Homeostasis (PAGES 72-75)

The term homeostasis was first used by American Walter Bradford Cannon in 1820s

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What happens in your body when you get cold? Sensor (receptor): detects a change Integrating Center (control center): processes info; directs appropriate response Effector: causes the response

Feedback loops  A process in which a signal tends to initiate or inhibit a process  NEGATIVE FEEDBACK: causes a response to decrease the change. Most common form.  POSITIVE FEEDBACK: causes a response which increases (amplifies) the signal/change.

How does temp regulation work in ectothermic organisms?

Ectothermic temp regulation Too hot  Seek shade  Torpor, inactive  Seek water  Estivation Too cold  Sunbathe (basking)  Huddle  Vibrate  Heat exchange mechanisms

Neg feedback: blood sugar levels

POSITIVE FEEDBACK Increases a process; amplifies an action. Continues until a negative feedback response takes over.

How is fruit ripening a positive feedback?

Failure to maintain homeostasis results in disease

Example case: Failure to maintain steady blood sugar levels

Diabetes.. A few facts  Diabetes is a group of metabolic diseases in which a person has high blood glucose.  No insulin production (type 1; 10% of cases)  Inadequate insulin production (type 2; about 90% of cases)  Cells do not respond to insulin  Gestational  In 2013, over 328 million people in the world had diabetes.

SYMPTOMS INCLUDE:

EFFECTS OF UNREGULATED BLOOD SUGAR LEVELS

Research a feedback loop  Show normal values  Show interactions (diagram with labels)  Explain in paragraph how it works  Identify as positive/negative  What happens when not balanced (disease state)?

MAINTAINING HOMEOSTASIS: EVOLUTIONARY CONSERVATION Pages 84-84

Living organisms need to maintain proper water balance (osmoregulation)

Systems change and become more complex, but continue to perform the functions necessary to maintain homeostasis

KEEPING THE BALANCE: INDENTIFYING PATTERNS

CHANGES IN ENVIRONMENT INFLUENCE HOMEOSTASIS of cells and of organisms

Cells are affected by biotic and abiotic factors  Biotic: cell density, cell types, predation (single celled organism), etc  Abiotic: water availability, chemical messages, pH, temperature, light, etc

Example: Quorum Sensing in bacteria

Change in Environment influences Homeostasis of organisms Pagse 77-82

Organisms are affected by biotic and abiotic factors Dispersal Patterns are an example of responses…

What determines dispersal patterns? BIOtICABIOTIC

Biotic  Competition  Seed dispersal  Behavior  Herd/pack  Protection  aggression abiotic  Limited resources  Water  Sunlight  Shelter/space  Nutrients  toxins

Estimating population size

Direct count

Mark and recapture

How does mark-recapture work?

Challenge: How many mealworms?

How can I use mark-recapture to estimate the number of mealworms in the container? Use larval form. Marking should not harm the organism. How will you capture your sample? What problems can you anticipate? Solutions?

Disruptions in homeostasis: Ecosystems in peril Page 85

Green ash, which commonly grows along bodies of water such as rivers, lakes, and streams, and in floodplains, serves as habitat for several species of wildlife, particularly birds, and, in Indiana, endangered species of bats and snakes. White ash prefers upland slopes and ravines, and black ash favors areas near rivers and streams, and along bogs. Ash trees in these areas produce shade that cools the water, improving the habitat for fish and insects. ash trees and their fruit provide habitat and food for various animals, such as birds, squirrels, and insect larvae.fruitbirdssquirrelsinsect

Invasive species  “WANTED” POSTER  WNY THREAT  PICTURE  FACTS ABOUT ORGANISM  COUNTRY OF ORIGIN  ROUTE OF INTRODUCTION/WHY  IMPACT ON ENVIRONMENT  MAP OF CURRENT DISTRIBUTION  POSSIBLE CONTROL/IRRADICATION