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27 Cards in this Set
- Front
- Back
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What are the stages of Development? |
1. Fertalization 2. Cleavage 3. Gastrulation 4. Organogenesis 5. Growth |
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What are the four major events that occur during fertalization? |
1. Contact and recognition between sperm and egg 2. Sperm entry is regulated 3. Egg becomes activated 4. Sperm and egg fuse nuclei |
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What is polyspermy? |
Fertilization of an egg by more than one sperm |
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What is fast block to polyspermy? |
1. Fusion of membranes opens up sodium channels 2. Sodium enters the egg and depolarizes the membrane 3. Other sperm cells cannot fuse with the depolarized egg membrane |
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What is slow block to polyspermy? |
1. Fusion of egg and sperm membranes causes Ca+2 to be released form the egg endoplasmic reticulum 2. Ca+2 stimulates cortical granules to fuse with membrane |
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What is cleavage? |
1. Series of rapid divisions with no growth 2. Occurs shortly after fertilization 3. Cleavage does NOT increase the size of the embryo, only the number of cells 4. The cells that form from each division are called blastomeres |
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What are the Major stages of Cleavage? |
1. Morula 2. Blastula 3. Gastrula |
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How many cells are in a Morula and is it solid or hollow? |
32 cells and solid |
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How many cels are in a blastula and is it solid or hollow? |
64 to hundreds |
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What is the cavity in the Blastula called? |
Blastocoel |
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What is yolk? |
food for a developing embryo |
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What pole is the yok most concentrated in? |
Vegetal pole |
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What pole is the anterior end of the embryo? |
Animal pole |
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What are the 3 germ layers? |
1. Endoderm 2. Mesoderm 3. Ectoderm |
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What is the cavity of the developing gut called in Frogs? |
Archenteron |
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What is the opening where the future anus will be called? |
Blastopore |
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What are some structures found in the Ectoderm? |
1. Nervous system 2. Outer layer of skin and associated structures 3. Pituitary Gland |
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What are some structures found in the Mesoderm? |
1. Notochord 2. Skeleton 3. Muscles 4. Circulatory System 5. Excretory System 6. Reproductive System 7. Inner layer of skin 8. Outter layers of digestive tube |
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What are some structures found in the Endoderm? |
1. Lining of digestive tube |
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What is organogenesis? |
organ formation |
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How is the Nervous system Developed? |
1. The notochord induces the overlying ectoderm to thicken and differentiate into the neural plate 2. The neural plate folds downward to form the neural tube, the future brain and spinal cord. |
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How long is the typical pregnancy? |
266 days or 38 weeks or 9 months |
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When does Organogenesis begin? |
During the first trimester and continues throughout development |
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what is happening with the fetus during the second trimester? |
1. heartbeat can be heard 2. Fetus moves 3. Organ systems are developed but not mature |
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What is happening with the fetus during the third trimester? |
1. fetus completes development and can start to grow
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what are teratogens? |
Are drugs or other substances that interfere with morphogenesis, and so cause malformations.
ex. Alcohol and cigarettes |
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What is Teratogenesis? |
The process by which congenital malformations are produced in an embryo or fetus. |
