Lecture 1 /2 Flashcards
What is hyponatremia and why does it leas to swelling of the brain?
Hyponatremia- a lack of sodium in the blood.
Low extracellular sodium. They are dehydrated going to keep drinking more water. Going to further dilute the sodium in their ECF. Initial effect: decreased osmolarity in ECF. This is going to cause water to move into your cells. So going to get osmotic diffusion of water into your cells. That is going to increase ICF Volume which will cause your cells to swell and you get a decrease in ECF volume. Overall you will get a decreased osmolarity of both ECF and ICF.
Issue is: low ECF sodium. Causes water to diffuse into cells. Becomes an issue for the brain- stuck in skull. Exerts pressure. Too much pressure will press onto brainstem. can leas to death.
Ultramarathon- depleted sodium. And throughout marathon they keep ingesting more and more water…
What is Renin?
Kidney can act as an endocrine gland and secrete this.
An enzyme that controls the formation of angiotensin, which influences blood pressure and sodium balance
What is the renal corpuscle made of?
Is the filtration unit of the corpuscle
1) bundle of capillary loops = glomerulus
Afferent arteriole feeding into glomerulus
Efferent arteriole
2) fluid filled Bowman’s capsule.
What is the order of fluid flow in renal tubules. Starting with the glomerulus.
1) GLOMERULUS
Fluid and substances filtered from
Glomerulus into the
2) BOWMAN’S CAPSULE the first part of renal tubules.
From bowman’s capsule fluid enters into the
3) PROXIMAL TUBULE
and then to LOOP OF HENLE
4) thin descending portion of loop of henle
5) thin ascending portion of loop of henle
6) thick ascending portion of loop of henle
These anatomical differences become quite important because there are different things being actively absorbed and diffused across these different sections of the loop of henle.
7) distal tubule
then they empty into the
8) collecting ducts
And from there it enters into the
9) ureters
There
What are the three processes involved in urine formation?
1) Glomerula filtration
2) tubular reabsorption
3) tubular secretion
Kidney plays an important role in composition of the solutes and the volumes of your body fluid compartments. The kidney does this by controlling what you lose in your urine.
It is the balance of these three components that determined the VOLUME AND COMPOSITION of the urine EXCRETED
What can diffuse through the glomerula capillaries?
‘Glomerula filtration barrier’
- passive; non-selective process
Small molecules filter freely
(H2O, glucose, amino acids) - larger molecules cannot freely cross the ‘glomerula filtration barrier’ (proteins)
Things like plasma proteins generally get retained within the capillaries in the plasma.
Filtrate inside Bowman’s capsule is virtually identical to plasma but essentially free of protein (0.02%)
How much blood is filtered through the glomerula capillaries?
Not everything is filtered through at once, essentially about 20% of your plasma volume will be filtered & the other 80% goes on into your efferent arteriole & then into your peritubular capillaries.
What body fluid compartment can we attribute these substances to?
1) Tritium oxide
2) inulin
3) evans blue
1) Tritium oxide is radioactive water.
Total body water
2) Inulin is a natural sugar, cannot cross cell membrane. Will only remain in ECF
Therefore can tell is volume of extracellular fluid.
3) Evans Blue has a high affinity for plasma albumin. It stays within the plasma portion of the body. Tells us the volume of the PLASMA portion
What happens in tubular reabsorption?
What happens in tubular reabsorption is that materials that have been filtered into the renal tubules go back and thus reabsorb back into peritubular capillaries.
Taking beneficial substances back into the body. Things that are going to be retained get reabsorbed into the peritubular capillaries.
What is tubular secretion?
Movement of solutes from the peritubular capillaries into the tubules.
A substance X has been secreted via tubular secretion. List the order of pathway starting at the interlobar artery.
What type of substance could substance X be?
1) interlobar artery
2) afferent arteriole
3) glomerula capillaries (not filtered)
4) efferent arteriole
5) peritubular capillaries
6) secreted (out of body) into the renal tubules.
To be excreted
Substance X could be an exogenous substance. Penicillin, diuretic drugs.
Metabolic substances such as ammonium and hydrogen ions produced and generated in the tubular cells.
Why are glomerula capillaries more efficient filters than other capillaries?
Glomerula capillaries more efficient filters than other capillaries because:
- high hydrostatic pressures driving filtration (55mmHg vs 18mmHg - in normal
Capillary beds)
This is possible because of having the system
Of 2 arterioles on either side of this capillary bed. - very large fenestrations (openings)
What are the layers of the glomerula filtration barrier?
Lumen of renal glomerula capillary
1) single-celled capillary endothelium. (Fenestrations, pores)
2) non-cellular basement membrane
3) single-celled epithelial lining of Bowman’s capsule. (Podocytes & filtration slits)
Bowman’s space
What could an increase or decrease in Glomerula filtration rate (GFR) mean to the function of the kidneys?
Increased glomerula filtration rate
Inadequate reabsorption –> important substances lost in urine
Decreased glomerula filtration rate
Reabsorption increased –> wastes not excreted
What is renal clearence ?
Renal clearence = the volume of plasma that is completely cleared of a particular substance by the kidney per unit time
