Chapter 20: Blood Vessels and Circulation

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Questions and Answers

What is the primary function of arteries in the circulatory system?

To carry blood back to the heart

To regulate blood pressure and composition

To connect arterioles to venules

To carry blood away from the heart (correct)

Which layer of blood vessels is responsible for secreting chemicals to dilate or constrict the vessels?

Tunica Externa

Varo Vasorum

Tunica Media

Tunica Interna (correct)

What is the primary function of capillaries in the circulatory system?

To connect arterioles to venules (correct)

To carry blood back to the heart

To carry blood away from the heart

To regulate blood pressure and composition

Which type of artery is characterized by a thick tunica media and is responsible for distributing blood to specific organs?

Distributing arteries Signup and view all the answers

What is the term for the network of small blood vessels that supply nutrients to the walls of the large blood vessels?

Varo Vasorum Signup and view all the answers

What is the term for the point of convergence between two blood vessels, excluding capillaries?

Anastomosis Signup and view all the answers

Where does arteriovenous anastomosis typically occur?

Fingers, palms, toes, and ears Signup and view all the answers

What is the term for the amount of blood flowing through a tissue or organ in a given time?

Flow Signup and view all the answers

What is the correct relationship between pressure difference and blood flow?

The greater the pressure difference, the greater the flow Signup and view all the answers

What type of receptors are found in the carotid bodies that monitor blood chemistry?

Chemoreceptors Signup and view all the answers

What is the term for the flow per given volume or mass of tissue in a given time?

Perfusion Signup and view all the answers

What percentage of blood is in veins at rest?

64% Signup and view all the answers

What helps push blood upwards in veins?

Muscle milking and respiratory pump Signup and view all the answers

What is the name of the system where blood flows through two consecutive capillary networks before returning to the heart?

Portal system Signup and view all the answers

What is the result of blood pooling in veins of the lower legs, causing the vein to stretch and pull valves apart?

Varicose veins Signup and view all the answers

Which of the following is a cause of increased capillary filtration?

Kidney failure Signup and view all the answers

What is the main factor that affects oncotic pressure?

Concentration of albumin in blood Signup and view all the answers

What is the result of obstructed lymphatic drainage?

Edema Signup and view all the answers

What is the most important force in venous return?

Pressure gradient generated by the heart Signup and view all the answers

What is a potential consequence of severe edema?

All of the above Signup and view all the answers

What is the primary cause of vasodilation in septic shock?

Bacterial toxins Signup and view all the answers

What is the term for a life-threatening condition that occurs when the body's compensatory mechanisms fail to restore blood flow?

Decompensated shock Signup and view all the answers

How long can the brain survive without oxygen before permanent damage occurs?

4-5 minutes Signup and view all the answers

What is the primary stimulus for regulating blood flow in the brain?

pH levels Signup and view all the answers

What is the term for the sudden death of brain tissue caused by ischemia?

Stroke Signup and view all the answers

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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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.

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