HUMAN DEVELOPMENT AND AGING

What are some effects of exercise, making it an important activity even as we age?

-maintain strength -reducing the incidence of diabetes -reducing the incidence of hypertension

Which circulatory changes occur just after birth?

-the ductus anteriosus collapses -the foramen ovale closes

Why is it difficult for premature infants to ingest milk?

-underdeveloped sucking and swallowing reflexes -small stomach volume ~~must be fed by nasogastric or nasoduodenal tubes ~~infants under 3.3lbs require supplements of calcium, phosphorus, & protein

What are the 3 primary germ layers?

1. ectogerm 2. mesoderm 3. endoderm

Which 2 structures of fetal circulation allow blood to bypass the non-functional lungs?

1. foramen ovale -direct connection between right & left atria so blood bypasses the pulmonary circulation system 2. ductus anteriosus -small amounts of blood flow from right atrium into right ventricle but this blood also takes shortcut into aorta via d. anteriosus

What are the effects of senescence on the integumentary system?

1. graying hair 2. rosacea 3. loss of skin elasticity -hair turns grayer/thinner as melanocytes die out, mitosis slows down, dead hairs are not replaced -atrophy of sebaceous glands leaves the skin & hair drier -epidermal mitosis declines and collagen is lost from the dermis, the skin becomes almost paper-thin and translucent

Stages of gestation

1. preembryonic stage 2. embryonic stage 3. fetal stage

Steps of the preembryonic stage.

1. zygote: 0-30 hours - a single diploid cell formed by the union of egg & sperm 2. clevage: 30-72 hours -mitotic division of the zygote into smaller, identical blastomeres 3. morula: 3-4 days -spheroidal stage consiting of 16 or more blastomeres 4. blastocyst: 4-16 days -a fluid-filled, spherodial stage with an outer mass of trophoblast cells & inner mass of embryoblast cells -becomes implanted in the endometrium -the inner cell mass forms an embryonic disc and differentiates into 3 primary germ layers

Out of an ejaculate of approximately 300 million spermatozoa, how many reach the vicinity of the egg?

200

Sperm remain viable for how many days after ejaculation?

3-6 days

The normal gestation period for a single (non-twin) baby is how many weeks?

40

T or F: The first sperm to reach an egg is the one that fertilizes it.

False it may require hundreds of sperm to clear a path for a single sperm to finally be able to penetrate

What is a mutation?

a change in DNA structure

What is a morula?

a spherical stage of conceptus development with 16 or more cells

The ___________ reaction is the process by which the sperm releases the enzymes it needs to penetrate the egg.

acrosomal

When does meiosis II complete in a secondary oocyte?

after fertilization occurs -meiosis II is complete only if fertilization occurs, resulting in a fertilized mature ovum (zygote) and the 2nd polar body

What is a teratogen?

agents that cause deformities in the fetus (i.e. brith defects)

What is the transparent sac that encloses an embryo called?

amnion -inner of the 2 embryonic membranes -chorion is the outer embryonic membrane

What is the narrow space between the embryoblast and the trophoblast during early embryogenesis called?

amniotic cavity

A morula develops into a hollow ball of cells called a

blastocyst

During development, a morula hollows out to enter what stage?

blastocyst

Daughter cells formed by the first cell division following fertilization are called

blastomeres

What are the cells formed by the first cleavage of the fertilized egg called?

blastomeres (daughter cells)

Mechanisms called fast and slow ___________ are used by an egg to prevent poly

block

During sperm migration, the membrane of the sperm head becomes more fragile. This change is part of a process called

capacitation

Sperm cells undergo _____________ during migration that makes it possible for them to penetrate an egg.

capacitation

What is the leading cause of death in old age?

cardiovascular disease

The term ______________ cleavage refers to the mitotic divisions that occur in the first 3 days after fertilization.

cleavage

What is the cell division that occurs in the earliest stages of zygote development called?

cleavage -the mitotic divisions that occurs in the first three days after fertilization

A fertilized egg to a full-term fetus as well as the placenta, umbilical cord, and membranes associated with the embryo is known as

conceptus

A ___________ anomaly is an abnormal structure or position of an organ at birth resulting from a defect in prenatal development.

congenital

The term ___________ means "present at birth". Examples include an anatomical defect, a syphilis infection, or hereditary disease.

congenital

Oxygen, carbon dioxide, nutrients, and wastes cross the placenta by the process of

diffusion -concentration gradient between maternal & fetal blood allows small molecules to cross thin walls of the placental sinus and chronic villi by simple diffusion

