BIOS-255 Week 3 Assignment: Cardiovascular System: Blood Vessels | part B | GRADED A

Document Content and Description Below

BIOS255 Week 3 Cardiovascular System: Blood Vessels Learning objectives: 1. Identify the structural layers of arteries and veins. 2. Distinguish between the structure of arteries and veins. 3. ... Explain the factors that affect arterial blood flow and blood pressure. 4. Define shock, and identify the signs of shock. 5. Identify key blood vessels of the cardiac, systemic, and pulmonary circulations. Introduction: Blood is transported around the body in 3 different types of blood vessels: arteries, capillaries, and veins. Each blood vessel is composed of 3 layers of tissue. Blood pressure and flow depend on multiple factors. There are a number of mechanisms by which shock can occur. We will track blood through the pulmonary and systemic circulations noting the major arteries and veins in our path. Assignment: Part 1 Complete the activities in the following sections of Anatomy.TV Cardiovascular system: Blood vessels, Blood flow and Pressure, Circulatory Pathways, Vessels of the Trunk, Vessels of the Head and Neck, Vessels of the Limbs To access Anatomy.TV: Resources tab>Library>Library Resources-Database A- Z>Anatomy.TV>Titles(default tab): Choose assigned system>choose assigned sections You will then work through the material and activities by scrolling down on the right. This will allow you to see and work through all activities for that section. Part 2 Complete the lab report. Blood vessel Lab report 1. Purpose: Please state the purpose of the lab. -Relate the design of the heart to its function. -Explain the cardiac conduction cycle and its regulation. -Explain the factors that influence the exchange of material between the blood within capillaries and the interstitial fluid surrounding body tissues. 2. Procedure: Briefly discuss the procedure for this lab. -Distinguish between the structure of arteries and veins. -Identify factors that influence cardiac output, blood flow, and blood pressure. -Identify essential blood vessels of the cardiac, systemic, and pulmonary circulations. -Identify the structures of the heart. 3. Data and Details: a. Describe the different types of blood vessels by completing the following chart: Blood vessel Description/special characteristics Function Large arteries Elastic arteries, also referred to as conducting arteries, are large and conduct blood from the heart to muscular arteries. They have well defined internal and external elastic laminae, and their tunica media is thick and full of elastic fibers (elastic lamellae), enabling their walls to stretch easily with an increase in blood pressure (high compliance), as seen during systole. They propel blood from the heart during ventricular diastole. Their elastic properties are essential to accommodate the volume of blood created when blood is expelled from the heart. As they stretch, elastic fibers store mechanical energy, which is converted into kinetic energy as the elastic fibers recoil and force the blood away from the heart. Medium arteries Muscular arteries are also referred to as distributing arteries, as they repeatedly branch until reaching their target organs. They are less elastic than the conducting arteries as they do not have to deal with the same degree of pressure changes. They have well- defined internal but thin external elastic laminae. Depending on the size of the artery, the thick tunica media is made up of 3-40 concentrically arranged layers of smooth muscle cells. The tunica externa is often more viscous than the tunica media, consisting of longitudinally oriented fibroblasts, collagen fibers, and elastic fibers. The loose arrangement of these cells enables arteries to alter their diameter. Lack of elastic fibers in the walls of muscular arteries means that recoil does not propel the blood as in elastic arteries. Instead, smooth muscle cells maintain a state of partial contraction or vascular tone, ensuring that vessel pressure and efficient blood flow are sustained and enable efficient adjustment of the rate of blood flow by vasoconstriction and vasodilation. Arterioles Arterioles, also referred to as resistance vessels, are numerous, microscopic arteries that feed blood into capillary networks. Vessel diameter varies from 15-300 μm depending on the location; wall thickness is about half the total diameter. Supply triggers vasoconstriction and vasodilation, regulating the rate of blood flow, blood pressure, and vascular resistance. The smaller the vessel diameter, the higher the vascular resistance and the slower blood flow rate. Capillaries Capillaries, also referred to as exchange vessels, have a diameter varying between 5-10 μm. Therefore, red blood cells, 8 μm in diameter, must fold upon themselves to fit through smaller capillaries. A capillary wall is approximately 0.2 micrometers (0.02 mm) thick and is composed of a single layer of endothelial cells adhered to a basement membrane. Capillary networks provide a large surface area in contact with tissues throughout the body. Venules Venules, like arterioles, are numerous and microscopic. However, their walls Venules drain blood from the capillary networks are much thinner. Postcapillary venules are continuous with capillary networks. They are small in diameter, 10-50 μm, and have gaps between the endothelial cells that make up their walls. As venules extend further from their capillary networks, they become more extensive in diameter, 50-200 μm, and more muscular with more layers of concentrically arranged smooth muscle cells. and feed the return flow of blood to the veins. Postcapillary venules function as an exchange unit. However, the larger, thicker-walled venules do not. Medium veins Medium veins are around 1 cm in diameter. They have all three layers of a typical blood vessel: the tunica externa is the thickest