Biology40A: 02/06/24

Commensals

Commensals are those type of microbes that reside on either surface of the body or at mucosa without harming human health. The microbes living in harmony with human mostly consist of bacteria, also known as commensal bacteria, which are 10 times more than the cells present in our body.

Just Skin Deep — Your Immune System at the Surface

June 5, 2015 Rachel Cotton Biology Blog Pick of the Month Body Medicine PLoS PLoS Blogs ResearchBlogging Student Column Students The Student Blog

The skin is the human body’s largest organ. At 1.8 square meters for the average adult, skin covers about as much area as a large closet, and accounts for 12-15% of total body weight. The incredible variation in skin — oily, moist, or dry, exposed to light and cold, or dark and warm — even on an individual, creates unique habitats for the thousands of bacterial and fungal species (called commensal microbiota) that live on our skin. The skin immune system may control skin microbes, but our skin commensals can also educate our immune system. How our skin orchestrates this dialogue with microorganisms and physical insult is integral to its function, and to our health.

The skin is an immunologic organ. There are an estimated 20 billion T cells in human skin — far greater than the number of T cells in the blood — suggesting that immune defense in the skin is a high priority. The interaction among skin microorganisms and the immune system is likely not adversarial most of the time. Interestingly, the incidence of inflammatory skin conditions like atopic dermatitis in children has about doubled in the last thirty years, in parallel with the decreased exposure to microorganisms in early life.

Monocytes

a large phagocytic white blood cell with a simple oval nucleus and clear, grayish cytoplasm.

oxygen gas

Oxygen is a chemical element with an atomic number of 8 (it has eight protons in its nucleus). Oxygen forms a molecule (O₂) of two atoms which is a colorless gas at normal temperatures and pressures. Four representations chemists use for molecular oxygen.

Glactose

Galactose is a monosaccharide and has the same chemical formula as glucose, i.e., C6H12O6. It is similar to glucose in its structure, differing only in the position of one hydroxyl group. This difference, however, gives galactose different chemical and biochemical properties to glucose.

Is galactose good or bad for you?
Summary: Galactose is crucial for human metabolism, with an established role in energy delivery and galactosylation of complex molecules, and evidence for other roles is emerging.