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It belonged to the practice test (Human Anatomy & Physiology part ).
Which of the following substances is not normally found in filtrate?
- nitrogenous waste particles, such as urea
- water and small solutes
- blood cells and large particles
- ions, such as sodium and potassium
The correct answer is below.
Related info
Nitrogenous waste particles
The wastes produced by metabolism in animals are mainly nitrogenous wastes.
Nitrogenous wastes refer to ammonia (NH3), urea (CON2H4), and uric acid (C5H4N4O3)
It should be noted here that purine metabolism produces uric acid.
However, only humans, primates, birds, and reptiles excrete uric acid directly. Other mammals synthesize uric acid and then continue to break it down to produce allantoin.
But the human body lacks the enzyme uric acid oxidase needed for the breakdown of uric acid, all the human body is directly excreted uric acid.
Blood cells
Blood cells, also known as hemocytes, are cells that are present in the blood and can travel throughout the body with the blood flow.
In mammals, blood cells consist of three main types: red blood cells, white blood cells, and platelets.
The main function of red blood cells is to transport oxygen.
White blood cells play a major role in immunity. When germs invade the body, leukocytes cross the capillary walls and concentrate on the site of invasion, surrounding the germs and then engulfing them.
Platelets play an important role mainly in the process of hemostasis.
Blood cells make up about 45% of the blood volume and include red blood cells, white blood cells, and platelets.
Under normal physiological conditions, blood cells and platelets have a certain morphological structure and a relatively stable number.
Blood cells are derived from hematopoietic pluripotent stem cells of the bone marrow.
In addition to their ability to proliferate, stem cells can, under certain circumstances, migrate out of the bone marrow hematopoietic tissue and reach the extramedullary tissue with the blood flow to form hematopoietic cells nodules, called colony-forming units.
Each nodule consists of many differentiated cells of the same type that have been differentiated from a single stem cell division.
Sodium and potassium
Sodium is mainly found in table salt, which is the metal element that makes up salt.
It is an important condiment in cooking and the most important substance to ensure the hydration balance of the muscles.
Without salt, human survival would be hampered. Salt plays an important role in preventing food spoilage, and sodium is an indispensable component of salt.
Main physiological functions of sodium
- Sodium is the main positively charged ion in the extracellular fluid and participates in the metabolism of water, ensuring the balance of water in the body.
- It maintains the balance of acid and alkali in the body.
- It is a constituent of pancreatic juice, bile, sweat, and tears.
- Participates in the regulation of cardiac muscle and nerve function.
Sodium-potassium pump (also called sodium-potassium transporter), a protein molecule that carries out the exchange between sodium and potassium ions. For each ATP molecule consumed, three sodium ions are pumped out against the electrochemical gradient.
Because of the sodium-potassium pump in the cell membrane, each time one molecule of ATP is consumed, three sodium ions are pumped out to the outside of the cell and two potassium ions are pumped into the inside of the cell.
The role of potassium ions is to control the osmotic pressure inside the cell membrane, while sodium ions control the osmotic pressure outside the cell membrane.
Correct Answer
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