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## Ceruminous Glands - Are modified apocrine sweat glands - Located only in the external acoustic meatus (ear canal) - Secrete earwax, called cerumen - Help trap foreign particles and small insects - Lubricate the external acoustic meatus and eardrum ## Mammary Glands - Are modified apocrine sweat...

## Ceruminous Glands - Are modified apocrine sweat glands - Located only in the external acoustic meatus (ear canal) - Secrete earwax, called cerumen - Help trap foreign particles and small insects - Lubricate the external acoustic meatus and eardrum ## Mammary Glands - Are modified apocrine sweat glands - Present in both males and females - Become functional only during pregnancy and lactation - Produce breast milk which nourishes the offspring - Development is controlled by the interaction between gonadal and pituitary hormones ## What Did You Learn? 1. How do apocrine sweat glands differ from merocrine sweat glands in terms of their location, secretions, and function? 2. What do sebaceous glands secrete, and where is this material secreted? ## Repair and Regeneration of the Integumentary System ### Learning Objectives 1. Distinguish between regeneration and fibrosis. 2. Describe the process of wound healing. ### Repair and Regeneration - The integumentary system responds to stressors, trauma, and damage. - Repetitive mechanical stresses stimulate cell division in the stem cells of the stratum basale, thickening the epidermis - This increases the ability to withstand stress. - For example, walking without shoes causes the soles of the feet to thicken - This provides more protection for underlying tissues. ### How Damaged Tissues Repair - Tissues can be repaired in two ways: regeneration or fibrosis. - **Regeneration:** Replacement of damaged or dead cells with the same cell type by cell division. - **Fibrosis:** Scar tissue deposition in connective tissue during healing. - Occurs when regeneration is not possible because of severe damage or lack of cell division capacity. - Scar tissue binds damaged parts together and is composed primarily of collagen fibers. - Structural restoration occurs, but functional activities are not restored. ### Wound Healing Stages 1. Cut blood vessels result in bleeding into the wound. - Blood brings clotting proteins, numerous leukocytes, and antibodies. 2. A blood clot forms, temporarily patching the wound edges. - Acts as a barrier to prevent the entry of pathogens. - Macrophages and neutrophils clean the wound of cellular debris. 3. Cut blood vessels regenerate and grow in the wound. - A soft mass deep in the wound becomes granulation tissue, a vascular connective tissue initially forming in a healing wound. - Macrophages remove the clotted blood. - Fibroblasts produce new collagen fibers. 4. Epithelial regeneration occurs due to epithelial cell division at the edge of the wound. - New epithelial cells migrate over the wound - Connective tissue is replaced by fibrosis. ### Skin Repair and Regeneration Process - Dependent on the extent of the injury. - The wider and deeper the affected surface, the longer it takes for skin to repair. - Area under repair is susceptible to complications due to fluid loss and infection. - As the severity of the damage increases, repair and regeneration ability of the integument decreases. - Some components that are not repaired may not be able to regenerate. ## Psoriasis - A chronic autoimmune disease. - Periods of flare-ups and remissions throughout a person’s lifetime. - T-lymphocytes mistakenly attack keratinocytes. - Causes rapid overgrowth and overproduction of new skin cells. - Normal sloughing-off cycle of keratinocytes disrupted. - Proliferation of cells develops into patches of typically whitish, scaly skin (called plaques) that form on the epidermal surface. - Plaques are not contagious, but may cause severe itching, pain, and skin cracking and bleeding. - Any part of the skin may be affected, but common areas include the scalp, limbs, and buttocks. - Nail pitting may also be present. - Treatments include topical corticosteroids, ultraviolet light therapy, and certain oral medications that may interfere with the production of skin cells. ## Clinical View 6.5  - Multiple whitish plaques on the forearm of a person with psoriasis. ## Integrate: Concept Connection - The process of wound repair requires stimulation and activation of the immune system, potentially resulting in an inflammatory response.