Question

Internal respiration refers to a. the exchange of gases between alveolar air and the blood in the lungs. b. the movement of air into the lungs. c. the exchange of gases between the blood and tissue fluid. d. cellular respiration, resulting in the production of ATP.

Short answer

The correct definition of internal respiration is: \(c. \) the exchange of gases between the blood and tissue fluid.

Step-by-step solution

Understanding internal respiration

Internal respiration is a biological process in which gases are exchanged between the blood and the tissue fluid (or cells) within the body. This allows oxygen to be transported from the blood to the cells, and carbon dioxide to be transported from the cells to the blood. This is a crucial process for maintaining adequate levels of oxygen and carbon dioxide in the body, which is essential for the proper functioning of cells.

Review the given options

Let's look at each option provided in the exercise: a. the exchange of gases between alveolar air and the blood in the lungs. - This option refers to external respiration, which involves the exchange of gases between the air in the lungs and the blood. b. the movement of air into the lungs. - This option refers to inhalation, which is the process of drawing air into the lungs. c. the exchange of gases between the blood and tissue fluid. - This option correctly describes internal respiration. d. cellular respiration, resulting in the production of ATP. - This option refers to the process in which cells break down glucose and generate ATP, which provides energy for cellular activities.

Identify the correct answer

Based on the definitions provided in previous steps, the correct answer for the definition of internal respiration is: c. the exchange of gases between the blood and tissue fluid.

Key concepts

Gas Exchange

Gas exchange is a vital physiological process where oxygen and carbon dioxide are exchanged between the blood and tissue fluid at the cellular level. This process is key in maintaining homeostasis within the body since it ensures that all cells receive the oxygen they need for survival.
Within the capillaries, oxygen diffuses from the blood into the surrounding tissue fluid and then into cells. Simultaneously, carbon dioxide produced as a waste product from cellular metabolism diffuses from cells into the tissue fluid and then back into the blood.

• Oxygen enters the bloodstream in the lungs and travels to tissues.
• Carbon dioxide, a waste byproduct of cellular activities, returns from tissues to the blood to be exhaled.

This exchange occurs due to the concentration gradients of the two gases, allowing the diffusion process to naturally occur without energy input from the body.

Tissue Fluid

Tissue fluid, also known as interstitial fluid, is the fluid that surrounds and bathes the body's cells. It plays a crucial role in the exchange of substances between blood and cells.
This fluid forms when components of blood plasma leak out of the capillaries, minus red blood cells and large proteins, and seep into the spaces between the cells. The presence of tissue fluid enables:

• Nutrient transport from blood to cells.
• Waste removal from cells to blood.

Without tissue fluid, cells would not receive nutrients or be able to remove waste effectively, impacting cellular health and overall bodily function.

Oxygen Transport

Oxygen transport is a critical component of the respiratory and circulatory systems, allowing oxygen to move from the lungs to the tissues throughout the body. Hemoglobin, a protein in red blood cells, binds to oxygen in the lungs and carries it through the bloodstream.
As blood reaches systemic capillaries, hemoglobin releases the oxygen, which diffuses into the tissue fluid and finally into cells where it is utilized for cellular respiration.

• Oxygenated blood leaves the lungs and travels via the arterial system.
• The oxygen is used for energy production in the form of ATP through cellular respiration.

This efficient transport system ensures that cells have an adequate supply of oxygen to meet metabolic demands.

Carbon Dioxide Transport

Carbon dioxide transport involves moving carbon dioxide, a byproduct of metabolism, from the body's tissues back to the lungs for exhalation. In the blood, carbon dioxide is transported primarily in three forms: dissolved in plasma, chemically bound to hemoglobin, and as bicarbonate ions.

• Dissolved carbon dioxide in plasma makes up a small fraction of carbon dioxide transport.
• The majority of carbon dioxide is transported as bicarbonate ions, as carbon dioxide reacts with water to form carbonic acid, which dissociates into bicarbonate and hydrogen ions.
• Some carbon dioxide binds directly to hemoglobin in red blood cells.

This transport system is crucial as it helps maintain the acid-base balance in the body, preventing changes in pH that could disrupt normal cellular functions.