Presentation on theme: "Chemistry of Our World – The Human Body"— Presentation transcript:
1 Chemistry of Our World – The Human Body HOMEOSTASIS
2 What is Homeostasis?The ability of the Body to maintain a balanced internal environment that is within the normal range of health for that organismThe organism must have this balance in order to thrive and survive
3 How it all WorksHomeostasis involves a system of checks and balances to keep stability of the animal’s internal environment.The skin, kidneys, liver, endocrine system, nervous system and sensory system all play a part in maintaining the internal environment within narrow limits
4 Regulated Factors in the Body Some factors homeostatically regulated include:Concentration of nutrient molecules (food)Concentration of water, salt, and other electrolytesConcentration of waste productsConcentration of O2 = 100mmHg and CO2 = 40 mmHgAverage pH = 7.35Blood volume 4-6 L and pressure 120/80Temperature = 37o C (98.6 F)Heart Rate = Average bpm
5 Effects of Homeostasis Homeostasis is continually being disrupted byExternal stimuliheat, cold, lack of oxygen, pathogens, toxinsInternal stimuliBody temperatureBlood pressureConcentration of water, glucose, salts, oxygen, etc.Physical and psychological distressesDisruptions can be mild to severeIf homeostasis is not maintained, death may result
6 Maintaining ControlIn order to maintain homeostasis, the control system must be able to1. Detect abnormalities from the normal range2. Integrate this information with other body systems, external environmental factors, etc.3. Make appropriate adjustments to restore the system to normal.
8 Two Types of ControlFeedforward - term used for responses made in anticipation of a changeExample: Salivation and release of extra stomach acid due to smell or sight of foodFeedback - refers to responses made after change has been detectedTwo Types of feedback systemsNegativePositive
9 Feedback Loops Negative feedback loop Positive feedback loop original stimulus reversedmost feedback systems in the body are negativeused for conditions that need frequent adjustmentExamples: heart rate, blood pressure, temperaturePositive feedback looporiginal stimulus intensifiedseen during normal childbirth
11 Example: Body Temperature All mammals maintain a constant body temperature.Human beings have a body temperature of about 37ºC.E.g. If your body is in a hot environment your body temperature is 37ºCIf your body is in a cold environment your body temperature is still 37ºC
13 ExamplesSweatingWhen your body is hot, sweat glands are stimulated to release sweat.The liquid sweat turns into a gas (it evaporates)To do this, it needs heat.It gets that heat from your skin.As your skin loses heat, it cools down
15 Examples Vasodilation Your blood carries most of the heat energy around your body.There are capillaries underneath your skin that can be filled with blood if you get too hot.This brings the blood closer to the surface of the skin so more heat can be lost.This is why you look red when you are hot!
16 This means more heat is lost from the surface of the skin If the temperature rises, the blood vessel dilates (gets bigger).
17 Vasoconstriction This is the opposite of vasodilation The capillaries underneath your skin get constricted (shut off).This takes the blood away from the surface of the skin so less heat can be lost.