M104 T3 L2 Flashcards
What are the functions of the urinary system?
Excretion
Elimination
What are the essential functions of the kidneys?
excreting endogenous waste products excreting drugs and their metabolites balancing water and electrolyte levels maintaining the acid-base balance the production of hormones
What happens to the essential functions of the kidneys during kidney failure?
reduced renal excretory function
reduced renal excretory function
can’t maintain salt - water balance and acid-base balance
compromised hormone function
What are the effects of renal function if severe and untreated?
then it leads to death
What are examples of conditions that can arise when there is a reduction in renal excretory function?
azotaemia, uraemia
What is an example of a consequence of that can arise when there is a reduction in renal excretory function?
drug toxicity
What percentage of renal failure cases are accounted for by Acute Kidney Injury?
about 10%
What percentage of renal failure cases are accounted for by chronic kidney disease?
about 90% of renal failure
What are the differences between AKI and CKD?
AKI - rare and suddenly occurs
CKD - much more common but takes months / years to develop
In renal failure, how is renal function supplemented?
artificially, either by dialysis or by a transplanted kidney
Where are the kidneys located?
on the posterior wall of abdomen
behind the peritoneum
on either side of the vertebral column
How much does each kidney weigh in an adult human?
120-170 g
What are the approx dimensions of each kidney in an adult human?
11 cm long, 6 cm wide, 3 cm thick
What structures are the kidneys connected to on their medial side? (RaV.UN)
renal artery & vein
ureter, nerves
What proportion of the population have one kidney only, due to agenesis?
1 in 750, mostly males
What are the two major layers of the kidneys?
Cortex (outer layer)
Medulla (inner layer)
How many nephrons make up the cortex?
~ 1.25 M nephrons
What two things are the nephrons responsible for?
urine formation and composition
Where do the Medulla drain into?
the ureters
What happens to the amount of nephrons in the cortex with age?
the numbers (and therefore renal function) decline with age
How many nephrons are lost per year from about 50 years?
10,000 nephrons
GFR 50% of normal adult rate by age 75
What are the five distinct sections of nephron?
Renal corpuscle
Proximal tubule, Distal tubule
Loop of Henle
Collecting duct
What does a renal corpuscle consist of?
glomerulus
Bowman’s capsule - a glomerular capsule
What is a renal corpuscle otherwise known as?
malpighian body
What are the two types of nephron?
cortical
juxtamedullary
What percentage of all nephrons in a body are cortical?
70-80% of all nephrons in human
What percentage of all nephrons in the kidneys are juxtamedullary?
20-30%
Where are cortical nephrons located?
in the cortex, in the short Loop of Henle into medulla
Where are juxtamedullary nephrons located?
Situated closer to medulla, where the Loop of Henle extends deep into the renal pyramids
What percentage of cardiac output goes to the kidneys?
20%
What is the high percentage of cardiac output that goes to the kidneys used for?
E-consuming transport processes
What is the innervation of the kidneys?
Sympathetic postganglionic fibres
Parasympathetic efferent supply (vagus)
What is the role of the sympathetic innervation of the kidneys?
to supply the arteries, afferent and efferent arterioles and granular cells
What is the effect of the sympathetic innervation of the kidneys?
reduces blood supply to kidney during stress (fight or flight response)
Where does the parasympathetic efferent supply come from?
from the vagus nerve - ganglion in hilum
What is the effect of the parasympathetic innervation of the kidneys?
may control tone of efferent arterioles
may modify glomerular filtration rate and renal blood flow
Where does the sympathetic efferent supply come from?
from the sympathetic chain and fibres from coeliac ganglion
What are the three major functions of the nephrons?
filtration (produces a filtrate)
reabsorption
secretion of waste products into tubular fluid
What are the two lesser functions of the nephrons?
Transcellular and Paracellular transport
What substances are reabsorbed in the nephrons?
water, ions and organic nutrients
Where does filtration occur at?
the glomerulus
What is the initial step in urine formation?
glomerular filtration
What small molecules are filtered out at the glomerulus? (MEAG.DM)
Metabolic waste, Electrolytes
amacs, glucose
some drugs, metabolites
What substances remain in the blood during glomerular filtration?
RBCs, Lipids
Proteins
Most drugs, metabolites
What percentage of filtered water, electrolytes and nutrients are reabsorbed back into the blood?
more than 99%
How are substances reabsorbed in the kidneys?
down concentration and/or electrochemical gradients co- transport
osmotic gradient via aquaporins
What does the reabsorption of solutes require?
E (ATP) to drive Na+ reabsorption via the Na+K+ATPase transporter
What type of substances can’t be filtered at the glomerulus?
some endogenous substances and drugs
Why can’t some substances be filtered at the glomerulus?
due to their size or their protein binding
What can transport compounds from the plasma into the nephron for excretion?
specialised pumps in the PT
What are the two types of pumps that can transport compounds from the plasma into the nephron for excretion?
pumps that transport organic acids or drugs
pumps that transport organic bases or drugs
