The Kidney Flashcards
What is the fluid released by kidney called
Filtrate
What are the calyces in the kidney
Cup shape cavities tk help collect filtrate
Why is maintaining blood pH important
Effect tertiary structure if not normal, anti body antigen complex, protein transporters, neurotransmitters & binding sites
Kidney function
Regulate fluid and electrolyte balance of the body by continually filtering the blood
This is vital to maintain a constant extra cellular fluid volume and composition
To perform these functions they are able to:
Excrete / conserve salt and water, control body pH, free body of waste products of metabolism
What are the 3 main processes that enable the kidneys to filter the blood
Glomerular filtration, tubule secretion, tubule resorption
What is glomerular filtration
Aka ultrafiltration
Where does blood enter the kidneys
Through the renal artery
Where does blood exit the kidneys
Through the renal vein
What is a nephron
The functional unit of the kidney
A series of tubules and associated capillaries
Each kidney has 1 million nephrons
How are substances filtered into the blood
Through ultrafiltration
Useful substances are reabsorbed into blood stream through selective reabsorption
What is the glomerulus
A ball of capillaries located inside a cup like sack called the Bowman’s capsule
Selective reabsorption process:
Once inside the nephron, molecules flow through a series of folded tubules.
○ Molecules initially flow through the proximal convoluted tubule (PCT).
○ They then pass through the loop of Henle.
○ Finally, molecules travel through the distal convoluted tubule (DCT).
● As useful molecules pass through the tubules, they are selectively reabsorbed by a
mixture of facilitated diffusion and active transport.
-Glucose is reabsorbed through active transport.
-Salts are reabsorbed through facilitated diffusion.
● Water is reabsorbed into the blood capillaries by osmosis.
● Waste products are passed to the bladder through the ureter.
● A mixture of water, salts and urea makes up urine.
-Urine is stored in the bladder until it is excreted during from the body during urination.
Process of osmoregulation:
Water is essential for a variety of metabolic processes.
○ It is therefore important that the water potential (ψ) of the blood is maintained.
● The maintenance of blood ψ is referred to as osmoregulation.
● Osmoregulation is an example of negative feedback:
○ If the ψ of the blood is too low (dehydration), the amount of water reabsorbed by the nephron
increases.
■ This means that less water will be excreted from the bladder, so the urine will appear more
concentrated.
○ If the ψ of the blood is too high (overhydration), the amount of water reabsorbed by the nephron
decreases.
■ This means that more water will be excreted from the bladder, so the urine will appear more
dilute.
● Water is primarily reabsorbed at the DCT, the loop of Henle and the collecting
duct.
The loop of henle
The loop of Henle is located in the middle of the kidney.
○ The middle of the kidney is referred to as the medulla.
● The loop of Henle is made up of 2 sections, called limbs.
○ The ascending limb (AL).
○ The descending limb (DL).
● The loop of Henle uses countercurrent multiplication to regulate the ψ of the blood.
○ This is a mechanism that uses energy to create a concentration gradient.
1. At the top of the AL, sodium ions (Na+) are actively transported out of the nephron, into
the medulla.
a. The AL is permeable to Na+, but impermeable to water.
b. This means that water will remain inside the AL.
c. A low ψ is now present in the medulla.
