Week 1 Flashcards
What is osmolarity?
Concentration of osmotically active particles present in a solution.
What two factors allow osmolarity to be calculated?
- Molar concentration of the solution
2. Number of osmotically active particles present
What happens to a cell in a hypertonic solution?
Shrinkage
What happens to a cell in a hypotonic solution?
Lysis
What is the tonicity of sucrose solution and urea?
Sucrose - isotonic
Urea - hypotonic
What two components does total body water exist as?
ICF (67%) and ECF (33%)
What four substances does extracellular fluid contain?
- Plasma (20%)
- Interstitial fluid (80%)
- Lymph
- Trascellular fluid
What is the tracer for TBW?
H2O
What is the tracer for ECF?
Inulin
What is the tracer for plasma>
Labelled albumin
How do you measure distribution volume of a tracer?
- Add known quantity of tracer to body
- Measure equilibration volume of X in body
- Distribution volume is tracer added divided by equilibration volume
Name two insensible losses of water from the body
- Skin
2. Lungs
Name 3 sensible losses of water from the body?
- Sweat
- Faeces
- Urine
Is there more sodium outside or inside the cell?
Outside
Is there more potassium outside or inside the cell?
Inside
Is there more chloride outside or inside the cell?
Outside
Is there more bicarbonate outside or inside the cell?
Outside
What can be said about the osmotic concentrations of both ECF and ICF?
Identical
In relation to fluid shifts - what happens when there is a gain or loss of water?
Change in fluid osmolarity and similar changes in ICF and ECF volumes so both increase or decrease
In relation to fluid shifts - what happens when there is a gain or loss of NaCl?
Change in fluid osmolarity. Na excluded from ICF and osmotic water movements. These two factors combine to produce opposite changes in ICF and ECF volumes.
In relation to fluid shifts - what happens when there is a gain or loss of isotonic fluid?
No change in osmolarity so change in ECF only
What structure alters the composition and volume of ECF?
Kidney
90% of the osmotic concentration of the ECF results from what?
Sodium salts
What is the nephron composed of?
Renal corpuscle and renal tubules
What is the renal corpuscle composed of?
Glomerulus and Bowman’s capsule
Two layers seperate the blood from the glomerular filtrate: the capillary endothelium and a specialised epithelium which lies on top of the glomerular capillaries - what are these epithelial cells called?
Podocytes
What function do mesangial cells have?
Support and removl of debris
What distinctive feature do proximal convuluted tubules show?
Hairy appearance to apical ends of cells
Where is the loop of henle located?
In the medulla
What cells line the thick ascending limb of the loop of Henle?
Simple cuboidal cells with abundant mitochondria
What is the term for thin walled blood vessels that dip down into the medulla from above and then climb back up to the cortex?
Vasa recta
What lines distal convoluted tubules?
Lined by simple cuboidal epithelium however unlike the proximal tubules dont have a brush border of microvilli
In the medulla the collecting ducts are gathered together in parallel bundles called what?
Medullary rays
What lines the collecting ducts?
Simple columnar epithelium
What is the term for the specialised region formed at the site where the distal convuluted tubule passes adjacent to the vascular pole of the same renal corpuscle that forms part of its very own nephron?
Juxtaglomerular apparatus
What three things make up the juxtaglomerular apparatus?
- Macula densa
- Juxtaglomerular cells
- Extraglomerular mesangial cells
What part of the juxtaglomerular apparatus is on the side of the distal CT and is beleived to function in sensing ion composition in teh DCT?
Macula densa
What part of the juxtaglomerular apparatus is modified smooth muscle cells in the wall of the afferent arteriole?
Justaglomerular cells
What cells secrete renin?
Juxtaglomerular cells
What part of the juxtaglomerular apparatus are modified mesangial cells extending outside of the renal corpuscle?
Extraglomerular mesangial cells (lacis cells)
What are most of conducting parts of urinary tract lined by?
Transitional epitheliun or urothelium
In the conducting parts of urinary tract what are cells at the luminal surface called?
Umbrella cells - sepcial thickened and inflexible membrane
What is the lining of the female urethra?
Initially transitional epithelium then stratified squamous at termination
What is prostatic urethra lined by?
Transitional epithelium
What is membranous urethra lined by?
Transitional epithelium changing to stratified columnar
What is the lining of penile urethra?
Stratified columnar then stratified squamous
What structure has tubulo-alveolar glands lined typically by simple columnar secretory epithelium?
Prostate
What do the kidneys do to vitamin D?
Turn it into active form calcitriol
What are the two types of nephron?
Juxtamedullary 20%
Cortical 80%
What is the difference between juxtamedullary and cortical nephrons in relation to the loop of Henle?
Much longer in juxtamedullary nephron
What is urine?
Modified filtrate of the blood
How much plasma that enters the glomerulus is filtered and how much leaves through the efferent arteriole unfiltered?
20% filtered
80% unfiltered
For any substance - what does filtration + secretion =
Resorption + excretion
What is the rate of filtration calculation?
Rate of X = [X]plasma x GFR
What is the rate of excretion equation?
Rate of X = [X]urine x Vu (urine flow rate)
If rate of filtration is bigger than rate of excretion then what has occured?
Net reabsorption
Rate of reabsorption of X = ?
Rate of filtration of X - rate of excretion of X
If rate of filtration is less than rate of excretion, what has occured?
Net secretion
Rate of secretion of X = ?
Rate of excretion of X - rate of filtration of X