Ashleigh Sargent Biology Chapter 42 Section One VOCAB Hormones- chemical messenger that travels through blood stream and excretes a distance from where they are produced Chemical substance made in one part that effects another part. Endocrine system- composed of glands that secrete hormones into bloodstream. Target Cells- cells that have receptors for a particular hormone Ovaries- produce eggs Gland- organ that produces a secretion Secretion- substance made inside a cell and released from that cell. Testes- produce sperm Endocrine Glands- major hormone producing organ of the endocrine system, doesn’t have glands, releases directly into blood stream. Exocrine glands- another group of glands that release their secretions through tube like structures called ducts Islets of Langerhans- hormone producing portion of the pancreas consist of clusters of cells Hormones bind to receptors on the cells and affect the cells behaviors. Body generally responds slower a longer lasting then responding to nerve impulses. Thyroid Gland Located at the base of the neck and wraps around the upper part of the trachea just below the larynx. - Needs iodine (salt) to secrete - secretes thyroxine - Increased levels can cause an increase in cellular respiration rate and cells have more energy and are more active. - Decreased levels cause a decrease in cellular respiration and cells have less energy and are less active. - If too much is provided a condition called Hyperthyroidism occurs= nervousness, elevated body temperature, increased heart and metabolic rates, increased blood pressure, weight loss - Surgical removal of part of the gland or certain drugs can slow the production. - If not enough is produced, a condition called hypothyroidism occurs which is a low metabolic rates and body temperature lack of energy and weight gain. - In infancy, it can effect skeletal, muscular, and nervous system causing cretinism=dwarfism and mental retardation. - Thyroxin injections solve this. Goiter is an enlargement of the thyroid gland CRETINISM- not enough thyroxin and characterized by dwarfisms and mental retardation ACROMEGALY- too much GH from pituary gland, causing gigantism DIABETES TYPE I- little or no secretion of insulin, mostly juvenile onset. DIABETES TYPE II- mainly in people after 40 cells do no have enough insulin receptors Pituary gland disorders-if to little GH, it could cause dwarfisms, if too much, it could cause gigantism HYPOTHALAMUS- controls the secretions of the Pituary gland. - neurosecretory cells extend their axons into the posterior pituary which cause hormones to enter directly into capillaries. - BIOLOGY 42-2 CONTROL OF THE ENDOCRINE SYSTEM VOCAB Negative feedback system- occurs when an increase in a substance inhibits the process leading to the increase Prostaglandins – fatty acids that cause contractions in smooth muscles like the uterus, bronchioles, and walls of blood vessels also causes pain -Polypeptide hormones affect the target cell by means of receptor molecules embedded in the cell membrane - Steroid hormones pass through the cell membrane in the cytoplasm, forming a hormone receptor complex.