 6: Integumentary System Essentials Of Anatomy And Ph

Lecture 6 Integumentary Systemessentials Of Anatomy And Physiologyre

Discuss the role of the skin in the protection of the body from disease and external injury, and the regulation of body fluids and temperature, absorption, synthesis, sensory reception and communication. Discuss the functions of skin, hair, glands and nails. Name the glands of the skin and describe the secretions they produce. Describe the structure and function of the epidermis, dermis and hypodermis. Explain how melanin, carotene, blood and collagen affect skin color.

Review Questions:

1. Name the components of the integumentary system.
2. What functions does the Integumentary system serve?
3. In what ways does the integumentary system provide protection?
4. What are the layers of the Integumentary system? What components does each layer have/lack?
5. Why is it important that the epidermis serve as a barrier against UV rays, yet not block them out completely?
6. What kind of tissue is the epidermis? Where are new cells formed? From where are they sloughed (i.e., gotten rid of)?
7. Define keratinization. What role does keratinization play?
8. Name the cells that produce melanin. What role does melanin play?
9. Describe the factors that determine the amount of melanin produced in the skin.
10. Explain the differences in skin color between individuals and in different parts of the body.
11. What structure aids to protect us from UV damage to our nuclei? What is skin cancer, what kinds are there and how can we prevent it?
12. What type of tissue is the dermis? What is responsible for its structural strength? How does the dermis supply the epidermis with blood?
13. What type of tissue is the hypodermis and what are its functions?
14. What does it mean that a structure is a “skin derivative”?
15. Briefly describe the structure of hair. What part of hair is the site of hair growth? Is most of the hair alive or dead?
16. What happens when the arrector pili of the skin contract?
17. What roles do the sebaceous and sweat glands play? How are these glands similar/different?
18. What functions does each of the above types of glands provide?
19. Why is it that sweat is sometimes smelly?
20. What are nails made up of? Describe the structure of the nail and where it grows from. What purpose do nails serve?
21. Explain the role of the Integumentary system in wound healing. How does a wound heal? At what level does healing begin? Where does the blood come from when you receive a wound? Where do new cells come from? What if you don’t bleed when you cut yourself, what does that mean? List the steps of wound healing and explain what is occurring in each.

Paper For Above instruction

The integumentary system, composed predominantly of the skin, hair, nails, and glands, serves vital functions in protecting the body, regulating temperature, sensory reception, and communication. Its complex structure allows it to act as a barrier against pathogens, injury, and ultraviolet (UV) radiation, while also playing a crucial role in thermoregulation and synthesis of important substances like vitamin D. Understanding its components and functions provides insight into how this system sustains overall health and withstands environmental challenges.

Components and Functions of the Integumentary System

The primary components include the skin (comprising the epidermis, dermis, and hypodermis), hair, nails, and various glands. The skin acts as a physical barrier that protects underlying tissues from external injury and microbial invasion. It also prevents excessive water loss, thus maintaining fluid balance. Sensory receptors embedded within the skin detect touch, pressure, pain, and temperature changes, facilitating communication with the nervous system (Gray, 2018). Additionally, the skin performs absorption and synthesis, notably producing vitamin D when exposed to UV rays, which is essential for calcium absorption and bone health.

Layers of the Integumentary System

The skin comprises three main layers: the epidermis, dermis, and hypodermis. The epidermis, primarily made of stratified squamous epithelium, provides an outer protective barrier. Its keratinized cells are continuously renewed in the basal layer, while dead cells are sloughed from the surface. The dermis, composed mainly of dense irregular connective tissue, supplies strength and elasticity to the skin through collagen and elastin fibers. It houses blood vessels, nerves, hair follicles, and glands, serving as the nutritive layer for the avascular epidermis (Kanitakis, 2002). The hypodermis, also called subcutaneous tissue, mainly consists of adipose tissue that cushions internal organs and insulates the body.

Skin Color and Its Influencing Factors

Skin color results from the interplay of melanin, carotene, blood supply, and collagen. Melanin, produced by melanocytes in the epidermis, determines pigmentation and protects against UV damage. The amount and type of melanin influence whether skin appears darker or lighter. Carotene, derived from dietary sources, deposits in the stratum corneum causing a yellow-orange hue. Blood flow, particularly oxygenated hemoglobin, imparts a pinkish tint, while collagen fibers contribute to skin’s firmness and tone (Barrett & Bodey, 2019). Variations in these factors lead to diverse skin tones among individuals and across different body regions.

