Question

A typical hematocrit value for a human is around \(42 \% .\) This means that a. the typical fluid portion of blood is about \(42 \%\) of the total volume. b. the leukocytes make up \(42 \%\) of the blood volume. c. the erythrocytes make up \(42 \%\) of the blood volume. d. the leukocytes and erythrocytes together make up \(58 \%\) of the blood volume. e. the erythrocytes alone make up \(58 \%\) of the blood volume.

Short answer

Option c - the erythrocytes make up 42% of the blood volume - is the correct answer as it correctly interprets the hematocrit value.

Step-by-step solution

Understanding hematocrit value

The term 'hematocrit' refers to the percentage of blood volume that is occupied by red blood cells, or erythrocytes. Therefore, when we say that the typical hematocrit value for a human is around 42%, it implies that erythrocytes compose about 42% of the total blood volume. This knowledge will guide the interpretation of the provided statements.

Analyzing each statement

Now let's analyze each option: \na. Fluid portion of the blood, or plasma, is not what the hematocrit value refers to, so this statement is incorrect. \nb. Leukocytes are white blood cells, not what the hematocrit value refers to, hence it is incorrect. \n c. This statement correctly asserts that erythrocytes compose 42% of the blood volume, which is what the hematocrit value represents. \nd. This statement combines leukocytes and erythrocytes, but the hematocrit value only refers to erythrocytes. Thus, it's incorrect. \ne. This statement incorrectly asserts that erythrocytes compose 58% of the blood volume; the hematocrit suggests it should be 42%, therefore it's incorrect.

Selecting the correct option

After analyzing each statement in light of what the hematocrit value represents, it becomes clear that the correct option is c. Erythrocytes make up approximately 42% of the blood volume in a typical human.

Key concepts

red blood cells

Red blood cells are vital components of our blood. Also known as erythrocytes, they play a crucial role in transporting oxygen from the lungs to tissues throughout the body. Red blood cells contain a protein called hemoglobin, which is responsible for binding to oxygen.

• Primary function: Oxygen transportation
• Contain hemoglobin
• Make up the majority of the cells in our blood

Red blood cells have a unique biconcave shape. This shape increases their surface area, allowing for efficient oxygen absorption and release. Unlike many other cells in the body, mature red blood cells lack a nucleus, which enables them to carry more hemoglobin.

erythrocytes

Erythrocytes are another term for red blood cells. These cells are essential in the circulatory system, not just because of their role in oxygen transport but also due to their contribution to carbon dioxide removal. Erythrocytes develop from stem cells in the bone marrow. During their development, they undergo several changes. Initially, they do have a nucleus. However, as they mature, they lose it. This loss increases space within the cell for hemoglobin, maximizing their oxygen-carrying capability. Erythrocytes are incredibly adaptable, allowing them to squeeze through tiny capillaries to deliver oxygen and nutrients to tissues.

• Arise from bone marrow
• Undergo unique development process
• Flexible for capillary travel

blood volume

Blood volume refers to the total amount of blood circulating within a person's body. It consists of both plasma and cellular components like erythrocytes and leukocytes. Typically, an adult has about 5 liters of blood, though this can vary based on age, sex, and overall body size. An important concept related to blood volume is the hematocrit. It measures the proportion of blood volume that is occupied by red blood cells. In a healthy human, the hematocrit value is usually between 38% and 48%, with erythrocytes comprising the majority of the cellular blood components. Thus, if a person's hematocrit is measured at 42%, it indicates that 42% of their blood volume is made up of red blood cells.

plasma

Plasma is the liquid component of blood. It makes up more than half of the blood's overall volume and consists mainly of water, electrolytes, hormones, and waste products.

• Functions as the blood's transport medium
• Contains dissolved proteins like albumin and antibodies
• Critical for maintaining blood pressure and volume

Plasma plays a fundamental role in the circulatory system by acting as a carrier. It facilitates the movement of nutrients, hormones, and waste products throughout the body. Additionally, plasma helps in maintaining a stable environment for cellular activities by balancing pH and temperature.