Ch_21_Lecture_Objectives

Ch 21 Blood Vessels and Circulation Lecture Objectives:

1. What are the 3 layers of the blood vessel wall? What specific kind of tissues make up each of those layers?

   • Tunica Intima: Endothelial cells + connective tissue.

   • Tunica Media: Smooth muscle cells + elastic fibers.

   • Tunica Externa (Adventitia): Connective tissue.

2. Compare/Contrast arteries vs. veins:

   • Vessel Wall Thickness: Arteries have thicker walls; veins have thinner walls.

   • Vessel Lumen: Arteries have narrower lumens; veins have larger diameters.

   • Vessel Lining (Appearance): Arteries have a pleated lining; veins have a smooth lining.

   • Valves: Veins contain valves to prevent backflow; arteries do not.

   • Blood Reservoir: Veins act as a blood reservoir, holding up to 70% of blood volume.

3. What are the 3 main types of arteries?

   • Elastic Arteries: e.g., aorta, pulmonary trunk.

   • Muscular Arteries: e.g., femoral artery, radial artery.

   • Arterioles: Smallest branches leading to capillary beds.

4. What are the 3 main types of capillaries? How are they different (what they allow through)?

   • Continuous Capillaries: Small intercellular clefts; found in muscles and brain.

   • Fenestrated Capillaries: Contain pores; found in kidneys and intestines.

   • Sinusoidal Capillaries: Large openings; found in liver and spleen.

   • Precapillary Sphincters: Muscles regulating blood flow into capillary beds based on metabolic needs.

5. What are the 3 main types of veins?

   • Large Veins: e.g., superior/inferior vena cavae.

   • Medium Veins: e.g., femoral vein, with valves to prevent backflow.

   • Venules: Smallest veins collecting blood from capillary beds.

6. What is angiogenesis and what molecule is important for this process?

   • Angiogenesis is the formation of new blood vessels; important molecule is Vascular Endothelial Growth Factor (VEGF).

7. What is vasoconstriction and vasodilation? Which occurs when oxygen is low?

   • Vasoconstriction: Narrowing of blood vessels.

   • Vasodilation: Widening of blood vessels.

   • Vasodilation occurs when oxygen is low.

8. What is venoconstriction? When do we need this?

   • Venoconstriction is the constriction of veins to increase venous return, needed during physical activity or low blood volume conditions.

9. What value is BP coming out of the heart into the aorta? BP entering the arterial end of capillaries? BP leaving the venule end of capillaries?

   • BP in aorta: ~120 mmHg; BP at arterial end of capillaries: ~35 mmHg; BP at venule end of capillaries: ~15 mmHg.

10. How is the amount of blood flow related to blood pressure? And to the amount of peripheral resistance?

    • Blood flow is directly proportional to blood pressure and inversely proportional to peripheral resistance.

11. What are the 3 factors that can affect the amount of peripheral resistance?

    • Vessel Diameter: Smaller diameter increases resistance.

    • Vessel Length: Longer vessels increase resistance.

    • Blood Viscosity: Thicker blood increases resistance.

12. Know the changes of these features going from arteries -> capillaries -> veins:

    • Diameter: Increases from arteries to veins;

    • Cross-Section Areas: Increases from arteries to veins;

    • Pressures: Highest in arteries, decreases in capillaries, lowest in veins;

    • Velocity: Highest in arteries, decreases in capillaries, increases in veins back to the heart.

13. Why is hypertension dangerous? How does it affect the heart? Blood vessels?

    • Hypertension increases heart workload, can cause heart muscle hypertrophy; damages blood vessels' lining, raising atherosclerosis risk.

14. How does muscle compression and respiratory pump help with venous return?

    • Muscle compression applies pressure to veins during muscle contraction, pushing blood to the heart; respiratory pump uses pressure changes in thoracic cavity during breathing to promote blood flow.

15. What is the difference between filtration and reabsorption between capillaries and surrounding tissues?

    • Filtration: Movement out of capillaries into tissues due to blood pressure;

    • Reabsorption: Movement back into capillaries due to osmotic pressure.

16. What is BCOP? What contributes to this pressure?

    • BCOP: Blood Colloid Osmotic Pressure, primarily due to plasma proteins (like albumin), helps maintain fluid balance.

17. What are the CHP values at the arterial end? In the middle? At the venous end?

    • CHP at arterial end: ~35 mmHg; at middle: decreases; at venous end: ~15 mmHg.

