Lecture 3: Blood Vessels

When you are relaxing on the couch after dinner, the precapillary sphincters in the capillary bed relax to allow blood flow to the true capillaries of your gastrointestinal organs to receive the breakdown products of digestion. This is because the statement mentions that the relative amount of blood entering a capillary bed is regulated by chemical conditions and arteriolar vasomotor nerve fibers. In this case, the relaxation of the precapillary sphincters is a result of the chemical conditions and nerve signals, allowing the blood to flow into the capillaries and deliver the breakdown products of digestion. Therefore, the answer is true.

Veins carry blood back to the heart at a lower pressure compared to arteries. This is because the blood has already delivered oxygen and nutrients to the body's tissues and organs, so it has less force when returning to the heart. As a result, the walls of veins can be much thinner and less muscular than arterial walls without the risk of bursting. This is why the statement is true.

The lymph node plays a crucial role in the immune system activation. It acts as a filtering station for the lymphatic system, where immune cells called lymphocytes are present. These lymphocytes help in identifying and attacking foreign substances, such as bacteria or viruses, that enter the body. The lymph nodes also produce and release antibodies, which are essential in fighting off infections. Therefore, immune system activation is one of the main functions of the lymph node.

The given statement is true. Cardiac output (CO) is calculated by multiplying the heart rate (HR), which is the number of times the heart beats per minute, by the stroke volume (SV), which is the amount of blood pumped by each ventricle with each heartbeat. Therefore, the formula CO = HR x SV is used to calculate the cardiac output.

Venous valves are formed from folds of the tunica intima. This is true because the tunica intima, the innermost layer of the blood vessel wall, contains specialized folds that form valves. These valves help to prevent the backflow of blood in the veins, ensuring that blood flows in the correct direction towards the heart.

The Brachiocephalic artery is indeed an artery that branches from the Aorta. It supplies blood to the right arm, head, and neck. Therefore, the statement is true.

Systemic veins and venules collectively hold approximately 60% of the total blood volume throughout the cardiovascular system. This is because veins and venules are responsible for returning deoxygenated blood back to the heart from the body tissues. The majority of the blood volume is found in the systemic circulation, which includes the veins and venules. Therefore, the correct answer is 60%.

The transport of the lymphatic system lacks an organ that acts as a pump, which makes it slow and sporadic. However, there are several actions that can promote lymph flow. The pulsation of nearby arteries can help push the lymph along, while the smooth muscles in the lymphatic vessels can contract and create a pumping effect. Additionally, increasing physical activity and engaging in passive movements can also promote lymph flow. Therefore, all of the answers above are correct as they all contribute to promoting lymph flow.

120 mmHG

The superior mesenteric artery does indeed arise from the abdominal aorta, just inferior to the origin of the celiac trunk. This anatomical relationship is important as the superior mesenteric artery supplies blood to the small intestine, ascending colon, and part of the transverse colon. The celiac trunk, on the other hand, supplies blood to the liver, stomach, spleen, and part of the pancreas.

The statement "hydrostatic pressure is higher at venous end than at arterial end" is false. In reality, hydrostatic pressure is higher at the arterial end of the capillaries compared to the venous end. This pressure difference is due to the pumping action of the heart, which generates higher pressure in the arteries to push blood towards the capillaries. As blood flows through the capillaries, hydrostatic pressure gradually decreases, and it is lower at the venous end. This pressure difference helps facilitate the exchange of nutrients, gases, and waste products between the blood and the surrounding tissues.

The intima layer forms the venous valves.

All options above are correct. Arteries have larger branches that are buried deep into the tissues for protection. Arterial blood pressure is relatively high compared to other blood vessels. Additionally, blood flow velocity in arteries is fast, allowing for efficient transportation of oxygenated blood to various parts of the body.

As the veins ascend towards the heart, the blood flow encounters less resistance and the pressure gradually decreases. This is because the veins have valves that prevent backward flow of blood and help to propel it towards the heart. Additionally, the veins have thinner walls compared to arteries, resulting in lower pressure. Therefore, it is true that blood pressure decreases as the veins ascend towards the heart.

Microcirculation is the flow of blood from an arteriole to a venule, not the other way around. The correct direction of blood flow in microcirculation is from the arterioles, which are small branches of arteries, to the venules, which are small branches of veins. This allows for the exchange of oxygen, nutrients, and waste products between the blood and the surrounding tissues.

This statement is incorrect. Osmotic pressure is the pressure exerted by a solvent to prevent the inward flow of water across a semipermeable membrane, while hydrostatic pressure is the pressure exerted by a fluid at rest. Osmotic pressure does not "push" and hydrostatic pressure does not "suck."

