Excretion (Unit 13) Flashcards
(22 cards)
What is excretion?
Excretion is the removal of toxic materials and substances in excess of requirements from organisms, including waste products from metabolic reactions, excess water, and excess salts.
How does excretion differ from egestion?
Excretion involves removing waste products from metabolism, while egestion refers to the expulsion of undigested food in the form of feces.
Why is excretion necessary for maintaining homeostasis?
Excretion is necessary to remove waste products like urea and CO2 from body fluids, preventing toxic buildup, maintaining proper pH levels, and ensuring oxygen binds effectively to hemoglobin.
Where does urea come from in the body?
Urea is formed by the breakdown of excess amino acids in the liver through a process called deamination, where the nitrogen-containing part of amino acids is removed.
What are the main functions of the kidneys in the excretory system?
The main functions of the kidneys are filtration and reabsorption, which include glomerular filtration, tubular reabsorption, and urine formation.
What are the three steps involved in urine formation?
The three steps in urine formation are:
Glomerular Filtration
Tubular Reabsorption
Formation of urine
What occurs during glomerular filtration?
During glomerular filtration, blood enters the glomerulus under high pressure, filtering out water, nutrients, salts, wastes, and toxic compounds into the Bowman’s capsule.
Where does tubular reabsorption occur?
In the proximal convoluted tubule (PCT)
How is water reabsorbed into the blood capillaries from the filtrate in the PCT?
By osmosis
How are nutrients reabsorbed from the filtrate into the blood capillaries in the PCT?
By active transport
What remains in the nephron tubule after reabsorption in the PCT?
Wastes and toxic substances
What is the function of Loop of Henle?
It concentrates the filtrate by removing more water, which removes into the distal convoluted tubule (DCT)
What does the concentrated filtrate become after entering the collecting duct?
Urine, containing urea, excess water, and ion
Describe the path of urine from the kidneys to its exit from the body
Urine moves from the Renal pelvis to the ureter, then to the bladder for temporary storage, and exits the body via the uretra.
What is the nephron?
Functional unit of kidney responsible fr filtering blood and forming urine
What are the main parts of the nephron?
The nephron consists of the renal corpuscle (glomerulus and Bowman’s capsule) and the renal tubule (proximal tubule, loop of Henle, distal tubule, and collecting duct).
What is the glomerulus?
The glomerulus is a network of capillaries where blood filtration begins, located within the renal corpuscle
What is the role of Bowman’s capsule?
Bowman’s capsule surrounds the glomerulus and collects the filtrate that is filtered out of the blood
What is the proximal convoluted tubule?
The PCT is the first part of the renal tubule where reabsorption of water, ions, and nutrients from the filtrate occurs.
What is the loop of Henle?
The loop of Henle is the U-shaped portion of the nephron that creates a concentration gradient in the medulla to facilitate water and sodium reabsorption
What i the dista convoluted tubule?
The DCT is the part of the renal tubule that further regulates sodium, potassium, and pH balance in the filtrate.
What is the collecting duct?
The collecting duct is where multiple nephrons’ filtrate collects, and it plays a role in the final concentration of urine before it enters the renal pelvis
