Well, it is also known as iron-poor blood, and and it occurs when the person's blood cells impedes the delivery of oxygen, so that's what make's them tired and worn out.
I beleive the correct answer is shortage of oxygen supply to the muscles.
Anemia is a condition in which there is a lesser number of red blood cells in the body than the required levels in the body with men ranging from 4.2 - 6 million rbcs/microliter of blood and females ranging from 4.7-5.4 million rbcs/microliter of blood. The disparity is because men have more muscle and require more oxygen.
Red blood cells are a group of blood cells formed in the spinal chord and function to transport oxygen around the body from the heart where they are taken to the lungs via the pulmonary artery to pick up oxygen and then back to the heart via the pulonary vein where they go to the resto of the body. They supply tissues all over the body with oygen which is bound to an intracellular called hemoglobin that gives them the distinct red color. After relieving the oxygen to the tissues, they bind to the carbon dioxide forming a compound called carbyhaemoglobin that is also taken back to the heart then to the lungs where the carbon is removed then they pick up oxygen afresh. In some instances for example after a person has been shot, a blood vessel raptures and blood which contains these red blood cells is lost. That means that there will be no enough red cells to supply the muscles of the body with oygen which is required for them to contract and relax making a person walk. If you loose too much blood, the heart muscles will lack the oxygen to beat, the brain will lack its best food-oxygen- essentially every organ dies and withers away. So you essentially lack the fuel to walk. It is not only by getting shot but in some diseases such as blood cancer, the parent cells that make red cells can multiply so fast than they form red cells and you end up with immature cells that cannot carry the heavy oxygen. You also can get anemia if you lack iron in your food. The iron you eat from food is used to make the hemoglobin that binds the oxygen also it is used by the red blood cells themselves to mature. If it lacks then nothing will be available to carry oxygen meaning you will be weak until you get blood from another person or receive treatment with enough iron to make new cells and hemoglobin. A condition called sickle cell anemia also destroys the normal shape of red blood cells and they cannot carry enough oxygen.
Level: High School
Subject: Biology
Topic: Homeostasis
