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Chapter 23: Pregnancy Growth & Development
Terms in this set (122)
an increase in size; development is the process of changing from one phase of life to another.
includes both prenatal and postnatal life phases.
Transport of sex cells
-The secondary oocyte is ovulated and enters the uterine tube.
-a sperm cell moves, by its tail lashing and muscular contraction in the female reproductive tract, into the uterine tube.
-With the aid of enzymes, a sperm cell penetrates the zona pellucida.
-When a sperm cell penetrates a secondary oocyte membrane, changes in the oocyte cell membrane and the zona pellucida prevent entry of additional sperm.
-Completion of meiosis II forms the second polar body.
-Fusion of the pronuclei of a sperm and a secondary oocyte completes fertilization.
-The product of fertilization is a zygote with 46 chromosomes.
the presence of a developing offspring in the uterus.
The Prenatal period of the offspring
Cleavage, the embryonic stage, and the fetal stage.
During the Period of Cleavage
-The zygote undergoes mitosis, and the newly formed cells divide mitotically.
-Each subsequent division produces smaller and smaller cells.
-A solid ball of cells (morula) forms, and it becomes a hollow ball called a blastocyst.
-The inner cell mass that gives rise to the embryo proper forms within the blastocyst.
-The blastocyst implants in the uterine wall
1) Enzymes digest the endometrium around the blastocyst.
2) Fingerlike processes from the blastocyst penetrate the endometrium.
-Cleavage lasts through the first week of development.
-The trophoblast secretes hCG, which helps maintain the corpus luteum, helps protect the blastocyst against being rejected, and stimulates the developing placenta to secrete hormones.
Embryonic cells produce
hCG that maintains the corpus luteum, which continues to secrete estrogens and progesterones.
produces high concentrations of estrogens and progesterones.
1) Estrogens and progesterones maintain the uterine wall and inhibit secretion of FSH and LH
2) Progesterone and relaxin inhibit contractions of uterine muscles
3) Estrogens enlarge the vagina
4) Relaxin helps relax the ligaments of the pelvic joints
The placenta secretes
placental lactogen that stimulates the development of the breasts and the mammary glands.
During pregnancy, increasing secretion of
aldosterone promotes retention of sodium and body fluid, and increasing secretion of parathyroid hormone helps maintain a high concentration of maternal blood calcium.
Other changes during pregnancy
-The uterus greatly enlarges
-The woman's blood volume, cardiac output, breathing rate, and urine production increases.
-The woman's dietary needs increase, but if intake is inadequate, fetal tissues have priority for use of available nutrients.
The embryonic stage extends
from the 2nd through the 8th week
During the embryonic stage
-The placenta and main internal and external body structures develop.
-Chorionic villi develop and are surrounded by spaces filled with maternal blood.
-a fluid-filled amnion develops around the embryo.
-The embryonic disc becomes cylindrical and attached to the developing placenta by the connecting stalk.
The cells of the inner mass fold
inward, forming a gastrula that has 2 and then 3 primary germ layers.
gives rise to the nervous system, portions of the skin, the lining of the mouth, and the lining of the anal canal.
gives rise to muscles, bones, blood vessels, lymphatic vessels, reproductive organs, kidneys, and linings of body cavities.
gives rise to linings of the digestive tract, respiratory tract, urinary bladder, and urethra.
The yolk sac forms on the
underside of the embryonic disc.
1) It gives rise to blood cells and cells that later form sex cells.
2) It helps form the digestive tube.
extends from the yolk sac into the connecting stalk.
1) It forms blood cells.
2) It gives rise to the umbilical vessels.
During the embryonic stage
the chorion and amnion fuse.
The umbilical cord is formed as the
amnion envelopes the tissues attached to the underside of the embryo.
1) The umbilical cord includes 2 arteries and a vein.
2) It suspends the embryo in the amniotic cavity.
The placenta develops in the
disc-shaped area where the chorion contacts the uterine wall.
1) The embryonic portion consists of the chorion and its villi.
2) The maternal portion consists of the endomentrium.
The placental membrane consists of the
epithelium of the chorionic villi and the endothelium of the capillaries inside the chorionic villi.
1) Oxygen and nutrients diffuse from the maternal blood through the placental membrane and into the fetal blood.
2) Carbon dioxide and other wastes diffuse from the fetal blood through the placental membrane and into the maternal blood.
The embryo develops
a head, face, upper limbs, lower limbs, and mouth, and appears more humanlike.
By the beginning of the 8th week
the embryo is recognizable as a human.
During the embryonic stage, the most critical period of development
teratogens can cause congenital malformations.
this stage extends from the end of the 8th week and continues until birth.
