Weird Body Quirks Brain freeze “Ice cream headaches” happen when something cold touches nerves in the roof of the mouth, triggering blood vessels in the front of your head to constrict -- producing pain. Try this quick pain relief trick: Press your tongue to the roof of your mouth to warm it up.

HOMEOSTASIS & Control Systems UNIT 4 Also Known As… If it ain’t broken, don’t waste my valuable time & energy trying to fix it, fool!

When things just work…. Honda Accord – The Cog Commercial https://www.youtube.com/watch?v=_ve4M4UsJQo

Learning goals . . . To explain the process of maintaining homeostasis through feedback loops and their components. You will show your understanding by . . . Presenting an explanation (diagrammatic, written or kinesthetic) of thermoregulation

Homeostasis Regulation of the internal environment through the constant physiological adjustments of the body in response to the external environment changes. Also known as Dynamic Equilibrium Requires energy to work Homios = Similar Stasis = Standing Still Ideal Body Conditions: Organs and body systems are constantly adapting http://www.lionden.com/homeostasis.htm Temperature 37oC (98.6oF) Blood pH 7.35 Blood sugar level 0.1%

Examples of Homeostasis Class Brainstorm: Give 3 physical effects observed in your body when you exercise. What are these factors trying to counteract? Summary: Sweat(increase body temperature), increase heart rate & breathing rate(increasing oxygen demand), muscle aches(increased cellular respiration but anaerobic occurring d/t insufficient oxygen) Cell Resp increases Body Temp increases to 39 degrees Celsius (due to heat from CR rxns) Sweat is produced to dissipate heat This loss of water, drops blood pressure Heart responds, Kidneys conserve water Electrolytes (salts) are lost in sweat Body must use hormones to keep a steady supply of glucose to CR pathways Nervous systems monitors CO2 levels, increasing breathing rate if necessary Nervous systems also work with the circulatory system to divert blood to essential areas (muscles, brain, heart…away from stomach etc)

Homeostasis of Exercise Body temperature increases Evaporation of sweat to cool the skin Oxygen levels being used up Heart and breathing rate increase to move more blood around (increase blood flow) Increased cellular metabolism Pancreas signals the breakdown of biomolecules (glycogen/fat)

The Main Internal Dynamic Equilibriums Water Balance/Blood Pressure Blood Oxygen/CO2 levels (pH) Body Temperature Water/Ion Balance Blood Glucose (Sugar) Levels The brain and the adrenal system (hormones) do most of the regulating. All body organ systems work together to maintain homeostasis

Homeostasis Dynamic Equilibrium (self-regulation) Stable within fluctuating limits

Common Examples of Homeostatic Balance Being Maintained Sneezing due to pollen Asthma attack due to irritants Birthing hormone oxytocin increasing intensity, duration, and frequency of contractions Fever due to infection Kidney’s maintenance of water & ion balance.

Forms of Regulation Voluntary  Involuntary  Requiring though and conscious action Eg. Rubbing your hands together when cold Involuntary  Body adjusts without conscious thought Eg. Release of insulin after a meal

Regulation Mechanisms 1. Osmotic Pressure differences between 2 solutions on opposite sides of a membrane (semi-permeable) Eg. Kidney & urine formation, or CO2 2. Hormonal Chemical messenger Eg. Growth hormone

Regulation Mechanisms 3. Nervous Works with the endocrine system (into the bloodstream) involuntary Eg. Shivering, goose pimples 4. Immune Defense body against microorganisms and viruses Eg. fever

Negative Feedback Loop

Example of a Negative Feedback System

Control Systems: 3 functional components Monitors/Receptors Senses change Eg Brain stem receptors detect increased CO2 in the blood, thermoreceptors Coordinating/Control Centre Relays message Eg brain Regulator/Effector Restores balance Eg. Diaphragm increases depth and rate of breathing, blood vessels Monitor sales and stock of stores and report to factory manager. Based on stocks, factory manager instructs more or less of something to be made. Works increase or decrease production of certain items.

Feedback Loops The fluctuations are kept within an acceptable range by the use of feedback systems Negative feedback is most common and restores things back to their original state/acceptable range. Prevents small changes from becoming large ones RESISTS change Positive feedback amplifies a reaction – reinforces away from equilibrium Very quick, shuts off once finished

Example of a Positive Feedback System

Homeostatic Control System Stimulus Deviation from set point Response Move system towards set point Sensor Constantly monitors conditions Negative feedback (-) Integrating Centre Compares conditions to a set point based on a desired value Effector Causes changes to compensate for deviation

Dynamic Equilibrium There will always be fluctuations in levels Homeostatic mechanisms ensure that all body systems function within an acceptable range. Mammalian Diving Reflex Check out the ICEMAN! http://www.youtube.com/watch?v=madoDvtKE es Homework…Read p344-347 (Feedback) Do Q 2, 4, 9, 10 p348