Protection Against UV Radiation and Skin Cancer

The epidermis contains keratinocytes that produce melanin, which absorbs and disperses UV rays, protecting nuclear DNA from damage. However, excessive exposure can overwhelm melanin's protective capacity, leading to skin cancer. Types of skin cancer include basal cell carcinoma, squamous cell carcinoma, and melanoma—each varying in severity and metastatic potential. Protective measures include using sunscreen, wearing protective clothing, and avoiding peak sun hours (American Cancer Society, 2020). Melanocytes, located in the stratum basale, are the cells responsible for melanin production, with their activity modulated by genetic and environmental factors.

Structure and Function of Dermis and Hypodermis

The dermis’s structural strength is predominantly due to collagen fibers, which resist tearing and provide tensile strength. Blood vessels within the dermis supply nutrients and oxygen to the avascular epidermis. The hypodermis, rich in adipocytes, insulates the body and provides cushioning, facilitating movement and absorbing shocks (Kanitakis, 2002).

Skin Derivatives: Hair, Nails, and Glands

Hair follicles, sebaceous (oil) glands, and sweat glands are skin derivatives. Hair is primarily composed of keratin, and its growth occurs in the hair matrix located in the follicle's bulb. Most hair is dead keratinized cells, with only the follicle's matrix being alive and responsible for growth. Contracting arrector pili muscles cause hairs to stand up—a response often associated with cold or fear, creating "goosebumps" (Fowler et al., 2017). Nails are made of keratin and grow from the nail matrix at the proximal end of the finger or toe, serving protective and functional roles.

Glands and Their Roles

The sebaceous glands produce sebum, an oily secretion that lubricates skin and hair, providing a barrier against water loss and microbial invasion. Sweat glands produce sweat, aiding thermoregulation and waste excretion. Eccrine glands are involved in temperature regulation, while apocrine glands, located mainly in the axillae and groin, produce body odour through bacterial decomposition (Lloyd et al., 2019). Sweat's smell arises from bacterial metabolites acting on the secreted fluid.

Wound Healing Process

The skin’s ability to heal wounds involves a complex, multi-stage process beginning immediately upon injury. Healing initiates with hemostasis, where blood clotting occurs to prevent further bleeding. Subsequently, inflammation takes place, recruiting immune cells to combat infection and clear debris. The proliferative phase involves the formation of new tissue, involving fibroblasts producing collagen to rebuild the dermis, and keratinocytes migrating to close the wound. Finally, the remodeling phase strengthens the repaired tissue. Blood supply, originating from nearby vessels, delivers essential nutrients and cells necessary for regeneration (Gurtner et al., 2008). If an individual does not bleed when cut, it may suggest impaired blood clotting or damage to blood vessels, which can complicate healing and necessitate medical evaluation.

Conclusion

The integumentary system is vital for protecting internal structures, maintaining homeostasis, and facilitating communication with the external environment. Its intricate architecture and diverse functions underscore its importance in overall health and disease prevention. Knowledge of its components, functions, and healing mechanisms enhances our understanding of skin-related conditions and promotes effective management and preventive strategies.

References

• American Cancer Society. (2020). Skin Cancer Treatments and Prevention. https://www.cancer.org/cancer/skin-cancer.html
• Barrett, A., & Bodey, S. (2019). Skin pigmentation: Melanin and genetic factors. Journal of Dermatological Science, 94(3), 453-460.
• Fowler, J., et al. (2017). The biology of hair growth. Scientific Reports, 7, 11744.
• Gurtner, G. C., et al. (2008). Wound repair and regeneration. Nature, 453(7193), 314-321.
• Kanitakis, J. (2002). Anatomy, histology and immunohistochemistry of human skin. In Recent Advances in Skin Biology (pp. 27-68). Springer.
• Lloyd, K., et al. (2019). Sweat glands: Function and regulation. Journal of Clinical & Diagnostic Research, 13(2), 1-4.
• Gray, H. (2018). Anatomy of the human body. Lea & Febiger.