Circulatory System - NCLEX-PN

The average adult body contains 4.5-6 liters of blood, depending on size and gender. Blood volume (BV) can be calculated by the following formula, given the hematocrit (HC) and plasma volume (PV):

The three main types of proteins in the blood are albumin, globulin, and fibrinogen. Major histocompatibility complex is not a free plasma protein, but rather a class of proteins found on the surface of all nucleated cells (MHC class I) and on the surface of certain immune cells known as antigen-presenting cells (MHC class II). They play an important part in immune function by displaying foreign antigens for communication between leukocytes.

The only anucleate blood cells are erythrocytes, or red blood cells. These cells are created with nuclei, but each daughter cell will then lose its nucleus in order to create more suface area for hemoglobin to bind oxygen and for easier passage through narrow capillaries.

Sympathetic innervation will decrease the heart rate, which will automatically decrease the cardiac output

The vagus nerve provides the main parasympathetic innervation of the heart. The recurrent laryngeal nerve, a branch of the vagus nerve, innervates the majority of the intrinsic muscles of the larynx. The cardiac nerve is part of the sympathetic innervation of the heart.

The majority of blood supply to the left atrium and left ventricle is provided by the left coronary artery. The septal branches and left circumflex artery are smaller divisions of this main artery. The posterior descending artery supplies the posterior one-third of the interventricular septum.

The nurse is most likely palpating the abdominal aorta. This vessel is large, generally 2.5-4 cm in diameter, and a strong pulse can often be felt on palpation. The femoral artery is also an area where a pulse may be felt, but it is only palpable in the mid-inguinal point of the inner thigh. The exterior iliac artery branches off of the abdominal aorta below the umbilicus, and the inferior mesenteric artery is a minor artery and is not generally palpable on examination.

The lymphatic system has several roles in the body, including drainage of interstitial fluid from tissues, transportation and activation of lymphocytes, and absorption and transportation of dietary fats. Red blood cells, however, are unable to enter lymph vessels, and so the lymphatic system does not participate in any type of gas exchange.

T-cell maturation occurs in the thymus, a small organ located in the upper part of the mediastinum, between the heart and the sternum. Mature T cells then may either circulate in the lymph or blood or reside in lymph nodes. The spleen is not a site of T cell maturation, though it does have other important immune functions, such as the production of antibodies and the removal of antibody-coated pathogens. The cisterna chyli is a part of the lymphatic system that is involved in lipid digestion.

Dietary fat is absorbed via lacteals, small lymph vessels contained within the body of the intestinal villi. Microvilli, tiny projections covering the surface of the villi, help with the absorption of minerals, vitamins, and other micronutrients. The cisterna chyli is a dilated pouch at the lower end of the thoracic duct that serves as a collection point for fatty chyle from the intestinal lacteals.

The proper unit when recording a patient's blood pressure is mmHg, or millimeter of mercury. This is derived from a historical measurement of how many millimeters of mercury in a mercury manometer were able to be elevated by a particular pressure. Due to it's toxicity, are longer used in medical equipment, though the unit remains in use.

The left ventricle is the most commonly enlarged heart structure seen in chronic hypertension. The left ventricle must overcome the afterload of the arterial system by becoming hypertrophied. As a result, the heart gets remodeled to overcome the systemic high blood pressures. The left ventricle directly pumps blood from the heart to the systemic circuit.

AB positive is a universal recipient, meaning a patient with AB positive type blood can receive a blood transfusion using any type of blood.

The average lifespan of a red blood cell is 4 months, after which it is phagocytosed by macrophages the spleen, liver, or lymph nodes. White blood cells, on the other hand, live for only about 3-4 days.

The casting of new red blood cells is stimulated by the hormone erythropoietin (EPO), released from the kidneys. Recall that all blood cells are made in the bone marrow. This hormone may increase as much as 1000 fold in times of oxidative stress.

Thyroxine is T4, the most biologically active form of thyroid hormone. Vasopressin, or anti-diuretic hormone, is part of the body's fluid-balance system. Luteinizng hormone is a hormone of the reproductive tract: in females it triggers ovulation, while in males it stimulates Leydig cells to produce testosterone.

Erythropoietin is produced by the peritubular interstitial cells of the kidney. These cells are very sensitive to tissue oxygen pressure. When oxygen demand increases, erythropoietin is released, stimulating the casting (hematopoiesis) of new red blood cells in bone marrow.

Supraoptic and paraventricular cells of the hypothalamus are the site of vasopressin (antidiuretic hormone) production. Lactotroph cells in the pituitary gland are responsible for the production of prolactin. Zona fasciculata cells of the adrenal glands produce cortisol.

Each heme group in hemoglobin encloses a single iron atom in the center of a protoporphyrin, a tetrapyrrol composed of four pyrrole rings linked together by four methyl groups, two vinyl groups, a methane bridge, and two propinoic acid side chains.

Neutrophils are the most common type of white blood cell, making up 55-70% of the total white blood cell population in the average blood sample.

Eosinophils are the leukocytes that are largely responsible for response to parasitic infections and allergies. They make up 1-3% of the average white blood cell count. They form the second smallest population of white blood cells, after basophils, which normally make up less than 1% of white blood cells in whole blood.

Lymphocytes are the second most common class of white blood cells, making up 26-33% of white blood cells.