The right lymphatic duct drains lymph from the right upper limb, right side of the head, and right side of the thorax. Lymph is a clear fluid that carries waste products and immune cells throughout the body. The lymphatic system helps to remove toxins and foreign substances from the body, and the lymphatic ducts are responsible for draining lymph back into the bloodstream. The right lymphatic duct specifically collects lymph from the aforementioned areas and returns it to the bloodstream for circulation.

The given statement is true because precapillary sphincters are small muscles that are located at the entrance of capillaries. They act as valves by constricting or dilating to control blood flow into the capillaries. This helps regulate the distribution of blood throughout the body and ensures that tissues receive an adequate blood supply based on their needs.

The femoral triangle is a region in the upper thigh that is bounded by the inguinal ligament, adductor longus, and sartorius muscles. These structures form the borders of the triangle and are important landmarks in the anatomy of the thigh. The inguinal ligament is a band of connective tissue that stretches from the anterior superior iliac spine to the pubic tubercle. The adductor longus muscle is one of the muscles of the inner thigh, while the sartorius muscle is the longest muscle in the body and runs diagonally across the thigh. Together, these structures define the boundaries of the femoral triangle.

The statement is false because the structural basis of the "blood-brain barrier" actually consists of non-fenestrated capillaries. Fenestrated capillaries have small pores or fenestrations that allow for the exchange of substances between the blood and tissues. However, in the blood-brain barrier, the capillaries are non-fenestrated, meaning they do not have these pores. Instead, the capillary endothelial cells are tightly packed together, forming tight junctions that restrict the passage of substances and protect the brain from potentially harmful molecules.

This statement is false. Hydrostatic pressure and osmotic pressure both push rather than pull. Hydrostatic pressure is the pressure exerted by a fluid at rest, which pushes against the walls of its container. Osmotic pressure, on the other hand, is the pressure exerted by the movement of solvent molecules across a semipermeable membrane, which also pushes against the membrane.

Stroke volume refers to the amount of blood that is ejected from each ventricle during each contraction of the heart. It is an important measure of the heart's efficiency in pumping blood. By calculating the stroke volume, healthcare professionals can assess the heart's ability to deliver an adequate amount of blood to the body's tissues and organs. A higher stroke volume indicates a stronger and more efficient heart, while a lower stroke volume may indicate a problem with the heart's pumping function.

The correct answer is Tunica intima. The tunica intima is the innermost layer of the artery wall and is composed of a subendothelial layer and an internal elastic lamina. The subendothelial layer is located just beneath the endothelium and contains connective tissue and smooth muscle cells. The internal elastic lamina is a layer of elastic fibers that provides structural support to the artery. Therefore, both the subendothelial layer and internal elastic lamina are present in the tunica intima.

The statement is true because hydrostatic pressure refers to the pressure exerted by a fluid at equilibrium due to the force of gravity. Capillary blood pressure, on the other hand, is the pressure exerted by blood in the capillaries. Since blood is a fluid and is affected by gravity, the hydrostatic pressure and capillary blood pressure are indeed the same.

Fenestrated capillaries

The statement suggests that the total amount of fluids leaving the body is greater than the rate at which fluids are being reabsorbed. This implies that the body is losing more fluids than it is retaining, which can lead to dehydration or other fluid balance issues. Therefore, the answer "True" indicates that the statement is correct.

Lateral. Remember NAV

When the body is at rest, the abdominal organs receive the most blood. This is because during rest, the body does not require a high level of oxygen and nutrients for physical activity. Instead, blood flow is directed towards the abdominal organs to support essential functions such as digestion, metabolism, and maintenance of organ health. The kidneys, brain, and skeletal muscles may still receive blood, but the priority is given to the abdominal organs.

The femoral triangle consists of the inguinal ligament, sartorius muscle, and adductor longus muscle. These structures form the boundaries of the triangle and are important landmarks in the thigh region. The inguinal ligament is a fibrous band that runs from the anterior superior iliac spine to the pubic tubercle. The sartorius muscle is the longest muscle in the body and runs obliquely across the thigh. The adductor longus muscle is located on the medial side of the thigh. Together, these structures define the boundaries and contents of the femoral triangle.

Red blood cells do not leave the blood together with oxygen through diffusion. Instead, oxygen binds to the hemoglobin molecules within the red blood cells, forming oxyhemoglobin. This oxygen-rich blood is then transported to tissues and organs throughout the body, where oxygen is released from the red blood cells and diffuses into the cells that need it. Therefore, the statement is false.

The statement is false because there are actually more afferent lymphatic vessels entering a lymph node than efferent vessels leaving it. Afferent vessels bring lymph fluid into the lymph node, allowing it to be filtered and immune responses to occur. Efferent vessels then carry the filtered lymph fluid away from the lymph node. This arrangement ensures that the lymph node can effectively filter and process the lymph fluid before it is returned to the bloodstream.

