Outline of Last LectureOutline of Current LectureEndocrine SystemHormone RegulationNegative Feedback and the Pituitary HormonesRegulation of Glucose levelsCalcium RegulationStressEnergy and ReactionsThermodynamicsBond EnergiesATP (adenosine triphosphate)Reactions and EnzymesBIO SCI 150 1st Edition Lecture 6Outline of Last Lecture 1. The Cella. How to Studyi. Observationii. Microscopic Examinationiii. Cell Fractionationb. Cell Typesi. Prokaryoticii. Eukaryoticc. Membrane, Wall, and Junctions2. Cell Membranea. Purposeb. To Studyc. Structurei. Permeability1. Kinds of Transportd. Large MoleculesOutline of Current Lecture 1. Endocrine Systema. Propertiesb. Types per Locationc. Regulation2. Energy and Reactionsa. Key termsb. Thermodynamicsi. Bond Energiesii. Reactions and EnzymesEndocrine SystemHormones secreted by endocrine glands are transported via the circulatorysystem to target cells. Exocrine glands secrete into ducts. Paracrine and synapticsignaling are local. The hormone molecules range widely as to type and target.The major endocrine glands and their products are:- Anterior Pituitaryo Gland located at the base of the brain synthesizes direct hormones whichact on target cells andtropic hormones which act on other endocrine glands to release hormones.- Hypothalamuso Neurosecretory cells produce hormones that are stored and released by the posterior pituitary.- Thyroid and parathyroido Located on the trachea the thyroid; produces iodine-containing hormones.- Adrenal Cortexo Located on the kidney; produces the corticosteroids- Adrenal Medullao Sympathetic nerve cells that secrete catecholamines (derivatives of aminoacids) into thecirculatory system.- Pancreaso Secretes digestive enzymes into small intestine. The islets of Langerhans produce hormones.- Testeso Male sex organ.- Ovaryo Female sex organ; production also in the placenta.- Pinealo Gland at the base of the neck, associated with circadian rhythms. Gland isregulated by light anddark- Hearto Heart produces hormone involved in water and salt balance- Thymuso Essential in the development of the immune system, it is the site of T cell maturation.Hormone RegulationNegative Feedback and the Pituitary Hormones- To maintain a constant level of cortical hormones high levels will inhibit release ofCRF and ACTH. Without CRF the anterior pituitory stops ACTH secretion andthehormone secretion by the adrenal cortex stops.- Low levels of cortical hormones will stimulate CRF release, stimulating ACTHsecretion by the anterior pituitary, which causes release of adrenal corticalhormones by the adrenal cortex.Regulation of Glucose levels- Low glucose in the bloodstream stimulates the release of glucagon. Glucagonpromotes the breakdown of glycogen by cells and release of glucose.- High glucose in the bloodstream stimulates the release of insulin. Insulinpromotes the uptake of glucose by adipose (fat) and mucscle cells and the storageof glucose as glycogen by muscle and liver cells.- Diabetes mellitus characterized by hyperglycemia (high blood glucose levels) canresult from failure to produce or respond to insulin.Calcium Regulation- High Calcium levels in blood stimulates the thyroid gland to release calcitionin.Calcitonin stimulates calcium doposition in bones, and recduces calcium uptake inthe intestines and kidneys.- Low calcium stimulates the parathyroid gland to release parathyroid hormone.Parathyroid hormone (PTH) stimulates calcium release from bones, andincreasescalcium uptake in intestines and kidneys.StressStress causes the hypothalamus to:- Signal the adrenal medula with nerve impulses (short term response)o Secrete epinephrine and norepinephrine Increase blood glucose, metabolic rate Increase blood pressure, breathing Change blood flow, increase alertness- Signal the adrenal cortex with hormones (long term response)o Secrete mineralocorticoids and glucocorticoids cause sodium ion and water retention by kidneys increase blood volume and pressure. Stimulate protein and fat breakdown increase glucose levelEnergy and Reactions- Metabolism - all cellular reactions- Catabolic - reactions that break down complex molecules usually cells obtain energy from these reactions- Anabolic - reactions that build up complex molecules These reactions usually require an energy input - Energy - capacity to do work- Kinetic - doing work, motion- Potential - stored energy- Chemical - energy stored in moleculesThermodynamics- First Law: Energy in universe is constant. It can be transformed or transferred but cannot be created or destroyed.- Second Law: Every energy transfer or transformation increases the disorderofuniverse (entropy) thus entropy increases and the amount oforder in the universe decreases- In any spontaneous process the free energy decreases- In any process that requires energy the free energy increasesBond Energies- Energy is required to break a bond- Energy is released when a bond is formedLiving systems often couple exergonic and endergonic reactions. Overallthey couple the breakdown of glucose to drive endergonic reactions like thesynthesis of protein. At the molecular level endergonic and exergonicreaction steps are coupled to drive a reaction. Living systems utilize ATP tostore and transfer energy.ATP (adenosine triphosphate)ATP is used by living systems to do work:- Mechanical - muscle contraction- Transport - across cell membranes- Chemical - synthesis of polymers- Kinetic - heatIn living systems ATP is used to transfer a phosphate group to amolecule. This phosphorylated intermediate is more reactive than theoriginal molecule.- The generation of ATP is endergonic and some exergonic pathway, such as cellular metabolism, must provide energy.- In muscle cells about 10 million molecules of ATP are recycled eachsecond in each cell.Reactions and EnzymesEnzymes are catalytic proteins that change the rate of a reaction withoutbeing consumed. They allow reactions to proceed in a way that is favorableto the cell. Often biological reactions occur under conditions or withconcentrations that do not favor the desired reactions. The living systemuses enzymes and enzyme pathways to create situations that allow essentialreactions to proceed efficiently under biological conditions.- Enzymes lower the energy barrier for a reaction- Enzymes reduce the free energy of activation or activation energy- Enzymes allow the reactants to reach the transition state- Enzymes bind to the substrate with an induced fit- The