Is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away fromthose same cells. Blood is circulated around the body through blood vessels by the pumping action of the heart. In animals with lungs, arterial blood carries oxygen from inhaledair to the tissues of the body, and venous blood carries carbon dioxide, a waste product of metabolism produced by cells, from the tissues to the lungs to be exhaled.
The intestines have several layers, the first mucosal epithelium composed of a lamina propria consists of connective tissue, the second layer is calledthe submucosa consists of connective tissue and muscle fibers, then a third and a smooth muscle layer with collagen fibers and serous blood vessels.
Obviously the structure is morecomplex but basically the digestive tract in general consists of epithelial tissue, connective, muscular, and infiltrated vessels and nerve plexus sanguienos.
Nervoustissue is one of four major classes of vertebrate tissue. Nervous tissue is the main component of the nervous system - the brain, spinal cord, and nerves-which regulates andcontrols body functions. It is composed of neurons, which transmit impulses, and the neuroglia cells, which assist propagation of the nerve impulse as well as provide nutrients tothe neuron. Nervous tissue is made of nerve cells that come in many varieties, all of which are distinctly characteristic by the axon or long stem like part of the cell thatsends action potential signals to the next cell. Functions of the nervous system are sensory input, integration, controls of muscles and glands, homeostasis, and mental activity.