1. Homeostasis

2. What is homeostasis? The ability of the organism to maintain a constant internal state. This process by which conditions are returned to a set value is achieved by a Negative Feedback Loop. It requires; sensory receptors to detect changes in the environment. (stimuli- change to the system) Monitors (eg. brain, pancreas) that receive and analyze the measures and commands the effector how to respond. And effectors, (muscles, glands) to perform the appropriate response and restore the ‘change’ to its homeostatic value

3. Equilibriums of you body… Temperature : 37 C Blood pressure : 120/80 mmHg Blood pH : 7.4 Blood Osmolarity : 300m osmoles Heart Rate: 60-70 per minute Breathing Rate : 15/16 per minute Blood Glucose : 0.1%

4. Homeostasis… There are two main systems that control homeostasis…

5. Endocrine System… Eg. The Pancreas Produces hormones Insulin & Glucagon Regulates blood sugar through negative feedback High blood sugar = release of Insulin Low blood sugar = release of glucagon

6. Nervous System… Consists of the Medulla Oblongata & Hypothalamus Nerve stimulation and sometimes hormones to regulate: blood pressure, temperature, fluid and electrolyte balance etc.

7. Major monitors in homeostasis… Medulla OblongataHypothalamus

8. Negative Feedback… Turns off stimuli Low/high blood pressure, decrease/increase of body temperature, decrease/increase of breathing rate, regulation of blood sugar ssugarglucose…etc.

9. Types of receptors… External: Thermoreceptors, pressure receptor, mechano receptor, olfactory receptor, light rods/cones receptor Internal: chemoreceptors, pressure receptor, osmoreceptor, baroreceptors, C0 2 receptor, Islets of Langerhans

10. Thermoreceptors… Negative feedback Loop Hypothalmus sends motor nerves to muscle effectors (erector pili) and glands (sweat)

11. Negative Feedback… Stimulus Receptor Monitor Effector Response (-) Head rush Pressure in Medulla Smooth muscle Vaso constriction Cartoid Oblongata Cardiac muscle Increased heart rate Artery

12. Positive Feedback… Increases Stimuli Giving birth, blood clotting

13. Positive Feedback… Stimulus Receptor Monitor Effector Response (+) Baby’s head pressure hypothalamus posterior contract uterine On cervix receptors pituitary releases muscle oxytocin

14. References http://images.google.ca/imgres?imgurl=http:// http://en.wikipedia.org/wiki/Human_homeostasis http://pespmc1.vub.ac.be/HOMEOSTA.html http://www.gonzaga.k12.nf.ca/academics/science/sci_page/biology/ho meostasis_notes.htmhttp://www.gonzaga.k12.nf.ca/academics/science/sci_page/biology/ho meostasis_notes.htm

15. The End…