Fluids and Secretions
Fluids and secretions are substances produced, transported, or released by organisms, including blood, lymph, saliva, mucus, and digestive juices.
Blood: A circulating tissue composed of plasma, blood cells, and platelets. Blood transports gases, nutrients, waste, and immune components through the body.
Homeostasis: The regulation of internal conditions within ranges compatible with life. Fluid balance helps keep blood volume, temperature, and electrolyte levels stable.
Blood test: A laboratory analysis of a blood sample to assess cells, chemicals, or biological markers. Blood measurements reveal changes in organ function, immunity, and metabolism.
Edema: An abnormal accumulation of fluid in the spaces between cells or within body cavities. Edema occurs when fluid movement out of tissues exceeds its return or removal.
Lymph: A fluid that circulates through lymphatic vessels and returns tissue fluid to the bloodstream. Lymph carries immune cells and drains fluid from tissues.
Exocrine gland: A gland that releases its products through ducts onto a surface or into a cavity. Exocrine glands produce many secretions, including saliva, mucus, and digestive juices.
Urinalysis: The examination of urine for physical, chemical, and microscopic features. Urine testing assesses kidney function and can reveal systemic conditions.
Dehydration: A deficit of body water that disrupts normal physiological function. Losses through sweat, urine, or the digestive tract can reduce circulating fluid volume.
Saliva: A fluid produced by salivary glands that moistens food and begins digestion. Saliva lubricates the mouth and supplies enzymes that start starch digestion.
Endocrine gland: A gland that releases hormones into the bloodstream rather than through ducts. Endocrine products travel in blood, unlike secretions delivered through ducts.