Question

Production of which of the following blood cells is stimulated by a hormone secreted by the kidneys? a. Lymphocytes b. Monocytes c. Erythrocytes d. Neutrophils e. Thrombocytes

Short answer

The production of erythrocytes (red blood cells) is stimulated by the hormone erythropoietin, which is secreted by the kidneys. Therefore, the correct answer is c. Erythrocytes.

Step-by-step solution

Identify the hormone secreted by the kidneys

The hormone secreted by the kidneys that stimulates blood cell production is called erythropoietin (EPO). Erythropoietin is primarily produced by the kidneys, and its main function is to stimulate the production of red blood cells in the bone marrow.

Review each blood cell type and its function

a. Lymphocytes: Lymphocytes are white blood cells that play a crucial role in the immune system's response to infection. They are not stimulated by a hormone from the kidneys. b. Monocytes: Monocytes are white blood cells that are involved in the immune system's defense against pathogens and help with tissue repair. They are not influenced by a hormone produced by the kidneys. c. Erythrocytes: Erythrocytes, also known as red blood cells, primarily function to transport oxygen and carbon dioxide in the body. Erythropoietin, the hormone produced by the kidneys, stimulates the production of erythrocytes. d. Neutrophils: Neutrophils are white blood cells that specialize in defending the body against bacterial infections. They are not directly regulated by a hormone produced by the kidneys. e. Thrombocytes: Thrombocytes, also known as platelets, play a crucial role in blood clot formation. They are not directly regulated by a hormone produced by the kidneys.

Determine the correct answer

Based on the information in Step 2, the correct answer is c. Erythrocytes, as their production is stimulated by erythropoietin, the hormone secreted by the kidneys.

Key concepts

Erythrocytes

Erythrocytes, commonly known as red blood cells, are pivotal in our body's ability to transport oxygen and carbon dioxide. These cells are highly specialized, allowing them to carry oxygen from the lungs to every part of the body and return carbon dioxide to the lungs for exhalation.
A unique characteristic of erythrocytes is their biconcave shape, which increases their surface area and helps in the quick exchange of gases. They contain a protein called hemoglobin, which binds to oxygen and carbon dioxide, making it possible for gas transport.
Did you know? Red blood cells lack a nucleus, which allows more space for hemoglobin but means they can't repair themselves. This results in a lifespan of about 120 days, after which they are recycled by the body.

Kidney function

The kidneys are remarkable organs that perform many vital functions, beyond just filtering waste from the blood. One of their crucial roles is the production of the hormone erythropoietin (EPO).
EPO is synthesized primarily in the kidneys in response to low oxygen levels in the blood. This adaptive mechanism ensures that there are ample red blood cells to meet the body's oxygen needs. When blood flows through the kidneys, cells called peritubular fibroblasts sense oxygen levels and secrete EPO when required.
Moreover, kidneys also regulate blood pressure, balance electrolytes, and manage fluid volumes. All these functions underline the kidneys' importance in maintaining homeostasis within the body.

Red blood cell production

Red blood cell production, or erythropoiesis, is a continuous process occurring in the bone marrow. The hormone erythropoietin (EPO), secreted by the kidneys, plays a fundamental role in this process.
When the kidneys detect low oxygen levels, they produce and release more EPO, which travels through the bloodstream to the bone marrow. Upon arrival, EPO stimulates the bone marrow to increase the production of red blood cells. This ensures that adequate oxygen is supplied throughout the body.
The process involves several stages, starting from hematopoietic stem cells that differentiate into erythrocytes. Nutrients like iron, vitamin B12, and folic acid are essential for healthy red blood cell formation, highlighting the importance of a balanced diet.