Presentation on theme: "Regulating the Internal Environment"— Presentation transcript:
1 Regulating the Internal Environment Homeostasis is the maintenance of thebody’s multicellular environment with thebody’s external environment or any changesin activity caused.The bodies homeostatic response controls waterconcentration in the blood, body core temperature,blood glucose levels and heart rate by a processcalled negative feedback control.
2 Receptors and Effectors Any change to the environment will be detected by receptors found in the sensory organs and glandsEffectorsThe receptor sends a message to the effector which alters the bodies response and returns it back to normal. Gland and muscular contraction, hormone and enzyme production are all effector responses.
4 Control of Heart Rate Although the pacemaker initiates heartbeats, the rate of heart beating is not fixed and canbe altered as a result of nervous orhormonal activity.The autonomic nervous system regulates theheart, blood vessels, lungs, alimentary canal andsweat glands. This is when the body workautomatically without the individual havingto think about making the body do certain jobs.
6 Cardio Accelerator Cardio Inhibitor Centre Centre Medulla of BrainCardio Accelerator Cardio InhibitorCentre CentreSympathetic Parasympatheticcardiac nerves cardiac nervesAntagonistic responseIncrease in Decrease innerve impulses nerve impulsesIncrease in heart rate Decrease in heart rate
7 Hormonal Control of Heart Rate AdrenalineAdrenaline is produced inthe adrenal glands whichare situated above thekidneys. The sympatheticnervous system in asituation which wouldrequired adrenaline e.g.fight of flight situation, stimulatesthe adrenal glands to releaseadrenaline into the blood system.When it reaches the pacemaker itincreases the heart rate
8 Exercise and Heart Rate When we exercise the muscle cells whichare working are at a higher metabolic rateand therefore require a higher levels ofoxygen and glucose. As a consequencethey also produce higher levels of carbondioxide. This all needs to be balanced.
9 Distribution of Blood During Exercise During exercise the heart rate (pulse) increases, the volume of blood(stoke volume) pumped through the heart in each contraction increasescardiac output = heart rate X stoke volumeThis increase in heart rate and stoke volume increases the rate ofoxygen delivery to working cells and tissues. Not all organs require anincrease in blood during exercise, only the ones which are doing theextra work:Increase in blood flow to tissue during exercise would be in the heartcardiac muscle, skeletal muscle and the skin where excess heat is lost.To help with this increase arteries and arterioles vasodilate to allowA larger volume of blood to pass through at a faster rateDecrease in blood flow to tissue during exercise would be in the kidneys,stomach, intestines etc.. The function of the kidneys to purify blood and thefunction of the intestine to digest and absorb nutrients are processes that canwait until exercise is complete. This decrease in blood is as a result ofvasoconstriction of the arteries and arterioles carrying blood to these organs.
10 Control of Blood Sugar Levels Glucose is essential toall living cells as energyis released fromGlucose. The liverstores excess glucoseas glycogen so when itis needed there is areserve.
11 The Pancreas and Sugar Levels Cells in the pancreas called theIslets of Langerhans producetwo hormones – insulin andglucagon which help control bloodglucose levels. These levels are controlled through negative feedback mechanisms.InsulinGlucose GlycogenStored in liverGlucagonGlycogen Glucose
12 Diabetes Diabetes mellitus is a disorder in people and animals who do nothave or have less functionalinsulin secreting cells in thepancreas. As a result of havinglittle or no insulin, their bloodglucose levels increase and arenot stored in the liver. This can bedetected in their urine as there isso much glucose in the blood thatit is not reabsorbed but excretedin the urine. This used to be a fataldisease but with controlledadministration of insulin by injectiondaily, their glucose levels can bemaintained.
13 Control of Body Temperature The hypothalamus is thebodies temperaturemonitoring centre. Heat andcold thermoreceptors in theskin convey information tothe hypothalamus. A bodycore temperature from theblood and body shelltemperature form the skintriggers a response toreturn the temperature backto normal .
15 Temperature Control in Infants Brown FatBabies have a relatively largesurface area to volume ratio andtherefore loose heat more rapidlythan an adult. When a baby isborn its thermoregulation mechanisms are not fullydeveloped. When it gets cold itinvoluntarily responds byvasoconstriction and brown fatgenerates heat as it is suppliedwith blood vessels.
16 Preterm babies, infants HypothermiaHypothermia is whensomeone's bodytemperature is belowwhat is considered anormal level.Preterm babies, infantsand the elderly are atrisk.