The collecting ducts amass contents from multiple nephrons, fusing together as they enter the papillae of the renal medulla. Urine leaves the medullary collecting ducts through the renal papillae, emptying into the renal calyces, the renal pelvis, and finally into the bladder via the ureter.
Learning Objectives Explain the role of the nephron as the functional unit of the kidney. Key Points Kidneys contain two types of nephrons, each located in different parts of the renal cortex: cortical nephrons and juxtamedullary nephrons.
A nephron comprises a renal corpuscle, a renal tubule, and the associated capillary network. Internally, kidneys are mainly composed of over one million nephrons and an extensive network of blood vessels and capillaries. Only 1 to 2 quarts become urine. Clinical trials are part of clinical research and at the heart of all medical advances. Clinical trials look at new ways to prevent, detect, or treat disease.
Researchers also use clinical trials to look at other aspects of care, such as improving the quality of life for people with chronic illnesses.
Find out if clinical trials are right for you. Clinical trials that are currently open and are recruiting can be viewed at www. The NIDDK translates and disseminates research findings to increase knowledge and understanding about health and disease among patients, health professionals, and the public.
How do my kidneys work? How does blood flow through my kidneys? Clinical Trials The kidneys are two bean-shaped organs, each about the size of a fist.
You have two kidneys that filter your blood, removing wastes and extra water to make urine. Why are the kidneys important? Without this balance, nerves, muscles, and other tissues in your body may not work normally. Your kidneys also make hormones that help control your blood pressure make red blood cells keep your bones strong and healthy Watch a video about what the kidneys do.
Each nephron has a glomerulus to filter your blood and a tubule that returns needed substances to your blood and pulls out additional wastes. The end of the loop of Henle becomes the distal convoluted tubule near its original glomerulus. The loops of Henle run in parallel to capillary loops known as the vasa recta. Recall from Physiology that the loop of Henle serves to create high osmotic pressure in the renal medulla via the counter-current multiplier system.
Such high osmotic pressure is important for the reabsorption of water in the later segments of the renal tubule. The distal convoluted tubule is shorter and less convoluted than the proximal convoluted tubule. Further reabsorption and secretion of ions occur in this segment. The initial segment of the distal convoluted tubule lies right next to the glomerulus and forms the juxtaglomerular apparatus.
The juxtaglomerular apparatus is a specialized structure formed by the distal convoluted tubule and the glomerular afferent arteriole. It is located near the vascular pole of the glomerulus. The main function of the apparatus is the secretion of renin, which regulates systemic blood pressure via the renin-angiotensin-alodosterone system. The juxtaglomerular apparatus is composed of:. The terminal portion of the distal tubule empties through collecting tubules into a straight collecting duct in the medullary ray.
The collecting duct system is under the control of antidiuretic hormone ADH. When ADH is present, the collecting duct becomes permeable to water. Numerous collecting ducts merge into the renal pelvis, which then becomes the ureter. The ureter is a muscular tube, composed of an inner longitudinal layer and an outer circular layer.
The lumen of the ureter is covered by transitional epithelium also called urothelium. Recall from the Laboratory on Epithelia that the transitional epithelium is unique to the conducting passages of the urinary system. Its ability to stretch allows the dilation of the conducting passages when necessary.
The ureter connects the kidney and the urinary bladder. The ureter empties the urine into the bladder. The transitional epithelium continues over the surface of this organ. The thickened muscular layers become interwoven and cannot be clearly identified at this point. The urethra carries the urine away from the bladder to the outside of the body.
In the male, it is joined by the genital system. The epithelium changes from transitional to stratified or pseudostratified columnar in the urethra, and to stratified squamous in the distal end of the urethra. Answer: Podocyte: Foot processes assist in filtration barrier function by repelling negatively-charged molecules. Mesangial Cell: Provides structure support and regulate diameter of capillaries. Macula Densa: Senses blood pressure, regulates blood flow in afferent arteriole to maintain the glomerular filtration rate and stimulates release of renin.
Juxtaglomerular Complex: synthesize, store and release renin.
0コメント