Chapter 1 Flashcards
Why do organisms need a circulatory system?
Organisms need a circulatory system for two reasons. 1) Cells need metabolites, substrates and fluids in order to function. This requires a steady supply of these materials in order to survive. The materials are sources from the environment. Therefore, the materials need to be transferred from the environment to the cell. In an organism, this requires the circulatory system being the highway from environment to cell. In a single celled organism, this is accomplished without a circulatory system due to the ability to diffuse directly across the membrane with the environment. 2) The opposite is also equal, due to metabolic wastes that accumulate in the cell. This requires that the waste be taken away and discarded via the circulatory system.
What organs are involved with the exchange that occurs between the blood and outside environment?
Lungs, GI, skin and kidneys
What substances are exchanged?
Nutritional substances are exchanged in the GI. This includes breaking down carbohydrates, fats and proteins to glucose, fatty acids and amino acids.
The lungs, o2 and co2 are exchanged at the alveolar level.
The skin is great for energy exchange in regard to heat distribution
The kidneys adjust fluid and solute concentration (electrolytes)
Where are each of these substances exchanged?
The lungs- alveoli diffuse o2 for blood uptake and receive co2 for waste disposal
GI- Intestinal villi and microvilli diffuse nutrients for blood uptake
What is the pulmonary circulation?
Pulmonary circulation is a part of the series of blood flow through the heart. This starts with blood ejection from the RV through the pulmonary valve into the pulmonary artery. The pulmonary artery splits both left and right, ending at each lung. Blood is re-oxygenated and sent back to the heart, via the pulmonary veins. The pulmonary veins feed into the LA, which dumps into the LV via the mitral valve.
What is the systemic circulation?
Systemic circulation refers to the circulating blood which feeds the various organs and cells throughout the body. Once the blood is ejected from the LV (at 100-140 mmHg), it enters the aorta through the aortic valve. From here, the blood travels superior and inferior to supply o2 and nutrients throughout the body. When at the destination tissue, the blood exchanges o2 and nutrients via local capillary beds in exchange for metabolic waste products. Metabolic waste is returned to the organ of disposal via venous portion of the circulatory system. Final destination for systemic venous blood is the LA via the inferior and superior vena cava.
Draw an overview of the cardiovascular circulation.
IVC/SVC-RA-Tricuspid Valve-RV-Pulmonary Valve-Pulmonary Artery-L/R Lung-Pulmonary Vein-LA-Mitral Valve-LV-Aortic Valve-Aorta-Systemic Arterial flow-Capillary bed-Systemic Venous flow- IVC/SVC
List and define each of the major anatomical structures of the circulatory system.
Heart: The main organ which is involved in receiving low pressure blood from the venous system and imparting energy on it, by increasing pressure, in order to maintain arterial flow.
Veins: The part of the vasculature in which blood is returning to the heart and is of lower pressure
Arteries: The part of the vasculature in which blood is traveling away from the heart and is of higher pressure
Capillaries: Local to the tissue of delivery. A much smaller version of vasculature that is specific to the destination and allows for diffusion of nutrients.
Valves: Valves both exist in the venous system and the heart itself. The main goal is to limit backwards flow of blood
Blood: Fluid containing nutrients, oxygen and waste materials in addition to other needs for the tissues it is delivering to
Systemic Circulation: Circulation from outside of the heart in which blood is traveling all around the body and supplying organs/tissues with nutrients and removing their wastes
Pulmonary Circulation: An in-series portion of the blood flow in the heart. The blood leaves the RV and enters the pulmonary artery via the pulmonary valve. The blood flows to each lung where oxygen and co2 can be exchanged at the alveoli and return to the heart via the pulmonary vein and enter the LA.
Coronary Circulation: A portion of circulation supplying the heart tissues with blood and therefore nutrients to function. This is typically viewed as vasculature on the outside of the heart in diagrams.
What are lymphatic vessels and what is their function?
Reintroduction of fluid from the lymph system into circulation
Define and differentiate “in series” vs. “in parallel”.
In series is referring to a series of events happening. In regard to the circulatory system, this refers to the blood flow through the heart. Blood must enter the RA and flow through the RV before entering the pulmonary circulatory system. If it were stopped at the RA, the RV would not receive blood.
In Parallel refers to the distribution of blood systemically, except for the liver and GI. The brain and kidneys both have equal opportunity to receive blood flow, because one is not prior to the other and therefore if one failed, the other would not necessarily fail like if it were in series.
Why must the output of the two sides of the heart closely match?
The output of the two sides of the heart must closely match to not cause a major volume shift between the pulmonary and systemic circulations.
What is unique about the liver and how it fits into the arrangement of the circulatory system?
The liver receives most of its blood flow from an in-series sources in addition to receiving part of it from an in parallel source. The liver receives the in-series circulation via the venous blood from the intestinal tract. This is dumped into the hepatic portal system to get to the liver. In addition, the liver receives in-parallel source of blood flow via the aorta, entering from the hepatic artery. A majority of the circulation to the liver is in-series.
What are the significant hemodynamic implications of parallel vs. in series vascular beds?
If an in-series organ has altered blood flow, the next organ will most likely be affected as well. In parallel organs are not as affected by changes at different organs.
According to the textbook, how should the function of the heart be viewed?
The function of the heart is that it receives low pressure blood from the venous system and imparts energy, by increasing pressure through contraction, on blood to properly circulate throughout the arterial system
Is organ blood flow driven by the output of the heart or by the pressure generated within the arterial system?
Pressure generated within the arterial system.
