BIO 361 Week 1 Notes
BIO 361 Week 1 Notes Bio 361
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This 7 page Class Notes was uploaded by Kelsey Battelle on Monday January 18, 2016. The Class Notes belongs to Bio 361 at Missouri State University taught by Day Ligon in Spring 2016. Since its upload, it has received 8 views. For similar materials see Physiology in Biology at Missouri State University.
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Date Created: 01/18/16
BIO 361 Exam 1 PHYSIOLOGY: THE STUDY OF HOW ORGANISMS FUNCTION Physiology is an expansive discipline, and can be subdivided into many fields of specialization. Pharmacology: the study of how drugs interact with living organism to change function Exercise physiology: the study of human function and performance during physical activity o Limits to an organisms performance Plant physiology: the study of plant function o Example: skunk cabbage It is an endotherm that generates heat to melt snow around It so it can bloom early. It also smells rotten so that it attract pollinators such as beetles Reproductive physiology: the study of reproductive function Environmental physiology (toxicology): the study of environmental impacts on organism function o Example: Galapagos Island There was an oil spill and they studied effects of oil spill on community and organism o Example: Radiograph of 8 year old boys femur and tibia Shows that the boy has very dense bone ends. The problem is that he is so young that it should still be cartilage but his growth was stunted because his bones calcified due to lead poisoning. An animal through physiologists’ eyes. External systems o If it doesn’t break through a membrane or get ingested, it is never internalized o Integumentary: skin Some animals is impermeable (ours) some permeable (amphibians) o Respiratory: lungs o Urinary and Digestive: excretion external Internal systems o Circulatory: reacts with external environment chemicals that break through membrane o Musculoskeletal: responsible for most of our body movement o Nero-endocrine: connection and communication between body systems The ultimate goal that defines biological success. To be biologically successful, you have to have high fitness (reproduce) o This is what defines Darwinian fitness o In order to reproduce you have to survive long enough to reproduce o Example: Mayflies live one day on average and are very successful The immediate concern is maintaining homeostasis o Homeostasis: a tendency to maintain stability in the internal environment of an organism Does not mean that the internal environment never changes o Allostasis: achieving homeostasis through behavioral or physiological change Is dynamic Example: regulating blood glucose levels we like to maintain consistent blood glucose levels but to do that we need to allostatically regulate glucose and insulin Variable have tolerances within which the internal environment is maintained o pH: influences chemical shape of lots of things so it is very important If a cell is in a too acidic/basic environment it will denature Our body is a little bit basic and if can tolerate a pH of 6.8-8.0 o Body temperature varies because at different times f the day out internal thermostat changes its set point To maintain homeostasis a balance must be maintained o Intake External environment, diet, diffusion in lungs, absorption in skin, etc. Could metabolically produce the substance o To maintain homeostasis, we must loose it too Excrete via liver, lungs, kidney, across skin Take it and metabolize it into another material o Example: Take in glucose via sugar or make it, it is metabolized into new substances (energy), we don’t really excrete is because it is so useful If you excrete it in your kidney you have diabetes o Example: Oxygen is everywhere throughout your body and is taken in through the lungs (we cant make oxygen), we metabolize it into other substances o Example: Water is taken in in the intestines, we also make water metabolically (one thing that happens to oxygen), then we excrete it The body maintains homeostasis via control systems. Generic control system o Stimulus: detected by a receptor cells in you body o Receptors: detect and send signal in the from of an electron action potential o Afferent pathway: sends receptor electron to integrating center o Integrating center: interpretes and sends the information out o Efferent pathway: sends infor from integrating center to the effector o Effector: an organ or tissue that respond to the effector o Response: actual action taken There are negative and positive feed back loops o Negative feedback loop: effector output decreases the stimulus Example: Your home’s climate control There is a drop in temperature (stimulus) that the thermostat detects (receptor). The receptor will the send this info via copper wire (afferent pathway) to the thermostat switch (integrating center) which will interpret the information and send the info via copper wire (efferent pathway) to the effector (furnace) which will increase the temperature (response) Example: your body o Positive feedback loop: effector output increases the stimulus Are generally unstable because they just cause more and more aggressive loops but some have external events happen that end the cycle Example: Giving birth Post pituitary gland creates oxytocin, which then binds to receptors in uterus causing it to contract. This creates the fetus’s head to go towards the cervix where receptors there detect stretch. The stretch then generates action potential and goes to brain signaling it to generates oxytocin. This cycle continues causing the contractions to get stronger and stronger until the stretch is eliminated when baby comes out causing positive feedback cycle to end. Other concepts basic to physiology Local control/response: a response to a local stimulus that is limited to a small area (no nervous or glandular involvement) o Example: when you scratch and it inflames a little biological response, brain nor hormones tell you to do that o Example: pacemaker o Example: in Indiana jones when he pulls out the heart and it still beats 3 mechanisms we use for moving stuff in our body (passive) o Bulk flow: occurs through tubes or vessels Can move a lot of material in a small about of time