During the fetal stage
-Existing structures grow and mature; only a few new parts appear.
-The body enlarges, upper and lower limbs reach final relative proportions, the skin is covered with sebum and dead epidermal cells, the skeleton continues to ossify, muscles contract, and fact is deposited in subcutaneous tissue.
The fetus is full term
at the end of the 9th month, which equals approximately 266 days.
1) It is about 50 cm long and weighs 2.7- 3.6 kg
2) It is positioned with its head toward the cervix.
Umbilical vessels carry blood between the
placenta and the fetus
Fetal blood carries
a greater concentration of oxygen than does maternal blood because the concentration of oxygen-carrying hemoglobin is greater in fetal blood, and fetal hemoglobin has greater affinity for oxygen.
Blood enters the fetus through
the umbilical vein and partially bypasses the liver by means of the ductus venous.
Blood enters the right atrium and partially bypasses the lungs by means of
the foramen ovale
Blood enters the pulmonary trunk partially bypasses the lungs by means of
the ductus arteriosus
Blood enters the umbilical arteries from the
internal iliac arteries
Pregnancy usually lasts
38 weeks after fertilization
During pregnancy, placental progesterone inhibits
Several events occur at birth:
1) a decreasing concentration of progesterone and the release of prostaglandins may initiate the birth process.
2) The posterior pituitary gland releases oxytocin.
3) Uterine muscles are stimulated to contract, and labor begins.
4) Positive feedback causes stronger contractions and greater release of oxytocin.
Following the birth of the infant
placental tissues are expelled
During pregnancy, the breasts change
1) Estrogens cause the ductile system to grow.
2) Progesterones causes development of alveolar glands.
3) Prolactin is released during pregnancy, but progesterone inhibits milk productions.
the concentrations of placental hormones decline.
1) The action of prolactin is no longer blocked.
2) The mammary glands begin to secrete milk.
Reflex responses to mechanical stimulation of the nipple causes
the posterior pituitary gland to release oxytocin, which releases milk from the alveolar ducts.
As long as milk is removed from the breasts
more milk is produced; if milk is removed, production ceases.
During the period of milk production
the reproductive cycle may be inhibited.
Neonatal period extends from
birth to the end of the 4th week
The newborn must begin to
respire, obtain nutrients, excrete wastes, and regulate is body temperature.
The first breath must
be powerful to expand the lungs
1) Surfactant reduces surface tension.
2) A variety of factors stimulate the 1st breath.
The liver is
immature and unable to supply sufficient glucose, so the newborn depends primarily on stored fat for energy.
Immature kidneys cannot
concentrate urine vey well
1) The newborn may become dehydrated.
2) Water and electrolyte imbalances may develop.
Homeostatic mechanisms may
function imperfectly, and body temperature may be unstable.
The cardiovascular system changes when
placental circulation ceases
1) Umbilical vessels constrict.
2) The ductus venous constricts.
3) The foramen oval is closed by a valve as blood pressure in the right atrium falls and the blood pressure in the left atrium rises.
4) The ductus arterioles constricts.
Infancy extends from
the end of the 4th week to 1 year of age
Infancy is a period of
1) The muscular and nervous systems mature, and coordinated activities become possible.
2) Communication begins
Rapid growth depends on
an adequate intake of proteins, vitamins, and minerals in addition to energy sources.
Childhood extends from
the end of the 1st years to puberty
Primary teeth erupt and are replaced by
Childhood is a period of
rapid growth, development of muscular control, and establishment of bladder and bowel control.
Adolescence extends from
puberty to adulthood
Physiological and anatomical changes result in a
reproductively functional individual.
Females may be
taller and stronger than males in early adolescence, but the situation reverses in late adolescence.
Adolescents develop high levels of
motor skills, their intellectual abilities increases, and they continue to mature emotionally.
Adulthood extends from
adolescence to old age
The adult remains relatively unchanged
physiologically and anatomically for many years.
After age 30
degeneration changes begin.
1) Skeletal muscles lose strength.
2) The cardiovascular system becomes less efficient.
3) The skin loses elasticity.
4) The capacity to produce sex cells declines.
is growing old.
-Degeneration changes continue, and the body becomes less able to cope with demands.
-Changes occur because of prolonged use, effects of disease, and cellular alterations.
An aging person usually loses
some intellectuals functions, sensory functions, and physiological coordination capacities.
Death usually results from
mechanical disturbances in the cardiovascular system or from disease processes that affect vital organs.
