1.8 Excretory System Flashcards
What is the biochemical reaction carried out by living things called? What is the removal of their products called?
Metabolism
Products of metabolism include carbon dioxide and urea (contains nitrogen) are removed from the body through excretion
What is the main responsibility of the excretory system?
Removing waste products from the body and maintaining the correct levels of water and dissolved substances in the body (osmoregulation)
What is the main function of the kidneys?
1) To filter out waste products from the blood
2) Balance the concentration of water, pH and other dissolved substances
What are the two regions of the kidney?
Cortex: outer region
Medulla: inner region
Where does the blood enter from? Where does the filtered blood leave?
Enters from the renal artery
Leaves by the renal vein
What is the nephron?
The structural and functional unit of the kidney that allows urea to be removed
Name the three main elements of the nephron.
1) Glomerulus (ball of capillaries) contained in the Bowman’s capsule
2) A renal tubule surrounded by blood capillaries
3) Collecting duct which the tubule drains into
How do nephrons regulate the composition of the blood? What are the processes called?
Filtration and reabsorption
What is the small artery blood travels through called?
afferent arteriole
How does the blood end up in the Bowman’s capsule?
Forced out of the capillaries due to the blood pressure in the glomerulus capillaries
What is reabsorption?
- What is reabsorbed?
- What is not reabsorbed?
The selective process where the nephron moves water and essential solutes from the tubules back into the bloodstream
- water, glucose and amino acids
- excess water and urea
Where is the proximal convoluted tubule located?
Closest to Bowman’s capsule
How are the selected substances reabsorbed? How is water reabsorbed?
Salts, glucose and amino acids are reabsorbed into the capillaries by diffusion and active transport. Water is reabsorbed via osmosis.
What happens down the loop of Henle?
Water continues to be reabsorbed
Water decreases, the solute concentration increases
95% of water lost is reabsorbed
5% remaining is needed for urine
As the filtrate goes up the loop of Henle, what happens to the remaining salts?
The remaining salts are reabsorbed into the capillaries by active transport and diffusion
Where is the distal tubule located? What is its function?
In distant proximity to the Bowman’s capsule
Reabsorbs calcium, sodium and chloride
Regulates the pH of the blood
What is the collecting duct? What is its function?
Receives unwanted blood and it drains into the bladder (storage for urine) via the ureter to be excreted out of the body as urine
What is the importance of filtration and reabsorption?
F- Unnecessary substances from the bloodstream can be expelled by filtration
R- specific substances in the filtrate can return to the bloodstream
What is osmoregulation?
Maintaining the correct balance of water and salt in the blood
The rate of reabsorption for osmoregulation is influenced by hormones
How does ADH (anti diuretic hormone) control the reabsorption of water
ADH presence allows the collecting duct to be permeable to water – water is reabsorbed into the body
Less ADH makes the walls less permeable to water
If you are dehydrated what happens to your urine?
Dehydration could mean less water and a higher concentration of salt.
ADH will be released (by the pituitary gland) to make the collecting duct more permeable to water. Therefore, more water is reabsorbed in the surrounding vessels in the medulla through osmosis
How can severe kidney diseases be treated?
Severe kidney disease can be treated through dialysis or kidney transplant
