Erythrocytes (Red Blood Cells):
Humans and other vertebrates have erythrocytes that carry oxygen throughout the body. In humans, erythrocytes are unique because they are biconcave in shape and lack a nucleus. This shape maximizes the surface area for efficient gas exchange. Other vertebrates, such as mammals, birds, reptiles, amphibians, and fish, also possess erythrocytes. However, their shapes and structures can vary across different vertebrate groups.
Leukocytes (White Blood Cells):
Humans and vertebrates share the presence of various types of leukocytes that play crucial roles in the immune system. These include neutrophils, lymphocytes, monocytes, eosinophils, and basophils. These cells are responsible for detecting and eliminating pathogens, foreign substances, and damaged cells.
Platelets (Thrombocytes):
Humans and mammals possess platelets, which play a vital role in blood clotting and preventing excessive bleeding. Platelets are small, irregularly shaped cells that clump together to form plugs that seal damaged blood vessels. Other vertebrates, such as birds, reptiles, amphibians, and fish, have different mechanisms for blood clotting, but they do not have platelets analogous to those found in humans and mammals.
Nucleated Red Blood Cells:
In embryonic development and certain pathological conditions, humans and some other vertebrates, like amphibians and fish, can produce nucleated red blood cells. Nucleated red blood cells contain a nucleus and other cellular components, unlike the mature erythrocytes found in circulation.
Hemoglobin:
Most vertebrates, including humans, utilize hemoglobin as the primary oxygen-carrying protein in their red blood cells. Hemoglobin binds to oxygen in the lungs and releases it in tissues where oxygen is needed. However, some vertebrates, such as certain fish and invertebrates, use different respiratory pigments like hemocyanin or chlorocruorin for oxygen transport.
In summary, while humans share general similarities in blood cells with other vertebrates, there are variations and adaptations across different groups in terms of erythrocyte shape, the presence or absence of platelets, and the types of respiratory pigments used for oxygen transport.