Lecture 33 Flashcards
What are the four critical parameters of body fluids
- Volume
-Osmolarity - The individual concentrations of specific solutes
-pH
How can water/solutes be gained
- Eating/ drinking
- Biochemical reactions that interconvert solutes
- Aerobic metabolism (H2O is a byproduct of aerobic metabolism)
How are water/solutes voided
- H2O evaporation across permeable epithelia
-Excretion via urine and feces - Excretion via exocrine glands
How can the stability of fluid volumes and osmolarity be maintained?
By altering the amount and concentration of urine produced is (main mechanism)
How is urine produced?
Through a combination of active transport and very specific anatomical adaptations
-Urine is produced from blood plasma
What is hyperosmotic, hypoosmotic, and isosmotic urine?
U/P>1 Hyperosmotic (more solutes per unit volume in urine compared to plasma)
- Urine is less dilute than plasma
U/P<1 Hypoosmotic (less solutes per unit voume in urine compared to plasma)
- Urine is more dilute than plasma
U/P=1 isoosmotic (formation of urine leaves the ratio of solutes to water in the plasma unchanged)
- isoosmotic urine can still be a part of body fluid volume regulation
What is the two main functional zones that the kidney is subdivided into?
- Cortex (outer)
- Medulla (inner)
Where is the urine formed and drained?
Urine is formed in the cortex/medulla and drains into the central calyces (most inner part of the medulla) and then out via the ureter (carries the urine to the bladder)
Describe the function of the nephron
1.) Blood plasma is filtered into the lumens of nephrons through the afferent arteriole side, excluding red blood cells and most proteins
2.) Solutes and water are reabsorbed from and/or secreted into the filtrate via passive and active processes.
3.) Filtration/reabsorption/ secretion rates can be modified semi-independently under neuroendocrine control.
4.) Fully formed urine is ready to be excreted into the environment. (urine exits to the bladder)
What equals the amount of solute excreted?
Amount filtered- amount reabsorbed + amount secreted (back into the lumen of the nephron)
What direction is the net filtration rate?
From plasma to Bowman’s capsule
Where is primary urine initially formed by (ultra)filtration of blood plasma?
Glomerular capillaries (glomerulus) into the Bowman’s capsule of the nephron
- Each nephron has a bowman’s capsule.
What is the afferent and efferent arterioles for?
Afferent arteriole is for moving solutes AWAY from the region.
Efferent arterioles is for moving solutes towards an important region.
- Blood flows in through the afferent arteriole and goes though the glomeruli
- Whatever does not filter leaves through the efferent arteriole.
What is the first major energy input into kidney function?
The first place we put energy is through the pumping action of the heart (generates blood pressure)
- The high hydrostatic pressure keeps the process going and ensures filtration happens at a proper direction
What does the glomerular filtration exclude, but allow to enter the lumen of the nephron?
Passes through:
- water
- electrolytes
- glucose
- amino acids
- fatty acids
- vitamins
-urea
- uric acid
- creatinine
Excludes:
- blood cells
- plasa proteins
- large anions
- protein bound minerals and hormones
- most molecules greater than 8nm.
