Final Exam- Reproductive System Flashcards
What are hormones?
Hormones are proteins in an endocrine gland and they travel up to the blood to target organs.
Explain how a fetus formed
- The nucleus of the ovary and the sperm each have 23 chromosomes. Each ovary produces one egg a month. The eggs travel down the oviduct to the uterus. The testes produce sperm. Sperm swim in a fluid called semen made by the prostate gland.
- When two people have sex, the man’s penis enters the woman’s vagina and semen is deposited into vagina. Sperm then swim from the vagina, through the uterus and into the oviduct. The sperm and egg meet and the nuclei fuse this is called conception. The fusing of the nuclei is called fertilization. -
- The fused nuclei is called a zygote, which is the combined 46 chromosomes.
- Cell division the occurs and forms a ball of cells called an embryo. Once the embryo is formed it will begin to produce HCG. HCG helps to maintain the thickness of the endometrium. Once the embryo is prepared to travel to the uterus it will begin to produce its own progesterone as will the mother which ensures the thickness of the endometrium. The embryo is them implanted into the endometrium.
- -Eventually the cells develop and the embryo consists of billions of cells and has all the parts of a human being. It is then a fetus.
Describe what occurs during the 28 day menstruation cycle.
- Days 0-4- The estrogen and progesterone levels are relatively low. The low hormone levels result in menstruation. A loss of the endometrium.
- Days 4-15- There is a great increase in estrogen in the estrogen levels. There is a slight increase in progesterone. The estrogen levels rise therefore the endometrium thickens. It must regain what was lost during menstruation. 15- The estrogen levels decrease and the progesterone levels rise to meet the estrogen levels.
- On day 15 the estrogen and progesterone levels are relatively the same. At this time ovulation is occurring. After ovulation the progesterone levels rise to maintain the thickness of the endometrium. The estrogen are about the same as they were during ovulation. The endometrium is preparing for the a fertilized egg.
- On day 28 if the ovum is not fertilized then progesterone levels will lower. Since both hormone levels are low this triggers the menstrual cycle to begin again. If a woman is pregnant than the progesterone levels will stay the same to maintain the thickness of the endometrium.
What is ovulation
ovulation occurs when an ovum is released from the ovary
How does fetal blood get to and from the placenta?
The embryo quickly splits into two parts the fetus and the placenta. The two are linked by the umbilical chord which contain the umbilical artery and vein. The fetus’s heart pumps blood from the fetus to and from the placenta.
Which substances does the fetus obtain from the mother’s blood in the placenta that are necessary for development?
oxygen, protein and glucose.
How do the fetus and mother exchange substances?
Substances are exchanged in the placenta by diffusion between the mother’s and fetus’s blood. The maternal blood and fetal blood never mix.
Which substances are passed from the fetal blood to the maternal blood to be removed by the mother’s system.
Carbon dioxide, and urea
Explain how urea is removed from the fetus
The fetus has a high concentration of urea in the capillary. The urea must exit the fetus therefore it diffuses to the maternal blood as there it a low concentration there. After diffusion occurs urea travel to the kidney where it is filtered. The urea then passes through the ureter, bladder and urethra. The fetus’s urea is finally released.
Explain how oxygen is delivered to the fetus
The mother inhales oxygen in the atmosphere and it moves through the trachea and bronchi. Once the oxygen reaches the alveolus it diffuses into the capillary as there is a low concentration of oxygen there. The oxygen then travels to the placenta where it is diffused into the fetal blood.
Explain what amniocentesis is.
Amniocentesis is a test in which a needle goes into the mother’s abdomen. A sample of fluid is taken from the amniotic sac surrounding the fetus. Each cell in the fluid contains the baby’s complete set of DNA. This allows the doctor to check for abnormalities in the fluid which the baby may therefore obtain. Amniocentesis is usually performed on women over 40, or who have a family history of abnormalities. i.e. Downs Syndrome.
What is a Foramen Ovale?
The foramen ovale is the hole between the right and left atria. The hole allows oxygen to bypass the non-functioning lungs and oxygenated blood directly into the left ventricle. An ultrasound is taken before birth to ensure that the foramen ovale is closed.
When the fetus is ready to be born many changes takes place in the woman’s body. What are these changes?
- Pelvis- dilates and becomes more flexible so that the baby can pass through
- Cervix- Dilation of 10 cm also occurs
- Breasts- Enlarge to prepare for milk secretion
How is a fetus born?
- The fetal brain sends a signal to the mother’s brain to begin the labor process. -
- The mother’s pituitary gland secretes oxytocin. -
- This causes the myometrium to contract. These contractions continually increase in frequency and strength. -
- The contractions causes the baby’s head to hit the cervix.
- The hitting of the head on the cervix sends nerve impulses back to the mother’s brain. The mother’s pituitary gland secretes more oxytocin. Increase in oxytocin results in stronger contractions. This causes the baby’s head to hit the cervix harder sending an even stronger nerve impulse to the brain so on so fourth.
What is positive feedback?
Positive feedback is when one variable triggers the next the next variable to rise. Each variable causes the next one to become even stronger.
Label the diagram
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