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Chapter 20 BIOL 2404
Terms in this set (54)
Levels of hCG remain high until the __ can produce enough hormones on its own to maintain the pregnancy
Development, which includes ___, is the continuous process by which an individual changes from one life phase to another.
The life phases are the ____ period, which begins at fertilization and ends at birth, and the ____ period, which begins at birth and ends at death.
Pregnancy is the presence of developing offspring in the uterus, an event resulting from _______.
Sperm cells must reach the secondary ____ of the uterine tubes for fertilization to occur.
Under the influence of ___ during the first half of the menstrual cycle, uterine secretions are ____, allowing sperm cells to swim easily toward their destination
With the aid of the ____ enzyme, the sperms cells erode away the __ and ____ surrounding the secondary ____, and one sperm cell penetrates the egg cell membrane
acrosomal, corona radiate, zona pellucida
What prevents the entry of additional sperm cells?
The fertilization membrane
_______ of egg and sperm nuclei completes fertilization.
Fertilization results in a diploid cell called the ______.
Cells undergo a period of mitosis called ____, when cells become smaller and smaller.
The dividing mass of cells (called a __) moves down the uterine tube to the uterus, where a stage called the ___ implants in the lining of the uterus.
The offspring is called an ___ during the first eight weeks of development, and a ____ after that time.
Some of the cells become the ____, which also secretes hormones.
The outer layer of cells called the _of the blastocyst stage secrete the hormone ____(hCG), which maintains the corpus _____ and thus also maintains the uterine lining and the pregnancy.
This structure also secretes placental _____ for breast development and estrogens.
The embryonic stage lasts from the ___ to the ___ week of development, during which
second to eighth
time the placenta develops, and all the main internal ___ and major external features appear.
During the second week, the embryo is now called a __ and its inner cell mass transforms into the _____ disk, and layers form within it.
These layers become the three primary ____ layers and give rise to all organ systems.
____ gives rise to the nervous system, portions of special sensory organs, the epidermis and epidermal derivatives, and the linings of the mouth and anal canal.
the first site of blood cell formation and also gives rise to the cells that will become ___ cells
lymphatic vessels, internal reproductive organs, kidneys, and epithelial linings of the body cavities.
____ cells produce the epithelial linings of the digestive tract, respiratory tract, urinary bladder, and urethra.
As the embryo implants, the trophoblast sends out extensions that develop into ____.
By the _____ week, the heart is beating, the head and jaws appear, and limb buds form.
By the _____week, the trophoblast is now the chorion, a portion of which develops into the ___.
During this time, another membrane, the __, is developing around the embryo and will hold cushioning _______ fluid.
An umbilical cord containing __ umbilical arteries and ____ vein forms.
The ____ forms during the third week and joins the connecting stalk of the embryo; it forms blood cells and gives rise to the umbilical arteries and vein.
By the beginning of the _____ week, the embryo is 3 millimeters in length and all essential body systems have formed
The fetal stage begins at the end of the eighth week of development and lasts until _______.
During this period, _______ is rapid and body proportions change considerably.
Existing structures grow and mature and only a few new parts of the bone __.
When does the mother usually feel the fetus move?
About the fifth month
In the final trimester, ___ cells form rapidly and organs grow and mature as the fetus greatly increases in size.
Substances diffuse through the ____ membrane.
____ vessels carry them to and from the fetus
fetal blood has a ___ oxygen-carrying capacity than maternal blood.
The umbilical ____, transporting blood rich in oxygen and nutrients, enters the body and travels to the liver where half of the blood is carried into the liver and half bypasses the liver through the vessel called the ______on its way to the inferior vena cava.
vein, ductus venosus
An opening, called the ____, conveys a large portion of the blood entering the right atrium from the inferior vena cava, through the _____ septum, and into the left atrium, thus bypassing the ____.
foramen ovule, atrial, lungs
A second lung bypass is the ____, which conducts some blood from the pulmonary trunk directly to the aorta.
Umbilical _____ carry blood from the internal iliac arteries to the placenta, where it can exchange wastes and again pick up nutrients and oxygen.
What happens to these structures after birth?
These ducts close off and become sealed over
Pregnancy continues for ____ weeks and terminates in the birth process.
As the placenta ages, less ____ is produced, which normally inhibits uterine contractions.
A decreasing progesterone concentration may stimulate the synthesis of ___, which may initiate labor.
Stretching uterine tissues stimulates the release of ____ from the posterior pituitary, which stimulates uterine contractions.
As the fetal head stretches the cervix, a ___ feedback mechanism results in stronger and stronger uterine contractions and a greater release of oxytocin.
Following birth, the ______ is expelled by the continued uterine contractions (afterbirth).
Following childbirth, the action of ___ is no longer inhibited and the mammary glands are stimulated to produce large quantities of milk.
First milk called ___, is a watery fluid rich in proteins and ___.
Milk does not readily flow into the ductile system. What triggers it?
What is the best possible food for human babies?
THIS SET IS OFTEN IN FOLDERS WITH...
Chapter 3 BIOL 2404
Chapter 9 Anatomy: Nervous System
Chapter 9-Spine and spinal nerves
Anatomy Chapter 10: Somatic and Special Senses
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