Unit 8: Excretory System Flashcards
what is elimination
the removal of undigested material
what is excretion
the removal of metabolic wastes
does the digestive system perform elimination or excretion
it performs elimination
does the excretory system perform elimination or excretion
it performs excretion
explain the general function of the excretory system(aka the urinary system)
it removes metabolic wastes from the blood while reabsorbing useful molecules
what are the 4 specific roles of the excretory system
excretion of metabolic wastes, regulation of water and salt in blood (osmoregulation), regulation of acid and base balance, and the secretion of hormones
what is the main organ in the excretory system?
kidney
What organs make up the urinary tract?
Kidneys
Ureters
Urinary Bladder
Urethra
What are nephrons and what do they do?
Nephrons make up the kidney and they perform filtration of the blood and produce urine
they are tiny regions in the kidney that connect to the renal capillaries and filter the blood
a single nephron consists of a small network of capillaries that are interwoven with tubules that act to filter and remove waste molecules
explain the process of urination
the bladder fills to a point where the stretch receptors send a signal to the spinal cord. the spinal cord then sends nerve impulses to the urinary bladder which causes the sphincters to relax and open. urine leaves the body.
break down the nephron into parts
it can be broken down into the glomerulus, the proximal convoluted tubule, the loop of henle, the distal convoluted tube, and the collecting duct
what are the three processes of the formation of urine
pressure filtration, selective reabsorption, and tubular excretion
what is pressure filtration and where does it occur
it is when the glomerulus moves molecules from the blood into the tubule.
when blood enters the glomerulus, it is subjected to high pressures due to the folding of the capillaries. this high pressure causes water and small molecules(nutrients, nitrogenous wastes, ions) to move from the glomerulus into the surrounding glomerular capsule. large molecules and formed elements will not be able to pass through the capillary walls and will remain
what is selective reabsorption and where does it occur
it is when the convoluted tubules move molecules from the tubules into the blood
molecules are reabsorbed into the blood capillaries from the nephron. sodium ions are actively reabsorbed into the capillaries which causes chlorine ions to follow passively because of their attraction(their charges), and this causes the concentration of salt (NaCl) in the blood to increase which causes water to move from the tubule back into the blood passively. through selective reabsorption, most nutrients are absorbed
what is tubular excretion and where does it occur
it is when the convoluted tubules move molecules from the blood into the tubule
molecules are moved from the blood capillaries into the tubules to be excreted through the collecting duct. the secreted molecules are often actively transported into the convoluted tubules as they weren’t previously done so at the glomerulus because of their size
