PH 346 - Exam 1 Review Study Guide
Describe the first 14 days of life, compared to the second 14 days of life. - ANSWER First
14: the egg is fertilized and implants
Second 14: the embryo begins to develop neural basis and heart
Why are the second 14 days of life so critical? - ANSWER Because the nervous system
and the heart begin to develop
Explain: implantation, formation of germ layers: - ANSWER Implantation: the attachment
of a fertilized egg to the wall of the uterus at the beginning of a pregnancy
Formation of germ layers: germ layers develop early in embryonic life, through a
process called gastrulation. During this process, a hollow cluster of cells called a
blastula form two primary germ layers—the endoderm and the ectoderm.
When do the heart and nervous system develop? - ANSWER The heart begins to form
around 18 to 19 days after fertilization and begins to beat/pump at around 21 to 22. The
nervous system begins to lay its foundation roughly 16 days after fertilization and will
eventually begin to form a neural tube.
What is a syncytiotrophoblast? - ANSWER It is an epithelial covering on the wall of the
uterus that determines what substances will/will not be transferred across the placenta
from mother to fetus. Helps to establish blood vessels and begins to produces hCG
hormone (the one detected in pregnancy tests)
When is the phenomenon of implantation complete? - ANSWER Implantation occurs
when a fertilized egg attaches itself to the wall of the uterus. It is complete around 10-14
days after fertilization.
How long does a fertilized zygote stay in the human reproductive tract? - ANSWER
About 5-6 days, until the trophoblast (egg) adheres to the uterine wall.
Describe gastrulation in humans: - ANSWER Gastrulation begins at about day 15 after
fertilization, after cleavage takes place. The cells in the blastula (hollow ball of cells
embryo) rearrange themselves to create 3 different layers of cells that are responsible
for later developing into certain body systems.
Describe the 3 germ layers. Which of the 3 layers gives rise to the nervous system? -
ANSWER Endoderm (inner layer): gives rise to inner linings in the body (gut)
Mesoderm (middle layer): gives rise to the heart, blood vessels, muscles
Ectoderm (outer layer): gives rise to the nervous system
Describe neurulation and neural tube formation. - ANSWER Neurulation: A process in
, which the neural plate bends up and later fuses to form the hollow tube that will
eventually differentiate into the brain and the spinal cord of the central nervous system.
Neural tube formation: Occurs 17-30 days after fertilization. neural folds pinch in
towards the midline of the embryo and fuse together to form the neural tube
What is spina bifida? Neural tube closure failures? - ANSWER Spina bifida: a birth defect
that occurs when the spine and spinal cord don't form properly and failed to close all the
way during development.
Neural tube closure failures: failure of the neural tube to close during neurulation. May
cause problems with brain development (anencephaly) or spinal cord (spina bifida)
How many eggs does a female human have throughout the life course? Is this too many
or not enough? - ANSWER Born with nearly 1-2 million eggs, but approximately 11,000 of
them die each month prior to puberty and only 300,000 remain by the puberty begins.
Only 300-400 of them will be ovulated during a woman's reproductive lifetime.
What hormones are related to ovulation? What is the luteinizing hormone? When is it
released during the menstrual cycle? - ANSWER FSH: Follicle stimulating
hormone—stimulate ovarian follicles to mature
LH: Luteinizing hormone—causes rupture of mature ovarian follicle, causes egg to be
released. Is released at ovulation (14 days into the menstrual cycle)
Progesterone: builds up uterine lining in case there is an implantation
Estrogen: builds up and matures the uterine lining
What day does ovulation occur on? Is this the prime time for fertilization, why? -
ANSWER Occurs on/around day 14 of the menstrual cycle. This is the best time to
reproduce because the egg is in the fallopian tubes, the ideal location for fertilization.
Also at this time, the consistency of cervical mucus will help sperm reach the egg for
fertilization.
Explain the anatomy of a sperm; the flagella, acrosome, and enzymes. What happens if a
sperm can't swim? - ANSWER If sperm can't swim they are considered immotile. They
cannot fertilize the egg and the male is infertile.
