Answer:
(i) Vena cava – Circulatory system. Veins of human circulatory system that carries deoxygenated blood from the upper part of the body are known as the superior vena cava, while the vein carrying deoxygenated blood from the lower part is known as the inferior vena cava.
(ii) Glomerulus – Excretory system. Nephron is the excretory unit of a kidney. It is also called the structural and functional unit of the kidney. The nephron has two main components: Glomerulus and the tubular system.
(iii) Alveoli – Respiratory system. Gas exchange occurs in the millions of alveoli in the lungs and the capillaries that envelop them.
(iv) Villi – Digestive system. Villi; villus (singular) is the small, slender, vascular projections in the small intestine that increase the surface area of the membrane.