Question

1. Name the major organs of the urinary system and their basic function. 2. List 5 substances that are regulated by the kidneys, 2 substances that are secreted by the kidneys, and 2 substances that are excreted by the kidneys. 3. There are 2 fluid flow patterns in the kidney. What are they? 4. What is the name of functional unit of the kidney? Name the main components. 5. What are the components of the juxtaglomerular apparatus? 6. The fluid in the capsular space is called ____________________. Once it enters the PCT, it is called __________ fluid. When it reaches the papillary ducts it is referred to as ____________. 7. What are the three processes of urine formation?

Answer 1

Answer :

1. The urinary system, also known as the renal system or urinary tract, consist of the kidneys, ureters, bladder and the urethra.The purpose of the urinary system is to eliminate waste from the body , regulate blood volume and blood pressure, control levels of electrolytes and metabolites, and regulate blood pH.

Functions of kidney :

• Controlling acid-base balance
• controlling water balance
• maintaining electrolyte balance
• removing toxins and waste products from body
• controlling blood pressure
• producing the hormone erythropoietin
• activating vitamin D

Functions of ureters and urethra:

The ureters carry the urine away from kidneys to the urinary bladder , which is a temporary reservoir for the urine . The urethra is a tubular structure that carries the urine from the urinary bladder to the outside.

Functions of bladder :

Temporary storage of urine- the bladder is a hollow organ with distensible walls.It has a folded internal lining (known as rugae), which allows it to accommodate up to 400 to 600 ml of urine in healthy adults.

2. 5 substance regulated by the kidney :

1. The kidneys ensure that the make-up and volume of the fluids in the body is correct.
2. They help control the chemical balance of gthe blood and regulates the body 's level of sodium, potassium and calcium.
3. The kidneys remove waste products and excess water from the body and so helps to regulate blood pressure.
4. They acyivate vitamin D which helps to maintain strong bones.
5. They produce erythroprotietin, a hormone that is vital for the production of red blood cells.

Substances that are secreted by the kidneys are hydrogen, ammonium and potassium.

Substances that are excreted by the kidneys are nitrogenous wastes urea, from the protein catabolism and uric acid from nucleic acid metabolism.

3. Capillary flow and laminar flow . The Reynolds number in the renal tubule is extremely low, consistent with laminar flow. Capillary flow is a property that is exhibited when liquids spontaneously penetrate narrow passageways.

4. Nephron. The nephrone is the functional unit of the kidney. The glomerulus and convoluted tubules of the nephrone are located in the cortex of the kidney.While the collecting ducts are located in the pyramids of the kidney's medulla. Main components are : glomerulus, Bowman's capsule, proximal convoluted tubule, distal convoluted tubule, collecting duct, descending limb and ascending limb.

5. The juxta glomerular apparatus comprises afferent and efferent arterioles, complimented by granular, renin secreting cells, the macula densa, a specialized group of distal tubular cells and lacis cells (Goormaghtigh cells, polar cushion, extraglomerular mesangial cells).

6. The fluid in the capsular space is called Capsular urine. Once it enters in the PCT is called Filtrate (glomerular) fluid. When it reaches the papillary ducts it is reffered to as urine.

7. The kidney filter unwanted substances from the blood and produce urine to excrete them. There are three processess of urine formation:

• glomerular filtration: The fluid in the lumen of the Bowman's capsule of the nephrone that has been filtered from the capillaries of the glomerulus.  
• reabsorption : reabsorption takes place mainly in the proximal convoluted tubule of the nephrone, Loop of Henle and distal convoluted tubule. Reabsorption occurs primerly by passive transfer based on a cocentration gradien, moving from a high concentration to the lower concentration in the capillaries.
• secretion: It is involves the transfer of hydrogen ions, creatinine, drugs, and urea from the blood into the collecting duct, and is primerly made of water. Blood and glucose are not normally found in urine.