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Questions and Answers
What is the primary function of arteries in the circulatory system?
Which layer of blood vessels is responsible for secreting chemicals to dilate or constrict the vessels?
What is the primary function of capillaries in the circulatory system?
Which type of artery is characterized by a thick tunica media and is responsible for distributing blood to specific organs?
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What is the term for the network of small blood vessels that supply nutrients to the walls of the large blood vessels?
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What is the term for the point of convergence between two blood vessels, excluding capillaries?
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Where does arteriovenous anastomosis typically occur?
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What is the term for the amount of blood flowing through a tissue or organ in a given time?
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What is the correct relationship between pressure difference and blood flow?
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What type of receptors are found in the carotid bodies that monitor blood chemistry?
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What is the term for the flow per given volume or mass of tissue in a given time?
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What percentage of blood is in veins at rest?
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What helps push blood upwards in veins?
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What is the name of the system where blood flows through two consecutive capillary networks before returning to the heart?
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What is the result of blood pooling in veins of the lower legs, causing the vein to stretch and pull valves apart?
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Which of the following is a cause of increased capillary filtration?
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What is the main factor that affects oncotic pressure?
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What is the result of obstructed lymphatic drainage?
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What is the most important force in venous return?
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What is a potential consequence of severe edema?
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What is the primary cause of vasodilation in septic shock?
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What is the term for a life-threatening condition that occurs when the body's compensatory mechanisms fail to restore blood flow?
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How long can the brain survive without oxygen before permanent damage occurs?
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What is the primary stimulus for regulating blood flow in the brain?
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What is the term for the sudden death of brain tissue caused by ischemia?
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Study Notes
Blood Vessels and Circulation
- Arteries carry blood away from the heart, while veins carry blood back to the heart.
- Capillaries connect arterioles to venules and complete the circuit.
Structure of Blood Vessels
- Both arteries and veins have three layers called tunics: tunica interna (intima), tunica media, and tunica externa (adventitia).
- Tunica interna (intima) lines the blood vessels on the inside and can secrete chemicals to dilate or constrict the vessels.
- Tunica media consists of smooth muscle, collagen, and elastic tissue.
- Tunica externa (adventitia) has a network of small blood vessels called varo vasorum, which supply nutrients to the walls of the large blood vessels.
Arteries
- Arteries are divided into three classes by size: conducting (elastic or large) arteries, distributing (muscular) arteries, and resistance arteries.
- Conducting arteries have a big diameter and expand during systole and recoil during diastole.
- Distributing arteries distribute blood to specific organs.
- Resistance arteries have a significant impact on blood pressure, and the heart has to overcome the resistance.
- Some major arteries above the heart have sensory structures in their walls that monitor blood pressure and composition.
Anastomosis
- Anastomosis is a point of convergence between two blood vessels other than capillaries.
- There are three types of anastomosis: arteriovenous anastomosis (shunt), venous anastomosis, and arterial anastomosis.
Blood Flow and Pressure
- Hemodynamics is the study of the physical principles of blood flow based on pressure and resistance.
- The greater the pressure difference between two points, the greater the flow.
- The greater the resistance, the less the flow.
- Flow is the amount of blood flowing through an organ, tissue, or blood vessel in a given time.
- Perfusion is the flow per given volume or mass of tissue in a given time.
Baroreceptors and Chemoreceptors
- Baroreceptors in the walls of the internal carotid artery monitor blood pressure.
- Chemoreceptors in the carotid bodies and aortic bodies monitor blood chemistry.
- These receptors transmit information to the brainstem to regulate heartbeat, blood vessel diameter, and respiration.
Capillaries and Veins
- Capillaries are exchange vessels between blood and tissue fluid.
- Veins are capacitance vessels with thin walls that collapse when empty.
- Veins have a greater capacity for blood than arteries.
- At rest, 64% of blood is in veins.
- Low pressure in veins means they need the sympathetic nervous system, muscle milking, and valves to get blood back to the heart.
Circulatory Routes
- The simplest and most common circulatory route is: heart -> arteries -> capillaries -> veins -> heart.
- The portal system is a route where blood flows through two consecutive capillary networks before returning to the heart.
Edema
- Edema is caused by three fundamental factors: increased capillary filtration, reduced capillary reabsorption, and obstructed lymphatic drainage.
- Effects of edema include disrupted O2 delivery and waste removal, tissue death, and circulatory shock.
Venous Return and Circulatory Shock
- Venous return is the flow of blood back to the heart and is achieved by five ways: pressure gradient, muscle milking, valves, respiratory pump, and sympathetic nervous system.
- Circulatory shock can be caused by septic shock, anaphylactic shock, compensated shock, or decompensated shock.
- Brain blood flow is regulated by pH, and a decrease in pH triggers vasodilation, while an increase in pH triggers vasoconstriction.
Cerebral Blood Flow
- Cerebral blood flow is regulated by pH, and a decrease in pH triggers vasodilation, while an increase in pH triggers vasoconstriction.
- The brain regulates its own flow and can shift blood to more active parts of the brain as needed.
- Cerebral arteries dilate and constrict as blood pressure changes.
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Description
Test your knowledge on the structure and function of blood vessels, including arteries, veins, and capillaries, as well as the three layers of tunics. This quiz covers the basics of blood circulation and the importance of each blood vessel type.
