Chapter 21. Blood Vessels and Circulation

Transcription

1 Chapter 21 Openstax: Chapter 20 Blood Vessels and Circulation Chapter 21 Learning Outcomes After completing Chapter 21, you will be able to: 1. Distinguish among the types of blood vessels based on their structure and function. 2. Explain the factors regulating blood flow, including autoregulation, neural and hormonal regulation. 3. Describe the forces that account for capillary exchange. 4. Know and label the major blood vessels of the systemic and pulmonary circulation. 5. Compare fetal circulation to that of an individual after birth. Learning Outcome 1: distinguish among the types of blood vessels based on their structure and function. Martini: 21-1 Types of Blood Vessels, pg. 724 Openstax: 20.1 Structure and Function of Blood Vessels, pg What is the function of blood vessels? deliver blood to 2. List the five types of blood vessels: a) b) c) d) e) 2a. The vital functions of the cardiovascular system depends entirely on which blood vessel? 1 1

2 3. Describe briefly the function for each type of blood vessel: 3a. Arteries: carry blood 3b. Arterioles: 3c. Capillaries: 3d. Venules: collecting blood from 3e. Veins: Basic Structure of a Blood Vessel 1. The walls of arteries and veins are composed of three layers (or tunics): a) or b) c) or What is the lumen of a blood vessel? Artery Vein Circle One: Which blood vessel has a thicker wall? A) artery B) vein 2

3 2. Comparing a typical artery to a typical vein: Martini: Fig Openstax: Fig Tunica externa Tunica media Tunica interna Lumen of vein Tunica media Tunica interna Tunica externa Lumen of artery ARTERY Fill in: Tunica Location Tissue types Function Interna (Intima) VEIN Media Externa (Adventitia) Differences between Arteries and Veins: 1. Arteries and veins supplying the same region lie. 2. have thicker walls and higher blood pressure. 3. Compare the lumen of an artery vs. lumen of a vein: 3

4 4. Arteries are 5. Veins (mainly in the limbs) have REVIEW QUESTIONS: 1. Are arteries elastic and contractile (contract and change their diameter)? A) Yes B) No 2. Circle One: Are arteries more muscular than veins? A) Yes B) No 3. Which layer of the vessel wall is thicker in arteries? 4. Circle One: because arteries are more muscular than veins, what is the shape of arteries when: a) empty? 1. round 2. Square 3. Flat b) in tissue sections? 1. Flat 2. Triangular 3. Circular 5. Which type of blood vessel has venous valves? 6. Which layer of the heart wall gives rise to venous valves? 7. Why arteries have a thicker wall when compared to veins? 8. List the layers of an artery and describe the type of tissue/tissues that each one is made of. 9. List the layers of a vein and describe the type of tissue/tissues that each one is made of. 4

5 Structure and Function of Arteries 1. are elastic and contractile. The tunica media (made of smooth muscle): 2. From the heart to peripheral capillaries, arteries change: a) from b) to c) to ELASTIC ARTERIES A. Also known as arteries B. The largest and closest arteries to the heart: C. Have high amounts of During ventricular systole elastic arteries: During ventricular diastole elastic arteries: MUSCULAR ARTERIES A. Also known as arteries B. Most common size of artery in the body. C. The smooth muscle layer (tunica media): Their thick tunica media allows muscular arteries to ARTERIOLES A. Smallest type of artery. B. Have: C. Main site for both: 5

6 Structure and Function of Blood Capillaries 1. Blood capillaries are the ONLY capillaries Venule Arteriole capillaries 2. Describe the composition of a typical (common) blood capillary wall: Consists of Average diameter of a blood capillary: 3. Types of blood capillaries: a) b) c) Martini: Fig Os: Fig Continuous capillaries 3a. 3b. Have a continuous 3c. List substances that cannot pass through continuous capillaries: See Fig Continuous Continuous Capillary Fenestrated Capillaries 3d. Endothelial cells have many 3e. List molecules passing through fenestrations: 3f. List organs that contain fenestrated capillaries: Fenestrated Capillary 6

