Midlands Technical College 15

Modified Glands

  • Modified African Sweat Glands: Include ceruminous glands responsible for producing earwax (cerumen).

  • Function of Earwax:

    • Protects against water getting into the ears when showering, preventing ear infections.

    • Excessive cleaning can lead to reduced wax levels, increasing susceptibility to bacteria due to moist conditions.

Sebaceous Glands

  • Sebaceous Glands: Secrete an oily substance called sebum.

  • Purpose of Sebum:

    • Prevents skin dryness and water loss.

    • Associated primarily with hair follicles.

    • Lubricates skin and hair, keeping them soft and waterproof.

    • Contains antibacterial properties to inhibit bacterial growth on the skin.

  • Acne: Often results from clogged sebaceous ducts, exacerbated by increased testosterone during puberty. More prevalent in males due to higher testosterone levels.

Skin Functions

  • Protection:

    • Chemical Barriers: The skin's pH is more acidic due to the combination of sweat and sebum, which prevents bacterial growth.

    • UV Barrier: Protects from UV radiation.

    • Physical Barrier: Keratin provides resistance to water loss, making the skin tougher.

  • Thermoregulation:

    • Blood vessels in the skin dilate to release heat. Sweating also aids in cooling.

  • Biological Barriers: Dendritic cells (Langerhans cells) in the epidermis act as immune cells presenting antigens to the immune system.

  • Sensory Functions: The skin has the ability to detect touch, pressure, pain, and temperature through various receptors.

  • Vitamin D Production: Sunlight stimulates the conversion of precursor molecules in the skin to Vitamin D, essential for calcium metabolism and immune function.

  • Blood Reservoir: Skin can store blood and regulate its distribution when needed, which increases heat generation during physical activity.

  • Lipid Absorption: The skin absorbs certain lipids while potentially allowing harmful substances to enter.

Skin Cancer Risks

  • Types of Skin Cancer:

    • Basal Cell Carcinoma: Slow-growing, often localized, arises from the basal layer of the epidermis.

    • Squamous Cell Carcinoma: Affects cells in the stratum spinosum; can metastasize if untreated.

    • Melanoma: Cancer of melanocytes, aggressive and more likely to spread. Significant risk factors include UV exposure, fair skin, and having moles.

  • ABCD Rule for Melanoma:

    • Asymmetry: One half of the mole does not match the other.

    • Border: The edges are irregular, ragged, or blurred.

    • Color: Multiple colors or an uneven distribution of color.

    • Diameter: Larger than 6mm, roughly the size of a pencil eraser.

    • Evolution: Any changes in the mole over time, such as size, shape, or color variation.

Burns and Their Classification

  • Types of Burns:

    • First-degree burns: Affect only the epidermis; symptoms include redness and minor pain.

    • Second-degree burns: Damage epidermis and upper dermis; involve blisters and more severe pain.

    • Third-degree burns: Affect all skin layers and may damage deeper tissues; require skin grafts for healing.

  • Concerns:

    • Main threats are fluid loss, infection, and eschar (dead tissue) forming, which must be removed to prevent toxin release into the bloodstream.

Bone Development and Function

  • Functions of Bones:

    • Support, protection for organs, and movement facilitated by muscle attachment.

    • Storage of minerals and fat; red marrow for blood cell production (hematopoiesis).

    • Detoxification from heavy metals and maintenance of pH balance.

    • Hormonal functions, such as osteocalcin influencing insulin release.

  • Bone Marrow:

    • Red Bone Marrow: Responsible for hematopoiesis, predominantly found in children and in some adult bones.

    • Yellow Bone Marrow: Fat storage; can convert to red marrow in cases of severe anemia.

Bone Structure Types

  • Long Bones: Characterized by a shaft (diaphysis) and two enlarged ends (epiphysis).

  • Short Bones: Cube-shaped bones like carpals and tarsals.

  • Flat Bones: Generally flat surfaces, such as sternum and skull.

  • Irregular Bones: Do not fit into other categories, like vertebrae.

  • Sesamoid Bones: Bones embedded within tendons (e.g., patella).

Growth Plates and Bone Growth

  • Growth Plates: Growth occurs at these plates until they closure marks the end of height increase (approximately age 18 for females, 21 for males).

  • Articular Cartilage: Covers joint surfaces to minimize friction in articulations.