Organization of Life & Homeostasis Ms. Day/ AP Biology

Multicellular Organisms Cells in multicellular organisms often specialize (take on different shapes & functions)

Cell Specialization = DIFFERENTIATION

Cell Differentiation Do all cells look alike? NO!!! Do all cells have the same functions? Cell Differentiation Process by which unspecialized cells (stem cells) develop into different cell forms and functions

How Do Cells Specialize Their Functions? Cells in multicellular organisms become specialized by turning ON or OFF different genes different parts of their DNA

Levels of Organization How are living things organized? Chemical Cells Tissues Organs Systems Organism

Organism Organization Chemical Atoms, molecules, compounds Cell Basic unit of living things Tissue Similar cells doing specific function Organ Similar tissues performing specific task Organ System Organs working together Organism All systems working together

Four Basic Types of Tissues groups of cells similar in structure and perform common or related functions Epithelial Tissue Skin, lining of organs Connective Tissue Blood, bones, cartilage Muscle Tissue Smooth, striated, cardiac Nervous Tissue Nerves and fibers

What is Homeostasis? Process that occurs in ALL living things All organ systems work together to achieve homeostasis Definition: The ability of an organism to maintain its internal environment despite changes to its internal or external environment http://balancewines.wordpress.com/2009/12/

Negative Feedback It ensures that small changes don’t become too large Process that activates body to RESTORE conditions to their ORIGINAL STATE Counteract further change in the same direction STOPS THE CHANGE! It ensures that small changes don’t become too large MAINTAINS HOMEOSTASIS EX: Thermoregulation, Blood sugar levels, Blood Calcium level, O2/CO2 levels in blood

Positive Feedback Allows for small changes to become too large Process that activates body to AMPLIFIES original change CONTINUES more change in the same direction INCREASES the change! Allows for small changes to become too large DOES NOT MAINTAINS HOMEOSTASIS EX: Uterine contractions, Lactation, blood clotting

Homeostasis Control Systems 3 components: Receptor Control Center Effector detects a change in organism’s internal environment, such as a change in temperature control center Processes information it receives from receptor and directs appropriate response by the effector Receptor Control Center Effector Normal balance Change in balance http://higheredbcs.wiley.com/legacy/college/sarafino/0470129166/animations/homeo1a/frameset.htm

Homeostasis Example: household thermostat Receptor- Thermometer Detects decrease in temperature Control Center- Thermostat switches on furnace Regulator- Furnace Thermostat detects temperature increases over “normal” Furnace turns off Whole control system is called a negative feedback system

Sweat (liquid) turns to gas  requires HEAT Negative Feedback Example #1: Thermoregulation in body What happens when you are too hot? Sweat (liquid) turns to gas  requires HEAT Heat comes from your body/skin  skin cools down

Negative Feedback Example #1: Regulating Blood Sugar (Glucose) Levels http://www.mhhe.com/biosci/bio_animations/MH11%20Homeostasis_Web/index.html

Negative Feedback Example #2: Regulating Calcium Levels in Blood Why do you need calcium? Carries messages in body Muscle contractions Nervous system homeostasis Bone/teeth formation Helps blood clotting

CO2 levels rise pH of blood decreases Negative Feedback Example #3:Regulating Oxygen and Carbon Dioxide Levels in Blood O2 / CO2 level returns to normal Holding breath, CO2 levels rise pH of blood decreases Control system forces exhale, inhale

Positive Feedback Example #1: Uterine Contractions During childbirth… Baby’s head PUSHES against sensors near opening of uterus Oxytocin (hormone) released  stimulates uterine contractions More contractions  more oxytocin ONLY STOPS when pushing STOPS

Positive Feedback Example #2: Lactation (making milk) Suckling by baby stimulates brain to release hormone (prolactin) Prolactin makes milk More suckling by offspring (baby)  more milk production

Positive Feedback Example #3: Blood Clotting Damaged blood vessel stimulates release of clotting factors  Platelets build up at injured site More chemicals released  more platelets Platelets continue to pile up and until clot is formed Finally, growth hormones stimulate cell division   platelets fibrin white blood cell red blood cell blood vessel clot

Animation of Blood Glucose Regulation http://bcs.whfreeman.com/WebPub/Biology/hillis1e/Animated%20Tutorials/at3902/at_3902_insulin_glucose_reg.html