Cardiovascular System Flashcards
What are the three major functions of the cardiovascular system?
Homeostasis, chemical distribution, and protection
In what ways does the cardiovascular system maintain homeostasis?
Temperature regulation, pH balance, blood pressure and fluid volume
what kinds of chemicals does the cardiovascular system distribute?
Oxygen, nutrients, hormones, and waste products
How does the cardiovascular system function for protection?
Immune responses (white blood cells) and preventing blood loss (clotting factors)
Describe the location of the heart in the body
In the mediastinum of thoracic cavity, diaphragm is inferior, sternum is ventral to it, spine is dorsal to it
From inside to outside, what are the layers of the heart wall?
Endocardium
Myocardium
Epicardium
What is another name for the epicardium?
Visceral pericardium
From inside to outside, what are the layers of the heart coverings?
Visceral pericardium
Pericardial space with serous fluid
Parietal pericardium
Fibrous pericardium
Trace a drop of blood through the heart
Inferior and superior vena cava Right atrium Tricuspid valve Right ventricle Pulmonary semilunar valve Pulmonary trunk Pulmonary arteries (to lungs) Pulmonary veins (away from lungs) Left atrium Bicuspid (mitral) valve Left ventricle Aortic semilunar valve Aorta
Structure and function: interatrial septum
Separates the right and left atria
Structure and function: interventricular septum
Separates the right and left ventricles
Structure and function: auricle
Structure on atria that allows for further expansion when atrium is very full
Coronary arteries: location and function
Come off the base of the aorta and supply oxygenated blood to heart tissue
Coronary veins: location and function
Put deoxygenated blood from heart tissue back into the heart via the coronary sinus into the right atrium
Intercalated discs
Cell membranes on cardiac muscle cells form a zipper like interlocking pattern for greater strength
Desmosomes
Also called anchoring junctions, help to hold cells together at the intercalated discs
Gap junction
Hole between cells that allow for electrical impulses to be communicated. Present on intercalated discs
What does functional syncitium mean? What causes this phenomenon?
This means that the heart functions as one unit, not as individual cells. The presence of gap junctions makes this possible, because the cells can communicate with one another
Compare and contrast cardiac muscle and skeletal muscle
Cardiac: more mitochondria, less visible striations, calcium is used for a contraction stimulus but so are autorhythmic impulses. Longer refractory period, cannot achieve tetany
Skeletal: less mitochondria than cardiac, more visible striations, calcium is used as a contraction stimulus. Motor neurons serve for stimuli, with a shorter refractory period and an ability to achieve and maintain tetany
What ion is responsible for the plateau in cardiac muscle cell actions potentials?
Calcium ions (leak slowly into cell)
What is the purpose of the long AP plateau in cardiac muscle cells?
This happens so that no more stimulation of the membrane can occur. It forces the cell to level off and then depolarize so it doesn’t achieve tetany
What ion is responsible for the unique resting membrane potential of cardiac autorhythmic cells? What does this do?
Sodium is responsible for it. Sodium leaks slowly into the cell at a set rate, so that the muscle will depolarize at a constant rate (hence autorhythmic)
What is the role of the intrinsic conduction system?
It initiates and conducts autorhythmic impulses throughout the cardiac muscle cells
What are other names for the intrinsic conduction system?
Pacemaker potential or unstable membrane potential
In what order do the autorhythmic cells fire?
SA node, AV node, AV bundle, right and left bundle branches, and the Purkinje fibers
What happens if the SA node malfunctions? What will happen to heart rate?
The AV node will take over and set the autorhythmic pattern, but heart rate will decrease because he AV node only fires about 50 times per minute
How often do the Purkinje fibers fire?
Around 30 times per minute
The P wave represents which electrical event?
Atrial depolarization
The QRS complex represents which electrical event(s)?
Ventricular depolarization and atrial repolarization
The T wave represents which electrical event?
Ventricular repolarization