BIO 242 1st Edition Lecture 2Outline of Last Lecture I. Syllabus OverviewOutline of Current Lecture II. AnnouncementsIII. HomeostasisIV. Chemistry ReviewCurrent LectureI. Announcementsa. Camtasia for slides 1 – 28 of the BIO 242 PowerPoint are available for students nowb. Camtasia lectures are essential in order to catch up due to snowdaysc. If class is cancelled the material will be posted on Camtasiad. Reminder: Syllabus quiz is due Feb 1st II. Homeostasisa. Homeostasis- the maintenance of relatively consistent conditions in the internal environment.i. The internal environment is in a dynamic, steady stateii. To say that the internal environment is regulated to remain constant means that the composition, temperature, and volume of extracellular fluid do not change significantly under normal conditions. These factors apply to various homeostatic states within the body.These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.1. i.e. concentration of glucose increases when you eat an applea. Glucose is in a dynamic state because it changes but also in a steady state.iii. The ability to maintain such consistency is important because the body continually faces potentially disruptive changes that can originate either in the external environment or within the body itself.iv.v. The internal environment is considered to be outside the cells but inside the body. Consists of:a. Extracellular fluid (ECF) – fluid located outsidecells. ECF contains few proteins and is relatively rich in sodium.b. Plasma- the portion that is present in blood (The liquid, noncellular part of the blood).c. Interstitial fluid (ISF)- the portion that is present outside of the blood and that bathes most of the cells in the body. vi. There are many factors that contribute to keeping the body in a range in order to keep a steady state.b. Negative Feedback i. Most homeostatic regulatory mechanisms operate by negative feedback.ii. Negative feedback- a response to a change in a controlled variable (ex: glucose) is in our position oppose to change. 1. Examples:a. A fall in temperature, the body is going to try and warm it up.Orb. An increase in body temperature, the body is going to try and cool the body down.c. Note: She suggests students look up and understand the thermostat example of negative feedback.c. Positive Feedbacki. Positive feedback- a response to enhances the change that was set in motion.1. Example: contraction of the uterusa. The hormone secreted to cause contractions during a pregnancyis called oxytocin.i. Oxytocin increases contractions.1. This hormone does this by sending the brain a message to release more oxytocin.2. This signal continues to be sent to the brain until the baby is born.III. Chemistry Reviewa. Note: the basics of chemistry are needed to understand physiology.b. Terms:i. Solution- is a mixture that consists of a solvent and a solute.ii. Solvent- is the substance of a solution that dissolves another substance (the solute).iii. Solute- the substance that dissolves in the solvent to create a solution.iv. Matter- anything that occupies space and has mass.c. Mass vs. Weighti. Mass- the amount of matter something is composed of.ii. Weight- the effect of gravity it has on an object.iii. Note: these two are not really interchangeable.d. The atomi. Atoms- consist of subatomic particles. Atoms consist of mostly empty space.ii. Subatomic particles are protons, electrons, neutrons.1. Protons- have a + charge and are found in the nucleus.2. Neutrons- have no charge or are known as neutral and are found in the nucleus.3. Electrons- have a negative charge and are found in shells in the electron cloud that surrounds the nucleus.e. Elementsi. Most living things are made of these 4 main elements:1. Carbon2. Hydrogen3. Nitrogen4. Oxygenii. Example of an element on the periodic table below : Carbon Atomic mass units (amu)  atomic number atomic mass units – (amu) consists of the number of protons plus neutronstogether.Atomic number- represents the number of protons- NOTE: Exam question- What distinguishes different elements from eachother? o Answer: the number of protons- She will also ask students to find the number of neutrons in carbon (orsomething similar).12C6o Ex: how many neutrons are there in carbon? There are 6 neutrons in a neutral carbon - 12 amu – 6 protons = 6 neutrons- Note: most hydrogens has no neutrons- There are exceptions to this example (isotopes).- IMPORTANT: the number of electrons and protons are the same. Thenumber of electrons can change under certain conditions. f. Isotopesi. Isotopes are exceptions because they vary in the number of neutrons.1. Example: carbon – 13 has 7 neutrons, carbon-14 has 8 neutrons (notethat both still have 6 protons!)2. Most hydrogens have no neutrons and some have 1 or 2 neutrons.g. Chemical Bondingi. Electrons orbit in electron shellsii. 1st shell only has 2 electronsiii. 2nd shell has 4 electronsiv. 3rd shell has 8 electronsv. Valence shell- the outer most shellvi. The purpose is to have the outer most shell filled because this is the most stablestate h. Ionic Bondingi. Ionic bonds- weak bonds, means they tend to disassociate (break bonds) in thesolution.1. NaCl (table salt, sodium chloride)a. Na = 11 electrons so it has one in in its last shell and Cl has 17electrons and only needs one more electron to fill its outer mostshell.b. Na loses 1 electron while Cl gains 1 electron = Na+ and Cl-c. Why do they stay together still now that they are both stable?i. Answer: Na is not neutral anymore => Na+ because ithas 10 electrons. Cl is Cl- because it now has 18electrons. ii. If you put NaCl in water -> bonds will break ordisassociate in the solution. iii. Ions are good conductors of electricity.2. Electrolytes- ions in biological systemsa. i.e. potassium or sodiumii. Remember: there are over 100 elements therefore it gets more complex.iii. Cation- an element of a molecule that is a + charged ioniv. Anion – an element of a molecule that is a – charged ion.i. Covalent Bondsi. Electrons are shared when they are involved in covalent bonding.1. These are strong bonds 2. They do not disassociate in solutiona. Ex: methane (CH4) i. Note: the subscript indicates the number of atomspresent.ii. To make both atoms happy, they have to shareelectrons. H needs 1 more