Medical Linguistics and Anatomy

HTH 2306, Medical Linguistics and Anatomy 1

Course Learning Outcomes for Unit IV Upon completion of this unit, students should be able to:

8. Examine the structure and function of the organs located within the skeletal, muscular, integumentary, cardiovascular, lymphatic and immune, nervous, sensory, endocrine, gastrointestinal, urinary, reproductive, and respiratory systems.

9. Identify the common signs, symptoms, and illnesses associated with the structure and functions of

the skeletal, muscular, integumentary, cardiovascular, lymphatic and immune, nervous, sensory, endocrine, gastrointestinal, urinary, and reproductive and respiratory systems.

10. Recall terms that describe diagnostic, surgical, and other treatment techniques associated with the

skeletal, muscular, integumentary, cardiovascular, lymphatic and immune, nervous, sensory, endocrine, gastrointestinal, urinary, and reproductive and respiratory systems.

Reading Assignment Chapter 12: The Cardiovascular System: Transport and Supply Chapter 13: The Respiratory System: It’s a Gas

Unit Lesson The Cardiovascular System The major components of the cardiovascular system are the heart, blood, and blood vessels. The heart is an organ that serves as a pump through the system, blood is a form of connective tissue that has a liquid component in the form of plasma, and blood vessels serve as the series of passageways for the transport of blood to and from the cells of the body (Colbert, Ankney, & Lee, 2013). The heart beats about 100,000 times every day. If you do the math, you will note that this adds up to more than 35 million beats per year! The heart is truly a fascinating organ, but it does not act alone. There are several other supportive structures and processes that allow the heart to do its work while at rest and even in the most strenuous physical situations imaginable. Anatomy of the Heart The heart is located in the thoracic cavity between the two lungs, and it rests upon the diaphragm. An average human heart weighs approximately 300 grams and is 14 centimeters long by 9 centimeters wide (Moini, 2013). The heart is approximately the size of a closed fist. The apex of the heart is the pointed end that forms the tip of the left ventricle, a lower chamber of the heart. The base of the heart is on the posterior aspect and it is formed by the atria, or the upper chambers of the heart. The heart is surrounded by a series of protective layers that help to hold it in place. This protective layer is known as the pericardium. The pericardium consists of two different layers: the fibrous pericardium and the serous pericardium. The fibrous pericardium is the tougher, outer layer whereas the serous pericardium is the thinner, more delicate inner layer. The outer layer of the parietal layer of the serous pericardium is fused to the fibrous pericardium and the inner visceral layer of the serous pericardium (also known as the epicardium).

UNIT IV STUDY GUIDE

Cardiovascular and Respiratory Systems

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Between the parietal and the visceral layers is a thick liquid known as pericardial fluid. Pericardial fluid helps to reduce the friction between the membrane as the heart pumps (Tortora & Derrickson, 2012). The Layers and Chambers of the Heart The outermost layer of the wall of the heart is the epicardium. Under the epicardium is the second layer of the wall of the heart. This layer makes up the bulk of the heart and is known as the myocardium. The myocardium is the layer of cardiac muscle tissue. The cells of this layer of the heart are involuntary, striated, and branched (Rizzo, 2010). The third and inner most layer is known as the endocardium. This layer is penetrated by tiny blood vessels and bundles of smooth muscle. The endocardium serves as the lining of the myocardium. The heart consists of four chambers that receive blood from various parts of the body. The two upper chambers are called the right and left atriums, and the two lower chambers are known as the right and left ventricles. The Great Vessels and Valves of the Heart The right atrium receives oxygen-poor blood from three veins that return the blood to the heart. The superior vena cava is a large vein that brings blood from parts of the body above the heart. The coronary sinus then drains blood from most of the vessels supplying the wall of the heart. The right atrium delivers the deoxygenated blood into the right ventricle, which then pumps the blood into the pulmonary trunk. The pulmonary trunk then divides into the right and left pulmonary artery, and each one carries blood to the corresponding lung. The blood then passes through the left ventricle, which pumps blood into the ascending aorta. From there, the now-oxygenated blood is carried to all parts of the body (Moini, 2013). As each chamber of the heart contracts, it pushes blood volume into a ventricle or out of the heart into an artery. Valves are in place to prevent blood from flowing backward. The atrioventricular (AV) valves lie between the atria and the ventricles. The atrioventricular valve located between the right and left ventricle is known as the tricuspid valve. It has this name because it has three leaflets. The atrioventricular valve between the left atrium and left ventricle is called the bicuspid or mitral valve. The valves open and close based on the level of pressure exerted across the valves. Blood Supply to the Heart Like other tissues, the wall of the heart has its own blood supply. The flow of blood through the numerous vessels in the myocardium is known as coronary circulation. The primary coronary vessels are the left and right coronary arteries, which originate from the ascending aorta. When a blockage of a coronary artery deprives the heart muscle of oxygen, reperfusion is necessary to reestablish blood flow and to minimize further damage. Cardiovascular Disease More than 60 million Americans have some form of cardiovascular disease. It is the leading cause of non- accidental death in this country. Major risk factors include high blood pressure, high cholesterol, diabetes, obesity and overweightness, smoking, inactivity, heredity, age, and male gender. Some patients have heart attacks without even being aware of it. This phenomenon, known as a silent MI, is usually discovered when a screening electrocardiogram (ECG) shows evidence of an old heart attack. Diabetics are particularly susceptible to this phenomenon. Contributing factors include stress, postmenopausal drops in hormonal levels, and heavy alcohol consumption. It has been shown that people who are overweight and carry most of their weight around their middle are at higher risk for heart attacks than those who carry their weight distributed over their frame. Deficient blood flow to the heart not only can cause heart attacks, but it also can cause arrhythmias. When a portion of the ventricle gets hypoxic, it begins to get “twitchy” and may begin to beat very quickly. This rapid beating, called ventricular tachycardia, is independent of the rhythm ordered by the heart’s pacemaker and, unfortunately, is not particularly effective at pumping blood. The condition can rapidly degrade into total cardiac arrest. The Respiratory System: Introduction The respiratory system has two main functions. The first function is to bring oxygen from the environment into the body (into the bloodstream). Secondly, the respiratory system functions to remove carbon dioxide waste

