ENDOCRINE SYSTEM Chapter 10

Systems Functions Regulation of homeostasis (along with the nervous system). Regulation of homeostasis (along with the nervous system). Regulates and maintains the synthesis of hormones (chemical signals that affect the behavior of other glands and tissues.) Regulates and maintains the synthesis of hormones (chemical signals that affect the behavior of other glands and tissues.)

System Anatomy Endocrine glands (ductless glands that secrete their hormones into tissue fluid.) Endocrine glands (ductless glands that secrete their hormones into tissue fluid.) Hormones (either classified as peptides or steroids). Hormones (either classified as peptides or steroids).

Hormones and Homeostasis Negative feedback: opposes the hormones release. Negative feedback: opposes the hormones release. Maintains the level of the hormone in the blood within its normal range. Antagonistic regulation: hormones oppose each others actions. Antagonistic regulation: hormones oppose each others actions. In this circumstance you usually have two or more hormones that regulate the release or uptake of variables in the body (one that turns off and one that turns on).

Chemical Signals and Hormone Function Steriod Hormones, because they are fats, easily diffuse through the plasma membrane. Binding to receptors occurs only after the steroids have entered the cell. Steriod Hormones, because they are fats, easily diffuse through the plasma membrane. Binding to receptors occurs only after the steroids have entered the cell. Hormone-Receptor complexes bind to DNA and activate particular genes. This activation leads to the production of a cellular enzyme in multiple quantities. Hormone-Receptor complexes bind to DNA and activate particular genes. This activation leads to the production of a cellular enzyme in multiple quantities.

Chemical Signals and Hormone Function Peptide hormones bind to a receptor protein on the plasma membrane of the target cell. Peptide hormones bind to a receptor protein on the plasma membrane of the target cell. The binding of these hormones sets off a set of reactions ATP is converted to cAMP (1 st messenger) which tells the (2 nd messenger) calcium. This sets off an enzyme cascade. This may culminate in the release of a product. The binding of these hormones sets off a set of reactions ATP is converted to cAMP (1 st messenger) which tells the (2 nd messenger) calcium. This sets off an enzyme cascade. This may culminate in the release of a product.

Hormones from Other Tissues Heart – atrial natriuretic hormone Heart – atrial natriuretic hormone Stomach and Small Intestines – peptide hormones (regulate digestive secretions) Stomach and Small Intestines – peptide hormones (regulate digestive secretions) Adipose Tissue – Leptin (peptide hormone which acts on the hypothalamus where it signals satiety). Adipose Tissue – Leptin (peptide hormone which acts on the hypothalamus where it signals satiety). Cells and Organs – GF’s (stimulate cell division and mitosis) these are produced by cells that are often involved in healing so are prone to injury. Cells and Organs – GF’s (stimulate cell division and mitosis) these are produced by cells that are often involved in healing so are prone to injury. Arachidonate cells – Prostaglandins (act locally – uterus contractions, mediate pyrogens (temp reg), reduce gastric secretions, lower blood pressure. Arachidonate cells – Prostaglandins (act locally – uterus contractions, mediate pyrogens (temp reg), reduce gastric secretions, lower blood pressure.

Pheromones Chemical signals that act between individuals. Chemical signals that act between individuals. Humans produce airborne chemicals from the scalp, oral cavity, arm pits, genital areas, and feet. Humans produce airborne chemicals from the scalp, oral cavity, arm pits, genital areas, and feet. E.g. Armpit pheromones from one woman could affect the menstrual cycle of another woman. E.g. Armpit pheromones from one woman could affect the menstrual cycle of another woman.