What are the organs and structures of the urinary system?
The kidneys, the ureters, the urethra and the bladder
What are functions of the kidneys?
Fluid homeostasis, filtration of wastes and homeostasis of blood volume and chemical makeup
Which glands sit atop the kidneys?
The adrenal glands
Describe kidney anatomy.....
the kidneys are bean shaped, about the size of a can of of soup and weigh approx 5 ounces ... They are located in the lumbar region between the T12 and L-3 vertebra. The renal hilus is a cleft on the medial concave (curves inward) that leads to a space called the renal sinus. Ureters, blood vessels and nerves are located in the sinus and entering the kidney at the hilus.
What are the three layers of specialized tissue protecting the kidney surface ?
The outer renal fascia - dense fibrous connective tissue that keeps the kidney in place inside the abdominal cavity The adipose capsule- fatty layer that protects the kidney from trauma The renal capsule - tough fibrous outer skin of the kidney which protects it from injury and infection
What are the three regions of the kidney?
The cortex, the medulla and the pelvis
What does the renal cortex consist of ?
This is the outer region that is just inside the renal capsule. It has a number of projections called cortical columns that extend down between the renal medulla pyramids. Located within the renal cortex are the glomerular capsule and the distal and convoluted tubule sections of the nephrons along with associated blood vessels.
What does the renal medulla consists of ?
This is a region below to the renal cortex- it is divided into sections called pyramids that point toward the center of the kidney. Located within the medulla are the Loop of Henle and the collecting duct sections of the nephrons.
What does the renal pelvis consist of ?
The renal pelvis is the centermost section of the kidney near the renal hilus. It is a funnel shaped tube that connects to the ureter as it leaves the hilus. This is done through extensions of the renal pelvis called calyces- these collect urine which drains continuously into the renal pelvis and then into the ureter, which transports it to the bladder for storage.
How many ml of blood are delivered to the kidney per minute?
The renal arteries deliver about 1200 ml of blood per minute directly from the abdominal aorta which amounts to 20% of the cardiac output.
What are the branches of the renal arteries?
The renal arteries branch into 5 segmental arteries which divide further into lobar arteries then further into interlobar arteries which pass between the renal pyramids. The interlobar arteries then divide into the arcuate arteries which branch into several interlobular arteries that feed into the afferent arterioles that supply the glomeruli. After filtration occurs the blood moves into the efferent arterioles and either the peritubular or vasta recta capillaries and then drain into interlobular veins which converge sequentially into arcuate then interlobar veins then to the renal vein which exits the kidney
Why are the kidneys are innervated by many blood vessels?
So that they can filter the blood to regulate its composition.
How do the kidneys and the nervous system collaborate?
They interact via the renal plexus whose fibers follow the renal arteries to reach the kidney. Input from the sympathetic nervous system adjusts the diameter of the renal arteries thereby regulating renal blood flow.
What is the pathway of blood from the renal artery to the renal vein within the kidney?
Renal Artery → Segmental Artery → Lobar artery → Interlobar Artery → Arcuate Artery → Interlobar Artery → Afferent arteriole, (8) Glomerular capillaries, (9) Efferent arteriole, (10) Peritubular or Vasa recta capillaries, (11) Interlobular vein, (12) Arcuate vein, (13) Interlobar vein, (14) Renal vein
What is the basic structural and functional unit of a kidney and how many are there in each kidney?
The nephron - there are about a milliion present in each kidney.
What are the functions of a nephron?
To control the concentration of water and soluble materials by filtering the blood, reabsorbing needed materials and excreting the rest as urine thereby eliminating wastes from the body, regulating blood volume, pH and pressure, controlling levels of electrolytes.
What are the two parts of a nephron?
The Renal corpuscle and the Renal tubule, which are connected, by way of the tubule to associated collecting ducts.The renal corpuscle filters the blood, the renal tubule reabsorbs needed materials and the collecting ducts carry the remaining material away as urine to be excreted.
What composes the renal corpuscle of the nephron?
The glomerulus which is a tiny network of blood capillaries surrounded by the glomerular Bowman's capsule,a double-walled simple squamous epithelial cup.
What is unique about the glomerular capillaries?
They are extremely porous and are the only arteriolds in the body which lie between two arterioles. (the afferent arteriole and the efferent arteriole) rather than between an artery and a vein.
What is the difference between afferent and efferent arteriole?
The afferent arteriole brings blood to the glomerulus and the efferent arteriole takes blood away from the glomerulus.
What causes blood to exit the blood and go into the glomerular (Bowman's) capsule ?
The afferent arteriole, which is fed by the interlobular artery, is much larger in diameter than the efferent arteriole causing an extremely high blood pressure in the glomerular capillaries forcing water and solutes out of the blood and into the glomerular capsule (as glomerular filtrate) and subsequently into the renal tubule.
What are the three parts of the renal tubule ?
The proximal convoluted tubule, the loop of Henle and the distal convoluted tubule.
What does the proximal convoluted tubule do ?
The highly coiled proximal convoluted tubule which is specialized to reabsorb water and many solutes from the glomerular filtrate into the low-pressure peritubular capillaries which surround the renal tubule as well as secrete certain unwanted substances.
What does the loop of Henle do ?
The loop of Henle has an initial descending limb followed by the ascending limb. The descending limb allows water loss and the ascending limb allows salt (NaCl) loss.
What does the distal convoluted tubule do ?
The highly coiled distal convoluted tubule allows hormonally controlled reabsorption of water and solutes but mostly secretion of unwanted substances
What happens to the filtrate as it makes it way through the tubule of the nephron?
The filtrate (which is now urine) from several tubules then drains into a collecting duct, many of which converge to form papillary ducts which drain into the calyces and subsequently into the renal pelvis and out of the kidney by way of the ureter.
Where are the nephrons of the kidney located ?
Most (about 85%) of the kidney nephrons are located mainly in the cortex (except for a portion of their loop of Henle which extends into the medulla). The remaining nephrons, called juxtamedullary nephrons, pass deeply into the medulla because of their location and their longer loops of Henle.
What three capillary beds are nephrons associated with?
the glomerular capillaries, the peritubular capillaries and the vasa recta
Talk about the glomerular capillaries...
They are very porous and They have a high pressure , which makes them specialized for filtration. These properties force solutes and fluids out of the blood into the Bowman's (glomerular capsule)
Approx what percent of the glomerular filtrate is reabsorbed through the renal tubule?
99% is reabsorbed and returned to the blood in the returned to the blood in the peritubular capillary bed.