- - AGRICULTURAL CORE CURRICULUM - - (CLF200) Core area: ANIMAL SCIENCE (CLF240) Unit title: MAJOR MAMMALIAN BODY SYSTEMS ___________________________________________________________________________ (CLF247) Topic: HORMONE INFLUENCE time taught in year 2 hours 2 ____________________________________________________________________________ Topic objectives: Upon completion of this lesson, the student will be able to: Learning Outcome: (C-1,9,10) - Define and use terminology related to hormone influence such as "receptor cells, negative feed back, endocrine gland, and homeostasis." (C-1,9,10) - Diagram a simple feedback example like one of those found in this topic. (Thyroxine and oxytocin control.) (C-1,9,10) - Discuss the way levels of hormones are controlled in the body. (C-1,9,10) - Explain the importance of hormones to body function and metabolism. Special Materials & Equipment: Overhead projector, chart of hormones and their major functions References: California Curriculum Guidelines - Ag Production: Vol I. Curtis, Helena. (1977). Invitation to Biology. Worth Publishers, Inc. Biology. (1986). Harcourt, Brace & Jovanovich, Orland, Fla. Evaluation: Tests, quizes, crossword puzzles. TOPIC PRESENTATION: HORMONE INFLUENCE A. How are hormones controlled and what do they influence? 1. Hormones affect many vital functions in the body. a. The amount of each hormone secreted varies with the state of the animal's body and the state of its environment (is it about to be milked, is it scared, etc.). b. Since these items change constantly, the amount of hormone secreted must be carefully controlled so the animal can maintain: 1) normal homeostasis (balance of the body - temperature, heart rate, blood pressure, etc.). 2. The ENDOCRINE glands that secrete hormones, do so directly into the blood. (Examples may be found in the diagrams below.) 3. Each hormone stimulates "receptor" cells (other cells that will respond to the hormone) in the target gland or organ. a. The response of the target gland or organ depends on the level of the hormone in the blood and is carefully monitored by the body systems. **************************************************************************** 4. The milk-ejection reflex is an example of endocrine gland activity. spinal cord _______ ==================================================> |brain | /|\ |______| | | | | | \|/ | ______________________ | | posterior pituitary | | | gland | | |_____________________| | / | / | / | / <-- oxytocin | / udder <-------------------------------- bloodstream /|\ /|\ | | | | stimulation of the udder by washing by the milker, or suckling by the calf When the udder is stimulated, nerve impulses pass through the spinal cord to the brain. The brain responds by "telling" the POSTERIOR PITUITARY to discharge OXYTOCIN into the bloodstream. The hormone is carried to the udder where it causes a muscle like contraction that brings about "milk-letdown". The milker or calf can easily obtain the milk that was made and (to a great extent) is held in the alveoli (milk producing cells). ***If the cow is scared, or is hurt (bitten by the calf or the milking machine, a nerve impulse will stimulate the adrenal gland to secrete epinephrine (adrenaline). The hormone will overcome the action of oxytocin and shuts off the "milk-ejection reflex." (Bovine moral of this story, "don't bite the udder that feeds you!) **************************************************************************** 5. Other hormones needed on at a constant level in the body are controlled by a continuous "feedback system" through the bloodstream. An example: ________________________ | hypothalmus | | ________________ | / ---------> |receptor cells| | ----> \ / |___|______________|___| \ / \ <--- releasing / \ hormone / \ bloodstream pituitary \ / \ / thyroxin-->\ / <---thyroid \ / stimulating \ <------------ thyroid gland <---------/ hormone (TSH) In this diagram the level of the hormone thyroxine is controlled by negative feedback. The hypothalmus regulates (controls) the level of thyroxin in the bloodstream. The receptor cells recognize thyroxine and monitor the level in the bloodstream all of the time. If the level is low, they "tell" the hypothalmus to secrete a releasing hormone that "tells" (stimulates) the PITUITARY to secrete THYROID STIMULATING HORMONE. This puts the thyroid gland into action and it releases THYROXIN into the BLOODSTREAM. When the level reaches normal again the RECEPTOR CELLS signal for shutdown of THYROXIN release. __________________________________________________________ ACTIVITIY: 1. Have the student generate a "feedback mechanism" of their choice as homework. It might be another hormonal system, or even the way behavior is monitored at your high school. 2. Using Supplemental Handout #1, review the glands, hormones secreted, and the major physiological function of each. 3. A crossword puzzle could be created, based on the handout also. __________________________________________________________ Supplement Handout#1: IMPORTANT HORMONES SECRETED BY THE ENDOCRINE GLANDS AND SOME OF THEIR MAJOR FUNCTIONS ============================================================================ ENDOCRINE GLAND HORMONE SECRETED MAJOR PHYSIOLOGICAL FUNCTIONS ---------------------------------------------------------------------------- Anterior pituitary Growth hormone (GH Promotes growth of tissues and or STH) bone matrix of the body. Adrenocorticotropin Stimulates secretion by the (ACTH) adrenal cortex. Gonadotropic Stimulates ova production in Follicle-stimulating the female and sperm production Hormone (FSH) in the male. Lutenizing hormone Causes ovulation in the female. (LH or ICSH) Causes testosterone production by the interstitial cells of the testes in the male. Prolactin or luteo- Maintains the corpus luteum of pin (LTH) of the ovary and progesterone secretion. Initiates and main- tains lactation. Induces broodiness in hens. Stimulates thyroid gland to secrete thyroxine. Hypothalamus Oxytocin Causes ejection of milk, expul- (stored in the sion of eggs in hens, and con- posterior traction of the uterus at pituitary) parturition. Vasopressin (anti- Causes constriction of the diuretic) peripheral blood vessels and water resorption in the kidney tubules. Hormone-releasing Cause release of hormones from factors the anterior pituitary. Thyroid Thyroxine Increases rate of cellular metabolism. (Growth, activity level, etc.) Thyrocalcitonin Promotes incorporation of calcium into bone. Parathyroid Parathormone Maintains or regulates the level of blood calcium and phosphorus. Adrenal glands Glucocorticoids Mobilize energy, increase blood (Cortex or outer shell) glucose level, have an anti- stress action. Supplemental Handout#1: continued IMPORTANT HORMONES SECRETED BY THE ENDOCRINE GLANDS AND SOME OF THEIR MAJOR FUNCTIONS ============================================================================ ENDOCRINE GLAND HORMONE SECRETED MAJOR PHYSIOLOGICAL FUNCTIONS ---------------------------------------------------------------------------- Adrenal Gland Mineralocorticoids Maintain salt and water balance (continued) in the body. Medulla (core) Epinephrine (adrenal- Stimulates dilation of the in) heart muscles and the rate and strength of their contraction. Norepinephrine Stimulates smooth muscles and glands and maintains blood pressure. Ovaries Estrogens Cause growth of reproductive tract & mammary duct system. Progesterone Prepares reproductive tract for pregnancy, maintains pregnancy, and causes development of mam- many lobule-alveolar system for lactation. Relaxin Causes relaxation of ligaments and cartilage in the pelvis, which assists in parturition. Testes Androgens Cause maturation of sperm and (e.g..- testosterone) their preservation during storage. Promotes development of male accessory sex glands and secondary sex character- istics. Pancreas (islets Insulin Lowers blood glucose. of Langerhans) Glucagon Raises blood glucose. Placenta (in some Gonadotropins, Stimulate hormone secretion by species) adrenocorticotropins, ovaries, uterus, and adrenals. estrogens, and progesterone. 10/4/88 gfv