INTRODUCTION TO CARDIOPULMONARY ANATOMY
It is important to emphasize that knowledge of anatomic structures (anatomy) is essential to understanding how it works. The explanations will be at a basic level, but will include the identification of pieces and parts and their functions within the respiratory and coronary systems. This will allow you to easily research individual areas as required by you.
We will start at the head and work our way down the body. Finally we will put it all together as it functions to supply oxygen to your body and remove carbon dioxide as you exhale.
Maxilla Bones on the top of the mouth
Concheal/Turbinates The top, middle and lower, warm and moisturize the air during inhalation
Frontal Sinus Produce mucus and act as a resonating chamber for production of sound
Sphenoid Sinus Produce mucus and act as a resonating chamber for production of sound
Eustachian Tube Connects the nasopharynx to the middle ear in order to equalize pressure
Nasopharynx The route air takes when you breathe through your nose
Soft Palate Closes the path to the nose when swallowing
Uvula Helps soft palate close the path to the nose when swallowing
Oropharynx The route air takes when you breathe through your mouth
Epiglottis Closes to protect the windpipe (trachea) when swallowing
Laryngopharynx Where the air you breathe through mouth or nose comes together
Esophagus The tube to the stomach
Trachea The windpipe to the lungs
Nasal Septum Not shown the above drawing. It separates the nasal cavity into two chambers which are approximately equal in size. A deviated septum can reduce or cutoff flow to one or both sides to the nasal cavity.
Epiglottis Closes to protect the windpipe or airway (trachea) when swallowing
Hyoid Bone Horseshoe shaped bone that suspends the upper portion of the thyroid cartilage by the Thyrohyoid membrane.
Thyrohyoid Supports the thyroid cartilage
Thyroid Cartilage Protects and supports the airway
Cricothyroid Connects the Thyroid Cartilage and the Cricoid Cartilage
Cricoid Cartilage Supports the airway
Trachea The windpipe to the lungs
Trachea The windpipe to the lungs
Cartilage Supports the airway
Right Main Bronchi to the right lung
Left Main Bronchi to the left lung
Right and Left Lobar Bronchi
The alveolar sacs are where the exchange of oxygen and carbon dioxide (waste gas) takes place. You can see how the freshly oxygenated arterial (red) and returning used venous (blue) bloods encircle the alveolar sacs. The red blood cells have an affinity for holding oxygen and carbon dioxide. Each red blood cell can hold approximately 1 1/3 molecules of oxygen. As you can guess, it takes a lob of red blood cells to supply oxygen to your body and remove the carbon dioxide. This supply and waste function is what your doctor is checking when he/she orders an Arterial Blood Gas (ABG). Everyone will tell you that ABGís hurt a lot. This is not necessarly true. It really depends on two things; the skill of the healthcare professional drawing the blood and the luck of not hitting a nerve. We will discuss the procedure in greater detail later.
So in review, you take a breath, the oxygen in the air enters your mouth and/or nose flowing through the Nasopharynx and/or Oropharynx, combining at the Laryngopharynx. The Epiglottis opens allowing air to flow down through the Trachea to the Right and Left Main Stem Bronchi, and to the Lobar Bronchi. Now things are starting to get narrow as the air enters the segmental Bronchi to the Sub segmental Bronchi, to the Terminal Bronchioles and down to the Alveolar Sacs where the gas exchange takes place. When you exhale, it all goes in reverse order and that is one breath which we repeat 12-20 times each minute. Itís interesting to note that we repeat our breathing cycle 6Ė10 million times each year and donít even notice.
Now that we have to fresh oxygen inside our blood itís time to do something useful, oxygenate our cells. Letís discuss the heart, itís our personal pump.
Right Atrium Receives return venous blood (high levels for carbon dioxide)
Right Ventricle Filled via the Right Atrium and pumps venous blood to the lungs
Left Atrium Receives blood from the lungs and fills the Left Ventricle
Left Ventricle Pumps fresh arterial blood (oxygenated) to the body
Superior Vena Returns blood to the heart (Right Atrium) from the upper part of the body
Aorta Output of the heart to the body (this is the Aortic Notch on X-rays)
Inferior Vena Returns blood to the heart (Right Atrium) from the lower part of the body
To review the blood flow, the heart pumps oxygenated blood from the Left Ventricle through the aortic valve into the Aorta. The arteries get smaller and become Arterioles and getting even smaller yet become the capillaries. The capillary bed is where the body gets its oxygen and gets rid of its carbon dioxide. The Venous side of the capillary bed expand from capillaries into Venules and again into Veins. The blood then returns to the heart via the Vena Cavaís to the Right Atrium. The blood in the Right Atrium flows through the tricuspid valve and fills the Right Ventricle and is pumped through the pulmonary semilunar valve into the lungs to have the carbon dioxide removed and pick up oxygen. Finally the blood flows back to the Left Atrium through the bicuspid valve (or mitral valve) into the Left ventricle. This cycle is completed 60-100 times per minute and 30-52 million times each year.
Supplies blood to:
Left Coronary The left ventricle, septum, SA node, His bundle, both right and
Artery left bundle branches, anterior and posterior hemibundles.
Right Coronary The right atrium, right ventricle, SA and AV Nodes, the proximal
Artery His bundle, posterior hemibundle
Note: Anterior is the front and posterior is the back. Proximal means close toÖ All these branches, nodes and bundles will be discussed on the next page.
These arteries supply the heart with oxygen and food. When a blockage occurs within these branches it will usually cause heart attack.
The heart is an electromechanically operated pump, similar to one in your car or home. Letís discuss the electrical pathways that make it function.
SA Node The sinoatrial node has a single muscle cell (a pacemaker) in the right atrium of the heart starts the pumping sequence
AV Node The atrioventricular node, located in the lower half of the right interatrial septum slightly delays the conduction of the pulse sent to it to allow the right atrium to pre-fill the right ventricle for maximum pumping ability
Bundle of HIS Times and conducts the signal to the right and left ventricles and
Right Bundle Branch ensures they contract at the same time. This ensures effective
Left Bundle Branch pumping.
Purkinji Fibers Fibers attached to the muscle to cause them to react
Posterior Hemibundle and Are the front and back conduction paths
Since the heart is electro-mechanical, the signals or pulses can be monitored in respect to time and signal strength (amplitude). This signal verses time is what the doctor calls an electrocardiogram (EKG) lets see how it works.
The EKG leads are place like this with a minimum of 3 leads are required to obtain the data your doctor will need. If your heart is beating, the EKG trace will look similar to this:
The "P" wave is the SA Node firing then being delayed slightly, but we wonít dwell any further in this chapter, but we will in the EKG chapter. They are just representation of your heart pumping and resetting. We will however discuss finding in-depth information later in the book.
We talked about the signals and timing, now if you have a blockage in the blood supply to the heart it can cause an acute (rapid onset) myocardial infarction (heart attack). Depending on where the blockage is located, side (lateral), front (anterior), bottom (inferior), back (posterior) the symptomatic pain and affect will vary. Donít ever think the pain will go away, get help, donít wait. As we say in the medical field "TIME IS MUSCLE" or the longer you wait the more heart muscle will be damaged or killed.