Unit 2

1. Unit 2 Organization of the Body

2. Hierarchy: a series of ordered groupings within a system Alpha male & female Pups & adults Outcasts / Dispersers

3. Levels of Organization

4. Stem Cells • Undifferentiated cells • have the potential to develop into many different cell types during early life & growth • Can be induced to become specialized cells • brain cells, red blood cells, skin cells, etc. • Embryonic stem cells: derived from fertilized eggs • Induced pluripotent stem cells: adult specialized cells that can be “reprogrammed” to become a different kind of cell • Blastocyst (early stage of development) • stem cells differentiate into specialized cells • Adults: stem cells still exist (in organs & bone marrow) to replace old/damaged cells

5. Hierarchy of Human Structure Guided Reading: • List the levels of organization, starting with molecules. • What are stem cells?

6. The Human Physiological Environment • All the internal conditions that allow cells to perform their functions effectively & efficiently. This positively impacts body organization • Involves internal & external cellular conditions. • Both rely on water. • Needs specific conditions to maintain homeostasis: • pH, ions, chemical reactions, transport of molecules between internal & external environments • Allows us to maintain homeostasis…

7. The Human Physiological Environment Guided Reading: • If humans live on land, why does the author say that the human physiological environment is “aqueous”? • What does it mean when people say that something acts as a “solvent”?

8. More on homeostasis • Homeostasis ≠ balance. • Allows us to adapt to changing environments. Maintained by negative feedback loops • Maintain constant conditions inside the body when the external environment fluctuates. • “Set point” • Often utilizes chemical messengers (e.g. hormones)

9. Negative Feedback Systems

10. Negative Feedback: Maintaining Homeostasis • “System” has a set point (ideal level) and “sensors” that detect changes… • If it drops below set point, something is produced… • If it exceeds that level, production stops… • Examples: • Thermostat • Toilet

11. Body Temperature Example

12. Negative Feedback Loop

13. Generic Example: • Gland X releases hormone X… • This stimulates target cells to release hormone Y. • Eventually, an excess of hormone Y exists • Gland X "senses" this… and inhibits its release of hormone X. Y X X

14. Positive Feedback

15. Defined… • “Feedback in which the system responds so as to increase the magnitude of any particular perturbation”

16. Results in amplification of the original signal instead of stabilization. • Any system where there is a net positive feedback will result in a runaway situation. • Requires a feedback loop to operate. • Examples: Fruit ripening, childbirth, breastfeeding

17. The Human Physiological Environment • The human physiological environment is aqueous. • Water is contained in the cells, the blood, body cavities, organ systems, and tissue. • Not just sloshing around under the skin!! • Water’s atomic structure provides it with all the properties that make it useful for the body.

18. The universal solvent. . . . • Water is polar  can dissolve most materials needed for human survival • Solvent = dissolves other chemicals & forms a solution • Solute = a particle that is dissolved in a solvent • Water is a good bio solvent b/c it is polar (charged) • Most chemical reactions require an aqueous environment

19. Water is a natural solvent for ions, needed for cellular functions • Adhesion & cohesion  won’t evaporate quickly (so we won’t become easily dehydrated) • High specific heat  water absorbs much heat energy when it evaporates

20. Living in a balance • Dehydration: tissues deprived of water • Diarrhea • Sweating • Vomiting • Indicators: extreme thirst, stop sweating, nausea & exhaustion • Water intoxication? • Body takes in more water than it loses at a given period of time. • Upsets natural balance of ions, minerals A Fraternity Hazing Gone Wrong : NPR

21. Do you need a tissue? How cells work together to perform a function…

22. Stem cells again?!?! • Remember… they retain ability to undergo cell division • Assist further body development and healing later in life • Stem cells from bone can produce a variety of human tissues • Brain stem cells can develop into many types of cells

23. Embryological germ layers • Ectoderm  skin and brain • Mesoderm  Bone and muscle • Endoderm  Digestive organs • Lay down the 4 human tissue types into the hierarchy that eventually forms a human

24. Four Types of Tissues • Connective: forms the supportive framework of the organs & body • Epithelial: covers internal & external body surfaces; forms layers of cells that line body cavities • Muscle: provides body w/ movement & support • Nervous: conducts & coordinates body info; highly specialized cells

25. Tissues Guided Reading: • What are the four types of tissue found in humans? • What are the major characteristics/functions of the four types of tissue? (Recommend you make a chart)

26. Create a Concept Map (aka Mind Map) for One Type of Tissue… • How to create a concept map • Constructing a concept map • Example • For each cell type….. • Names of cells & structures • Characteristics • Locations • Functions • Examples

27. Organs and Systems • Cardiovascular  regulates blood flow • Digestive  regulates nutrition • Integumentary  provides protection • Lymphatic  regulates body fluids, helps fight disease • Muscular  provides structure and movement • Skeletal  provides support and movement • Endocrine  regulates body function and development • Reproductive  regulates sexual function • Respiratory  regulates atmospheric gasses and certain body wastes • Urinary  regulates production, storage, and removal of urine

28. Organs, and Systems Guided Reading • What is the relationship between tissues and organs/systems? • What are the various organ systems found in humans?