the circulatory system
Functions:
- transport of oxygen and carbon dioxide
- distribution of products of digestion
- transport of waste and toxic materials
- distribution of hormones
-
body temperature regulation - control of bleeding
- defense against bacteria and viruses
The heart
E 'divided into two pumps, in turn divided into an atrium and ventricle.
The pump is right for the pulmonary circulation: blood low in oxygen reaches the right atrium, flows into the right ventricle, which pushes the contraction in pulmonary arteries.
The left pump is used for the systemic circulation.
Alternating contraction and relaxation of the chambers of the heart is the cardiac cycle. The contraction phase ventricular and atrial systole is called.
The relaxation of all the rooms is called diastole.
Because the blood is moving in the right direction just the circulatory system is equipped with check valves:
- tricuspid valve between right atrium and ventricle
- bicuspid valve between atrium and left ventricle
- two semilunar valves between the heart and the ' between the heart and aorta and pulmonary artery
The contraction of the heart is initiated and coordinated by the sinoatrial node (SA node), located in the wall of the right atrium: the rhythm rule independently of the nervous system. The atrioventricular node (AV node) slows the momentum from the SA node, allowing the atria to complete the transition blood before the ventricles contract. If the rhythm is not regulated, there is fibrillation.
Heart rate is also influenced by the nervous system and hormones.
Blood:
E 'tissue fluid and plasma formed by specialized cells. The plasma is composed of water they are dissolved proteins, salts, nutrients and waste. The main proteins are albumins (osmotic function), globulins (transport fats and immune processes) and fibrinogen (blood clotting).
Red blood cells (or erythrocytes) are shaped like biconcave, providing a greater surface area than the spherical shape and carry oxygen. The red color is given by hemoglobin, which collects oxygen and transfers it to body tissues that need it. A portion of hemoglobin binds then to carbon dioxide and the lungs. Red blood cells are produced from the red marrow of bones during their training, lose their nucleus, and therefore can not be played. Red blood cells are disposed of deaths from the liver and spleen, which recovered the iron. The red blood cell production is stimulated by a hormone called erythropoietin.
The blood is given by a glycoprotein, which can be either A or B. In the plasma of each individual are antibodies designed to detect glycoproteins present a different type to those in his own blood. In the event of blood transfusion with different glycoprotein, the antibodies into action causing agglutination (agglomeration) of red blood cells transfused and the resulting blockage of blood vessels. Another type of protein in red blood cells is the Rh factor.
White blood cells (or leukocytes) have a nucleus and are produced by bone marrow. They have a defensive function and are divided into different types. The monocytes and neutrophils move through the capillaries in the place where there is a bacterium. Monocytes give rise to a so called amoeboid macrophage cell which, together with neutrophils, encases the bacteria for phagocytosis. In this way, the white blood cells die and accumulate, forming a whitish substance called pus. Basophils and eosinophils produce compounds anticoagulants and involved in inflammatory reactions.
Platelets, no nucleus, are fragments of megacarioti (large cells in the bone marrow) and are essential for clotting. When they come in contact with an uneven surface and adhere to pile up, clog the tear, it is small. If the lesion is larger, involving an enzyme called thrombin, which produces fibrin molecules, giving rise to that weaves a web that immobilizes the fluid portion of blood.
Blood vessels are from the heart, arteries, arterioles, capillaries, venules, veins.
arteries, the contraction of the ventricles dilate, the blood then passes to the arterioles, which in turn branch in capillaries, arterioles atraverso rings attached to muscle tissue called precapillary sphincters. The capillaries are the thickness of a cell, the pressure inside them causes a discharge from the plasma: this liquid is called interstitial fluid, and is located around the capillaries: bathing every cell, the liquid allows the exchange of material between the blood capillaries and surrounding cells. Blood flow in the veins is facilitated by the contraction of skeletal muscles and directed by one-way valves.
EPITHELIAL TISSUE
covers the body and its cavities and form glands. Has the function of selective barrier and is composed of cells, arranged in one or more layers, which adhere firmly to each other through junctions and is constantly renewed. Some are introflex
epithelial tissues during development of the body, forming endocrine and exocrine glands.
exocrine glands remain in contact with the epithelium through a small channel called the excretory duct (sweat glands, salivary, sebaceous ...).
The endocrine glands are detached epithelium, and their main product is formed by hormones.
TISSUE
constitutes
: dermis, tendons, ligaments, cartilage, bone, blood, lymph.
cells are surrounded by a large amount of extracellular substances secreted by the cells themselves. All tissues connectives, except blood, are woven filament composed of fibrous collagen. The connective tissue acts as a support to the epithelial tissue and contains the capillaries that feed on the sap and the epithelium.
Cartilage is composed of cells far apart from each other surrounded by collagen.
Bone is a cartilage strengthened by deposits of phosphate and calcium carbonate. Bone cells (osteocytes) are surrounded by concentric layers of collagen that surround a central channel through blood vessels: each set of concentric layers with their own channel is called osteons.
Lymph is a fluid necessary to transport the blood to fat particles from the small intestine.
SYSTEM RESPIRATORY
nose or mouth ---> pharynx ---> --- epiglottis> larynx ---> --- trachea> bronchi two ---> many bronchioles ---> many alveoli
between the pharynx and the larynx is the epiglottis, a flap of cartilage tissue that regulates the passage of air.
Within the larynx lie the vocal cords, strips of elastic tissue that vibrate the air passage.
The wall of the trachea is reinforced by incomplete cartilaginous rings.
Along the way the air is warmed and moistened, and free from dust particles and bacteria, which remain trapped in the mucus secreted by cells lining the epithelium of the bronchioles, bronchus and trachea. The mucus is pushed up by cells equipped with cilia beat in sync.
The alveoli are surrounded by a dense network of capillaries. Externally
lung is the thoracic cavity, which has the task of protecting, below which the diaphragm is grim, a muscle-shaped dome. The chest and lungs are coated with a double layer membrane called the pleura.
With inspiration, the diaphragm contracts and flattens and the intercostal muscles raise the ribs: with the chest cavity expands the lungs, which adhere to the inside wall of the chest through the pleura. Upon completion of the exhalation, the lungs remains an amount sufficient air to prevent the alveoli sag.
The rhythm of breathing is automatic, but the muscles are volunteers and their contraction is stimulated by impulses generated by the respiratory center located in the medulla oblongata. There are also receptors in the walls of the aorta and carotid arteries that signal the respiratory center to a lower level of oxygen.
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