Lecture 16 Flashcards
What are the four components of the urinary system?
- kidney
- ureter
- bladder
- urethra
How much do kidneys weigh each?
150g
How much blood flow do the kidneys receive?
25%
What is the purpose of the kidney?
to regulate the composition and volume of body fluids
What does the kidney do?
it filters the blood and controlling what substances and how much of the substances, along with water are excreted from the body
What are 5 functions of the kidney?
- regulation of water and ion balance, body pH
- excretion of metabolic wastes
- excretion of foreign chemicals
- endocrine functions (calcitriol, EPO, renin)
- gluconeogenesis
What are some metabolic wastes excreted by the kidney?
- when nucleic acids are broken down to uric acid
- creatinine from muscle
- when urea is broken down to amino acids
Give an example of foreign chemicals that are excreted by the kidneys
drugs
What is the purpose of calcitriol?
for the absorption of Ca2+ in the small intestine
How many litres of plasma are filtered by the kidneys per day?
180L
Of our 5L of blood, about 3L are plasma. How many times do we filter this 3L of plasma per day?
60
What percentage of the filtrate is reabsorbed?
99%
99% of the filtrate is reabsorbed. What happens to the other 1%?
it is excreted as urine
How may years does the kidney so without breaking down?
70 years
What are the 3 sections of the kidney called?
- capsule
- cortex
- medulla
Describe the capsule of the kidney
this is the outermost layer of the kidney and it covers the kidney
Describe the cortex of the kidney
this is the outer portion of the kidney (inner from the capsule) and it has invaginations into the medulla
Describe the medulla of the kidney
this is the inner most portion of the kidney and it is where the medullary pyramids are located
As well as the capsule, cortex and medulla, what else is there in the kidney?
What is this for?
the pelvis
this is for collecting the urine to take it to the ureter
What arteries supply the kidney?
the renal arteries
What veins take blood away from the kidney?
renal veins
The renal artery divides to ultimately form the _________ capillaries and _________ capillaries and the ________ _________ which surround the nephron
glomerular capillaries
peritubular
vasa recta
Which of the following statements is TRUE?
A. The kidney filters about 200 litres of plasma per day.
B. The kidneys do not produce hormones.
C. The Urinary system has three ureters.
D. The kidneys excrete foreign chemicals.
D. The kidneys excrete foreign chemicals.
What is the smallest functional unit of the kidney?
the nephron
Describe the epithelium of the of the nephron
This is the singular line of epithelial cells
How many nephrons are in each kidney when we are young?
1.2 million
What percentage of nephrons have we lost by age 60?
50%
What are the two different types of nephrons and where are these located?
- superficial (cortical) nephrons: the whole nephron is located in the cortex
- juxtamedullary nephrons which are are partially in the cortex and partially in the medulla
Which has a higher osmolarity, the division between the cortex and the medulla or further into the medulla?
further down into the medulla (300 mOsmolL-1 compared to 1200 mOsmolL-1
What are the different parts of the nephrons called?
- Bowman’s space/Bowman’s capsule
- proximal convoluted tubule
- proximal straight tubule
- descending thin limb of Henle’s loop
- thin ascending limb of Henle’s loop
- thick ascending limb of Henle’s loop
- distal convoluted tubule
- cortical collecting duct
- medullary collecting duct
Describe the vascular arrangement around the nephron
The blood comes in the renal artery then interlobular artery, afferent arteriole then forms the glomerular capillaries. There is then the efferent arteriole then the peritubular capillaries then further down, there is the vasa recta
What direction is reabsorption?
from the lumen of the proximal tubule to the blood
What direction is secretion?
from the blood to the lumen
What three things happens in nephron?
- glomerular filtration
- tubular secretion
- tubular reabsorption
What do we change to change the loss of stuff?
by changing the glomerular filtration rate
Which of the following statements is FALSE?
A. The Nephron is the smallest functional unit
of the kidney.
B. The afferent arteriole branches to make the glomerulus.
C. Each kidney contains more that 1 million nephrons.
D. Reabsorption of material is from the blood to the F lumen of the nephron.
D. Reabsorption of material is from the blood to the F lumen of the nephron.
Bulk flow of protein free plasma into the Bowman’s space forms the what?
filtrate
What does the filtrate contain?
everything in the plasma except the RBC and proteins
What two structures make up the renal corpuscle?
- glomerulus
- the Bowman’s capsule
Describe the glomerulus epithelium
What is the purpose of this?
It is fenestrated with a basement membrane to act as a sieve
What are the two epithelium of the Bowman’s capsule?
there is the outer epithelium and the inner epithelium which is the podocytes
What do the granulosa cells do? What is the purpose of this?
this produces renin for baroreceptor function
What sort of receptors do macula densa cells have?
osmoreceptor cells
What three things form the filtration barrier?
- fenestrated glomerular cells
- the basement membrane
- podocytes
What is fenestrated epithelium freely permeable to?
water, ions, and small solutes but not cells
Describe the basement membrane and what it acts as
This is a matrix of negatively charged proteins which act as a charge based filtration barrier to protiens
Describe the podocytes
These are specialised cells of the Bowman’s capsule. The gaps between the foot processes form the filtration barrier which prevents the filtration of proteins and large macromolecules
Jonah Lomu died from kidney disorder nephrotic syndrome in 2015. What does this disorder mean?
There is a structural problem of podocytes which means that there is
- increased permeabiltiy of filtration barrier to proteins
- an increase in proteins excreted in the urine
- an inability to concentrate urine, low plasma proteins can lead to edema
Which of the following statements is FALSE?
A. The renal corpusle contains the glomerulus and the Bowman’s capsule.
B. Podocytes do not aid with filtration.
C. The basement membrane is negatively charged
to assist filtration.
D. Jonah Lomu died from nephrotic syndrome.
B. Podocytes do not aid with filtration.
Ultrafiltration at the glomerulus is similar to ultrafiltration seen across tissue capillaries. What are the two different pressures?
- hydrostatic pressure (blood pressure)
- oncotic (osmotic) pressure which comes from the proteins
What is the pressure/s favouring filtration?
- glomerular capillary hydrostatic pressure (blood pressure)
What is the pressure/s opposing filtration?
- hydrostatic pressure (Bowman’s space)
- oncotic pressure due to proteins in the glomerular capillary
What is the net glomerular ultrafiltration pressure?
(Puf) = Pgc - Pbs - πgc
where
Pgc = the glomerular capillary hydrostatic pressure
Pbs = Bowman’s space hydrostatic pressure
πgc = oncotic pressure due to proteins in the glomerular capillary
Is pressure higher at the afferent end or efferent end?
afferent
