IntroductionThe primary role of the kidneys is to maintain the homeostatic balance of bodily fluids by filtering and secreting metabolites (such as urea) and minerals from the blood and excreting them, along with water, as urine. The kidneys are also important regulators of blood pressure, glucose metabolism and erythropoiesis, since the kidneys are poised to sense plasma concentrations of ions such as sodium, potassium, hydrogen, oxygen, and compounds such as amino acids, creatinine, bicarbonate, and glucose. The blood enters the kidney through the renal artery in the renal sinus. It branches into segmental arteries, which further divide into interlobar arteries penetrating the renal capsule and extending through the renal columns between the renal pyramids. The interlobar arteries then supply blood to the arcuate arteries that run through the boundary of the cortex and the medulla. Each arcuate artery supply a variety of additional interlobar arteries that feed into the afferent arterioles to be filtered through the nephrons. After filtration occurs the blood moves through a small network of venules that converge into interlobar veins. As with the arteriole distribution the veins follow the same pattern, the interlobar provide blood to the arcuate veins then back to the interlobar veins which come to form the renal vein exiting the kidney. Show
The human kidneyThe kidneys are located in the posterior part of the abdominal cavity. There are two, one on each side of the spine; the right kidney sits just below the diaphragm and posterior to the liver, the left below the diaphragm and posterior to the spleen. Above each kidney is an adrenal gland. The asymmetry within the abdominal cavity caused by the liver results in the right kidney being slightly lower than the left one while the left kidney is located slightly more medial. The majority of the water re-absorption in the vertebrate kidney takes place in the loop of Henle. The kidneys are retroperitoneal and range from 9 to 13 cm in diameter; the left slightly larger than the right. The kidneys receive unfiltered blood directly from the heart through the abdominal aorta which then branches to the left and right renal arteries. Filtered blood then returns by the left and right renal veins to the inferior vena cava and then the heart. Renal blood flow accounts for 20-25% of the cardiac output. Your heart is an amazing organ. It continuously pumps oxygen and nutrient-rich blood throughout your body to sustain life. This fist-sized powerhouse beats (expands and
contracts) 100,000 times per day, pumping five or six quarts of blood each minute, or about 2,000 gallons per day. As the heart beats, it pumps blood through a system of
blood vessels, called the circulatory system. The vessels are elastic, muscular tubes that carry blood to every part of the body. Blood is essential. In addition to carrying fresh oxygen from the lungs and nutrients to your body's tissues, it also takes the body's waste products, including carbon dioxide, away from the tissues. This is necessary to sustain life and promote the health
of all the body's tissues. There are three main types of blood vessels: This vast system of blood vessels -- arteries, veins, and capillaries -- is over 60,000 miles long. That's long enough to go
around the world more than twice! Blood flows continuously through your body's blood vessels. Your heart is the pump that makes it all possible. The heart is located under the rib cage, under and to the left of your breastbone (sternum), and between your lungs. Looking at the outside of the heart, you can see that the heart is made of
muscle. The strong muscular walls contract (squeeze), pumping blood to the arteries. The major blood vessels that are connected to the heart include the aorta, the superior vena cava, the inferior vena cava, the pulmonary artery (which takes oxygen-poor blood from the heart to the lungs, where it is oxygenated), the pulmonary veins (which bring oxygen-rich blood from the lungs to the
heart) and the coronary arteries (which supply blood to the heart muscle). On the inside, the heart is a four-chambered, hollow organ. It is divided into the left and right side by a muscular wall called the septum. The right and left sides of the heart are further divided into two top chambers called the atria, which receive blood from the veins, and two bottom chambers called ventricles, which pump blood into the arteries. The atria and ventricles work
together, contracting and relaxing to pump blood out of the heart in a coordinated and rhythmic fashion. As blood leaves each chamber of the heart, it passes through a valve. There are four heart valves within the heart: The tricuspid and mitral valves lie between the atria and ventricles. The aortic and pulmonic valves lie between the ventricles and the major
blood vessels leaving the heart. The heart valves work the same way as one-way valves in the plumbing of your home. They prevent blood from flowing in the wrong direction. Each valve has a set of flaps, called leaflets or cusps. The mitral valve has two leaflets; the others have three. The leaflets are attached to and supported by a ring of tough, fibrous tissue called the annulus. The annulus helps to maintain the proper shape of the
valve. The leaflets of the mitral and tricuspid valves are also supported by tough, fibrous strings called chordae tendineae. These are similar to the strings supporting a parachute. They extend from the valve leaflets to small muscles, called papillary muscles, which are part of the inside walls of the ventricles. The right and left sides of the heart work together.
