Human Anatomy and Physiology : Development

Study concepts, example questions & explanations for Human Anatomy and Physiology

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Example Questions

Example Question #82 : Systems Physiology

Which developmental stage results in the rise of the three germ layers?

Possible Answers:

Blastocyst

Gastrula

Neurula

Morula

Correct answer:

Gastrula

Explanation:

After fertilization and the formation of a zygote, the developing organism undergoes several rounds of cell division known as cleavage. During this period the cells divide but do not grow in size, resulting in a dense cell mass. The morula is formed during this portion of development.

Following cleavage, the cell develops an inner cell mass and trophoblast, or outer layer, before implantation into the uterus. At this stage, the organism is considered a blastocyst.

Soon after implantation, cells begin to differentiate into the three germ layers through a process known as gastrulation. The resulting organism is considered a gastrula.

Gastrulation is quickly followed by development of the neural crest and preliminary nervous tissue, known as neurulation. The organism is then considered a neurula.

Note that the organism can be considered an embryo at any point from the first cleavage division to approximately the eighth week of development.

Example Question #11 : Reproductive Physiology And Development

Which of the following is necessary for the development of the testes?

Possible Answers:

Estrogen

Wolfian excitatory hormone 

Dihydrotestosterone (DHT)

SRY gene product

Testosterone

Correct answer:

SRY gene product

Explanation:

In order for the testes to develop, the only thing necessary is the SRY gene product, which is created from the SRY gene on the Y chromosome. DHT are involved in the development of other male sex traits during early development, such as the penis, while testosterone is involved in both early development and the development of secondary sexual traits during puberty. Wolfian excitatory hormone does not actually exist. Estrogen is not involved in the development of male sex organs.

Example Question #1 : Help With Gastrulation And Embryonic Structures

Which germ layer will develop into the skeletal and muscular systems?

Possible Answers:

Endoderm

The skeletal and muscular systems do not arise from the same germ layer

Mesoderm

Epiderm

Ectoderm

Correct answer:

Mesoderm

Explanation:

Following gastrulation, three primary germ layers form: the ectoderm, the mesoderm, and the endoderm. We can typically predict which structures will form from the germ layers based on the layers of the body. The endoderm will form the digestive tract, the mesoderm will form the skeleton and muscles, and the ectoderm will form the skin and nervous system.

Example Question #13 : Reproductive Physiology And Development

Which structure is responsible for bypassing the fetal liver and taking blood directly to the right atrium?

Possible Answers:

Ductus venosus

Foramen ovale

Umbilical vein

Ductus arteriosus

Correct answer:

Ductus venosus

Explanation:

Because the fetal lungs and liver are not fully functional until birth, the fetal circulation uses structures in order to bypass these organs.

The ductus venosus is used to reroute blood from the fetal liver and deposit it into the right atrium.

The ductus arteriosus connects the fetal pulmonary arteries to the aorta to bypass the lungs, while the foramen ovale connects the right and left atria to reduce flow to the pulmonary arteries.

The umbilical vein carries blood from the uterus, where it have been loaded with oxygen from maternal circulation, back to the body.

Example Question #86 : Systems Physiology

A fetal circulatory structure is used in order to take blood from the pulmonary trunk and reroute it to the fetal aorta. What does this structure become after birth?

Possible Answers:

Navel

Fovea ovalis

Ligamentum venosum

Fossa ovalis

Ligamentum arteriosum

Correct answer:

Ligamentum arteriosum

Explanation:

The ductus arteriosus is used to reroute blood from the pulmonary trunk and place it into the aorta of the fetus, preventing flow to the non-functional fetal lungs. After birth, this structure deteriorates and closes. The ligamentum arteriosum is the vestigial structure that is seen in adults. Instead of connecting the pulmonary arteries and aorta, it helps to stabilize these structures.

The foramen ovale is a fetal window between the right and left atria to help blood bypass the pulmonary circuit. After birth, this window closes to become the fossa ovalis.

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