The end of life
certain signs may appear in sequence when a person dies of a chronic illness.
takes up to 3 months. The person withdraws socially and appetite wanes.
takes up to 2 weeks. The person rests, may become confused or agitated, and eats very little. Gradually the organ systems shut down. The skin becomes mottles as circulation slows and congestion and loud breathing occur.
-Breakdown of structures and slowing or failure of functions.
-Connective tissue breaks down.
-DNA errors accumulate.
-Lipid breakdown in aging membranes releases lipofuscin.
-Free radical damage escalates.
In autoimmunity, the immune system attacks the body.
a form of programmed cell death. It occurs throughout life, shaping organs.
The theoretical maximum life span is
Life expectancy based on real populations is
75.4 years for men and 83.2 years for women in the United States, and many be lower in poorer nations and those ravaged by AIDS.
Medical technology makes life expectancy more
closely approach life span.
________ is an increase in the size of the individual, whereas ________ is the continuous process by which an individual changes from one phase to another.
________ is the period of development from fertilization to birth, whereas _________ is the period of development from birth to death.
prenatal period, postnatal period
How do sperm cells move in the female reproductive tract?
Prostaglandins in the semen stimulate lashing of sperm tails, and muscular contractions within the walls of the uterus and uterine tube aid the sperm cells' journey. The uterus and cervix contain a thin, watery secretion that promotes sperm transport and survival.
What are the events occurring after the sperm cell head enters the oocyte's cytoplasm?
Sperm entry triggers lysosome-like vesicles just beneath the oocyte cell membrane to release enzymes that harden the zone pellucid. This reduces the chance that other sperm cells will penetrate. The sperm nucleus enters the secondary oocyte's cytoplasm and swells. The secondary oocyte then divides unequally to form a large cell, whose nucleus contains the female's genetic contribution, and a tiny second polar body, which is later expelled. Meiosis is completed.
What is pregnancy?
The presence of a developing offspring in the uterus. It consist of a period of cleavage, an embryonic stage, and a fetal stage.
What is the process of cleavage?
The rapid cell division and distribution of the zygote's cytoplasm into progressively smaller cells. Results in the formation of blastomeres.
What is the difference between a morula and a blastocyst?
Morula- solid ball of cells
Blastocyst- non-hollow structure
How is the inner cell mass formed and what is its significance?
Formed within the blastocyst that eventually give rise to the embryo proper (the body of the developing off-spring)
What happens when the blastocyst nestles into the endometrium?
Implantation occurs due to the blastocyst sinking slowly into the resulting depression, becoming completely buried in the uterine lining. At the same time, the uterine lining is stimulated to thicken below the implanting blastocyst, and cells of the trophoblast begin to produce tiny, fingerlike extensions (microvilli) that grow into the endometrium.
What are the functions of hCG?
Human Chorionic Gonagotropin- maintains the corpus luteum during the early stages of pregnancy and keeps the immune system from rejecting the blastocyst. hCG also stimulates synthesis of other hormone from the developing placenta.
What are the hormonal changes that occur in the maternal body during pregnancy?
Secretion of hCG- maintains the corpus luteum, which continues to secrete estrogens and progesterone
Relaxin- from the corpus luteum inhibits uterine contractions and realizes the pelvic ligaments
Placental lactogen- stimulates breast development
Aldosterone- from the adrenal cortex promotes reabsorption of sodium
Parathyroid hormone- helos maintain a high concentration of maternal blood calcium
What are the nonhormonal changes that occur in the maternal body during pregnancy?
-The uterus enlarges greatly, pressing on the urinary bladder
-The abdominal organs are displaced upward and compressed against the diaphragm
-May be unable to eat large meals, may develop heartburn, and may have to urinate frequently
-Pregnant woman's blood volume, cardiac output, breathing rate, and urine production all increase
What is the difference between the chorion and amnion?
Chorion- (the yolk sac) 2 layers of cells beginning to line the trophoblast. Nutrients are provided here as the embryo implants in the uterus, proteolytic enzymes from the trophoblast break down endometrial tissue.
Amnion- (the allantois) develops around the embryo as the placenta is forming from the chorion. It appears during the 2nd week. Amniotic fluid fills the space between the amnion and the embryonic disc.
How is the placenta formed and what is its function?
Embryonic blood vessels carry blood to and from the embryo and extend through the connecting stalk, which attaches the embryo to the developing placenta. The establish capillary networks in the developing chorionic villi. The placenta is formed from the chorion.
What is the function of the amniotic fluid?
Provides a watery environment in which the embryo can grow freely without being compressed by surrounding tissues and protects the embryo from being jarred by the movements of the woman's body, and maintains a stable temperature for embryonic and fetal development.
How do the primary germ layers form?
