Chapter 3 The Cardiorespiratory System
Purpose To provide the fitness professional with a fundamental knowledge and explanation of the cardiorespiratory system.
Objectives Following this presentation the participant will be able to: Describe the structure and function of: The cardiorespiratory system The cardiovascular system The respiratory system Explain how each of those systems relates to human movement. Go through oxygen-testing procedures. Relate how oxygen is related to energy expenditure as well as the influence that dysfunctional breathing can have on the human movement system (HMS).
The Cardiorespiratory System To maintain a constant state of efficient operation, the HMS needs to have support systems. The cardiorespiratory system comprises the cardiovascular and respiratory systems. Together they provide the tissues of the HMS with oxygen, nutrients, protective agents, and a means to remove waste products.
Cardiovascular System The cardiovascular system is composed of the heart, blood, and blood vessels.
Heart A muscular pump that rhythmically contracts to push blood throughout the body Heart muscle is termed cardiac muscle and has characteristics similar to skeletal muscle. Cardiac muscle contraction is involuntary. The heart is in the mediastinum.
Cardiac Muscle Contraction Cardiac muscle fibers are shorter and more tightly connected. Enables the contraction of one fiber to stimulate the others to contract synchronously All cardiac muscle fibers have a built-in contraction rhythm, and the fibers with the highest rhythm determine the heartbeat or heart rate. Typical discharge rate (heart rate) is 70 80 beats per minute
Cardiac Muscle Contraction Specialized conduction system of cardiac muscle that provides the rhythm for the heart rate includes: Sinoatrial (SA) node Located in the right atrium. Called the pacemaker because it initiates the heartbeat Internodal pathways Transfers the impulse from the SA to the atrioventricular (AV) nodes Atrioventricular (AV) node Delays the impulse before moving on to the ventricles Atrioventricular (AV) bundle (bundle of His) Passes the impulse to the ventricles for contraction via the left and right bundle branches of the Purkinje fibers.
Structure of the Heart The heart is composed of four chambers that form two interdependent but separate pumps. Each side of the heart has two chambers. Atrium Ventricle Atrium gathers blood coming to the heart. Ventricle pumps the blood out to the rest of the body.
Function of the Heart Each contraction of a ventricle pushes blood from the heart into the body. The amount of blood that is pumped out with each contraction of a ventricle is the stroke volume (SV). The rate at which the heart pumps is the heart rate (HR). Together, the heart rate and the stroke volume make up the overall performance of the heart (cardiac output).
Monitoring Heart Rate Place index and middle fingers around the backside of the wrist (about one inch from the top of wrist, on the thumb side). Locate the artery by feeling for a pulse with the index and middle fingers. Apply light pressure to feel the pulse. When measuring the pulse during rest, count the number of beats in 60 seconds. When measuring the pulse during exercise, count the number of beats in 6 seconds and add a zero to that number. Example: Beats in 6 seconds = 17. Add a zero = 170. Pulse rate = 170 bpm
Blood Blood acts as a medium to deliver and collect essential products to and from the body s tissues. The average human body holds about 5 L (roughly 1.5 gallons) of blood at any given time. Blood is a vital support mechanism as it: Transports oxygen, hormones, and nutrients to specific tissues and collects waste products Regulates body temperature and ph levels Protects from injury and blood loss using clotting mechanism to seal off damaged tissue Provides specialized immune cells to fight foreign toxins within the body, decreasing disease and sickness
Blood Vessels Blood vessels form a closed circuit of hollow tubes that allow blood to be transported to and from the heart. Arteries: transport blood away from the heart. Veins: transport blood back to the heart.
Respiratory System The second functional component of the cardiorespiratory system is the respiratory system. Its primary role is to ensure proper cellular functioning. Works intimately with the cardiovascular system by providing a means to collect oxygen from the environment and transport it to the bloodstream.
Respiratory System The collection and transportation of oxygen is made possible by the respiratory pump and the respiratory airways.
Respiratory Pump Located in the thoracic cavity Provides framework and flexibility to allow for the expansion and compression needed for ventilation Divided into two phases Inspiratory (inhalation) Expiratory (exhalation)
Respiratory Pump Bones Sternum, ribs, vertebrae Muscles Inspiration: diaphragm, external intercostals, scalenes, sternocleidomastoid, pectoralis minor Expiration: internal intercostals, abdominals
Respiratory Passageways Air must have passageways to funnel it in and out of the lungs for proper utilization. Respiratory passageways are divided into Conduction passageway Respiratory passageway
Respiratory Passageways Conduction passageways Nasal cavity Oral cavity Pharynx Larynx Trachea Right and left pulmonary bronchi Respiratory passageway Alveoli Alveolar sacs
Cardiorespiratory Function Cardiovascular and respiratory systems make up the cardiorespiratory system. Respiratory system: provides the means to gather oxygen from the environment and transfer it to the body. Cardiovascular system: provides the means to transport oxygen to the tissues of the body.
Oxygen Consumption The use of oxygen by the body is known as oxygen consumption; at rest = 3.5 ml per kg per min. Maximal oxygen consumption is generally accepted as the best means of gauging cardiorespiratory fitness. Submaximal testing procedures have been established to estimate maximal oxygen consumption. Used in a fitness assessment, it can provide important structural and mechanical information that may help a fitness professional limit the risk of injury.
Dysfunctional Breathing The importance of all systems in the body working synergistically can be further demonstrated by the intimacy between the cardiorespiratory system and the HMS. If there is a dysfunction in the cardiorespiratory system, this can directly impact the components of the HMS and perpetuate into further dysfunction.
Dysfunctional Breathing Alterations in breathing patterns are a prime example of this relationship. During shallow breathing patterns, the secondary respiratory muscles are used more predominantly. If this shallow, upper-chest breathing pattern becomes habitual, it can cause overuse of muscles including the scalenes, sternocleidomastoid, levator scapulae, and upper trapezius. These muscles also play a major postural role in the kinetic chain as they all connect directly to the head and neck. Their increased activity and excessive tension often result in headaches, lightheadedness, and dizziness.
Summary The respiratory system gathers oxygen from the environment, inhales it through the nose and mouth, and processes it to be delivered to the tissues of the body. As cells use oxygen, they produce carbon dioxide, which is transported back to the heart and lungs in the deoxygenated blood to be released through exhalation. The collection and transportation of oxygen is made possible by the respiratory pump and the respiratory airways. If there is a dysfunction in the cardiorespiratory system, this can directly impact the components of the HMS and perpetuate into further dysfunction.