1. Animal form, function, & development
Chapters 40 & 47

2. You must know The importance of homeostasis and examples
How feedback systems control homeostasis
One example of positive feedback and one example of negative feedback
Programmed cell death (apoptosis) plays a role in normal development and differentiation (ex. morphogenesis)
Cell differentiation results from the expression of genes for tissue-specific proteins and the induction of transcription factors

3. I. Levels of organization

4. Control & Coordination
1. Endocrine system – produces hormones (chemical signals), releases them into blood, act at target tissues that contain receptors
2. Nervous system – transmit information between locations by nerve impulses

5. II. Homeostasis Maintaining a relatively stable internal environment
Must stay within a range of tolerance
1. Sensors detect stimulus above or below and trigger response

6. Negative Feedback
1. Keep body within range of tolerance (maintains homeostasis)

7. 1. Used to amplify a signal
Positive Feedback
1. Used to amplify a signal
Another example is blood clotting

8. III. Thermoregulation
Endotherms – warmed by heat generated by metabolism (mammals, birds)
Ectotherms – gain heat from external sources (reptiles)

9. C. Countercurrent exchange – heat transfer involves antiparallel arrangement of blood vessels so that heat iN vessels on the way to extremities transfers heat to blood returning from extremities

10. IV. Energy Requirements
Metabolic rate – energy used per time
1. Generally higher for endotherms
2. Standard v Basal Metabolic rates (both at rest)
3. Inversely related to body size

11. V. Embryonic Development
Fertilization
Many sperm start breaking down the zona pellucida (glycoprotein layer surrounding the secondary oocyte) by releasing hydrolytic enzymes from acrosome (acrosome reaction)
a. Also triggers oocyte to finish meiosis II
2. One spermatozoan reaches plasma membrane, releases more hydrolytic enzymes to penetrate egg
3. Plasma membranes fuse

12. 4. Cortical reaction – prevents more than one sperm from fertilizing egg – cortical granules fuse with plasma membrane and release enzymes outside, chemically changing the zona pellucida so that no other sperm can penetrate 5. Nuclei of egg and sperm fuse to restore diploid chromosome number

13. The early embryo
1. Zygote = fertilized egg
2. Cleavage = period of rapid mitotic division without cell growth
3. Blastula = hollow ball of about 100 cells

14. Gastrulation – blastula folds into a 3 layered gastrula
5. Organogenesis – development of germ layers into organs

15. Morphogenesis & Differentiation
1. Apoptosis – programmed cell death – elimination of tails, webbing between digits, etc.
2. Other cells are programmed to change shape or location

16. Cytoplasmic determinants – chemical signals, usually mRNAs and transcription factors, that are unevenly distributed during mitosis
4. Inductive Cell Signals – interaction between cells causes differentiation, usually by gene expression

17. 5. Notochord & neural tube formation - from dorsal lip of blastopore

18. 6. Stem cells
Totipotent – only until about 16-cell stage of embryo