urinary system

• ANH is secreted from cardiac muscle to right atrium of heart when blood pressure increases.
• ANH acts on kidneys to decrease Na+ reabsorption.
• Sodium ions remain in nephron to become urine.
• Increased loss of sodium and water reduces blood volume and blood pressure.
• Micturition reflex is activated by stretch of urinary bladder wall.
• Action potentials are conducted from bladder to spinal cord through pelvic nerves.
• Parasympathetic action potentials cause bladder to contract.
• Stretching of bladder stimulates sensory neurons to inform brain person needs to urinate.
• Intracellular fluid is a component of body fluid compartments.
• Extracellular fluid is a component of body fluid compartments.
• Thirst regulation controls water intake by hypothalamus in thirst center.
• Concentration of blood increases thirst center responds by initiating sensation of thirst.
• When water is consumed, concentration of blood decreases and sensation of thirst decreases.
• Regulation of acid-base balance involves buffers, which are chemicals that resist change in pH of a solution.
• Buffers in body contain salts of weak acids or bases that combine with H+.
• There are three classes of buffers: proteins, phosphate buffer, bicarbonate buffer.
• Respiratory system responds rapidly to change in pH and increased respiratory rate raises pH due to rate of carbon dioxide elimination being increased.
• Reduced respiratory rate reduces pH due to rate of carbon dioxide elimination being reduced.
• Nephrons secrete H+ into urine and directly regulate pH of body fluids.
• More H+ if pH is decreasing and less H+ if pH is increasing.
• Acidosis occurs when pH of blood falls below 7.35.
• There are two types of acidosis: respiratory acidosis and metabolic acidosis.
• Alkalosis occurs when pH of blood increases above 7.45.
• Renal artery and Abdominal aorta are the main vessels supplying blood to the kidneys.
• Renal Circulation involves segmental veins and consists of the movement of water, ions, small molecules through filtration membrane into Bowman’s capsule, with 19% of plasma becoming filtrate, 180 Liters of filtrate being produced by the nephrons each day, and 1% of filtrate becoming urine, the rest being reabsorbed.
• Only small molecules are able to pass through filtration membrane.
• Formation of filtrate depends on filtration pressure, which is influenced by blood pressure.
• Filtration pressure forces fluid across filtration membrane.
• Filtration pressure is influenced by blood pressure.
• 99% of filtrate is reabsorbed and reenters circulation, with the proximal tubule being the primary site for reabsorption of solutes and water, and the descending loop of Henle concentrating filtrate.
• Reabsorption of water and solutes from the distal tubule and collecting duct is controlled by hormones.
• Water, small ions, by products of metabolism, drugs, urea are found in urine.
• Ureters are small tubes that carry urine from the renal pelvis of the kidney to the bladder, with the urinary bladder storing urine and can hold a few ml to a max of 1000 ml, and the urethra being the tube that exits the bladder and carries urine from the urinary bladder to the outside of the body.
• The urinary bladder is in the pelvic cavity, stores urine, and can hold a few ml to a max of 1000 ml.
• The urethra is a tube that exits the bladder and carries urine from the urinary bladder to the outside of the body.
• Three hormonal mechanisms regulate urine concentration and volume: Renin - Angiotensin - Aldosterone, Antidiuretic Hormone, and Atrial Natriuretic Hormone.
• Renin acts on angiotensinogen to produce angiotensin I, angiotensin - converting enzyme converts angiotensin I to angiotensin II, angiotensin II causes vasoconstriction, angiotensin II acts on adrenal cortex to release aldosterone, aldosterone increases rate of active transport of Na + in distal tubules and collecting duct, volume of water in urine decreases.
• Antidiuretic Hormone is secreted by the posterior pituitary gland, acts on kidneys and they absorb more water, maintain blood volume and blood pressure.
• Atrial Natriuretic Hormone is secreted by the heart, acts on kidneys and they absorb more water, maintain blood volume and blood pressure.
• Kidney structures include the renal capsule, which is a connective tissue around each kidney that protects and acts as a barrier.