Problem 3 - Biology Concepts and Applications

Question

Which are not found in the blood? a. plasma b. blood cells and platelets c. gases and dissolved substances d. All of the above are found in blood.

Step-by-Step Solution

Answer

All components listed (plasma, blood cells, platelets, gases, and dissolved substances) are found in blood.

Step 1: Understanding the Components of Blood

Blood is comprised of several key components: plasma, blood cells (including red and white blood cells), platelets, and dissolved substances, such as gases (oxygen and carbon dioxide), nutrients, waste products, and hormones.

Step 2: Determine If Each Option is a Component of Blood

a. Plasma is the liquid part of blood that makes up about 55% of its volume. It serves as a transport medium for nutrients, hormones, and waste products. b. Blood cells and platelets are solid components; red blood cells carry oxygen, white blood cells are part of the immune system, and platelets help with clotting. c. Gases and dissolved substances, like oxygen, carbon dioxide, and nutrients, are carried by the blood. d. This option suggests that all the options (a, b, c) are found in the blood.

Step 3: Evaluate the Options and Choose the Correct Answer

Since options a, b, and c are all parts of blood, option d is the only logical choice that states all of the above are found in the blood.

Key Concepts

Plasma

Plasma is often referred to as the liquid portion of blood. It is a yellowish fluid that makes up about 55% of our total blood volume. Plasma plays a crucial role in transporting nutrients, hormones, and waste products around the body. It acts as a medium that carries essential substances to cells and takes waste away from them.
One of the primary components dissolved in plasma is water — in fact, about 90% of plasma is water. The remaining 10% is made up of various dissolved substances. Plasma helps maintain blood pressure and regulates body temperature as it circulates throughout the body.

Blood Cells

Blood cells are the building blocks of our circulatory system and come in three major types: red blood cells, white blood cells, and platelets.
Red blood cells (RBCs) are responsible for carrying oxygen from the lungs to the rest of the body and returning carbon dioxide from the body back to the lungs. These cells contain a protein called hemoglobin, which binds to oxygen in the lungs.
White blood cells (WBCs) serve as the body's primary defense against infections. They are part of the immune system and help fight off bacteria, viruses, and other pathogens.
Platelets are small cell fragments that play a key role in blood clotting. When there's an injury, platelets gather at the site to help stop bleeding by forming clots.

Platelets

Platelets, sometimes known as thrombocytes, are small fragments of cells in the blood that have an important job: to help stop bleeding. When an injury occurs, platelets spring into action. They rush to the damaged area and begin to stick together to form a clot.
This clump of platelets creates a temporary barrier, preventing further bleeding. Platelets are crucial for wound healing, as they send signals to attract more cells to help repair after the initial closure. Moreover, people with low platelet counts may experience prolonged bleeding, indicating their vital role in the body.

Gases

Gases such as oxygen and carbon dioxide are essential components carried by the blood. Oxygen is indispensable for cell and tissue function, and carbon dioxide is a waste product that must be expelled from the body.
Red blood cells are primarily responsible for transporting these gases. Oxygen is taken from the air we breathe, attaches to the hemoglobin molecules in red blood cells, and is then released into the tissues. Conversely, carbon dioxide produced by cells is carried back to the lungs to be exhaled. This gas exchange is vital for maintaining life-sustaining processes in the body.

Dissolved Substances

Dissolved substances in blood include a variety of nutrients, electrolytes, and waste products that circulate within plasma.

• Nutrients include glucose, amino acids, and fatty acids, which are crucial for energy production and cellular functions.
• Electrolytes like sodium, potassium, and calcium maintain fluid balance and play roles in nerve and muscle function.
• Waste products such as urea are transported in the plasma to the kidneys, where they are excreted from the body.

Hormones, another important group of dissolved substances, help regulate numerous body functions by acting as chemical messengers. These dissolved components ensure that our bodies can function efficiently and effectively each day.