Urinary System Functions and Structures

A network of capillaries within the nephron where blood filtration occurs. Blood enters through a large afferent arteriole and exits through a narrow efferent arteriole, creating high pressure and driving filtration.

The capsule surrounding the glomerulus, marking the beginning of the renal tubule. It receives the filtered fluid from the glomerulus.

A long, twisted tube responsible for reabsorbing essential substances and secreting waste products. It consists of several segments: Proximal convoluted tubule, Loop of Henle, and Distal convoluted tubule.

A type of nephron entirely located in the renal cortex, representing the majority of nephrons. They play a role in filtering blood and reabsorbing substances.

A type of nephron with a loop extending into the medulla of the kidney. They are important in creating concentrated urine and conserving water.

A network of capillaries that arise from the efferent arteriole of the glomerulus. They play a crucial role in reabsorbing substances from the renal tubule.

The process of filtering blood in the glomerulus, where water and small solutes pass into the glomerular capsule. This process separates blood cells and large proteins.

The process of reclaiming essential substances from the filtrate in the renal tubule and returning them to the bloodstream. Most water, electrolytes, and nutrients are reabsorbed.

The urinary system is responsible for eliminating waste products from the body, such as nitrogenous wastes, toxins, and drugs. It plays a crucial role in maintaining homeostasis by regulating water balance, electrolytes, acid-base balance in the blood, blood pressure, red blood cell production, and activating Vitamin D.

The kidneys are bean-shaped organs located against the dorsal body wall at the level of T12 to L3. The right kidney is slightly lower than the left due to the presence of the liver on the right side. Each kidney is attached to the ureters, renal blood vessels, and nerves at the renal hilus. Atop each kidney is an adrenal gland.

The kidneys have three main regions: the renal cortex, which is the outer region; the renal medulla, which is inside the cortex; and the renal pelvis, which is the inner collecting tube.

The functional units of the kidneys that are responsible for forming urine are called nephrons. Each nephron consists of a glomerulus, which is a network of capillaries, and a renal tubule, which is responsible for filtering and reabsorbing substances.

The glomerulus is a network of capillaries in the nephron that filters blood, allowing small molecules to pass through into the renal tubule but blocking larger molecules such as proteins and cells.

The renal tubule is a long, coiled tube in the nephron that processes the filtered fluid, reabsorbing needed substances back into the blood and secreting unwanted substances into the tubule.

The medullary pyramids are triangular regions of tissue in the medulla of the kidney. The renal columns are extensions of cortex-like material inward from the cortex. The calyces are cup-shaped structures that funnel urine towards the renal pelvis.

Blood enters the kidneys through the renal artery and flows through the nephrons, where it's filtered and processed. After filtering, the blood exits the kidney through the renal vein.

Waste products like urea, uric acid, and creatinine that are not reabsorbed and remain in the filtrate to be excreted in urine.

The movement of substances from the peritubular capillaries into the renal tubules, working in the opposite direction of reabsorption.

A yellowish color due to the pigment urochrome (from hemoglobin breakdown), its sterility, a slightly aromatic smell, a normal pH of around 6, and a specific gravity of 1.001 to 1.035.

Slender tubes that connect the kidneys to the bladder, transporting urine through peristalsis and gravity.

A muscular sac that stores urine before it is excreted from the body. It fills with urine and contracts to release it.

A tube that carries urine from the bladder out of the body.

A hollow, muscular organ that stores urine temporarily before it's released from the body.

The triangular region at the bladder's base where the ureters and urethra connect. This helps control urine flow.

The three layers of smooth muscle in the bladder wall that contract to expel urine.

A circular muscle that controls the flow of urine from the bladder. There are two: Internal (involuntary) and External (voluntary).

The process of emptying the bladder, involving relaxation of both internal and external sphincters.

The urethra is shorter in females (about 1 inch) and is located along the vaginal wall, while in males it's longer (8 inches) and passes through the prostate and penis.

In females, the urethra only carries urine, while in males it carries urine and sperm.

The amount of water inside cells, making up about two-thirds of the total body water.

The fluid outside of cells, encompassing interstitial fluid and blood plasma.

The fluid that surrounds cells and is a major component of extracellular fluid. It helps transport nutrients and remove waste products.

The liquid component of blood, containing plasma proteins, electrolytes, and dissolved substances. It's responsible for transporting nutrients, oxygen and waste products.

A hormone that regulates sodium ion concentration in the extracellular fluid by promoting reabsorption of sodium in the kidneys. It's activated by the renin-angiotensin mechanism.

A hormone that controls water reabsorption in the kidneys, reducing urine production and preventing excessive water loss. It's released when the body is dehydrated.

A process in the kidneys where essential substances are reabsorbed from the filtrate in the renal tubule back into the bloodstream.

The process by which the body regulates the balance of water and electrolytes, ensuring optimal fluid levels and electrolyte concentrations.

The pH of blood must stay within a narrow range (7.35 to 7.45) to maintain homeostasis, with values outside this range indicating alkalosis (above 7.45) or acidosis (below 7.35).

The kidneys are the primary organs involved in maintaining acid-base balance in the blood. They regulate the excretion of hydrogen ions (H+) and bicarbonate ions (HCO3-) to adjust blood pH.

Blood buffers, such as bicarbonate (HCO3-), act as temporary pH regulators by binding to excess hydrogen ions (H+) or releasing them to counteract changes in blood pH. This system offers immediate but short-lived buffering.

The respiratory system also plays a role in maintaining acid-base balance by regulating the amount of carbon dioxide (CO2) in the blood. CO2 combines with water to form carbonic acid (H2CO3), which can lower blood pH. By increasing respiration rate, the body can expel more CO2, reducing acidity, and vice versa for alkalosis.

Even though the kidneys develop by the third month of gestation, a newborn's bladder is small and cannot concentrate urine effectively. This makes infants susceptible to dehydration. Voluntary control of the urethral sphincter develops around 18 months of age.