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Questions and Answers
What physiological change must sperm undergo in the female genital tract to fertilize the ovum?
What occurs during the acrosomal reaction of sperm?
What is the primary purpose of the cortical reaction following fertilization?
What is the process called that occurs when a zygote burrows into the endometrial lining of the uterus?
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How long must sperm remain in the female reproductive tract before they can fertilize an ovum?
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Which structure connects the fetus to the placenta?
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What is the primary function of amniotic fluid during pregnancy?
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What happens to the zona pellucida after the first sperm penetrates it?
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At what age is a fetus considered to have reached the 'age of viability'?
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During which developmental period does implantation of the zygote into the endometrium occur?
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What is the primary role of the placenta during pregnancy?
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What do male and female gametes contribute to form a zygote?
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What is the first action sperm take upon reaching the zona pellucida?
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How long is the ovum fertilizable after ovulation?
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Which of the following is NOT a characteristic of the umbilical cord?
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What happens during fertilization?
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What is the term for the process where a zygote undergoes mitotic division to form smaller cells?
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During which stage does the morula transform into the blastocyst?
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What structure is formed from the inner cell mass of the blastocyst?
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At which day does implantation occur following fertilization?
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What is the role of pinopods during the apposition phase of implantation?
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Which of the following molecules is primarily involved in the adhesion of the blastocyst to the endometrium?
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What is the primary function of the trophoblast in the blastocyst?
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What defines the endometrial fluid absorbed by pinopods during implantation?
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What is the role of HCG during early pregnancy?
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Which layer of the decidua lies directly under the embryo?
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What is the function of the Syncytiotrophoblast cells?
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What facilitates the exchange of substances between mother and fetus in the placenta?
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Which hormone produced by the placenta acts as a glucose antagonist to ensure glucose availability for the fetus?
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How does maternal positioning affect placental circulation?
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What characteristic describes the fetal side of the placenta?
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What is the primary role of the placenta during pregnancy?
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What is the primary function of HCG during early pregnancy?
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Which hormone is responsible for reducing the contractility of the uterus during pregnancy?
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What role does the placenta play in fetal immunity?
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Which statement accurately describes the umbilical cord?
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What is the primary function of human placental lactogen during pregnancy?
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Which general function is associated with estrogen during pregnancy?
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What is the function of Wharton's jelly in the umbilical cord?
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Which membranes are involved in the formation of amniotic fluid?
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Study Notes
Pregnancy Overview
- Pregnancy refers to the period from conception to birth where a female carries a developing embryo or fetus.
- Begins with fertilization, the union of a sperm and an ovum, resulting in a zygote, which carries genetic material from both parents.
Fertilization Process
- Conception occurs when one sperm penetrates one ovum, determining the child's sex at this moment.
- Nidation, or implantation, occurs 7-10 days post-fertilization in the endometrial lining.
- Sperm lifespan: 48-72 hours; ovum is fertilizable for 24-48 hours.
Special Structures of Pregnancy
- Fetal Membranes: Form from the zygote and surround the developing fetus, containing amniotic fluid.
- Amniotic Fluid: Clear, yellowish liquid (average 1000 ml); allows fetal movement, maintains temperature, and provides oral fluid.
- Umbilical Cord: Connects fetus to placenta; contains 2 arteries and 1 vein, protected by Wharton's jelly, with no pain receptors.
- Placenta: Acts as an endocrine organ and protective barrier, facilitating nutrient and water exchange between mother and fetus.
Stages of Fetal Development
- Age of Viability: A fetus can potentially survive if born after 20 weeks or weighs at least 500 grams.
- Zygote Development: Begins with fertilization and involves cell division (cleavage) and formation of blastomeres.
Capacitation and Gamete Fusion
- Capacitation: Physiological changes in sperm required for fertilization; requires 4-6 hours in female tract.
- Acrosomal Reaction: Sperm releases enzymes to penetrate the ovum's layers; leads to the cortical reaction, making the ovum impermeable to additional sperm.
Zygote Development Phases
- Pre-embryonic Period: First 2 weeks post-fertilization; embryo travels to uterus and implants.
- Embryonic Period: Weeks 2-8 with significant growth and differentiation.
- Fetal Period: From 8 weeks until birth; further maturation and development.
Implantation Process
- Apposition: Pinopod formation aids in embryo absorption into the endometrial lining.
- Adhesion: Blastocyst attaches to endometrium via adhesion molecules.
- Penetration & Invasion: Blastocyst burrows into uterine wall through histolytic action.
Decidua and Chorionic Villi
- Decidua: The modified endometrium during pregnancy, composed of three layers.
- Chorionic Villi: Villi develop to form the placenta, using fetal capillaries for nutrient exchange.
Hormones Produced by the Placenta
- Human Chorionic Gonadotropin (HCG): Maintains corpus luteum; suppresses maternal immunologic response.
- Estrogen: Stimulates uterine growth and mammary development.
- Progesterone: Maintains endometrial lining and reduces uterine contractions.
- Human Placental Lactogen (HPL): Promotes mammary growth and regulates maternal metabolism for fetal needs.
Placenta Functionality
- Functions as fetal lungs, kidneys, and gastrointestinal tract; facilitates nutrient and waste exchange.
- Maternal antibodies provide passive immunity; some drugs and viruses can cross the placental barrier.
Umbilical Cord Structure
- Transports oxygen/nutrients to fetus and waste to the placenta; typically 55 cm long and 2 cm in diameter.
- Composed of 1 vein and 2 arteries; Wharton's jelly prevents pressure on vessels.
Amniotic Membranes
- Chorionic Membrane: Outermost membrane forming the amniotic fluid sac.
- Amniotic Membrane: Produces amniotic fluid and initiates labor by generating prostaglandins.
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Description
Test your knowledge on key physiological changes in human reproduction, particularly focusing on sperm maturation, the acrosomal reaction, and the implantation of the zygote. This quiz covers essential concepts related to fertilization and early development. Challenge yourself on these critical reproductive processes.
