1. Ch. 28 Notes: Human Systems and Homeostasis

2. Objectives  10C analyze the levels of organization in biological systems and relate the levels to each other and to the whole system  4B investigate and explain cellular processes, including homeostasis, energy conversions, transport of molecules, and synthesis of new molecules;

3. Objectives  10A describe the interactions that occur among systems that perform the functions of regulation, nutrient absorption, reproduction, and defense from injury or illness in animals;  11A describe the role of internal feedback mechanisms in the maintenance of homeostasis

4.  Cell differentiation  Specialized cells in multicellular organisms arise from a single cell, the zygote (sperm + egg)  Cell differentiate into hundreds of different types of cells  Cell differentiation - process by which cells become specialized and develop into their mature form and function. Bone cells, smooth muscle cells, skin cells, sperm cells, nerve cells- all different!

5.  Levels of organization  Contain 5 levels  Cells - preform a specific task  Ex- epithelial lung cell  Tissues - groups of similar cells working together to perform a function  Ex- epithelial lung tissue red blood cellnerve cell tissue

6.  Organs - A group of tissues that carry out a special function  Ex- lungs  Organ systems - Two or more organs the work together to preform body functions  Ex- respiratory system  Organism - all the combined organ systems. Must work together to stay alive  Ex- human being ORGANS ORGAN SYSTEM ORGANISM

7.  Mechanisms of Homeostasis  Conditions in the body must remain within a narrow range  Homeostasis - the regulation and maintenance of a stable internal environment  Ex- sweating when you’re hot  Can you think of another example of homeostasis in the body?  _________________ is an example of homeostasis in the body because _________________________

8. 28.2 Mechanisms of Homeostasis TEKS 4B, 10A, 11A Control systems help maintain homeostasis. –sensors gather data –control center receives data, sends messages –communication system delivers messages to target organs, tissues –targets respond to change pore sweat glands hair follicle muscle goose bump

9.  Feedback Loops are used by your body to maintain homeostasis  Negative feedback - a control system receives a stimulus and tries to counteract the change.  Ex- a thermostat. When it gets hot (the stimulus), the AC starts to blow cold air (tries to counteract the change ) Holding breath, CO 2 levels rise, Control system forces exhale, inhale O 2 / CO 2 level returns to normal

10.  Positive feedback - a control system receive a stimulus and tries to promote the change  Ex- think snowball effect platelets fibrin white blood cell red blood cell blood vessel clot

11.  Systems interact to maintain homeostasis  Each organ system affects other organ systems  Thermoregulation - process where the body regulates it internal temperature  Uses skin (integumentary system), muscles (muscular system), nervous system, circulatory, respiratory and endocrine systems.  Sweating :  Sensors in the skin provide information to the nervous system (brain and hypothalamus), which sends chemical messengers through the endocrine system to the circulatory and integumentary systems  Also works when you shiver when cold

12.  Disruption of homeostasis can be harmful  Short term effects- last for a few days or weeks- Ex: getting a cold  Long term effects- last much longer- Ex: diabetes- cannot regulate amount of glucose in blood  More serious than short term effects.