Chapter 33 Activites
What gland secretes FSH and LH into the blood?
Anterior pituitary of the brain
If you see an ultrasound image that indicates the embryo is several centimeters in length and about the size of a quarter, approximately how many weeks has the embryo been developing?
Approximately 8 weeks.
When does cleavage begin? What happens?
Cleavage begins about 36 hours after fertilization and is the process in which the zygote doubles its chromosomes and divides into two identical daughter cells through the process of mitosis.
If pregnancy does occur, what ovarian structure do you predict would remain intact during early pregnancy and secrete the hormones necessary for maintaining the endometrium?
Corpus Luteum
In terms of the process of meiosis, describe the egg's development during days 1-14 of the ovarian cycle.
During this time a primary oocyte, stopped in prophase meiosis 1, resumes meiosis until prophase f meiosis 2 and becomes a secondary oocyte.
What organs and systems do the ectoderm, mesoderm, and endoderm tissues develop into?
Ectoderm tissue develops into the embryo's skin and nervous system. Mesoderm tissue forms the skeletal and muscular systems as well as many other organs. Endoderm tissue forms the embryo's digestive tract and lungs.
Where does fertilization typically take place?
Fertilization typically takes place in the oviduct.
Do you recognize any features on the fetus?
Head, ear, arms, legs, fingers, toes, heart
Name the five major life stages.
Infancy, childhood, adolescence, adulthood, and old age
What happens on day 14 of the ovarian cycle?
Ovulation occurs. The follicle and adjacent wall of the ovary rupture, releasing the secondary oocyte.
List the three types of glands in the male reproductive system and state the function of the fluid produced by each.
Seminal vesicles: secrete a clear fluid that lubricates and nourishes the sperm, Prostate gland: secretes a milky fluid that helps to protect the sperm from the natural acidity of the vagina, Bulbourethral glands: Secrete only a few drops of fluid in to the urethra; this fluid is thought to lubricate the urethra, helping sperm to move through it.
What change in the ovarian cycle marks the beginning of another menstrual cycle?
The degeneration of the corpus luteum marks the beginning of another menstrual cycle.
What would you expect to "see" on an ultrasound image of a fetus that is 24 weeks old?
The fetus would probably have little body fat and the brain hemisphere would be visible. The eyes may be open and react to light. Fingernails and toenails are beginning to grow.
What is a follicle and what is its function?
The follicle is a cluster of cells that surrounds, protects, and nourishes a developing egg cell and also secretes hormones.
What is the function of the oviduct?
The function of the oviduct is to carry the secondary oocyte away from the ovary and towards the uterus.
Unlike the bird or reptile egg, the human yolk sac contains no yolk. In fact, it has a completely different function for humans than for birds and reptiles. What is the function of the yolk sac in humans?
The human yolk sac is important because it is the site of early formation of blood cells.
How does a human embryo receive nourishment?
The placenta provides nourishment and oxygen to the developing embryo
Give at least two examples of how structures in the male reproductive system support their functions
The scrotum is an external pouch that houses the testes and maintains an ideal temperature for developing sperm; sperm pass into a long, coiled tube called the epididymis where they are stored until mature; the seminal vesicle is a gland that secretes fluid, which nourishes and lubricates the sperm.
Explain the difference between a secondary oocyte, ovum, and zygote.
The secondary oocyte is the cell released during ovulation. Once a sperm penetrates the secondary oocyte, it is called an ovum. Following fusion of the two haploid nuclei, a zygote is created with a diploid set of chromosomes.
Give at least two examples of how structures in the female reproductive system support their functions.
The thick muscular wall of the uterus provides nourishment and protection for the developing fetus; the follicle is a cluster of cells that protect and nourish a primary oocyte, or developing egg cell; the ovuduct is a tube that carries the secondary oocyte toward the uterus, functioning as a passageway.
Explain the function of the thickened endometrium in the late part of the menstrual cycle.
The thickened endometrium lining is necessary for the possible embryo implantation and to provide nourishment if an egg is fertilized.
How does the blastocyst implant into the endometrium?
The trophoblast secretes enzymes that enable the blastocystto burrow into the endometrium.
Progesterone is one of the hormones that prepare the endometrium for implantation of the fertilized egg. A blood test can measure levels of hormones circulating in the blood. What do you predict would happen to the blood progesterone levels if fertilization and pregnancy occur?
They would remain elevated.
Can you infer what you are seeing 2?
Twins
Why is ultrasound an important diagnostic technique used during pregnancy?
Ultrasound can provide a fetus' size, age, gender, and possibly determine if there are any abnormalities.
Can you infer what you are seeing?
eyebrows/hair