7 Sinusoids (sinusoidal) capillaries 3g. Endothelial cells are separated by 3h. List substances that pass through sinusoids: 3i. List organs that have sinusoids: Sinusoids Structure and Function of Venules and Veins Venules 1. Are 2. Receive blood from 3. Have: 4. Main place (along with blood capillaries) for Medium-Sized Veins 1. Medium veins in the limbs have: 1a. Venous valves are folds of tunica Function of venous valves: 7

8 Large Veins 1. Have Intact tunica Thick tunica Thin tunica -Examples of large veins: Openstax: Table 20.2 Comparison of Arteries and Veins Arteries Conducts blood away from the heart Veins Conducts blood toward the heart Direction of blood flow General appearance Rounded Irregular, often collapsed Pressure High Low Wall Thickness Thick Thin Oxygen Concentration Higher in systemic arteries Lower in pulmonary arteries Lower in systemic veins Higher in pulmonary veins Valves Not Present Present in meium-sized veins of the limbs Distribution of Blood 1. Percent of blood volume in Heart, Arteries, Capillaries: percent (about 1.5 liters) 2. Percent of blood volume in the Venous System: percent (about 3.5 liters) 3. Why are veins regarded as capacitance vessels of the cardiovascular system? 8

9 Learning Outcome 2: Explain the factors regulating blood flow, including autoregulation, neural and hormonal regulation. Martini: 21-2 Pressure and Resistance, pg. 734 Openstax: 20.2 Blood Flow, Pressure, and Resistance, pg. 860 Principles of Blow Flow 1. Constant blood flow 1a. Blood flow = 2. What is blood flow? 3. What is the total blood flow at rest? Total blood flow at rest is equal to Review from Ch 20: What is cardiac output? Volume of blood Calculating CO: 4. Distribution of blood flow (F) to a tissue depends on and -F is proportional to P/R F = flow P = pressure difference R = resistance 9

10 Pressure Gradient ( P) 1. Pressure gradient it the difference between 2. The largest pressure gradient is found between 3. What is blood pressure (BP)? 3a. Blood pressure is usually measured at the artery. Label: brachial artery 3b. Two pressures are recorded: 3c. List the normal and abnormal blood pressure values: 10

11 3d. Blood pressure changes relative to distance from the heart: 4. Preventing excessive blood pressure is clear! 4a. Describe one of the body s chief mechanisms to prevent excessive blood pressure: The ability of arteries to 4b.What is the importance of arterial elasticity? Expansion and recoil of arteries maintains 4c. Why does blood pressure (BP) increases with age? Arteries are Vascular Resistance 1. What is vascular resistance? 1a. Three factors affect vascular resistance: Blood Viscosity 1a. What is blood viscosity? 1b. List the main factors that affect blood viscosity: 11

12 1c. Choose one: a. Deficiency of erythrocytes (anemia) increases/decreases blood viscosity b. Decrease in blood viscosity increases/decreases speed of blood flow c. deficiency in albumin (hypoproteinemia) increases/decreases blood viscosity d. dehydration increases/decreases blood viscosity e. dehydration increases/decreases speed of blood flow f. Leukemia increases/decreases blood viscosity g. Leukemia increases/decreases speed of blood flow Vessel Length 1. How does length of a blood vessel influences blood flow? Vessel Diameter (size of the lumen) 1a. Blood traveling in a blood vessel exhibits smooth silent flow called 1b. Describe laminar flow: 1c. Vasodilation (widening or dilation of vessel) -Describe what occurs to resistance to blood flow and blood speed when a vessel dilates: Vasodilation 1d. Vasocontriction (narrowing or contriction of vessel) -Describe what occurs to resistance to blood flow and blood speed when a vessel constricts: Vasoconstriction 12

13 Which of these is the most immediate adjustable resistance factor to change blood flow? a) blood viscosity b) vessel length c) vessel diameter Dilated arteriole Constricted arteriole Learning Outcome 3: Describe the forces that account for capillary exchange.. Martini: Capillary Exchange, pg. 739 Openstax: 20.3 Capillary Exchange, pg. 869 Arteriole Venule 13

14 1. The most important processes that move substances across common capillary wall are: Diffusion: net movement of substances from an area where their concentration is Arteriole Venule 2. At the arteriolar end of a blood capillary: 14

15 3. At the venule end of the capillary: Arteriole Venule Review some concepts from Chapter 21 by doing the review questions posted in EO2 15