18. What is the formula for calculating NFP? If it’s a positive value, what does this mean? If it’s a negative value, what does this mean?

    • NFP Formula: NFP = CHP - BCOP; a positive value means filtration predominates, a negative value means reabsorption predominates.

19. What happens to NFP when one is each of the following situations: hemorrhaging, dehydration, hypertension, starvation?

    • Hemorrhaging: Decreased CHP; leads to increased reabsorption.

    • Dehydration: Decreased CHP; leads to increased reabsorption.

    • Hypertension: Increased CHP; leads to increased filtration.

    • Starvation: Decreased BCOP; leads to increased filtration.

20. Homeostasis of BP with baroreceptors:

    • When BP is too high: Baroreceptors stimulate cardioinhibitory center, inhibit vasomotor center (vasodilation).

    • When BP is too low: Baroreceptors stimulate cardioacceleratory center, stimulate vasomotor center (vasoconstriction).

21. Homeostasis of BP with chemoreceptors:

    • Chemoreceptors are stimulated by elevated CO2, low oxygen, and blood acidosis; stimulate cardioacceleratory center, vasomotor center (vasoconstriction); increased respiratory rate improves gas exchange.

22. When Blood Pressure or Blood Volume Is Elevated:

• Hormones Released: Atrial Natriuretic Peptide (ANP)

• Effects:

  • Water Loss in Urine: Increases

  • Thirst: Decreases

  • Antidiuretic Hormone (ADH): Decreases

  • Vasodilation: Occurs

23. When Blood Pressure or Blood Volume Is Low:

• Hormones Released: Renin, Angiotensin II, Aldosterone

• Kidneys Release:

  • Erythropoietin (EPO)

  • Renin

  • Prostaglandins

• Effects:

  • Thirst: Increases

  • Vasoconstriction: Occurs

24. What Are the 3 Veins That Drain Blood Into the Hepatic Portal Vein?

    Superior Mesenteric Vein (collects blood from the small intestine)

    Inferior Mesenteric Vein (collects blood from the large intestine)

    Splenic Vein (collects blood from the spleen)

25. What Is the Goal of This Portal System?

• To transport nutrient-rich blood from the digestive organs to the liver for processing.

26. What Is the Difference Between Umbilical Arteries and Veins?

• Umbilical Arteries: Transport deoxygenated blood from the fetus to the placenta.

• Umbilical Vein: Carries oxygenated blood from the placenta to the fetus.

27. Three Extra Circulatory Structures in Fetuses:

1. Umbilical Arteries:

   • Location: Two umbilical arteries that arise from the internal iliac arteries and run in the umbilical cord.

   • Function: Transport deoxygenated blood from the fetus back to the placenta.

2. Umbilical Vein:

   • Location: One umbilical vein that runs from the placenta to the fetus in the umbilical cord.

   • Function: Carries oxygenated blood from the placenta to the fetus.

3. Ductus Venosus:

   • Location: A shunt in the fetal liver connecting the umbilical vein to the inferior vena cava.

   • Function: Allows oxygenated blood from the umbilical vein to bypass the liver and flow into the heart directly.

Diseases Associated with Blood Vessels:

1. Aneurysm: A localized dilation of a blood vessel wall, usually due to weakness in the vessel structure.

2. Atherosclerosis: A condition characterized by the buildup of fatty deposits (plaques) in the arterial walls, leading to reduced blood flow.

3. Varicose Veins: Swollen, twisted veins that occur when valves in the veins fail, causing blood to pool.

4. Deep Vein Thrombosis (DVT): The formation of a blood clot in a deep vein, typically in the legs, which can lead to serious complications if it dislodges.

5. Pulmonary Embolism: A blockage in one of the pulmonary arteries in the lungs, usually caused by blood clots that travel from the legs.

6. Patent Foramen Ovale: A small opening in the heart that didn't close at birth, potentially allowing blood flow between the left and right atria.

7. Tetralogy of Fallot: A congenital heart defect that involves four structural heart problems that affect blood flow.

8. Ventricular Septal Defect: A congenital heart defect characterized by a hole in the wall separating the two lower chambers (ventricles) of the heart.

9. Atrioventricular Septal Defect: A congenital defect that involves a combination of atrial septal defect and ventricular septal defect affecting the heart's structures.

10. Transposition of Great Vessels: A serious congenital heart defect where the two main arteries leaving the heart are reversed in position.