layer, consisting of collagen and elastic fibers; the tunica media, lacking in smooth muscle and elastic fibers, is thin along with the tunica interna. They do not have internal or elastic laminae and therefore are not able to withstand high pressure. With blood pressure in veins being relatively low, they rely somewhat on contraction of surrounding skeletal muscle and the heart's pumping action to boost venous return. Many medium veins contain valves, small extensions, or infoldings of the tunica interna into the lumen, creating flap-like cusps. The valves function to boost venous return by preventing the backflow of blood due to gravity. Large veins Large veins can be up to 3 cm in diameter. They have a thick tunica externa, similar to that of medium veins, but they lack valves. Large veins drain from their tributaries into the heart. b. Identify the 3 major layers of tissue that compose the wall of a blood vessel. From outside in they are: the tunica externa, tunica media, and tunica intima. c. Identify the 4 parts of the aorta in the order that blood flows from the heart. the ascending aorta, the aortic arch, the thoracic (descending) aorta, and the abdominal aorta. d. Identify the location of the origin of the left and right coronary arteries. Arise from the walls of the ascending aorta just above the cusps of the aortic valve. e. Identify the major artery that supplies blood to the head and neck. Which division of this artery supplies the head, and which division supplies the face? The right and left common carotid arteries supply a large proportion of the head and neck with blood: -The external carotid artery is a short, superficial vessel of the neck that branches to supply the face. -The internal carotid artery is a deep artery of the neck that enters the skull to supply the brain, eyes, nose, and forehead. 4. Questions: a. Compare the blood pressure of a small artery to the blood pressure in a vein. Blood pressure in the arteries is much higher than in the veins due to receiving blood from the heart after contraction and due to their contractile capacity. b. When a fall in arterial pressure is detected by baroreceptors, how does the cardiovascular center alter the parasympathetic and sympathetic stimulation of the sinoatrial (SA) node? When a fall in arterial blood pressure occurs, the arterial walls become less stretched. This decreases the frequency of impulses traveling from the baroreceptors to the cardiovascular center in the brain, through efferent fibers in the glossopharyngeal and vagus nerves. In response, the cardiovascular center reduces parasympathetic vagal stimulation to the sinoatrial node. At the same time, sympathetic stimulation, through cardiac accelerator nerves, is increased. The result is that autorhythmic cells grow spontaneous depolarization. The heart rate is raised, with an associated increase in blood pressure. As with most homeostatic mechanisms, this forms a negative feedback loop. The response leading to a reduction in stimulus (regular wall stretch leads to the standard frequency of impulses traveling from the baroreceptors to the brain's cardiovascular center). c. How does an increase in blood viscosity affect blood pressure? A number of factors can cause an increase in blood viscosity, and therefore increase blood pressure, including a decrease in water intake (dehydration), and increases in red blood cells, and plasma proteins per volume of plasma. d. Trace a drop of blood from the heart to the top of the foot by naming the blood vessels from the aorta to the artery that can be felt on the top of the foot (dorsalis pedis artery). Aorta-common iliac-external iliac-femoral-popliteal-anterior tibial-dorsal pedis 5. Discussion: a. Describe the signs and symptoms of shock as described under Blood Flow and Pressure. Decrease in blood pressure Drop in systolic blood pressure to below 90 mmHg may cause faintness. Increased heart rate Increased heart rate (HR) compensating for the decrease in cardiac output (CO), leads to a rapid but weak pulse. Sympathetic stimulation increases levels of epinephrine and norepinephrine in the blood, which leads to a rise in resting heart rate. Sweating and sickness Sympathetic stimulation induces vasoconstriction and sweating, causing the skin to become cool, pale, and clammy; vasoconstriction of vessels supplying to the digestive organs may lead to a feeling of sickness. Reduced urination, thirst, and dehydration Increased levels of aldosterone and antidiuretic hormone in the blood cause reduced urination. Loss of extracellular fluid leads to thirst and dehydration. Acidosis Lactic acid build up causes acidosis (low blood pH). Mental confusion Lack of oxygen supply to the brain may cause mental confusion. b. Briefly mention any difficulties with the lab and/or information you wish was present in the lab. At first, I didn’t understand how I would accomplish this assignment. It has seen to be missing the labster. Lucky, one of the other students explained how he completed the lab, which was extremely helpful. 6. Reflection: Reflect on at least 2 key concepts you have learned from this lab. I have learned from this lab that the cardiovascular system consists of the heart, blood vessels (arteries, veins, capillaries), and the blood that flows through them. I can also distinguish the different types of shock and the homeostatic response. An example is Hypovolemic shock, which is the most common form of shock resulting from sudden blood loss. Grading Rubric for Lab Report Activity Deliverable Point s Part 1 Complete lab activities/simulation 10 Part 2 Complete lab report and answer questions • Purpose (2 points) • Procedure (2 points) • Data and Details (5 points) • Questions (4 points) • Discussion (2 points) • Reflection (5 points) 20 Total Complete all lab activities 30 [Show More]

Last updated: 3 years ago

Preview 1 out of 8 pages