18.3 Erythrocytes

consists of four globin proteins, each bound to a molecule of heme.

A molecule of hemoglobin ________.

polycythemia.

A patient has been suffering for 2 months with a chronic, watery diarrhea. A blood test is likely to reveal ________.

macrophages.

Aging and damaged erythrocytes are removed from the circulation by ________.

copper, zinc, and vitamin B12

The production of healthy erythrocytes depends upon the availability of ________.

They have no nucleus.

Which of the following statements about mature, circulating erythrocytes is true?

Bilirubin is a breakdown product of the non-iron component of heme, which is cleaved from globin when erythrocytes are degraded. Excessive erythrocyte destruction would deposit excessive bilirubin in the blood. Bilirubin is a yellowish pigment, and high blood levels can manifest as yellowed skin.

A patient has thalassemia, a genetic disorder characterized by abnormal synthesis of globin proteins and excessive destruction of erythrocytes. This patient is jaundiced and is found to have an excessive level of bilirubin in his blood. Explain the connection.

She is at risk for anemia, because her unusually heavy menstrual bleeding results in excessive loss of erythrocytes each month. At the same time, her vegan diet means that she does not have dietary sources of heme iron. The non-heme iron she consumes in plant foods is not as well absorbed as heme iron.

A young woman has been experiencing unusually heavy menstrual bleeding for several years. She follows a strict vegan diet (no animal foods). She is at risk for what disorder, and why?