10.4 The Vascular Pathways Flashcards
What are the 2 circuits of the circulatory system?
pulmonary circuit and systemic circuit
What does the pulmonary circuit do?
circulates blood through the lungs
What does the systemic circuit do?
serves the needs of body tissues
Describe the pulmonary circuit path.
- blood from all regions of the body first collects in the right atrium
- then passes into the right ventricle, which pumps it into the pulmonary trunk
- pulmonary trunk divides into the right and left pulmonary arteries, which branch as they approach the lungs
- arterioles take blood to the pulmonary capillaries, where gas exchange occurs
- blood then passes through the pulmonary venules, which lead to the 4 pulmonary veins (2 from each lung) that enter the left atrium
Why is it not correct to say that all arteries carry blood high in oxygen and all veins carry blood low in oxygen?
because blood in the pulmonary arteries is oxygen poor but blood in the pulmonary veins is oxygen rich in the pulmonary circuit (reverse)
Where is blood in the pulmonary arteries is oxygen poor but blood in the pulmonary veins is oxygen rich?
- pulmonary circuit
- umbilical arteries and vein of a developing fetus
What does the systemic circuit include?
major arteries and veins
What is the largest artery in the systemic circuit?
aorta
What are the largest veins in the systemic circuit?
venae cavae
What does the superior vena cava collect?
blood from the head, chest, arms
What does the inferior vena cava collect?
blood from the lower body regions
Where do the venae cavae enter in the systemic system?
right atrium
What do the aorta and venae cavae do in the systemic circuit?
they serve as the major pathways for blood
Where does the path of systemic blood to any organ in the body begin?
left ventricle
Describe the path of blood to and from the legs.
left ventricle aorta common iliac artery femoral artery leg capillaries femoral vein common iliac vein inferior vena cava right atrium
What do you need to mention when tracing the path of blood?
- aorta
- proper branch of the aorta
- region
- vein returning blood to the vena cava
in most instances, artery and vein that serve the same region are given the same name
What do coronary arteries do?
serve the heart muscle itself (the heart is not nourished by the blood in its own chambers)
Where are the coronary arteries?
the first branches off the aorta
they originate just above the aortic semilunar valve, and they lie on the exterior surface of the heart, where they divide into diverse arterioles
Why may coronary arteries become clogged?
they have a very small diameter
What do coronary capillary beds form?
they join to form venules that converge to form the cardiac veins, which empty into the right atrium
What is the portal system?
a pathway of blood flow that begins and ends in capillaries
What is the hepatic portal system?
portal system associated with the liver
capillaries that occur in the villi of the small intestine pass into venules that join to form the hepatic portal vein
What does the hepatic portal vein do?
carries the blood to a set of capillaries in the liver
Where does the hepatic portal vein go through?
leaves the liver and enters the inferior vena cava
What is the liver?
an organ that monitors the makeup of the blood
What happens when the left ventricle contracts?
blood is forced into the aorta and then into other systemic arteries under pressure
What is systolic pressure?
results from blood being forced into the arteries during ventricular systole
What is diastolic pressure?
the pressure in the arteries during ventricular diastole
Describe blood pressure as blood flows from the aorta into the arteries and arterioles?
- blood pressure falls
- difference between systolic and diastolic pressure gradually diminishes
Why is blood flow slow and fairly even in the capillaries?
may be related to the very high total cross-sectional area of the capillaries
How long would all the blood vessels of the body be?
total distance would reach around Earth at the equator 2 times, most due to the large number of capillaries
What is blood pressure?
measurement of the force of blood pushing against the inside wall of blood vessels
What is a sphymomanometer?
measures blood pressure with a pressure cuff that determines the amount of pressure required to stop the flow of blood through an artery
Where is blood pressure measured?
normally on the brachial artery, an artery in the upper arm
Describe blood pressure in the veins.
low, by itself is an inefficient means of moving blood back to the heart especially from the limbs
What happens when skeletal muscles near veins contract?
they put pressure on the veins and the blood they contain
What do valves do?
prevent back flow of blood in the veins and therefore muscle contraction is sufficient to move blood toward the heart
What happens in the veins during long periods of sitting or other inactivity?
clots may form in the deep veins of the legs