Very non-selective Driven by a pressure gradient (flows from high to low pressure areas) o Diffusion: occurs across cell membranes Can only move a small amount of material Very selective Can only do this down a concentration gradient o Filtration: occurs across tube walls (shares characteristics of bulk flow and diffusion) Can move intermediate amounts (in-between cells) Usually not selective unless the material is to big (cells and plasma protein don’t get filtered out) Driven by a pressure gradient Tonic vs Phasic o Tonic: continuous, graded response Tonic receptors: Baroreceptors: sense blood pressure Proprioceptors: sense joint angle, muscle length, and muscle tension Nocirecepors: sense pain Example: brake and accelerator in car o Phasic: intermittent, on/off responses Phasic receptors: Olfactory (detect odors) Some tactile (detect touch) Example: light switch or gun trigger Mass action o Concentrations of reactants and products determine the direction of the reaction o Chemical reactions that release a lot of energy are considered to be irreversible. Fortunately, we have ways around such physical limitation Where there is a big energy release, there is mostly products and few reactants Enzymes will lower the reaction energy of a chemical reaction Example: In our red blood cells, we have hemoglobin and in we have oxygen. They like to chemically bind to each other to form oxyhemoglobin but they don’t always bind Active vs. Inactive States o Many enzymes are inactive in the absence of cofactors Cofactors: change the conformation of enzyme molecules so that they can bind with substrate molecules Can be metal or organic molecules CHEMICAL COMMUNICATION There are 2 kinds of cell-to-cell messages. Electrical communication: jump from cell to cell to convey information o Occurs via gap junctions Gap junctions: specialized intercellular connection between cells that directly connect the cytoplasm of two cells, which allows various molecules, ions and electrical impulses to directly pass through a regulated gate between cells o Electrical communication is the minority in how cell communicate Our nervous system does not do this o Example: cells that make out heart pump, some in smooth muscles Chemical communication: secreted from one cell to convey information o The receiving cell chemically reacts with the chemical communicating molecule All fit the same generalized structure: o There are several classes of chemical signals Hormones Secreted by endocrine cells Transported in the circulatory system via bulk flow (nonselective) Move out of the blood vessels to reach targeted cells via filtration Good for long distance communication Neurohormones (slow) Secreted by neurons Transported in the circulatory system via bulk flow (nonselective) Move out of the blood vessels to reach targeted cells via filtration Good for long distance communication Neurotransmitters Secreted by neurons Communicate with effectors or other neurons; do not get dumped into the circulatory system Don’t have bulk flow so they travel over tiny distances o Very specific Can combine with intracellular electrical signals to get very fast, long distance communication Paracrine/Autocrine compounds Local effects (don’t go into the blood or travel over long distances) Work via diffusion (very slow) Paracrine: talk with neighboring cells and tell them what to do Autocrine: talk with itself and tells itself to do something Why do we need chemical messengers? Allow you to have a wide variety of signals being sent and received Contributes most to negative feedback processes that contribute to maintaining homeostasis Helps promote cell recognition Types of cellular responses. Change membrane permeability to allow/not allow thing to cross membrane Alter cell metabolism o Change how much energy and heat it is producing Gene activation/transcription o Signal cell to up/down regulate the synthesis of some proteins Regulate secretions o Signal cell to up/down regulate the secretion of chemicals In order to produce these responses, messenger molecules must bind to receptor proteins on/in targeting cells General properties of receptors. Receptor must: o Exhibit chemical specificity and affinity Specificity: receptor protein has to bind to a specific kind of messenger molecule Affinity: the strength with which a chemical messenger binds to it receptor o Change conformation in response to binding of a messenger o Be inactive in the absence of a chemical messenger o Be found on cells that are intended message recipients Cells can: o Have many different chemical-specific receptors Can have a cell with different receptors on it o Vary the type and density of receptors Can regulate the type of receptors that are expressed and the density of receptors that are expressed Density will determine how big of a response will be given in response to the messenger Receptors can be located: o Intracellular: floating around in the cystol or nucleus Molecule has to get into the cell to bind so it happens less often o On the plasma membrane Binding site is sticking out so it happen more often Terms concerning receptors. Receptor: A specific protein in either the plasma membrane or the interior of a target cell that a chemical messenger combines with thereby invoking a biologically relevant response in that cell Saturation: the degree to which messengers occupy receptors; occurs when you don’t have enough receptors and cant get a bigger cellular response Competition: two messenger molecules competing for a receptor site receptor Antagonist: chemicals that bind to receptors but trigger the cells response, they just block the messenger molecule from binding Agonist: an artificial chemical that binds and mimics a normal messengers action Down-regulation: a decrease in the total number of target cell receptors for a given messenger; may occur in response to chronic high extracellular concentration of the messenger Up-regulation: an increase in the total number of target cell receptors for a given messenger; may occur in response to a chronic low extracellular concentration of the messenger Supersensitivity: the increased responsiveness of a target cell to a given messenger; may result from up-regulation of receptors
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