Chapter 18- The heart Flashcards
Trunk definition
Large artery
How much does the heart weigh?
250-350 grams
How long is the heart?
About 5 inches
Why is the heart tipped in the body, and where is the apex pointing to?
The heart is tipped in the body so the blood vessels at the top of the heart stay open. Apex (inferior “tip”) is pointed toward the left hip.
What covers the heart? (3)
- Fibrous pericardium
2. Serous pericardium (visceral and parietal)
What is the fibrous pericardium and what does it do?
External portion of the heart. Prevents heart from filling with too much blood, anchors heart in chest cavity, protects the heart
Serous pericardium
Internal portion of the heart covering. Divided into visceral and parietal layers- forms fluid filled sac around the heart. The visceral and parietal layers are separated by a small amount of serous fluid
3 layers of the heart
- Epicardium
- Myocardium
- Endocardium
Epicardium
Outermost layer of the heart. This is the visceral layer of serous pericardium
Myocardium
Middle layer of the heart. Contains cardiac muscle arranged in spiral/circular bundles- the heart needs to be contracting at the same time or blood flow will be impaired. Also forms the cardiac skeleton.
Cardiac skeleton
Dense connective tissue fibers that link muscle cells together. Importance- action potentials (APs) only spread in certain directions, prevents overstretching of the heart walls from repeated filling/emptying
Endocardium
Innermost layer of the heart. Covers internal surfaces of the heart, including valves. It’s continuous with linings of major blood vessels entering/leaving the heart
What two circuits move blood through the body?
- Pulmonary
2. Systemic
Pulmonary circuit
Any of the blood vessels that carry blood to and from the lungs. Includes the pulmonary arteries and the pulmonary veins.
Pulmonary arteries function
Pump oxygen poor blood from the right side of the heart to the lungs
Definition of arteries
Arteries are the blood vessels that pump blood away from the heart
Definition of veins
Veins return blood to the heart
Pulmonary veins function
Pump oxygenated blood from the lungs to the left side of the heart
Systemic circuit
Any of the blood vessels that carry blood to and from the body tissues. Includes the aorta and the inferior and superior vena cava.
Aorta function
Oxygenated blood leaves the heart through the aorta and its branches to body tissues. Part of the systemic circuit
Superior and inferior vena cava function
Oxygen poor blood returns to the heart via the superior vena cava and the inferior vena cava. Part of the systemic circuit.
What side of the heart is systemic?
The left side of the heart is systemic. Oxygenated blood travels through arteries, oxygen poor blood travels through veins
What side of the heart is pulmonic?
Oxygenated blood travels through veins, oxygen poor blood travels through arteries. This is the only place in the body where oxygen poor blood is carried by arteries and oxygenated blood is carried by veins
How is pressure different on each side of the heart?
The right side (pulmonic) is relatively low pressure, only needs to travel a short distance. The left side (systemic) is high pressure, travels longer distances, and involves more friction. Therefore, the walls of the left side of the heart (especially the ventricles) are very thick. The left ventricle contracts with more force than the right