By the end of the 2nd week the embryonic disc consists of 2 distinct layers: outer layer-ectoderm and inner-endoderm. A short time later, through gastrulation the middle layer-mesoderm is former.
What structures derive from the ectoderm, mesoderm and endoderm?
Ectoderm- NS, special sensory organs, the epidermis, hair, nails, glands of the skin, and linings of the mouth and anal canal
Mesoderm- loosely organized connective tissue; muscle tissue, bone tissue, bone marrow, blood, blood vessels, lymphatic vessels, internal reproductive organs, kidneys, and the epithelial linings of the body cavities
Endoderm- epithelial linings of the digestive tract, respiratory tract, urinary bladder, and urethra.
How does the yolk sac and the allantois related and what are their functions?
Yolk sac- forms during the 2nd week, and is attached to the underside of the embryonic disc. It forms blood cells in the early stages of development and gives rise to the cells that later become sex cells, produces stem cells of the bone marrow which are precursors to many cell types (blood cells), forms the embryonic digestive tube, and part of it becomes incorporated into the umbilical cord and the rest lies in the cavity between the chorion and the amnion near the placenta.
Allantois- forms during the 3rd week as a tube extending from the early yolk sac into the connecting stalk of the embryo. It forms blood cells and gives rise to the umbilical arteries and vein, eventually becomes enlarged and the membrane of the amnion contacts the thicker chorion around it, and fuse to form an amniochorionic membrane.
How does the umbilical cord form?
As the embryo becomes more cylindrical, the margins of the amnion fold, enclosing the embryo in the amnion and amniotic fluid. The amnion envelopes the tissues on the underside of the embryo, particularly the connecting stalk, by which it is attached to the chorion and the developing placenta forming the umbilical cord.
What is the placental membrane?
Embryonic portion- composed of parts of the chorion and its villi
Maternal portion- composed of the area of the uterine wall (decidua basalis) where the villi attach. The fully formed placenta is a reddish-brown disc.
A thin layer that separate the embryonic blood in the capillary of a chorionic villus from maternal blood in a lacuna. Composed of epithelium of the chorionic villus and the endothelium of the capillary inside the villus. Though the placental membrane, substances are exchanges between the maternal blood and the embryo's blood. Oxygen and nutrients diffuse from the maternal blood into the embryo's blood, and carbon dioxide and other wastes diffuse from the embryo's blood into the maternal blood. Active transport and pinocytosis also move substances through the placental membrane.
Why is the embryonic period so important?
During it, the embryo implants in the uterine wall and all the essential external and internal body parts form. Disturbances to development during the embryonic stage can cause major malformations or malfunctions. This is why early prenatal care is important.
What is the time frame for the fetus and what are the major changes that occur during fetal development?
The fetal stage begins at the end of the 8th week of prenatal development and lasts until birth. Growth is rapid, and body proportions change considerably.
What is a full-term fetus?
Approximately 266 days after a single sperm burrowed its way into a secondary oocyte; baby is ready to be born.
How does the fetal cardiovascular system adapt to intrauterine existence?
The maternal blood supplies oxygen and nutrients and carries away wastes. These substances diffuse between the maternal and fetal blood through the placental membrane, and the umbilical blood vessels carry them to and from the fetus.
What are the properties of fetal hemoglobin to those of adult hemoglobin?
The concentration of the oxygen-carrying hemoglobin in the fetal blood is about 50% greater than in the maternal blood, and fetal hemoglobin has a greater attraction for oxygen than does adult hemoglobin. As a result of these adaptations, at the oxygen partial pressure of the placental capillaries, fetal hemoglobin, can carry 20% to 30% more oxygen than adult hemoglobin. Different genes encode the protein subunits of hemoglobin in embryos, fetuses, and individuals after birth. The different subunits have different affinities for oxygen.
What is the pathway of blood from the placenta to the fetus and back to the placenta?
In the fetal cardiovascular system, the umbilical vein transports blood rich in oxygen and nutrients from the placenta to the fetal body. This vein enters the body through the umbilical ring and travels along the anterior abdominal wall to the liver.
What is the role of progesterone in initiating the birth process?
Progesterone plays a major role in its start. During pregnancy, this hormone suppresses uterine contractions. As the placenta ages, progesterone concentration in the uterus declines, which stimulates synthesis of the prostaglandin that promotes uterine contractions.
What are the events of the birth process?
Cervix is stretched, stretch receptors are stimulates, reflex is elicited that cause stronger uterine contractions, fetus is moved downward, fetal head is forced toward cervix
What is positive feedback and the role of hormones in expelling the fetus and the afterbirth?
