Human Cell Biology and Blood Components

20 question-and-answer flashcards covering key facts about human cells, blood components, and related physiology.

What is the largest cell in the human body?

The female ovum (egg cell).

Approximately how wide is a human ovum?

About 120 micrometers (0.0047 in) in diameter.

Roughly how many eggs does a female possess at birth?

About 1 million ova.

Which cell is considered the smallest by volume in the human body?

The male sperm cell.

What are the approximate dimensions of a sperm cell’s head and tail?

Head ≈ 4 µm long; tail ≈ 50 µm long.

Which blood cell type is the smallest in size?

Platelets (thrombocytes).

What is the normal diameter range of platelets?

Approximately 1–4 micrometers.

Which hormone primarily regulates platelet production in the bone marrow?

Thrombopoietin (TPO).

What is the average lifespan of circulating platelets?

About 5–9 days.

What disorder is characterized by abnormally low platelet counts?

Thrombocytopenia.

Which white blood cells are known as the body’s “natural scavengers”?

Macrophages.

Which granulocyte is the most abundant white blood cell in circulation?

Neutrophils (about 50–70 % of leukocytes).

Which granulocyte attacks parasitic worms and certain cancer cells?

Eosinophils.

Which granulocyte releases histamine and heparin during allergic reactions?

Basophils.

What is the largest type of blood cell?

Monocytes (15–18 µm in diameter).

Into what cell type do monocytes mature after entering tissues?

Macrophages.

Which blood cells are responsible for transporting oxygen throughout the body?

Red blood cells (erythrocytes).

Which hormone stimulates the production of red blood cells?

Erythropoietin (EPO).

What is the typical lifespan of a red blood cell?

Approximately 120 days (four months).

Which vitamin is essential for the body to manufacture red blood cells?

Vitamin B12.