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!

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

What happens in your body when you do a Triathalon? 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 Maintenance of a constant internal environment despite a changing external environment Homios = Similar Stasis = Standing Still W.B. Cannon coined the word homeostasis in 1032 Ideal Body Conditions: Organs and body systems are constantly adapting Temperature37 o C (98.6 o F) Blood pH7.35 Blood sugar level0.1%

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

Internal Dynamic Equilibrium All of our organ systems work together to maintain Homeostasis Examples: 1.Water Balance/Blood Pressure 2.Blood Oxygen/CO 2 levels (pH) 3.Body Temperature 4.Water/Ion Balance 5.Blood Glucose (Sugar) Levels The brain and the adrenal system (hormones) do most of the regulating.

What are some examples our body shows when it is working to maintain Homeostatic balance? 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  ▫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

Homeostatic Control Mechanisms 1.Monitors/Receptors ▫Senses state of system  Eg Brain stem receptors detect increased CO2 in the blood, thermoregulation 2.Coordinating/Control Centre ▫Receives incoming info about system and decides what the next steps should be  Eg brain 3.Regulator/Effector ▫Carries out the appropriate next step to keep system at homeostasis ▫Restores balance  Eg. Diaphragm increases depth and rate of breathing, blood vessels

Feedback The fluctuations are kept within an acceptable range by the use of feedback systems ▫Negative feedback  is most common and returns things back to their original state.  RESISTS change ▫Positive feedback  amplifies a reaction – reinforces away from equilibrium  Very quick, shuts off once finished

Negative Feedback Loop

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

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! eshttp:// es Homework…Read p (Feedback) Do Q 2, 4, 9, 10 p348