Chapter 11 Flashcards
Define excretion. Through what process does excretion occur?
Excretion is the removal of metabolic wastes from the body. It is performed by the formation and discharge of urine from the body.
What is the function of the urinary system?
The urinary system is the organ system that plays a major role in maintaining the salt, water, and pH homeostasis of the body.
Identify the following metabolic wastes: urea, creatinine, uric acid. What disease is caused by too much uric acid in the system?
Urea, a waste product of amino acid metabolism, is the primary nitrogenous end product of metabolism in humans. Elevated urea levels cause uremia. Besides urea, the kidneys secrete creatinine, a waste product of creatinine phosphate, and uric acid, formed from the metabolic processing of nucleotides. Too much uric acid causes gout.
Concerning maintenance of water-salt balance, what are the salts that kidneys regulate in the blood?
The kidneys regulate the water-salt balance, which affects blood volume and blood pressure. The kidneys maintain appropriate blood levels of sodium, potassium, bicarbonate, and calcium.
Kidneys keep the blood at what pH level?
The kidneys can rid the body of a wide range of acidic and basic substances, so the kidneys have ultimate control over blood pH, keeping it at 7.4.
What is the function of erythropoietin (EPO)?
The kidneys release renin, an enzyme that leads to aldosterone secretion. The kidneys also release erythropoietin (EPO), which regulates the production of red blood cells.
What vitamin can the kidneys synthesize?
The kidneys also reabsorb filtered nutrients and synthesize vitamin D.
Describe the layout of the urinary system regarding the kidneys, ureters, bladder, and urethra. Also, what are the functions of these structures?
The kidneys are paired organs located near the small of the back, on either side of the vertebral column. The kidneys produce urine. A renal artery enters a depression in the concave side of the kidney, where a renal vein and a ureter exit the kidney.
Describe the anatomy/parts of a nephron. Make sure to mention the structure and function of the: glomerulus, glomerular capsule, proximal convolutes tubule, distal convoluted tubule, collecting ducts,
renal pelvis.
Macroscopically, the kidneys are divided into the renal cortex, renal medulla, and renal pelvis. Microscopically, kidneys contain the nephrons, which filter the blood and produce urine.
Describe the following stages of urine formation: glomerular filtration, tubular reabsorption, tubular secretion.
During glomerular filtration, small molecules including water, wastes, and nutrients move from the glomerulus to the inside of the glomerular capsule.
During tubular reabsorption, nutrients and water move from the proximal convoluted tubule into the blood of the peritubular capillary network. Only those molecules recognized by carrier molecules are actively reabsorbed. The amount of a substance that can be reabsorbed is limited by its number of carrier molecules. In diabetes mellitus, the blood glucose level is above normal, and glucose appears in the urine. Increased urination and thirst are experienced by diabetics due to less water being absorbed from the filtrate into the blood.
Tubular Secretion
During tubular secretion, certain substances like hydrogen ions, creatinine, and penicillin move from the blood into the distal convoluted tubule.
What is the main type of metabolic waste removed by the kidneys?
The tubules of the kidney remove wastes, especially nitrogenous wastes, from the body.
What happens to most of the water found in the filtrate before urine leaves the body?
Most of the water found in the filtrate is reabsorbed into the blood before urine leaves the body.
What are the functions of: aldosterone, antidiuretic hormone, atrial natriuretic hormone?
The proximal convoluted tubule, the distal convoluted tubule, and the cortical portion of the collecting ducts are in the renal cortex. Most of the water entering the capsule is reabsorbed at the proximal convoluted tubule. Aldosterone, an adrenal
hormone, promotes excretion of potassium ions (K+),and sodium ions (Na+) are actively reabsorbed; chloride ions (Cl–) follow passively. The juxtaglomerular apparatus is where the afferent arteriole contacts the distal convoluted tubule, and it secretes renin when blood pressure falls. Antidiuretic hormone is produced by the hypothalamus and secreted by the posterior pituitary in response to low water intake. Atrial natriuretic hormone is secreted by the atria of the heart when cardiac cells are stretched, promoting excretion of sodium ions (Na+), which causes water excretion.
What is the function of diuretics?
Diuretics are chemicals that increase the flow of urine.
Diuretic drugs developed to counteract high blood pressure decrease absorption of sodium ions (Na+); decreased water reabsorption, blood volume, and blood pressure follow.
If the hydrogen ion concentration increases in the blood, how does the respiratory system respond?
The respiratory center in the medulla oblongata increases the breathing rate if the hydrogen ion concentration of the blood rises. Breathing readjusts the proportion of carbonic acid and bicarbonate ions in the blood.
