A&PII: CH23

What is the process of fertilization?

The union of a secondary oocyte and a sperm cell, taking place in the infundibulum of a uterine tube.

What is the zygote?

The fertilized egg formed when the sperm and ovum nuclei fuse, containing 46 chromosomes.

What prevents polyspermy during fertilization?

The membrane depolarizes after one sperm fuses with the ovum, releasing cortical granules that make the zona pellucida impermeable to other sperm.

What are the three stages of the prenatal period?

Pre-embryonic stage, embryonic stage, and fetal stage.

What occurs during the cleavage stage of development?

Rapid cell division with no size increase, producing blastomeres.

What is a morula?

A solid mass of about 16 cells that moves into the uterus and becomes a blastocyst.

What is the role of the trophoblast?

It forms the wall of the blastocyst, develops into chorion, and produces hCG to maintain the corpus luteum during early pregnancy.

What is gastrulation?

The process where the inner cell mass separates from the trophoblast to form the embryonic disk and primary germ layers.

What are the primary germ layers formed during gastrulation?

Ectoderm, mesoderm, and endoderm.

What is the significance of teratogens?

They are factors that cause malformations by affecting the embryo during periods of rapid growth and development.

What happens during the fetal stage?

Rapid growth occurs, body proportions change significantly, and organs mature until birth.

What is the function of the placenta?

It facilitates the exchange of nutrients and gases between maternal and embryonic blood.

What is the role of human chorionic gonadotropin (hCG) during pregnancy?

It maintains the corpus luteum, which secretes estrogens and progesterone to support pregnancy.

What physiological changes occur in the mother during pregnancy?

Increased blood volume, cardiac output, and metabolic demands to support the developing fetus.

What is parturition?

The process of childbirth, involving uterine contractions and the expulsion of the fetus and placenta.

What is colostrum?

The first milk produced after birth, rich in proteins and antibodies but lower in carbohydrates and fats.

What are the stages of postnatal development?

Neonatal period, infancy, childhood, adolescence, adulthood, and senescence.

What occurs during the neonatal period?

The newborn begins respiration, digestion, and temperature regulation, and makes cardiovascular adjustments.

What characterizes the infancy stage?

Rapid growth, development of motor skills, and beginning of communication.

What are the key developments during childhood?

High growth rate, establishment of bladder and bowel control, and development of communication skills.

What changes occur during adolescence?

Development of secondary sex characteristics, growth spurts, and maturation of motor and intellectual skills.

What happens in adulthood?

Muscle strength peaks, but body efficiency declines, and degenerative changes begin after age 30.

What is senescence?

The process of aging, characterized by degenerative changes and a decline in the body's ability to cope with demands.

What is the average life expectancy in the U.S. as of 2014?

76.4 years for males and 81.2 years for females.

What are the two stages of the dying process?

Preactive dying and active dying.

What occurs during active dying?

Distinct signs such as confusion, loss of appetite, and organ systems shutting down.

What is the role of surfactant in newborns?

It reduces surface tension in the lungs to aid in lung expansion after birth.

What are the effects of thalidomide during pregnancy?

It can cause malformation of limbs when taken early in pregnancy.

What is the impact of alcohol on fetal development?

It can lead to fetal alcohol syndrome, causing facial structure abnormalities and impaired intellect.

What is the role of the umbilical vein?

It transports oxygen-rich blood from the placenta to the fetus.

What is the function of the foramen ovale in fetal circulation?

It shunts blood from the right atrium to the left atrium, bypassing the non-functional fetal lungs.

What is the significance of the ductus arteriosus?

It connects the pulmonary trunk to the aorta, allowing most blood to bypass the lungs.

What is the role of relaxin during pregnancy?

It inhibits uterine contractions and relaxes pelvic ligaments.

What is the purpose of amniotic fluid?

It protects and cushions the embryo, maintaining a constant temperature.

What are the effects of maternal malnutrition during pregnancy?

It can slow fetal growth and lead to nutrient deficiencies in the mother.

What happens to the body during senescence?

Degenerative changes continue, leading to weakened immune responses and loss of sensory functions.