ENDOCRINE SYSTEMENDOCRINE SYSTEM

Chapter 10Chapter 10

Systems FunctionsSystems Functions

Regulation of homeostasis (along Regulation of homeostasis (along with the nervous system).with the nervous system).

Regulates and maintains the Regulates and maintains the synthesis of hormones (chemical synthesis of hormones (chemical signals that affect the behavior of signals that affect the behavior of other glands and tissues.)other glands and tissues.)

System AnatomySystem Anatomy

Endocrine glands (ductless glands Endocrine glands (ductless glands that secrete their hormones into that secrete their hormones into tissue fluid.)tissue fluid.)

Hormones (either classified as Hormones (either classified as peptides or steroids).peptides or steroids).

Hormones and HomeostasisHormones and Homeostasis

Negative feedback: opposes the Negative feedback: opposes the hormones release.hormones release.

Maintains the level of the hormone in the blood Maintains the level of the hormone in the blood within its normal range. within its normal range.

Antagonistic regulation: hormones Antagonistic regulation: hormones oppose each others actions.oppose each others actions.

In this circumstance you usually have two or more In this circumstance you usually have two or more hormones that regulate the release or uptake of hormones that regulate the release or uptake of variables in the body (one that turns off and one variables in the body (one that turns off and one that turns on).that turns on).

Chemical Signals and Hormone Chemical Signals and Hormone FunctionFunction

Steriod HormonesSteriod Hormones, because they , because they are fats, easily diffuse through the are fats, easily diffuse through the plasma membrane. Binding to plasma membrane. Binding to receptors occurs only after the receptors occurs only after the steroids have entered the cell.steroids have entered the cell.

Hormone-Receptor complexes bind Hormone-Receptor complexes bind to DNA and activate particular genes. to DNA and activate particular genes. This activation leads to the This activation leads to the production of a cellular enzyme in production of a cellular enzyme in multiple quantities.multiple quantities.

Chemical Signals and Hormone Chemical Signals and Hormone FunctionFunction

Peptide hormonesPeptide hormones bind to a bind to a receptor protein on the plasma receptor protein on the plasma membrane of the target cell.membrane of the target cell.

The binding of these hormones sets The binding of these hormones sets off a set of reactions ATP is off a set of reactions ATP is converted to cAMP (1converted to cAMP (1stst messenger) messenger) which tells the (2which tells the (2ndnd messenger) messenger) calcium. This sets off an enzyme calcium. This sets off an enzyme cascade. This may culminate in the cascade. This may culminate in the release of a product.release of a product.

Hormones from Other TissuesHormones from Other Tissues Heart – atrial natriuretic hormoneHeart – atrial natriuretic hormone Stomach and Small Intestines – peptide hormones Stomach and Small Intestines – peptide hormones

(regulate digestive secretions)(regulate digestive secretions) Adipose Tissue – Leptin (peptide hormone which Adipose Tissue – Leptin (peptide hormone which

acts on the hypothalamus where it signals acts on the hypothalamus where it signals satiety).satiety).

Cells and Organs – GF’s (stimulate cell division Cells and Organs – GF’s (stimulate cell division and mitosis) these are produced by cells that are and mitosis) these are produced by cells that are often involved in healing so are prone to injury.often involved in healing so are prone to injury.

Arachidonate cells – Prostaglandins (act locally – Arachidonate cells – Prostaglandins (act locally – uterus contractions, mediate pyrogens (temp reg), uterus contractions, mediate pyrogens (temp reg), reduce gastric secretions, lower blood pressure.reduce gastric secretions, lower blood pressure.

PheromonesPheromones

Chemical signals that act between Chemical signals that act between individuals. individuals.

Humans produce airborne chemicals Humans produce airborne chemicals from the scalp, oral cavity, arm pits, from the scalp, oral cavity, arm pits, genital areas, and feet. genital areas, and feet.

E.g. Armpit pheromones from one E.g. Armpit pheromones from one woman could affect the menstrual woman could affect the menstrual cycle of another woman.cycle of another woman.