2. Warm-up: 1.What do you think the term “feedback” means? 2.Give an example of a “feedback” you get from school? 3.How can this “feedback” be used for improvement? Information or communication given about a person's performance of a task, reactions to a product etc., used as a basis for improvement Progress Report or Report card Make better grades, correct inappropriate behavior

3. LEVELS OF ORGANIZATION: Cells  Tissue  Organs  Organ Systems  Organism CELLS – smallest basic unit of life TISSUE – 4 types made of similar cells performing similar functions. 1. Connective - Provides support for the body Ex: bones, tendons, cartilage, fat & blood) 2. Muscle - enables you to breathe, talk, move etc. 3. Epithelial - includes glands and tissues that cover interior & exterior body surfaces. 4. Nervous - COMPOSED OF 2 TYPES OF CELLS: a. Neurons - signals in form of electrical impulses b. Glial - support, protect & coordinate neurons

4. ORGANS ~ heart, liver, lungs, brain, etc. ORGAN SYSTEMS ~ circulatory, digestive, respiratory, etc. ORGANISM 

5. All human bodies have bilateral body symmetry and a vertebrae.

6. Cranial – holds the brain Spinal - contains the spinal cord. Thoracic : (Pleural & Pericardial) houses the lungs and heart Abdominal: stomach, liver, intestines Pelvic - bladder, reproductive organs There are 5 body cavities: spaces for organs and structures diaphragm

7. There are 12 human body systems that work together to maintain homeostasis. 1.Nervous system7. Integumentary system 2.Respiratory system8. Endocrine system 3.Circulatory system9. Immune system 4.Digestive system10. Lymphatic system 5.Excretory system11. Muscular system 6.Reproductive system12. Skeletal system

8. What is HOMEOSTASIS? “the tendency of an organism or cell to regulate its internal environment and maintain equilibrium, usually by a system of feedback controls.” Every organ in the body helps in achieving and maintaining homeostasis.

9. Examples of Interrelation among body systems: The circulatory system and the respiratory system work together to ensure that organ tissues receive enough oxygen because oxygen is necessary to carry out cellular functions. Oxygen enters the lungs and blood vessels carry that oxygen to cells in the rest of the body and pick up carbon dioxide (waste) for exhalation. We all eat! The food that we eat needs to be broken down into smaller molecules that our cells can use. Digestive system breaks down the food, Circulatory system carries the smaller molecules through the bloodstream to where they are needed and the Endocrine system sends messages to release hormones and enzymes in the digestive process to regulate blood sugar (gluose levels). The skeletal system works with the muscular system in order for us to move, bend etc.

10. All of this is done by way of a “Feedback Loop System”. There are 2 types of Feedback – Negative and Positive. What is a Feedback Loop? Feedback provides information/communication with body systems to maintain homeostasis. A loop system in which body systems respond to a situation either in the same direction (positive feedback ) or in the opposite direction (negative feedback ). A process in which the level of one substance influences the level of another substance

11. Negative Feedback Loop for Blood Glucose Control: Positive Feedback Loop for :

12. The image below is an example of how a homeostatic control system works. These are the factors needed to carry out this process: Stimulus – produces a change to a variable (the factor being regulated). Receptor – detects the change. The receptor monitors the environment and responds to change (stimuli). Input – information travels along the (afferent) pathway to the control center. The control center determines the appropriate response and course of action. Output – information sent from the control center travels down the (efferent) pathway to the effector. Response – a response from the effector balances out the original stimulus to maintain homeostasis.

13. There are 2 forms of Feedback/Communication: Negative Feedback and Positive Feedback. Body System Example: the control of blood sugar (glucose) in our blood. When blood sugar rises in the blood stream, receptors in the body sense a change. In turn, the control center (pancreas) secretes insulin into the blood effectively lowering blood sugar levels. Once blood sugar levels reach homeostasis, the pancreas stops releasing insulin. A negative feedback loop is a mechanism that inhibits or prevents the original stimulus from escalating and returns the body back to its homeostatic state. Real Life Example : a thermostat in a home heating system. If the heating system is set at 70 degrees Fahrenheit, the heat (effector) is turned on if the temperature drops below 70 degrees Fahrenheit. After the heater heats the house to 70 degrees Fahrenheit, it shuts off effectively maintaining the ideal temperature.

14. Examples of other Negative Feedback Loops: * Human body temperature ( The hypothalamus of a human responds to temperature fluctuations and responds accordingly. If the temperature drops, the body shivers to bring up the temperature and if it is too warm, the body will sweat to cool down due to evaporation.) * Human blood pressure (When blood pressure increases, signals are sent to the brain from the blood vessels. Signals are sent to the heart from the brain and heart rate slows down, thus helping blood pressure to return to normal) * Hunger (metabolism slows down to conserve energy and allow the human to continue living with less food) In nature: Carbon Cycle, Predator vs Prey, Global Warming

15. Stimulus Receptor Input Output Response Control Center

16. A positive feedback loop is a mechanism that enhances/increases the original stimulus. A good example of a positive feedback system is child birth. During labor, a hormone called oxytocin is released that intensifies and speeds up contractions. The increase in contractions causes more oxytocin to be released and the cycle goes on until the baby is born. The birth ends the release of oxytocin and ends the positive feedback mechanism.

17. Examples of Other Positive Feedback Loops: * Lactation : (production of mother’s milk - as the baby suckles on the nipple there is a nerve response into the spinal cord and up into the hypothalamus of the brain, which then stimulates the pituitary gland to produce more prolactin to produce more milk) * Ovulation : (increase in a hormone called estrogen during the follicular phase of the menstrual cycle) * Blood Clotting : (when injured tissue releases signal chemicals that activate platelets in the blood. An activated platelet releases chemicals to activate more platelets, causing a rapid cascade and the formation of a blood clot).