Blood is a fluid connective tissue that flows in the blood vessels. It consists of several cells floating in a straw-coloured liquid called plasma. Plasma constitutes more than half of the blood's volume and consists maximum amount of water. Plasma is the liquid component of blood, in which the red blood cells, white blood cells, and platelets are suspended. The main role of plasma is to take nutrients, hormones, and proteins to the parts of the body that need them.

The heart is a muscular organ that pumps blood to all the parts of the body. The rhythmic dilation of an artery generated by the opening and closing of the aortic valve in the heart is called a pulse.

The endothelium is an additional cell layer, which differentiates the ovule integument from the inner epidermis. After fertilisation, the endothelium separates from the integument and becomes an independent tissue developing next to the growing embryo sac. In the absence of fertilisation, the endothelium may proliferate and form a pseudo-embryo. In some species (unitegmic tenuinucellate), the integument's inner layer may become specialised to perform the embryo sac's nutritional function called endothelium or integumentary tapetum. Example: Asteraceae.