what do you mean I’m Hormonal? REALLY ?! https://www.youtube.com/watch?v=eWHH9je2zG4

Hormones Objectives: I will be able to: describe how hormones bring about their effects in the body. explain how various endocrine glands are stimulated to release their hormonal products. describe the role of negative feedback in regulating hormone levels.

The Endocrine System Two different systems control the body, sometimes working together and sometimes working alone. The Nervous System is built for speed and uses nerve impulses to initiate immediate reactions. The Endocrine System takes it slow and easy, using chemical messengers sent through the blood. The endocrine system is scattered all through the body and is made up of small organs with big functions.

The Endocrine System gland: an organ specialized to secrete or excrete substances for further use in the body or for elimination hormones: chemical messengers secreted by endocrine glands and responsible for specific regulatory effects on certain cells, tissues, or organs

The Chemistry of Hormones Hormones are chemical substances secreted by endocrine cells into the extracellular fluids between cells and tissues. Hormones are classified or divided into two different groups: amino acid-based molecules (proteins, peptides, amines) that are water soluble steroids that are lipid soluble

 Which systems control body functions? In which region of the body can you find the endocrine system? How are hormones classified? Nervous system and Endocrine system All over the body. 3. amino acid-based molecules that are water soluble and steroids that are lipid soluble

Hormone Action target cell/organ: any cell or organ that has a specific receptor for a specific hormone Hormones alter cellular activity by increasing or decreasing normal metabolic processes. Any given hormone targets or affects only certain tissue cells or organs in the body. Specific protein receptors are imbedded in a cell’s plasma membrane or in the interior cytoplasm. The hormone attaches to this receptor.

Hormone Action Hormone actions include: changing plasma membrane permeability changing membrane potential by opening or closing ion channels activating or inactivating enzymes stimulating or inhibiting cell division promoting or inhibiting secretion of a product turn on or turn off transcription of certain genes

Hormone Action Steroid hormones use direct gene activation to trigger changes in cells. Being lipid-soluble, steroids can diffuse through the cell membrane and attach to a receptor inside the cell. The hormone-receptor complex then binds to a specific site on the cell’s DNA to trigger the synthesis of new proteins.

Hormone Action cascade: a series of steps or stages that, once initiated, continues to the final step because each step is triggered by the preceding one Protein and peptide hormones use a second- messenger system of cascading steps to trigger changes in cells. Being water-soluble, they are repelled by the cell membrane and must bind to a receptor on the cell membrane surface. The activated receptor activates an enzyme that catalyzes reactions to produce second-messenger molecules that cause an effect.

 Walking barefoot, you step on a piece of broken glass and immediately pull your foot back. Why is it important that the signal triggering this motion come from the nervous system and not from the endocrine system? What does “target organ” mean? Describe a cascading effect of something in your everyday life! The endocrine response is too slow for the action needed to protect yourself. An organ that has a receptor for a specific hormone. Answers will vary. Should detail a series of events that can’t be stopped once started. (possible answers: implementing a tax on manufacturers, eliminating a food source for an organism at the bottom of a food chain, the Krebs cycle, nuclear fission in an atomic weapon)

Control of Hormone Release negative feedback: feedback that causes the stimulus to decline or end In negative feedback mechanisms, some internal or external stimulus triggers hormone secretion. Next, a rising level of the hormone inhibits further hormone release (even while the target organ is still being triggered). This keeps the desired result (such as blood levels) in a narrow, homeostatic range.

Control of Hormone Release Stimuli mechanisms are responsible for activating endocrine glands and include: Hormonal stimuli Humoral stimuli Neural stimuli

Control of Hormone Release Hormonal stimulus is the most common type of endocrine stimuli. An endocrine gland is stimulated by one hormone to synthesize another hormone. This hormone, in turn, stimulates another gland to synthesize a third hormone, and so on.

Control of Hormone Release Humoral Stimulus helps control the blood levels of certain ions and nutrients. Humoral stimuli occur when blood levels of these ions and nutrients decreases. Neural stimuli occur in rare cases where nerve fibers stimulate hormone release. E.G. The sympathetic nervous system stimulating the adrenal medulla to release norepinephrine and epinephrine for “fight or flight.”

 What is the desired result of most hormone release? Describe how a negative feedback mechanism works. Name the three types of stimuli that cause hormone release. Homeostasis External or internal stimuli cause release of hormones, those hormones, in return, inhibit further hormone synthesis. Hormonal, humoral, neural

 Review

Web Links Great Glands - Your Endocrine System: CrashCourse Biology #33 https://www.youtube.com/watch?v=WVrlHH14q3o Endocrine System, part 1 - Glands & Hormones: Crash Course A&P #23 https://www.youtube.com/watch?v=eWHH9je2zG4