The pattern described below is repeated over and over, causing blood to flow continuously to the heart, lungs, and body. Right side of the heart Left side of the heart Once blood travels through the pulmonic valve, it enters your lungs. This is called the pulmonary circulation. From your pulmonic valve, blood travels to the pulmonary arteries and eventually to tiny capillary vessels in the lungs. Here, oxygen travels from the tiny air sacs in the lungs, through the walls of the capillaries, into the blood. At the same time, carbon dioxide, a waste product of
metabolism, passes from the blood into the air sacs. Carbon dioxide leaves the body when you exhale. Once the blood is oxygenated, it travels back to the left atrium through the pulmonary veins. Like all organs, your heart is made of tissue that requires a supply of oxygen
and nutrients. Although its chambers are full of blood, the heart receives no nourishment from this blood. The heart receives its own supply of blood from a network of arteries, called the coronary arteries. Two major coronary arteries branch off from the aorta near the point where the aorta and the left ventricle meet:
These arteries and their branches supply all parts of the heart muscle with blood. When the coronary arteries narrow to the point that blood flow to the heart muscle is limited (coronary artery disease), a network of tiny blood vessels in the heart that aren't usually open (called collateral vessels) may enlarge and become active. This allows blood to flow around the blocked artery to the heart muscle, protecting the heart tissue from injury. How Does the Heart Beat?The atria and ventricles work together, alternately contracting and relaxing to pump blood through your heart. This is your heartbeat. The electrical system of your heart is the power source that makes this possible. Your heartbeat is triggered by electrical impulses that travel down a special pathway through your heart.
At rest, a normal heart beats around 50 to 90 times a minute. Exercise, emotions, anemia, an overactive thyroid, fever, and some medications can cause your heart to beat faster, sometimes to well over 100 beats per minute. Heart Health ResourcesYou can learn more about your heart and heart health from these organizations and resources: American College of Cardiology www.acc.org American Heart Association www.heart.org Food and Drug Administration www.fda.gov National Heart, Lung and Blood Institute Health Information Center www.nhlbi.nih.gov CardioSmart www.cardiosmart.org The Heart.org www.theheart.org How does blood flow from the heart to the kidneys?The renal arteries carry a large volume of blood from the heart to the kidneys. The kidneys filter waste and excess fluid from the blood. You have two renal arteries. The right renal artery supplies blood to the right kidney, while the left artery sends blood to the left kidney.
What is the correct order of the flow of blood through the heart?The right ventricle pumps the oxygen-poor blood to the lungs through the pulmonary valve. The left atrium receives oxygen-rich blood from the lungs and pumps it to the left ventricle through the mitral valve. The left ventricle pumps the oxygen-rich blood through the aortic valve out to the rest of the body.
Which is the correct order of blood flow to the kidneys?Blood flows into your kidney through the renal artery. This large blood vessel branches into smaller and smaller blood vessels until the blood reaches the nephrons. In the nephron, your blood is filtered by the tiny blood vessels of the glomeruli and then flows out of your kidney through the renal vein.
What is the path of blood flow to from each of the heart chambers?Blood enters the right atrium and passes through the right ventricle. The right ventricle pumps the blood to the lungs where it becomes oxygenated. The oxygenated blood is brought back to the heart by the pulmonary veins which enter the left atrium. From the left atrium blood flows into the left ventricle.
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Which of the following is the correct path of blood flow from the heart to the kidney?
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