Uterine contractions produce more intense uterine contractions until effort is maximal. Dilation of the cervix reflexly stimulates an increased release of oxytocin from the posterior pituitary gland.
What are the roles of prolactin and oxytocin in milk production and secretion?
Oxytocin- stimulates continued contraction of the uterus compressed the bleeding vessels and minimizes blood loss. Breastfeeding also contributes to returning the uterus to its original, pre pregnancy size, because suckling by the newborn stimulates the mother's posterior pituitary gland to release oxytocin.
Prolactin- release begins at the 5th week of pregnancy in the anterior pituitary gland. It is synthesized from early pregnancy throughout gestation, peaking at the time of birth.
What is the difference between a newborn and an infant?
Newborn- extends from birth to the end of the 1st 4 weeks, begins abruptly at birth. Newborn must respire, obtain and digest nutrients, excrete wastes, and regulate body temperature. Most immediate need is obtain oxygen and excrete carbon dioxide, the 1st breath is critical.
Why is a newborn's first breath particularly forceful?
The newborn's lungs are collapsed and the airways are small, offering considerable resistance to air movements. Surface tension adheres the moist membranes of the lungs. Breathing eases.
What are the factors that stimulate the first breath?
Increasing concentration of carbon dioxide, decreasing pH, low oxygen concentration, drop in body temp, and mechanical stimulation during and after birth.
Why do newborns tend to develop water and electrolyte imbalances?
A newborn's kidneys are usually unable to concentrate urine, so the baby excretes dilute urine, causing dehydration and a water and electrolyte imbalance.
What are the cardiovascular changes in the newborn?
Occurs when the placenta ceases to function and breathing begins. After birth, the umbilical vessels constrict. The umbilical arteries close 1st and if the umbilical cord isn't clamped or severed for a minute or so, blood continues to flow from the placenta to the newborn through the umbilical vein, adding to the newborn's blood volume.
What are the characteristics of an infant?
Development extending from the end of the 1st 4 weeks to 1 year. The infant grows rapidly and may triple its birth weight. Teeth begin to erupt through the gums, and its muscular and NS mature so that coordinated muscular activities become possible. Visually begins to follow objects, reach for and grasp objects, and sit, creep, and stand. Communication begins to develop. The body requires proteins to provide the amino acids necessary to form new tissues, calcium and vitamin D to promote the development and ossification of skeletal structures, iron to support blood cell formation, and vitamin C for production of structural tissues such as cartilage and bone.
What is the difference between a child and an adolescent?
Childhood- begins at the end of the 1st year and ends at puberty. Growth continues at a rapid rate, primary teeth erupt and secondary teeth replace them, development of voluntary muscular control and learns to walk, run, and climb, bladder and bowel controls are established, emotional maturing begins.
Adolescence- the period between puberty and adulthood when anatomical and physiological changes occur. Changes include hormonal, secondary sex characteristics, growth spurts in the muscular and skeletal systems, increasing levels of motor skills, intellectual ability, and emotional maturity.
What is adulthood?
Extends from adolescence to old age. Person remains relatively unchanged anatomically and physiologically.
What are some of the degenerative changes that begin during adulthood?
Hearing becomes less acute, heart muscles begin to thicken, elasticity of the ligaments between the small bones in the back lessens, metabolism slows, decrease activity level, may become shorter, vision may become farsighted, gray hair, immune system is less efficient, skeletal muscles lose strength, wrinkles
What is senescence?
Is the process of growing old. The body becomes less able to cope with the demands placed on it by the individual and by the environment.
What are some of the factors that promote senescence?
Normal wear and tear of body parts over many years.
What is the difference between preactive dying and active dying?
Active dying- a distinct set of signs, which might appear only on the day before death, or might begin up to 2 weeks earlier. The person sleeps often but can easily be awakened. The organ systems slowly shut down. Signs include calling blood pressure, raising or slow pulse, poor circulation, cool limbs.
Preactive dying- some people are aware of what is happening and begin the psychological process of coming to terms with their mortality.
What are the signs of passive and active aging and the physiological causes of these signs?
Passive aging- seen in the degeneration of the elastin and collagen proteins of connective tissues, causing skin to sag and muscle to lose its firmness. Biochemical abnormalities accumulate.
Active aging- lipofuscin granules or autoimmunity. The number of neurons in the fetal brain is halved as those that make certain synaptic connections are spared from death.
_______ is the length of time a human can theoretically live, whereas _______ is the realistic projection of how long an individual will live.
Human life span, life expectancy
THIS SET IS OFTEN IN FOLDERS WITH...
Chapter 22 Reproductive System
Chapter 13: The Endocrine System
Chapter 14 Pedi
TMC (LJU Version 10)
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