Continuous capillaries are the most abundant type of capillaries in the body. They are found in almost all tissues and organs, except for certain specialized areas like the liver, spleen, and bone marrow. Continuous capillaries have a continuous endothelial lining with tight junctions between the cells, forming a continuous tube. This type of capillary allows for the exchange of small molecules and fluids between the blood and surrounding tissues. They are important for the delivery of oxygen and nutrients to tissues, as well as the removal of waste products.

The statement is false because there are actually five major vessels in the human body, not four. The correct list includes arteries, capillaries, veins, lymphatics, and the heart. The heart is an important vessel that pumps blood throughout the body, and without it, the circulatory system would not function properly. Therefore, the given statement is incorrect.

Veins have thinner walls and larger lumens compared to corresponding arteries. This is because veins carry deoxygenated blood back to the heart at a lower pressure, so they do not need as much muscular and elastic tissue in their walls as arteries do. The larger lumen allows for easier blood flow and the thinner walls allow veins to be more flexible and accommodate changes in blood volume.

Liver, gallbladder and stomach

The superficial femoral artery is a major branch of the femoral artery, located in the thigh. It gives rise to several branches, including the deep femoral artery and the popliteal artery. The deep femoral artery supplies blood to the muscles of the thigh, while the popliteal artery continues down the leg and becomes the main blood supply to the lower leg and foot. Therefore, the correct answer is the popliteal artery, as it is one of the branches of the superficial femoral artery.

The correct answer is "greater and lesser saphenous vein". The saphenous vein is a large superficial vein that runs along the inner side of the leg. It is divided into two main branches: the greater saphenous vein, which is the longest vein in the body and runs from the foot to the groin, and the lesser saphenous vein, which runs from the foot to the back of the knee. Therefore, the saphenous vein consists of the greater and lesser saphenous vein.

A high hydrostatic pressure throughout the capillary bed would lead to increased filtration process. Hydrostatic pressure is the force exerted by a fluid against the walls of its container, and in this case, it refers to the pressure exerted by the blood within the capillaries. When the hydrostatic pressure is high, it overcomes the opposing force of osmotic pressure, which is the pressure exerted by solutes in the blood. This results in an increased filtration process, where fluid is pushed out of the capillaries and into the surrounding tissues.

Arteriosclerosis is a general term of all types of arterial changes.

Sinusoidal capillaries are characterized by having leaky capillaries. These capillaries have large gaps or fenestrations between their endothelial cells, allowing for the easy passage of large molecules and cells. This allows for efficient exchange of substances between the blood and surrounding tissues, making them important in organs such as the liver, spleen, and bone marrow. Therefore, the correct answer is sinusoidal capillaries.

1 = stage 1
2 = stage 3
3 = stage 1
4 = stage 4

The statement is true because venous valves are indeed absent in the thoracic and abdominal body cavity. Venous valves are structures found within veins that help to prevent the backflow of blood. However, in the thoracic and abdominal body cavity, such as in the veins of the chest and abdomen, the veins are larger and have thicker walls, which allows for the blood to flow more easily and without the need for valves. Therefore, venous valves are not present in these areas.

The ascending aorta is the first portion or branch of the aorta. It gives rise to several important structures, including the right and left coronary arteries. These arteries supply oxygenated blood to the heart muscle itself. Therefore, the correct answer is that the ascending aorta gives rise to the right and left coronary arteries.

External iliac artery

A capillary bed consists of vascular shunt and true capillaries. Vascular shunt is a short vessel that directly connects an arteriole to a venule, bypassing the true capillaries. True capillaries are the smallest and most numerous blood vessels in the body, where exchange of nutrients and waste products occurs between the blood and surrounding tissues. Together, the vascular shunt and true capillaries form the capillary bed, allowing for efficient blood flow and nutrient exchange in tissues.

Enlarged lymph nodes can be caused by both tumors and infections. Infections such as bacterial or viral infections can lead to lymph node enlargement as the body's immune system responds to the infection. On the other hand, tumors or cancerous growths can also cause lymph nodes to enlarge as the cancer cells spread through the lymphatic system. Therefore, both options are correct in this case.

Both options are correct because when fluid flows at a capillary, the osmotic pressure is expected to be constant. This is because osmotic pressure is determined by the concentration of solutes in the fluid, which does not change significantly as the fluid flows through the capillary. Additionally, the hydrostatic pressure is opposed by the interstitial fluid hydrostatic pressure, which helps to maintain a balance and prevent excessive fluid leakage from the capillary.