What is the outermost germ layer?

ectoderm

The implanting of the blastocyst somewhere other than the uterus is known as _____________ pregnancy

ectopic

What is a developing individual from the 16th day of gestation referred to as?

embryo

The blastomeres form 3 primary germ layers during the process of

embryogenesis

Which developmental stage is complete once the blastomeres arrange to form the three primary germ layers?

embryogenesis

The __________ is the germ layer that will form, among other structures, the inner layer of the digestive tract.

endoderm

During development, an individual is known as what from the beginning of the ninth week through birth?

fetus (9th week to birth)

What is osteopenia?

first signs of bone loss i.e. losing bone tissue (severe enough to compromise physical activity and health is osteoporosis) -bone is continually being formed and resorbed -bone formation and resorption are closely balanced by deposition of organic calcium matrix by osteoblasts, and calcium resorption by osteoclasts

The process by which a blastocyst attaches to the lining of the uterus is called

implantation -the process of attachment of the blastocyst to the maternal uterine wall

Senescence of which system includes one's hair turning gray and a loss of skin elasticity?

integumentary the degeneration that occurs in an organ system after the age of peak functional efficiency -gradual loss of reserve capacities -reduced ability to repair damage & compensate for stress -increased susceptibility of disease

In a secondary oocyte, which cell division stage begins before ovulation but will only complete if fertilization occurs?

meiosis II

Infant up to 6 weeks old called?

neonate *transitional period* : first 6-8 hours -heart + respiratory rates inc & body temp falls -physical activity falls -baby sleeps for 3 hours *neonatal period* : first 4 weeks -gags on mucus + debris in pharynx -becomes more stable -wakes up every 3 to 4 hours to feed

The process of ______________ is the differentiation of the primary germ laters into organ and organ systems.

organogenesis -16 days after conception, germ layers are present & embryonic stage begins -for 6 weeks, placenta forms on uterine wall & becomes embryo's primary means of nutrition while germ layers differentiate into organs and organ systems (organogenesis) -presence of organs at 8 weeks is transition to fetal stage

Stiffness and joint pain are symptoms of the most common joint disease in older people known as

osteoarthritis

What is bone loss that is severe enough to compromise physical health and activity called?

osteoporosis

The ___________ is a disc-shaped organ attached to the uterine wall that provides nutrition to the fetus via the umbilical cord.

placenta -baby is connected to the placenta via the umbilical cord -site of exchange of nutrients between mother and fetus -site of hormones needed to sustain the pregnancy are produced

The ____________ performs respiratory, excretory, nutritional, endocrine, and immune functions for the fetus.

placenta -nutritional role: permits nutrients to diffuse from the maternal to fetal blood; also acts as a reservoir of nutrients early in pregnancy in prep for the inc in fetal demand later during fetal rapid growth -excretory role: permits nitrogenous wastes (amonia, urea...) to diffuse from fetal blood to maternal blood -respiratory role: permits oxygen to diffuse from maternal to fetal blood & CO2 from fetus to mother -endocrine role: secretes hormones to fetus (estrogen, progesterone, relaxin...) & hormones between mother and fetus blood -immune roles: transfers maternal antibodies into the blood, conferring passive immunity on the fetus

The fertilization of an egg with more than one sperm is known as ___________ and may result in 3 or more sets of chromosomes.

polyspermy

The ____________ stage of development comprises the first 16 days of pregnancy.

preembryonic

Prior to joining (fusing) as fertilization completes, the organelles of the oocyte and the sperm called _____________ contain the genetic material contributed by each parent.

pronuclei

The term __________ refers to the degenerative changes that occur with aging.

senescence

The study of birth defects is known as

teratology

Why does the pathway of circulation change after birth?

to allow gas exchange to occur in the new environment

The ___________ period is the first six to eight hours of life after delivery.

transitional -series of physiological adjustments in the newborn infant to adapt from intrauterine placental support to extrauterine self-maintenance -critical period that requires continuous assessment & observation to ensure the survival of the newborn

A pregnancy is divided into three 3-month periods, each called

trimester

Which attaches to the fetus to the placenta?

umbilical cord

Where does fertilization occur?

within the distal one-third of uterine tube -contractions of the female reproductive tract help conduct sperm to the most common site of fertilization in the oviduct, the ampulla (located in the last third of the uterine fallopian tube)

A single-celled, fertilized egg is known as a

zygote