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Saliva on a baby's lips. Saliva (commonly referred to as spit or drool) is an extracellular fluid produced and secreted by salivary glands in the mouth.In humans, saliva is around 99% water, plus electrolytes, mucus, white blood cells, epithelial cells (from which DNA can be extracted), enzymes (such as lipase and amylase), and antimicrobial agents (such as secretory IgA, and lysozymes).
In humans, 1200 to 1500 ml of saliva are produced every day. [3] The secretion of saliva (salivation) is mediated by parasympathetic stimulation; acetylcholine is the active neurotransmitter and binds to muscarinic receptors in the glands, leading to increased salivation. [3] [4]
Saliva consists of mucus and serous fluid; the serous fluid contains the enzyme amylase, which is important for the digestion of carbohydrates. Minor salivary glands of von Ebner present on the tongue secrete the lipase. The parotid gland produces purely serous saliva. The other major salivary glands produce mixed (serous and mucus) saliva.
Human saliva contains a wide variety of bacteria that are harmless in the mouth, but that may cause significant infection if introduced into a wound. A notable case was a diabetic man who licked his bleeding thumb following a minor bicycle accident , and subsequently had to have the thumb amputated after it became infected with Eikenella ...
This means that tissue fluid has a different composition in different tissues and in different areas of the body. The plasma that filters through the blood capillaries into the interstitial fluid does not contain red blood cells or platelets as they are too large to pass through but can contain some white blood cells to help the immune system.
Pie charts of typical human body composition by percent of mass, and by percent of atomic composition (atomic percent) Body composition may be analyzed in various ways. This can be done in terms of the chemical elements present, or by molecular structure e.g., water , protein , fats (or lipids ), hydroxyapatite (in bones), carbohydrates (such ...
The blood–saliva barrier is primarily formed by the endothelial cells lining the blood vessels and the epithelial cells lining the oral mucosa, [4] [1] and also has a connective tissue layer. The epithelial cells of the blood–saliva barrier present in gingival epithelium (lining the gums) and junctional epithelium (that surrounds teeth at ...
Clinical samples are generally defined as non-infectious human or animal materials including blood, saliva, excreta, body tissue and tissue fluids, and also FDA-approved pharmaceuticals that are blood products. [7] In medical contexts, it is a specimen taken for diagnostic examination or evaluation, and for identification of disease or ...