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structures and functions of blood vessels
structures and functions of blood vessels
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1. Compare & contrast the structure, function, & roles of arterioles and veins in the regulation of circulation. Include their regulation by local factors, hormones, and the autonomic nervous system.
Veins are soft and thin walled since the pressure is steady. They collapse when empty but can expand easily and accommodate different volumes of blood. Arterioles are more muscular with one to three layers and little elastic tissue. Matched to the larger arties, they have thicker ratio of tunica media to lumen. Arterioles are the primary location of vascular resistance, also, large changes in blood pressure/velocity occurs at the location of transition between arterioles and capillaries.
For local factors, there are vasoactive chemicals such as histamine, bradykinin, and prostaglandins. There are also prostacyclin and nitric oxide that are secreted by blood rubbing against the endothelial cells (shear stress) which cause vasodilation. Reactive hyperemia results when a tissue’s blood supply is restricted for a period and then returned to normal. Three autonomic reflexes (baroreflexes, chemoreflexes, and medullary ischemic reflex) are integrated by the vasomotor center. For example, the baroreflex causes a negative feedback response to changes in the blood pressure. When glossopharyngeal nerve fibers transmit signals to the brainstem, it results in a reduced heart rate, cardiac output, and reduces the size of vessels. Chemoreflex responds to changes in the blood chemistry especially pH and concentrations of O2 and CO2.Their role is to adjust respiration and stimulate vasomotion. The medullary ischemic reflex responds to reduce perfusion of the brain checked by the medulla oblongata. If there is a drop in perfusion, within a matter of...
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...ers. This happens by promoting weakening of nerve cells in the hippocampus, which is vital for verbal and visual memory.
10. For the astronauts on the space station, where there is essentially zero gravity, what happens, if anything, to their circulation and blood pressure?
In space, there is a shift in fluid because the cardiovascular system does not have to work hard like it does on earth to fight gravity. Our bodies are equipped with several mechanisms to go against gravity to maintain a blood flow to our brains. When fluid moves up from legs to trunk of your body, the heart rate increases and pressure rises. Almost half of astronauts experience a ‘space sickness’ partially because of the circulation changes. Also, some studies show that in space red blood cells change to a more spherical shape and less inhabit bone marrow that when they are on Earth.
1.2 & 1.3 Explain The Cardiac Cycle And Describe How The Heart Rate Is Modified According To The Needs Of The Body
Hypovolemic shock specifically disrupts the cardiovascular system from a significant loss of blood volume that causes blood pressure to deplete and oxygen delivery to cells to slow. A victim entering into hypovolemic shock will experience three sequential stages as the body attempts to maintain homeostasis. These stages are named compensated, decompensated, and irreversible (Wang
The Mayo Clinic’s book on High Blood Pressure was full of detailed facts about blood pressure and what it is. This is extremely significant to the experiment because blood pressure is one of the variables being tested. Understanding blood pressure is one of the key components to receiving accurate results from this experiment. Most of the book is on high blood pressure, which is not necessary for the experiment, but the book still had plenty of useful information about blood pressure itself. The book explains that when the heart beats, a surge of blood is released from the left ventricle. It also tells of how arteries are blood vessels that move nutrients and oxygenated blood from the heart to the body’s tissues. The aorta, or the largest artery in the heart, is connected to the left ventricle and is the main place for blood to leave the heart as the aorta branches off into many different smaller
The pump is sensitive to the potassium concentration of the blood. When extracellular potassium increases the pump increases in activity and more potassium is taken up by the cell, when plasma concentration is low the reverse occurs. [5]
...Another difference between the three is that the arteries mainly carry oxygenated blood. This is different to the veins because they mostly carry de-oxygenated blood, furthermore out of the three, the capillaries have the smallest blood vessels out of the three.
Baroreceptors are sensors in the vascular system that respond to changes in pressure within blood vessels. Baroreceptors are found in the carotid sinus, aorta; the largest artery and the heart’s muscular pumping chamber, and wall of the left ventricle. They monitor the level of arterial pressure and act against in the order to lessen the force in the dilation of blood vessels, which decreases the blood pressure. Chemoreceptors, located in the brain, the two main arteries that carry blood to the head and neck, and aortic body of baroreceptors, are sensitive to changes in concentrations of oxygen, carbon dioxide, and hydrogen ions (Ph) in the blood. A decrease in arterial oxygen concentration or Ph causes a reflexive rise in pressure where an increase in carbon dioxide concentration causes a decrease in blood pressure. Ph is the numeric scale used to identify the basicity and acidity of a solution. Basic is on the top of the scale while acid is on the
Tortora, G., & Derrickson, B. (2012). The cardiovascular system: The blood. In B. Roesch (Ed.),
Sympathetic pathways change nerve activity during times of stress, exercise, low blood glucose levels, excitement or fear, due to the flight or fight response. These changes can have an effect on homeostasis by increasing heart rate, increasing blood flow, dilating pupils, sweating, releasing glycogen, increasing oxygen intake and diverting blood flow away from the gastrointestinal tract.
The ventricles send blood to the heart and are larger and stronger. Heart valves are another important aspect of the heart and body. We have atrioventricular and semilunar valves which help block regurgitation of blood. The heart has two states, it has a systole state where the heart is contracting to push blood out and diastole where the heart relaxes so the heart can fill back up with blood.
Blood pressure as the force of blood inside the blood vessel against the wall of the vessel. Systolic blood pressure is the peak of pressure of the left ventricle contracting and blood entering the aorta, influencing it to stretch, Marieb, E.N and Hoehn, K. (2010). Diastolic pressure is when the aortic valve closes, blood flow to the aorta to the small vessels. As the aorta recoils back the aortic blood pressure is at its lowest, this tend to reflect the resistance of the blood vessels, Marieb, E.N and Hoehn, K. (2010).
They arise in the interstitial spaces of organs and tissues and they then join with the large veins just before they enter the vena cava of the heart. These lymphatic vessels tend to run parallel with the veins which allows filtration to occur. The vessels are non- muscular and contain valves which stop the fluid from going back. (Hastie, 2012).
The cardiovascular system is made up of the heart which pumps blood to the lungs through pulmonary circulation, the heart muscle through cardial circulation and the body systems through systematic circulation. It is made up of various chambers and valves and its cycle is controlled by an electrical signal originating in the heart itself. There are various different vessels which control the blood flow throughout the body. Which include high pressure arteries and arterioles originate from the heart. Capillaries which have a semipermeable membrane that allows the exchange of gasses, nutrients and wastes between the blood and the tissues. Also veins which are low pressure and contain valves that prevent backflow. All of these together perform the main functions of the cardiovascular system; protection, transportation and regulation.
I found out that this is because the blood is feeding the muscles oxygen at first then the body wants to lose heat from the body created my movement as well so the blood vessels
The further the arteries get away from the heart they become smaller and narrower and are eventually called arterioles. Arterioles and arteries just about have the same structure and function. Arterioles have strong, thick, muscular walls and a rather small passageway for the blood to travel in and out. Also, they are the most highly regulated blood vessels in the blood and contain blood under high blood pressure.
blood flow since the fat, that you don’t work of or the salt in your diet, enters your bloodstream