Circulatory System PDF

Circulatory system  General characteristics of the Circulatory System It consists of two separate but related components: the cardiovascular system and the lymphatic system. The cardiovascular system is responsible for transporting blood between the heart and tissues, in both directions. The...

Circulatory system  General characteristics of the Circulatory System It consists of two separate but related components: the cardiovascular system and the lymphatic system. The cardiovascular system is responsible for transporting blood between the heart and tissues, in both directions. The lymphatic system collects the lymph, the excess of tissue fluid, and returns it to the cardiovascular system.  Cardiovascular system It is made up of blood vessels (that carry blood throughout the body) and the heart (a muscular organ that pumps blood in two separate circuits): - Pulmonary circuit: carries the blood from the heart to the lungs, where it is oxygenated and returns to the heart. - Systemic circuit: carries oxygenated blood from the heart to the rest of the body and returns without oxygenating. The vessels that make up this system are of three types: - Arteries: carry blood from the heart to the tissues. - Veins: carry blood from the tissues to the heart. - Capillaries: vessels with thin walls, where the exchange of substances between the blood and the tissues takes place, which will be where the arteries end, and the veins are born.  Heart It is the organ responsible for pumping blood to both circuits, both pulmonary and systemic. It consists of four chambers, 2 atria, which receive blood and two ventricles that push blood. Thanks to these cavities, oxygenated blood (left side) and non-oxygenated blood (right side) are always kept separate, since each one will follow its circuit. Heart The heart wall is formed by three layers: - Endocardium: the innermost layer, formed by a simple squamous epithelium (endothelium) and a fibroelastic layer. - Myocardium: the thicker middle layer, formed by cardiac striated muscle. - Epicardium: the outermost layer, formed by connective tissue and a simple squamous epithelium. Anatomy of the Human Heart: Chambers and Valves - | Biology | JoVe  Arteries Muscular artery Elastic artery They carry blood from the heart to the capillaries at high pressure, which will help the blood reach remote areas. Its walls are formed by three layers: - Tunica intima: the innermost layer; formed by the endothelium, a simple squamous epithelium and loose connective. There is a sheet of elastic fibers called internal elastic lamina. - Tunica media: the thickest layer; formed by smooth muscle and elastic fibers. At the end of this layer, especially in large arteries, an external elastic lamina is distinguished. - Tunica adventitia: composed of dense irregular connective tissue.  Veins The vein's walls have the same layers as the arteries, but in general the tunica media is thinner and does not have elastic fibers, since here the pressure is lower. They also tend to have a larger diameter than the arteries and thus carry a greater amount of blood. Structure of Blood Vessels - Concept | Anatomy and Physiology | JoVe  Capillaries They are the smallest vessels, and their wall is formed only by endothelium. Types of capillaries: - Continuous: present in muscle tissue, nervous, conjunctive, lungs and exocrine glands. Their endothelial cells have tight junctions that do not leave spaces between them. - Fenestrated: they have pores in their walls. They appear in the pancreas, intestine, kidneys and endocrine glands. - Sinusoids: large diameter and numerous perforations forming irregular channels for blood transport. They appear in the bone marrow, liver, spleen, lymphoid organs and some endocrine glands.  Lymphatic system It is a system of vessels that collects excess tissue fluid and returns it to the cardiovascular system. Unlike the cardiovascular system, it is an open system in which there is no pump to circulate the liquid. Lymphatic vessels: formed by an endothelium that is more permeable than that of blood capillaries.The fluid they collect, which is called lymph, goes through increasingly larger vessels, the lymphatic vessels, very similar in structure to the veins. Lymphatic nodes: small and rounded organs where lymphocytes and other immune cells abound and are responsible for filtering the lymph. – Other lymphatic organs: thymus, bone marrow and spleen. Introduction to Lymphatic and Immune System - Concept | JoVe Lymph Lymph is the excess interstitial (clear) fluid that circulates through the lymphatic system and has the following functions: Transport white blood cells (lymphocytes, macrophages, dendritic cells). Remove waste and toxins from the tissues. Maintain fluid balance in the body. Collect excess interstitial fluid.