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from the body (from the bloodstream). Gas exchange is an important aspect of respiration and ventilation. Oxygen is used by our cells to convert food into adenosine triphosphate (ATP) (through cellular respiration). This is of paramount importance because the cells must have a continuous supply of oxygen to survive and carry out their basic activities (Longenbaker, 2013). Carbon dioxide is the waste product generated by cellular respiration. This waste product must be removed from the body, or it will become toxic Major components of the respiratory system: The major components of the respiratory system are as follows:

1. two lungs that serve as the vital organs; 2. upper and lower airways that conduct, or move, gas throughout the system; 3. terminal air sacs called alveoli surrounded by a network of capillaries that allow gas exchange; 4. a thoracic cage that houses, protects, and facilitates function for the system; and 5. muscles of breathing (the diaphragm and accessory muscles).

Ventilation Versus Respiration Air contains many gases. The most abundant gas is nitrogen, which comprises 78% of the atmosphere. Nitrogen is inert, meaning it does not interact with the body (it travels into and out of the respiratory system virtually unchanged). It acts as a support gas that keeps the lungs open by adding volume. Oxygen is the next most abundant gas, comprising 21% of the atmosphere. Carbon dioxide is found only in very small concentrations (less than 0.05% of the atmosphere) (Colbert, Ankney, & Lee, 2013). The process of breathing has two components:

1. Ventilation: the movement of air into and out of the lungs 2. Respiration: the process of gas exchange (where oxygen is added to the blood and carbon dioxide is

removed from the blood) a. External respiration: gas exchange between the air and the blood b. Internal respiration: gas exchange between the blood and the cells

Breathing must take place continuously. Our bodies only have enough stored oxygen to last four to six minutes. If the reserves are used up and oxygen is not replenished, death will result. The Airways and the Lungs The respiratory system consists of a series of branching tubes (airways) that carry air deep within the lungs. The larger tubes are called bronchi. As the branching tubes get smaller, they are called bronchioles. The alveoli are the terminal ends of each tube. Each alveolus is surrounded by capillaries. The combination of alveolar walls and capillary walls is called the respiratory membrane; it is the place where gas exchange occurs (Colbert et al., 2013). The Upper Airways and the Respiratory Tract The upper airway begins at the nares (nostrils) and ends at the vocal cords. General functions of the upper airway include the following:

1. heating or cooling inhaled air to body temperature; 2. filtering particles from inhaled air; 3. humidifying inhaled air; 4. providing sense of smell (olfaction); 5. producing sounds (phonation); and 6. conducting gas to lower airways.

The nose is a rigid structure comprised of cartilage and bone. The nasal cavity is the space behind the nose; it has three main parts: the vestibular region, the olfactory region, and the respiratory region. The vestibular region is located inside the nostrils and contains coarse nasal hairs, called vibrissae (Colbert et al., 2013). The olfactory region is located at the roof of the nasal cavity and helps detect smells.

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How We Breathe The respiratory control center is the medulla oblongata, which is a portion of the brain. Inspiration is an active process initiated by the respiratory control center. A signal is sent through the phrenic nerve to the diaphragm. The diaphragm then contracts, causing it to flatten and increase the thoracic cavity space. This increase in thoracic cavity lung volume decreases the pressure inside of the chest. At that point, the pressure in the lungs is now lower than the pressure in the atmosphere, and air rushes into the lungs (Moini, 2013). Exhalation is a passive act caused by relaxation of the diaphragm and elastic recoil of the lungs. As the diaphragm relaxes, it regains its normal dome shape. Space in the thoracic cavity is then decreased, which increases the pressure in the chest, and air is pushed out. The lungs are made of elastic tissue that expands with inhalation. During exhalation, the elastic tissue recoils, returning the lungs to their original shape, and the air is pushed out. Interesting Fact

Too much breathing can be bad for you! Hyperventilation is a condition in which a person breathes much

too quickly, usually as a result of anxiety or panic. The high respiratory rate blows off large amounts of

CO2, causing abnormal blood pH. As a result, the patient begins to experience symptoms that are

sometimes frightening, including dizziness, weakness, and tingling in the arms and around the mouth.

The treatment of choice is to help the patient breathe more slowly, which will gradually correct the

abnormal pH. Breathing into a paper bag is no longer recommended.

References Colbert, B. J., Ankney, J., & Lee, K. T. (2013). Anatomy, physiology, & disease: An interactive journey for

health professionals (2nd ed.). Upper Saddle River, NJ: Pearson Education. Longenbaker, S. (2013). Mader’s Understanding human anatomy & physiology. New York, NY: McGraw-Hill. Moini, J. (2013). Anatomy and physiology for health professionals. Burlington, MA: Jones & Bartlett. Rizzo, D. (2010). Fundamentals of anatomy & physiology (3rd ed.). Clifton Park, NY: Delmar. Tortora, G., & Derrickson, B. (2012). Introduction to the human body: The essentials of anatomy and physiology (9th ed.). Hoboken, NJ: Wiley.

Learning Activities (Non-Graded) For a review of the Key Terms of the unit, click here to access the interactive Unit IV Flashcards in PowerPoint form. (Click here to access a PDF version.) Non-graded Learning Activities are provided to aid students in their course of study. You do not have to submit them. If you have questions, contact your instructor for further guidance and information.