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KIN 105 TERM TEST 1 REVIEW Homeostasis What is the definition of homeostasis: the maintenance of a stable internal environment Steady state environment can change. I.e. during exercise VO2 will increase and acclimatize within minutes. New level depends on intensity of exercise What maintains homeostasis and what are its components? Control system - Stimulus (change is temperature) - Receptor (signal detector sends change to integrating centre) - Integrating centre (command centre like the brain receives messages and makes decision) - Effector (produces the action required by the integrating centre i.e. muscles to shiver) What are the 2 methods used to control homeostasis and describe them. - Feedback system: the receptor detects a signal and sends it to the integrating centre making the effector alter the signal. Negative feedback sends signal back toward homeostasis (cold/hot). Positive feedback sends signal further from homeostasis (labour) - Feedforeward system: before a signal is detected my the receptor the integrating centre predicts stimulus and automatically sends message to effector cells. What are the advantages of feedback and feedforeward systems? - the feedback system is more accurate in changing signal - the feedforward system is faster What is gain of a control system? - gain of the system is the degree of response from stimulus. A large gain is when a small signal creates a large response (temperature) little deviation from homeostasis. Small gain says that there can be more of a change from homeostasis and a little response is generated. (more variation in normal values for small gain system) How does homeostasis explain exercise adaptation? - during exercise the cardiovascular system and muscular systems are stressed. Body than increases muscle mass and oxygen uptake so next time there wont be the deviation from homeostasis. Bioenergetics what is the molecule of energy in the body? ATP how is ATP created? - HEPT- (anaerobic system) creatine-phosphate donates a phosphate group to ADP via creatine kinase - - Glycolysis- (anerobic system) takes place in cytoplasm, requires input of 2 ATP to gain 4 ATP also produces lactic acid (strong acid changes pH and can only run for 30-60 sec) Oxidative phosphorylation- (aerobic) takes place in the mitochondria, its demanding on the cardiovascular system because it requires oxygen. Can change fat/protein/carbs into energy. Goes through a 2-stage process: Krebs cycle and electron transport chain. Oxygen is the electron receptor, for every 2 FADH one water molecule is made . cant function without oxygen because it needs to except electrons or hydrogen would build up. When using fat its called beta oxidation how long does each ATP producing system last? - HEPT : 5 seconds - Glycolysis: 40-60 - Oxidative phosphorylation: 3 minutes and beyond Aerobic Energy Production what is the difference between the energy in carbs and fat carbs give 4 Kcal of energy per gram, 5 Kcal per litre of O2. therefore when oxygen is limited can produce more energy when there is limited oxygen. - Fat gives 9 Kcal of energy per gram. Can only harness 4.7 Kcal per gram of O2. fat is better in the long term because not likely to run out of it. VO2 Concepts What is Flicks equation and why is it important? - flicks equation is used to calculate VO2 max - VO2 = cardiac output (Q) respiratory rate(a-v) O2 how do you calculate Q in flicks equation? - Q= HR SV what are the electrical events of the heart? - depolarization- negative inside becomes positive - repolarization- positive inside becomes negative what are the mechanical events of the heart contraction? - resting membrane potential of cardiac cells is –60mV - contraction threshold is –40 mV - peak is +20 mV - to reach threshold cell must open If channels and let Na in as well as opening calcium channels (pushes over threshold) - once at threshold all Ca channels open - at peak Ca channels close and K channels open (starts repolarization) - return to resting membrane what are normal VO2 values - females: 30 ml.kg/min (max), 3.5 ml/kg/min (r), 4 l/min (max) .25 l/min (resting) - males: 40 ml kg/min, 5 l/min (max) .25l/min (resting) what are normal cardiac output values? - females: 4 l/min resting, 20 l/min max - males: 5 l/min resting, 25 l/min max list some useful equations - VO2 (l/min)= (HR SV) (a-v) O2 - VO2(ml/min) = 2 WR + 300 - VO2 (ml/kg/min) = .2 speed (m/min) +3.5 - Energy production (kcal/min)= VO2(l/min) 5 kcal/l - 1 MET= .0175 Kcal/kg/min - energy production (kcal/min)= METS .0175 weight(kg) define rhythm, rate and shape - rhythm: normal sequence i.e P QRS T P QRS T - rate: normal P to P interval - shape: normal P=P QRS=QRS T=T what is S/T segment depression and what causes it? - the ventricles don’t repolarize as quick as they should (K channels?) caused by blocked coronary arteries obstructing blood flow Stroke Volume What is a normal resting and exercising SV? Males Females 70 (edv) 60(edv) 110(edv) 90(edv) 40 (sv) 40(sv) Athletes 100(edv) 180(edv) 40(sv) how do you calculate SV? - SV= EDV-ESV - Ejection fraction= SV/EDV what is inadequate ejection fraction - less than 40% is considered heart failure what is a normal EF and what happens to it during exercise? - it is normally 60-70% resting (athletes its higher) and during exercise it increases by 10% what influences EDV? - filling time (HR) faster HR decreases EDV - arterial contraction (increases EDV) compliance (how much ventrical can stretch) effective filling pressure (posture, venous tone muscle pump breathing pump blood volume) what is a normal blood volume - 5-6 L for normal people and 7-8 L for trained athletes what is frank starlings law - increase in EVD preload increases SV