Homeostasis Maintaining a stable internal environment despite their outside environment Claude Bernard 1813 78 Walter Cannon 1871 1945 o Homeostasis Negative Feedback o Dynamic equilibrium within a limited range around a set point o Thermostat to 68 degrees control center set point Attached to the thermostat there s a thermometer that will to activate the furnace unless it drops out of a range outside of the set point 70 65 degrees o Example Thermoreceptors sense changes in blood temperature Vasodilation Sweating Vasoconstriction Shivering Receptor o Receives the stimulus Integrating control center o Processes the signal and sends instructions to the Effector Effector o Carries out instructions Homeostasis and Negative Feedback Process in which the body sense a change an d activates mechanisms that negate or reverse it Person rises from bed o Blood drains from upper body creating homeostatic imbalance Baroreceptors above heart respond to drop in blood pressure Baroreceptors send signals to cardiac center of brainstem o Cardiac center accelerates heartbeat Blood pressure rises to normal homeostasis is restored For this example figure out which is the receptor integrating center and effector Understand the process ASK HER Positive feedback and Rapid Change Positive Feedback self amplifying cycle in which a physiological change leads to even greater change in the same direction rather than producing the corrective effects of negative feedback Self amplifying cycle o Leads to greater change in the same direction Normal way of producing rapid changes o Occurs with childbirth blood clotting protein digestion fever and generation of nerve signals Example Blood Clotting o Injury o Chemicals send message to white blood cells to react Platelets start setting up a clot Clot sends out more messages for the white blood cells to fight the infection o Clotting accelerates Positive feedback loop o Chemicals Cut keeps the signals coming until clot is sufficient ans tops calling white blood cells Figure out what the cycle is Childbirth o Head of fetus pushes against cervix o Nerve impulses from cervix transmitted to brain o Brain stimulates pituitary gland to secrete oxytocin o Oxytocin stimulates uterine contractions and pushes fetus toward cervix o Cycle starts over again Fever o Fever 104 F o Cycle continues to reinforce itself o Becomes fatal at 113 F o The effector increase in body temp doesn t stop o Infection cold virus Tricks body and tells them that homeostasis should be at 99 F but you re still at 98 so you shiver and try to get higher You re body goes higher Tricks again to be at 103 and your body responds and the fever keeps going up Hypothalamus would be the control center Gradients and Flow o Matter and energy tend to flow down gradients Gradient a difference in chemical concentration charge temperature or pressure between two points Down High value to low value o Ex Heart Pressure gradient High pressure from the heart is high Blood flow down pressure gradient decreasing to the periphery o To low pressure in the feet to low pressure Ex Water hose Low pressure at the end of the where it exits Thumb closing it off o Makes the water back up and find the lowest pressure pointholes o Chemical flow down concentration gradient Concentration gradients Dietary glucose intestinal cells Digest starch High concentration of free sugars accumulates in small intestine o Sugar flows from the intestinal space in cells lining the intestine with low concentration Absorbed into the tissues o Cell membrane channel Electrical gradient o Ion flow down electric gradient Sodium ions Na just outside a cell and much lower concentration inside Outer surface of cell membrane has a relatively positive charge and the inner surface is relatively negative Channel opens in the membrane sodium ions rush into the cell flowing down their electrical gradient Na carries a positive charge this flow constitutes an electrical current though the membrane Warm blood skin cool air Thermal gradient Warm blood flowing through small arteries close to the skin surface Air temp around skin is cooler Heat will flow from the blood to surrounding air Heat will be lost from the body The history of Anatomical Terminology Naming confusion during the Renaissance o Same structures with different names in different countries Standard international anatomical terminology o Terminologia Anatomica TA About 90 of medical terms Greek and Latin roots Analyzing Medical Terms Terminology based on word elements o Lexicon word elements on the inside back cover of textbook Scientific terms o Root o Prefix o Suffix Acronyms formed from first letter or first few letters of series of words o Calmodulin comes from the phase calcium modulating protein Plural Adjectival and Possessive Forms of medical terms Plural forms vary Adjectival form of a term can appear different than noun form Adjective often follows noun it modifies Singular Ending Plural Ending Examples a ae axilla axillae ax aces thorax thoraces en ina lumen lumina ex ices cortex cortices is es diagnosis diagnoses is ides epididymis epididymides ix ices appendix appendices ma mata carcinoma carcinomata on a ganglion ganglia um a septum septa us era viscus viscera us i villus villi us ora corpus corpora x ges phalanx phalanges y ies ovary ovaries yx yces calyx calyces