HOMEOSTASIS UNIT 4

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 o2 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)

4km swim, 180km bike, 42km run!

The “Ideal Body State” 37 degrees 0.1% blood sugar Blood pH 7.35 Environment doesn’t always allow for this! Organs and body systems are constantly adapting See page 324

Homeostasis All of our organ systems work together to maintain Homeostasis Homeostasis is a steady internal state, keeps conditions in the body constant. Examples: Blood Pressure (circulatory system) Respiration Rate (respiratory system) Body Temperature (circulatory system) Blood Sugar (digestive and circulatory) The brain and the adrenal system (hormones) do most of the regulating.

Three Components of Control Monitors (Brain stem receptors detect increased CO2 in the blood) Coordinating Centre (Nerve cells in brain receive and send a signal to the diapragm) Regulator (Diagragm increases depth and rate of breathing)

Dynamic Equilibrium There will always be fluctuations in levels Homeostatic mechanisms ensure that all body systems function within an acceptable range. Mammalian Diving Reflex (P. 340) Check out the ICEMAN! http://www.youtube.com/watch?v=madoDvtKE es Homework…Read P335-336 (Feedback) Do Q 1-5 P. 337 Read P338-341 – Thermoregulation!

Feedback Mechanisms Negative – Prevent small changes from becoming too large (i.e. A thermostat) Most controls in the body are negative feedback Positive – amplify small effects (i.e. Oxytocin and childbirth)

Thermoregulation Maintenance of body temperature within a range that enables cells to function efficiently Hypothalamus – Region of the vertebrate’s brain responsible for coordinating many nerve and hormone functions.

Ecto Vs. Endo Ectotherms – Invertebrates, fish, amphibians, reptiles...Depend on air temp to regulate body temp. Endotherms – Mammals – Are able to maintain a constant body temp regardless of surroundings.

Physiological Response Thermoregulation Stimulus Physiological Response Adjustment Decreased Enviro Temp -Constriction of blood vessels -Hairs stand on end -Shivering -Heat is conserved -More heat is generated by increased metabolism Increased Enviro Temp -Dilation of blood vessels of skin -Sweating -Heat is dissipated http://www.youtube.com/watch?v=eJEXdWHKDmg http://www.youtube.com/watch?v=vc86u0IsOwc&feature=related http://www.youtube.com/watch?v=Yotp6ov9-w0&feature=fvw