Lecture 17- Kidney Physiology Flashcards
(33 cards)
What makes up the urinary system?
2 kidneys, 2 ureters and bladder
What protects the kidneys?
ribs
How are the kidneys protected?
by the dorsal and ribs fused to the body wall
What is the cardiac output of the kidneys?
they filter 1.2 litres a minutes and recieve 25% of the blood
What is the kidney cortex made up of?
Cortex (outer pale layer) and the medulla
(pinky central area) contain nephrons. Highly perfused by blood vessels
What is the hilum?
: entry/exit of blood vessels, veins
and ureter
What are the nephrons and what are their characteristics?
Nephrons are the functional units, they are a
complex tubular structure that enables the
refinement of the filtrate, which will
eventually be excreted, based on what
components the blood needs.
What are the key parts of the kidneys?
3 main areas:
* Renal Corpuscle (Bowman‘s capsule& Glomerulus)
* Renal Tubule (filtrate)
* Collecting Duct
What is the difference in the functioning of the 2 nephrons?
*Two different kinds of nephrons:
* Cortical - deliver nutrients to the epithelial cells.
- Juxtamedullary – serve as osmotic exchangers for the production of
concentrated urine
Draw the structure of the nephron
How does blood travel through the nephron?
Fluid moves:
* through the barrier
of the Glomerulus
into Bowman‘s
capsule
* down the proximal
tubule
* down the loop of
henle
* In the distal tubule
* In the collecting duct
* out the renal vein
How does fluid travel through the nephron?
Fluid moves:
* through the barrier
of the Glomerulus
into Bowman‘s
capsule
* down the proximal
tubule
* down the loop of
henle
* In the distal tubule
* In the collecting duct
* out the renal vein
What is the renal corpuscle?
Sieve function
Movement back in circulation
Specific particles: big/charged Removed out of body
What is the renal tubule?
The renal tubule is involved in the reabsorption and secretion of various substances
What is the collecting duct?
The collecting duct receives filtrate from multiple nephrons and carries it towards the renal pelvis for excretion as urine.
It is lined with both principal cells and intercalated cells, which are involved in the reabsorption of water and electrolytes, as well as the secretion of potassium, hydrogen ions, and ammonia.
The collecting duct plays a crucial role in the final concentration or dilution of urine, depending on the body’s hydration status.
secretion and reabsorption occurs here
Where do filtration, reabsorption, secretion and excretion occur?
Filtration is the selection of blood components only based on size
(like a sieve)
Reabsorption is the movement of ions, flowed by water, back into the
capillaries from the lumen of the nephron. Greatest amount happens
in the proximal convoluted tubule. This process is much more
important than secretion for most (but not all) substances (in terms of
determining excretion rate).
Secretion is movement of molecules from the blood into the lumen of the nephron, more selective than filtration.
Excretion is the removal of urine from the body.
Summarise the nephron
- The functional unit of the kidney.
- Responsible for blood processing.
- Change in the types of cells along the length of the nephron to
enable it to perform its function. - 3 main areas:
- Renal Corpuscle (Bowman‘s capsule& Glomerulus)
- Renal Tubule (filtrate)
- Collecting Duct
- Two different kinds of nephrons:
- Cortical - deliver nutrients to the epithelial cells.
- Juxtamedullary – serve as osmotic exchangers for the production of
concentrated urine.
What are the different processes occurring in the nephron and at what rates?
Filtration is the selection of blood components only based on size
(like a sieve)
Reabsorption is the movement of ions, flowed by water, back into the
capillaries from the lumen of the nephron. Greatest amount happens
in the proximal convoluted tubule. This process is much more
important than secretion for most (but not all) substances (in terms of
determining excretion rate).
Secretion is movement of molecules from the blood into the lumen of the nephron, more selective than filtration.
Excretion is the removal of urine from the body.
What is the glomerular filtration process?
Glomerular filtration is the process by which blood is filtered across
the capillaries of the glomerulus and into Bowmans Capsule.
▶ The movement of fluid from the vascular space to Bowmans Capsule is
also known as ultrafiltration and the fluid us known as ultrafiltrate.
▶ The ‘ultrafiltrate’ fluid has a similar
composition to plasma (isotonic) but
with no protein/cells.
▶ The filtration barrier restricts movement
of solutes on a basis of size and charge
Why are podocytes important?
▶ Podocytes: finger-like projections on
glomerulus
What is ultrafiltration and what are the properties of the ultrafiltrate?
ultrafiltration in the kidneys refers to the selective removal of water, electrolytes, and small solutes from the bloodstream in the renal corpuscles, forming the glomerular filtrate that enters the renal tubules for further processing and urine formation
▶ Small molecules < 1.8 nm freely filtered; >3.6 nm not filtered.
▶ Cations are more readily filtered than anions with the same
molecular radius.
▶ Albumin has a radius of ~3.5 nm (LIMIT), but its negative charge
prevents filtration.
▶ In many diseases the negative charge on the filtration barrier is
lost so that proteins (e.g. albumine) are more readily filtered and
appear in the urine, known as proteinuria
What does a filtration barrier restrict?
The filtration barrier restricts movement
of solutes on a basis of size and charge.
What are the pedicels of the bowmans capsule?
▶ Podocytes: finger-like projections on
glomerulus
Draw the structure of the membrane at Bowman’s capsule
