Introduction to Human Development and Embryology

Study flashcards based on the lecture notes covering human development and embryology concepts.

What is oogenesis?

The process of female gamete formation, resulting in the production of oocytes.

What occurs during meiosis?

Redistribution of chromosomal material to create haploid gametes.

What hormones trigger ovulation?

FSH and LH from the pituitary gland.

At what stage are primary oocytes arrested in females?

Prophase I during fetal development.

What happens to secondary oocytes during ovulation?

They are released and will only complete meiosis II if fertilization occurs.

How many primary oocytes are females born with?

1-2 million primary oocytes.

What is the cleavage stage in embryo development?

A stage characterized by a series of mitotic divisions resulting in increased cell numbers.

Define blastocyst formation.

The early blastocyst forms a fluid filled cavity after entering the uterine cavity.

What is implantation?

The process where the blastocyst embeds into the uterine mucosa.

What does hCG stand for?

Human chorionic gonadotropin.

What are the three germ layers formed during gastrulation?

Ectoderm, Mesoderm, and Endoderm.

What is teratogenesis?

The process by which congenital malformations are produced in an embryo.

Describe the structure of the uterine tubes.

They carry oocytes from the ovaries to the site of fertilization and are lined with cilia.

What is the average length of human spermatogenesis?

Approximately 74 days.

What triggers the primary oocyte to complete meiosis I?

A surge of LH during ovulation.

What is the first product released during meiosis in females?

The first polar body.

What is the major function of the lymphatic system?

To maintain fluid balance and provide immunity by transporting lymphocytes.

What separates primary lymphatic organs from secondary ones?

Primary lymphatic organs are where lymphocytes mature; secondary organs are sites of activation.

At what stage does fertilization occur?

When the sperm penetrates the corona radiata and zona pellucida of the oocyte.

What structure is formed 6 days after fertilization?

The blastocyst, during implantation.

What is the outcome of fertilization?

Restoration of the diploid number of chromosomes and creation of a zygote.

What are the two primary functions of the chorionic gonadotropin (hCG)?

To maintain progesterone production and signal early pregnancy.

What provides the primary blood supply during early embryonic development?

The umbilical cord and early structures formed by the trophoblast.

What triggers the start of cleavage after fertilization?

The completion of meiosis II and restoration of the diploid chromosome number.

What can elevated hCG levels indicate?

Possible multiple pregnancies or certain tumors.

What two layers form from the trophoblast?

Cytotrophoblast and Syncytiotrophoblast.

What is the main site of fertilization in the female reproductive tract?

The ampulla of the uterine tube.

How long does the embryo spend in the uterus before birth?

Around 38 weeks.

What is the average gestation period?

40 weeks.

What hormones do the ovaries produce?

Estrogen and progesterone.

What is the state of the secondary oocyte before fertilization?

Arrested in metaphase II.

What signifies the end of the implantation process?

The degeneration of the zona pellucida.

What are embryoblasts and trophoblasts?

Embryoblasts are inner cell masses forming the embryo; trophoblasts form the outer layer and contribute to placenta.

When does the implantation process begin after fertilization?

Around 7 days.

What is the function of the uterine endometrium during implantation?

To provide a suitable environment for the blastocyst to implant.

What marks the end of the embryonic period and the start of fetal development?

The beginning of the 9th week of gestation.

What is significant about the structure of the uterine wall?

It has three layers including myometrium and endometrium.

What marks the onset of gastrulation?

Formation of the primitive streak.

How many layers are in the bilaminar disc?

Two layers: hypoblast and epiblast.

What does the ectoderm give rise to?

Nervous tissue and epidermis.

What characterizes the mesoderm?

It forms muscle, connective tissue, and the vascular system.

What is derived from the endoderm?

Epithelial lining of the digestive and respiratory tracts.

What is the role of the notochord during development?

To promote ectoderm formation of the neural plate.

What type of cells does the neural crest give rise to?

Peripheral nerves and ganglia.

What does the mesoderm eventually develop into?

The skeletal and muscular systems.

What is the primary contributor to the development of the cardiovascular system?

The mesoderm.

How does the heart function to circulate blood?

It pumps blood in a sequential manner through two circuits: pulmonary and systemic.

What are the primary vessels of systemic circulation?

Aorta and its branches.

What is the general function of veins?

To carry deoxygenated blood back to the heart.

What regulates capillary blood flow?

Arterioles through vasoconstriction and vasodilation.

What are the components of lymph?

Lymph fluid, lymphocytes, and macrophages.

What are the major lymphatic trunks?

Lumbar, intestinal, bronchomediastinal, subclavian, and jugular trunks.

What occurs during venous return to the heart?

Blood is propelled back via veins, assisted by muscle contractions and valves.

How does the circulatory system adapt during exercise?

By increasing heart rate and redirecting blood flow to muscles.

What is the primary characteristic of lymphatic capillaries?

They are closed-ended and highly permeable.

What is the flow of blood through the heart starting at the right atrium?

From the right atrium to right ventricle, then to lungs, back to left atrium, then to left ventricle.

What prevents backflow of blood in veins?

Venous valves.

What is the role of lymph nodes in the lymphatic system?

To filter lymph and mount immune responses.

What happens in a lymphadenopathy?

Lymph nodes become swollen or tender due to infection or disease.

What is the function of lacteals in the lymphatic system?

To absorb dietary lipids from the gastrointestinal tract.

What are the primary components of blood?

Red blood cells, white blood cells, platelets, and plasma.

What is the bulk transportation system of the body?

The circulatory system.

How does the kidney relate to the lymphatic system?

It filters blood and produces urine, influencing overall fluid balance.

What is the role of macrophages in the lymphatic system?

To engulf pathogens and dead cells.

What do T lymphocytes do?

They are responsible for cell-mediated immunity.

What is the purpose of the thoracic duct?

To drain lymph into the left subclavian vein.

Where does the right lymphatic duct drain?

Into the right subclavian vein.

What is the consequence of impaired lymphatic function?

It may lead to lymphedema, causing swelling.

How does the body maintain homeostasis?

Through fluid balance and immune responses via the lymphatic system.

What two factors can affect teratogenesis?

Genetic and environmental factors.

What is a possible outcome of teratogen exposure during critical development periods?

Congenital birth defects.

What is the significance of the placenta during pregnancy?

It provides nutrients and removes waste between the mother and fetus.

How does blood flow change during pregnancy?

Increased blood volume and changes in circulation patterns occur.

What helps prevent blood loss during childbirth?

Uterine contractions and blood clotting mechanisms.