Nursing Preparation Study Guide

Nursing Preparation Study Guide

7.3.4 Medical Terminology • Autonomic nervous system: Part of the nervous system that helps to control the body through unconscious and controls actions, such as heart rate, digestion, and respiratory rate. • Endocrinology: The study of the endocrine system and hormone balance. • Homeostasis: The ability of the human body to maintain a stable internal environment when dealing with changes in the internal and external environments. • Negative feedback: Helps to maintain the body’s homeostasis. If a gland is producing too much of one hormone, signals are sent to the brain and an opposing hormone is released, which reduces the levels of the first hormone. For example, glucagon and insulin both play roles in regulating blood glucose levels. • Positive feedback: Rarely seen in the body, a positive feedback loop increases the response over time. With an increase in the response, more of the hormone is secreted. An example is the secretion of oxytocin during delivery. Positive feedback increases oxytocin and uterine contractions become stronger to allow for the delivery of the baby. 7.4 The Cardiovascular System – Tour of the System Blood flows through a network of vessels that extend between the heart and peripheral tissues. Blood vessels are divided into two different circuits: the pulmonary circuit and systemic circuit. The pulmonary circuit is a network of blood vessels that carry blood to and from the gas exchange surfaces of the lungs, while the systemic circuit transports blood to and from the rest of the body. Blood travels through these circuits in one direction, beginning and ending at the heart. Thus, blood that is low in oxygen returning to the heart from the systemic circuit must complete the pulmonary circuit to pick up oxygen before reentering the systemic circuit. 7.4.1 The Pericardium The pericardium is the membrane that lines the pericardial cavity. As a delicate serous membrane, the pericardium can be subdivided into the visceral pericardium and the parietal pericardium. The epicardium is the visceral pericardium that covers and adheres closely to the outer surface of the heart. The inner surface of the pericardial sac, which encompasses the heart, is lined with the parietal pericardium. The pericardial sac consists of a dense network of collagen fibers, which form the fibrous pericardium. It stabilizes the position of the cardiovascular organs within themediastinum. The pericardial cavity is the small space between the parietal and visceral surfaces, and it normally contains 15-50 mL of pericardial fluid, which is secreted by the pericardial membranes. This fluid acts as a lubricant, reducing friction between the opposing surfaces as the heart beats. Inflammation and pathogens can infect the pericardium, leading to a condition called pericarditis. In this condition, the inflamed pericardial surfaces rub against one another, producing a distinctive scratching sound that can be heard using a stethoscope. It is common for pericardial inflammation to result in an increased production of pericardial fluid. Fluid then collects in the pericardial cavity, restricting the movement of the heart. This condition, called cardiac tamponade, can also be caused by traumatic injuries (such as stab wounds) that produce bleeding into the pericardial cavity.

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