erythrocyte red blood cells on white background. hand drawn scientific microbiology in sketch style

blood cell red erythrocyte vector hemoglobin hematology icon human body anemia flow isolated circulation bloodstream clot black graphic oxygen science circulatory biology artery coagulation realistic type healthy sugar hemostasis hypoglycemia line glucose sketch polycythemia health function rbc high corpuscle molecule transport medical system vein immunology microscope hyperglycemia medicine cells white background hand drawn scientific microbiology style background style