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Biology Lecture #4 - Metabolism.docx

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BIOL 103
Virginia K Walker

Biology Lecture 4MetabolismTopics to be covered Homeostasis and the control of energy balance metabolic rate and temperatureHomeostasis Process that allows animals through behaviour and physiology to maintain an acceptable state of body while facing external and internal challengesInvolves number interactions of metabolic and cellular processes in an animal such as negative and positive feedback loopsExamplebeing exposed to the coldSensor in neuronsIntegrator in brain realizes due to sensor that temperature is under 37 degreesEffector the activation of skeletal musclesResponse shivering which increases heat productionExample of a negative feedbackNegative feedbacka variable being regulated that brings responses that move the variable towards the opposite directionEg Decrease in body temperature leads to responses that result in an increase body temperatureMay occur at either the organ cellular or molecular levelImportant in organisms as it prevents homeostatic responses from overcompensatingHomeostatic challenge that initiates process a process a activates process b which turns down process aLooping around as b reduces strength of a which reduces activation b which causes soft landing effectPositive feedbackfar less common essentially accelerates a processInstead of inhibiting a process it accelerates a process by reinforcing the direction of the change via an explosive systemExamplebirth in mammalsHead of baby will stretch cervix stretch receptor neurons send a signal up to the brain which activates a hormone oxytoxin which increases the contraction of the smooth muscles in the cervix which further reinforces the stretch receptor neurons and the cycle will continue until delivery of the babyHomeostaticStrategies Animals differ to extent to which they maintain internal constancy in physiological conditions as they all operate based on variablesConformers allow a physiological process to change based on their environment
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