Where does sperm get its energy? - ANSWER From ATP in the mitochondria
What are the key components of sperm? - ANSWER Head: contains nucleus and DNA
Midpiece: holds mitochondria and gives sperm energy
Tail: gives the sperm mobility
Acrosome: helps the sperm to penetrate the egg. Contains enzymes that break down
the outer surface of the egg
Describe the first 14 days of life, compared to the second 14 days of life. - ANSWER First
14: the egg is fertilized and implants
Second 14: the embryo begins to develop neural basis and heart
Why are the second 14 days of life so critical? - ANSWER Because the nervous system
and the heart begin to develop
Explain: implantation, formation of germ layers: - ANSWER Implantation: the attachment
of a fertilized egg to the wall of the uterus at the beginning of a pregnancy
Formation of germ layers: germ layers develop early in embryonic life, through a
process called gastrulation. During this process, a hollow cluster of cells called a
blastula form two primary germ layers—the endoderm and the ectoderm.
When do the heart and nervous system develop? - ANSWER The heart begins to form
around 18 to 19 days after fertilization and begins to beat/pump at around 21 to 22. The
nervous system begins to lay its foundation roughly 16 days after fertilization and will
eventually begin to form a neural tube.
What is a syncytiotrophoblast? - ANSWER It is an epithelial covering on the wall of the
uterus that determines what substances will/will not be transferred across the placenta
from mother to fetus. Helps to establish blood vessels and begins to produces hCG
hormone (the one detected in pregnancy tests)
When is the phenomenon of implantation complete? - ANSWER Implantation occurs
when a fertilized egg attaches itself to the wall of the uterus. It is complete around 10-14
days after fertilization.
How long does a fertilized zygote stay in the human reproductive tract? - ANSWER
About 5-6 days, until the trophoblast (egg) adheres to the uterine wall.
Describe gastrulation in humans: - ANSWER Gastrulation begins at about day 15 after
fertilization, after cleavage takes place. The cells in the blastula (hollow ball of cells
embryo) rearrange themselves to create 3 different layers of cells that are responsible
for later developing into certain body systems.
Describe the 3 germ layers. Which of the 3 layers gives rise to the nervous system? -
ANSWER Endoderm (inner layer): gives rise to inner linings in the body (gut)
Mesoderm (middle layer): gives rise to the heart, blood vessels, muscles
Ectoderm (outer layer): gives rise to the nervous system
Describe neurulation and neural tube formation. - ANSWER Neurulation: A process in
, which the neural plate bends up and later fuses to form the hollow tube that will
eventually differentiate into the brain and the spinal cord of the central nervous system.
Neural tube formation: Occurs 17-30 days after fertilization. neural folds pinch in
towards the midline of the embryo and fuse together to form the neural tube
What is spina bifida? Neural tube closure failures? - ANSWER Spina bifida: a birth defect
that occurs when the spine and spinal cord don't form properly and failed to close all the
way during development.
Neural tube closure failures: failure of the neural tube to close during neurulation. May
cause problems with brain development (anencephaly) or spinal cord (spina bifida)
How many eggs does a female human have throughout the life course? Is this too many
or not enough? - ANSWER Born with nearly 1-2 million eggs, but approximately 11,000 of
them die each month prior to puberty and only 300,000 remain by the puberty begins.
Only 300-400 of them will be ovulated during a woman's reproductive lifetime.
What hormones are related to ovulation? What is the luteinizing hormone? When is it
released during the menstrual cycle? - ANSWER FSH: Follicle stimulating
hormone—stimulate ovarian follicles to mature
LH: Luteinizing hormone—causes rupture of mature ovarian follicle, causes egg to be
released. Is released at ovulation (14 days into the menstrual cycle)
Progesterone: builds up uterine lining in case there is an implantation
Estrogen: builds up and matures the uterine lining
What day does ovulation occur on? Is this the prime time for fertilization, why? -
ANSWER Occurs on/around day 14 of the menstrual cycle. This is the best time to
reproduce because the egg is in the fallopian tubes, the ideal location for fertilization.
Also at this time, the consistency of cervical mucus will help sperm reach the egg for
fertilization.
Explain the anatomy of a sperm; the flagella, acrosome, and enzymes. What happens if a
sperm can't swim? - ANSWER If sperm can't swim they are considered immotile. They
cannot fertilize the egg and the male is infertile.
Where does sperm get its energy? - ANSWER From ATP in the mitochondria
What are the key components of sperm? - ANSWER Head: contains nucleus and DNA
Midpiece: holds mitochondria and gives sperm energy
Tail: gives the sperm mobility
Acrosome: helps the sperm to penetrate the egg. Contains enzymes that break down
the outer surface of the egg
