Chapter 2:

Understanding the Human Body

 

Lesson Objectives

After completing this lesson, participants should be able to:

•   Understand how the nervous system, respiratory system, and circulatory system work together and how failure of one system to function properly can cause damage to the other systems.

•   Understand the major components of the nervous, respiratory, and circulatory systems.

•   Identify the normal breathing and pulse rates for adults, children, and infants.

•   List conditions that can compromise respiration.

•   Identify three medical conditions that can result from circulatory system failure.

Approximate Time: 10 minutes

Skill Practice: No

DVD Covers Points in Lesson: Yes

PowerPoint™ Presentation Supports Points in Lesson: Yes

 

Teaching Points

•   The nervous, circulatory, and respiratory systems work together to regulate breathing and heart rate. If one of these systems is not working properly, a respiratory or cardiac emergency could occur.

•   The health care provider provides BLS to help sustain life and correct conditions resulting from the failure of the body systems.

•   The nervous system is the command center of the human body. It is controlled by the brain, which regulates the heart rate and respiratory rate.

•   The nervous system allows the body to react to internal and external stimulation and controls movement. Signals travel from the brain through nerves that extend down the spinal cord and branch out through the body.

•   The brain and spinal cord are the headquarters and communication system for the body. The brain has three main parts (cerebrum, cerebellum, and brain stem) and is particularly sensitive to oxygen deprivation.

•   Whenever possible, it is important to determine the patient’s normal level of consciousness to determine whether his or her current level of consciousness is an indicator of illness or injury.

•   The respiratory system delivers oxygen to the lungs and removes waste products such as carbon dioxide. It must function continuously; if it stops for any reason, the brain will die within minutes.

•   The respiratory system begins at the mouth and nose, where air is taken in, and ends in the alveoli of the lungs, where actual oxygen and carbon dioxide exchange takes place.

•   Adults normally breathe 12 to 20 breaths per minute (respiratory rate). Normal breathing rates for children are 15 to 30 breaths per minute, and infants’ rates are between 25 and 50 breaths per minute.

•   The circulatory system is made up of the heart and blood vessels, which circulate blood to deliver oxygen and nutrients throughout the body while removing carbon dioxide and other metabolic waste products.

•   The heart is unique because it can generate its own electrical impulses without stimulation from nerves. Each time the heart beats, blood circulates and generates a pulse. The heart of the average adult at rest beats between 60 and 80 times per minute.

•   The pulse of an unresponsive adult or child is checked at the neck at the carotid artery. An infant’s pulse is taken at the inside of the upper arm at the brachial artery.

•   Without oxygen, brain cells begin to die in as little as 4 to 6 minutes. The goals of CPR are to supply oxygen to the blood and to keep the blood flowing to the brain until more advanced medical care is available.

•   Respiration can become compromised from disease, injury, choking, drowning, or cardiac arrest.

•   Signs and symptoms of respiratory distress include:

  Signs of hypoxia, such as restlessness, anxiety, and confusion.

   Signs of airway obstruction, such as grunting, stridor, and inability to speak.

   Flared nostrils.

   Unusually rapid, deep, or irregular breathing.

   Straining to breathe (for example, use of facial and neck muscles).

   Cyanosis (blue color) of fingernails and around lips.

•   The most severe sign of respiratory system failure is respiratory arrest, in which breathing stops and the skin becomes cyanotic or ashen. Without rapid intervention, brain cells will die.

•   Heart disease can narrow the coronary arteries, which may result in restriction of blood flow and diminished supply of oxygen to the heart. This may cause:

   Angina: a condition in which the heart is temporarily deprived of oxygen (ischemia) due to partial narrowing of a coronary artery. It usually does not damage the heart, but is a sign of heart disease and requires medical attention. Angina is often brought on by strenuous physical exertion, stress, or extreme heat or cold. It seldom lasts more than 15 minutes and is usually relieved by rest and nitroglycerin tablets or spray.

   Myocardial infarction (heart attack): more severe or prolonged interruption of blood flow. Angina and myocardial infarction are collectively known as acute coronary syndrome (ACS). The most common symptom of ACS is chest pain or discomfort.

   Acute myocardial infarction (AMI): commonly referred to as heart attack; occurs when the myocardium is deprived of oxygen to the extent that tissue necrosis occurs in the heart. AMI usually occurs as a result of atherosclerosis, a condition in which plaque significantly narrows or clogs one or more of the coronary arteries.

•   Signs and symptoms of AMI include:

   Chest pain or discomfort, radiating to the arms, jaw, or upper back.

   Difficulty breathing (dyspnea).

   Profuse sweating (diaphoresis).

   Nausea or vomiting.

   Irregular pulse in the presence of other signs and symptoms.

   Weakness.

   Cool, pale, moist skin.

•   Approximately 20% of AMI victims experience no chest pain (“silent” heart attack). Other patients, especially elderly, female, and diabetic patients, may experience vague or unusual symptoms such as weakness or “not feeling well.”

•   The signs and symptoms of AMI are similar to angina, but usually more intense. Chest pain lasts longer than 15 minutes and is not relieved by rest or nitroglycerin. Patients with AMI are at risk for experiencing sudden cardiac arrest.

•   A stroke occurs when a blood vessel in the brain delivering oxygen-rich blood becomes occluded (ischemic) or when a blood vessel ruptures (hemorrhagic). Nerve cells beyond the occluded or ruptured blood vessel cannot function and die within minutes.

•   Dead brain cells cannot be replaced, so the effects of a stroke are permanent. Stroke is the third leading cause of death.

•   Signs and symptoms of a stroke include:

   Weakness, numbness, or paralysis of the face, arm, or leg on one side of the body.

   Blurred or decreased vision, especially in one eye.

   Problems speaking or understanding.

   Dizziness or loss of balance.

   Severe, sudden, and unexplained headache.

   Deviation of the pupils from normal (ie, unequal pupils).

•   Use stroke assessment tools, such as the Cincinnati Stroke Scale or Los Angeles Prehospital Stroke Screen (LAPSS). Also evaluate for other causes of altered mental status, such as seizures and hypoglycemia.

•   Develop plans in advance for management of acute stroke patients.

Application

•   Participants should complete the “Check Your Knowledge” questions at the end of Chapter 2 in the textbook.

 

 

 

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