Vessels - Cardiovascular Flashcards
What vessel does blood move into once it travels through an artery.
Blood travels from the heart to arteries to arterioles to capillaries to venues to veins and back to the heart.
Which vessel (type) is the largest and describe why (anatomical reason and physiological reason)?
Arteries are the largest vessels of the cardiovascular system. They contain smooth muscle to help in the vasomotor responses. They are thicker than veins (and other vessels) because of the large amount of pressure they must withstand from the pumping action of the heart.
At what level (vessel) does the exchange of gases occur?
Gas exchange occurs primarily at the capillary level. Venules are somewhat porous allowing some exchange to occur; however, very little exchange occurs at this level.
Describe why an individual who is engaged in vigorous exercise cannot adequately digest food.
The digestive system (like all systems) needs oxygen to perform its function. When an individual is engaged in vigorous activity, the skeletal muscles need oxygen to perform their functions. Capillaries are permeable and allow the exchange of gas to occur; however, only about 25% of the capillary beds in the body are open at any given time allowing the exchange to occur. If a person engages in activity before food is digested, blood supply is not adequate to either system to sustain optimal performance.
Describe what happens when blood travels through a capillary bed.
Blood enters a capillary bed via a metarteriole (thoroughfare channel). If the precapillary sphincters for that capillary bed are open, blood is allowed to enter the capillaries and gases are exchanged via diffusion. After oxygen is unloaded, carbon dioxide is loaded into the blood to be taken back to the heart via the capillaries, venules, and veins.
Blood pressure is typically taken on the left arm. Describe why this is the location of choice to take this measurement.
The left brachial artery is the closest artery to the heart and, therefore, can most closely reflect the pressure/resistance of blood that is exerted on artery walls.
Describe what is measured when a blood pressure is taken.
Blood pressure measures the amount of pressure that blood forces on arterial walls (specifically the brachial artery if the measure is take on the arm). The pressure is greatest during ventricular contraction and less during ventricular relaxation. When the ventricles contract, they are in systole (top number); when the ventricles relax, they are in diastole (bottom number). The average blood pressure should be around 120/80 mm/hg.
Atrial systole and atrial diastole are NOT considered part of the blood pressure reading.
What factors contribute to blood flow resistance?
- ) Blood viscosity - the “thickness/thinness” of blood. The more viscous the blood, the more resistance placed on the artery walls. The less viscous the blood, the lower the resistance placed on the artery walls.
- ) Vessel radius - the lumen of the artery is very influential in determining blood flow resistance. Arteries are able to change their radius to adjust for pressures placed on them; this is known as vasomotion (vasoconstriction or vasodilation).
Control of vasomotor responses is controlled in the medulla oblongata. What systemic factors can trigger the medulla oblongata to respond and change vessel size?
Baroreceptors - located in vessel walls that respond to a change in pressure.
Chemoreceptors - located in vessel walls that respond to chemical changes in the blood.
Medullary ischemic receptors - located in vessels to detect the level of oxygen needed for a tissue.
Why do veins have a disadvantage (compared to arteries) in the movement of blood?
Veins are not under the same pressure that arteries are; therefore, blood is not forced through veins as easily. Veins are also very expandable and have a high capacitance. They, therefore, have the ability to hold more blood and hold it longer. Veins do not have smooth muscle to assist in the movement of blood.
Describes how blood is moved through veins.
The skeletal muscle pump assists when muscle is contracted, squeezing veins, which forces blood through the vein. Venus valves are located throughout the track of a vein and help in keeping blood from flowing backwards. The thoracic pump also assists; during inhalation, the thorax expands, causing blood to move along veins. Lastly, for blood returning to the heart from the head and shoulder region, gravity assists.
Verbally trace an erythrocyte through the cardiovascular system. The erythrocyte is starting in the right atrium and needs to deliver oxygen to the right great toe and needs to bring carbon dioxide from the same toe back to the right atrium.
The RBC passes through the right atrioventricular (AV) valve to the right ventricle…through the pulmonary semilunar valve in the pulmonary a….to the right lung via the pulmonary a.-arterial-cappillary bed on an alveoli…from the lung via the pulmonary v….to the left atrium…through the left AV valve to the left ventricle…through the aortic semilunar valve to the ascending aorta…to the aortic arch…down the thoracic aorta…abdominal aorta…right common iliac a….femoral a….popliteal a….posterior or anterior tibial a. to the great toe capillary bed.
Out of the capillary bed to the posterior or anterior tibial v….popliteal v….femoral v….right common iliac v….inferior vena cava…right atrium.
