Human Development and Aging Lecture Review

Comprehensive flashcards covering the stages of human development from fertilization through aging, including germ layers, fetal milestones, birth stages, and physiological changes associated with age.

When sperm and egg combine during fertilization, what is the resulting cell called?

A zygote.

What is the primary function of mitochondria within sperm cells?

They provide the $ATP$ necessary for the sperm to function.

During which timeframe does pre-embryonic development occur?

During week $1$.

What is the duration of embryonic development?

Weeks $2$ to $8$.

Which adult structures are derived from the Ectoderm primary germ layer?

Epidermis of skin; epithelial lining of oral cavity and rectum; nervous system.

Which adult structures are derived from the Mesoderm primary germ layer?

Skeleton; muscular system; dermis of skin; cardiovascular system; urinary system; reproductive system; outer layers of respiratory and digestive systems.

Which adult structures are derived from the Endoderm primary germ layer?

Epithelial lining of digestive tract and respiratory tract; associated glands of these systems; epithelial lining of urinary bladder.

Which organ system is the first to appear during the third week of development?

The nervous system.

What are the projections on the chorion called that connect to the future umbilical cord?

Chorionic villi.

By the end of the eighth week, approximately how long is the embryo?

$38\,\text{mm}$ ($1.5\,\text{in}$).

What are the two main functions of the progesterone and estrogen produced by the placenta during pregnancy?

$1$. They prevent new follicles from maturing via negative feedback; $2$. They maintain the endometrium to prevent menstruation.

What are the six large, membranous areas of the fetal skull called that allow the head to pass through the birth canal?

Fontanels.

By what age do the fontanels typically close?

By $2$ years of age.

What is the difference between lanugo and vernix caseosa?

Lanugo is a fine down covering the fetal skin, while vernix caseosa is a white cheese-like substance that protects the skin from amniotic fluid.

What are Braxton Hicks contractions?

Contractions that occur near the end of pregnancy which are known as "false labor."

What is an episiotomy?

An incision made to enlarge the vaginal orifice to speed up childbirth during Stage $2$ of birth.

What occurs during Stage 3 of birth, known as parturition?

The delivery of the placenta, or afterbirth, which usually happens about $15$ minutes after the baby.

What is the definition of Gerontology?

The study of aging.

How does aging affect the subcutaneous layer of the Integumentary System?

There is less adipose tissue, which causes older people to feel cold.

What significant change happens to the thymus as the immune system ages?

The thymus shrinks to less than $5\%$ of its original size.

Why do older individuals typically require less medication to maintain the same levels in the blood?

Blood flow to the liver is reduced, resulting in less efficient metabolism of drugs or toxins.

What is anosmia?

A total inability to smell.

What is the term for the common difficulty in focusing on near objects that often starts at age 40?

Presbyopia.

To what extent has muscle mass typically decreased in a 90-year-old compared to when they were 20?

By approximately $50\%.$

What are the physical symptoms associated with menopause occurring between ages 45 and 55?

"Hot flashes," dizziness, headaches, insomnia, sleepiness, and depression.

What is the name of the male sterilization procedure that involves cutting and sealing the vasa deferentia?

A vasectomy.