Illustration of an arthritic knee, showing arthritic changes on the cartilaginous articular surface of the distal femur.

Arthritis collage: illustrations of arthritic hands, shoulder, knee, and hip; a prosthetic hip replacement for surgical treatment of the disease; and an MRI scan used to diagnose arthritis. The background shows a bone matrix.

Atherosclerosis collage: illustrations of atherosclerotic plaque on the walls of a coronary artery and various treatment options (stent and balloon catheter) used to widen the vessel. A line drawing of the heart is shown in the background.

Cardiology collage, showing images of pathologies, such as infective endocarditis and atherosclerotic plaque, as well as surgical interventions, including pacemaker implantation, valve replacement, radiofrequency ablation, and open heart surgery.

Illustration of radiofrequency catheter ablation in the heart. The radiofrequency ablation catheter is used in the treatment of irregularities in the electrical conduction system of the heart.

Photo illustration of a coronary artery, showing an accumulation of atherosclerotic plaque in the lumen, cross section.

Illustration of the heart showing dilated cardiomyopathy of the left ventricle, cross section. There is enlargement of the left ventricle with noticeable thinning of its muscular wall.

Illustration of epilepsy, showing the brain, midsagittal section, with the pathways and foci of epileptic activity and neurons firing electrical impulses.

Photo illustration of the pelvis, showing a prosthetic hip joint replacement (left) and severe arthritis of the hip joint (right).

Illustration of the heart showing left ventricular hypertrophy, cross section. There is thickening and enlargement of the muscular wall of the left ventricle.

Illustration of placental complications during pregnancy. This image shows damage to the uterine wall vasculature due to antiphospholipid syndrome, which can cause excessive clotting and block the blood supply to the placenta and developing fetus, often resulting in miscarriage.

Illustration of Alzheimer's disease, showing the aging brain, highlighting the limbic system, basal ganglia, and cingulate gyrus, the brain structures significantly affected by the disease.

Illustration of appendicitis, the inflammation of the appendix.

Illustration of a coronary occlusion, the blockage of a coronary artery and often the cause of heart attack, with a detail of a thrombus (top right) and stent therapy (bottom right).

Illustration of a detached retina repair with scleral buckling.

Illustration of asthma, showing a bronchial tube filled with mucus, destruction of the cells lining the tube, and contraction of the bronchial smooth muscle (bronchospasm).

Illustration showing the synapse mechanism of a neuron (left to right): the synaptic end bulb before action potential, during action potential, and releasing neurotransmitters across the synaptic gap.

Illustration of Alzheimer's disease in the brain of an elderly woman, highlighting the hippocampus (red) and basal ganglia (blue). Alzheimer's dementia gradually leads to symptoms of memory loss and diorientation, as well as the inability to recognize people, speak, and perform basic tasks.

Illustration of an asthma attack. The smooth muscle cells surrounding the bronchioles of the lung begin to spasm in an allergic reaction, creating breathing difficulties. Meanwhile, the mucous membranes become congested and secrete mucous, further blocking the airway. The alveoli become extended, thus unable to empty any excess air.

Illustration of a bronchoscope within a bronchiole of the lung. A fiberoptic camera (endoscope) visualizes the bronchiole while a sample is biopsied for testing.