Physiology 4 Flashcards
What is GFR in litres per day
180litres per day
What substance does the kidney reabsorb
Fluid Salt Glycose Amino acids 50% of urea 0% creatinine
Reabsorption is specific/ non specific and filtration is specific / non-specific
Reabsorption os specific
Filtration is non-specific
How often is plasma filtered per day
Around 65 times
What is the initial tubular fluid
a modified filtrate of the blood
What does the blood have that the initial tubular fluid doesn’t have
RBC
Plasma proteins
How much fluid is reabsorbed in the proximal tubule
80ml/min of filtered fluid
What does iso-osmotic mean
There is no change in the osmolarity between one area and an other
What is the osmolarity of the proximal tubular fluid
300 (same as plasma)
Why is there no change in the concentration of things in the proximal tubule
we reabsorb salt and water in equal portions
Fluid reabsorbed in the proximal tubule is said to be: a) Hypo-osmotic b) Iso-osmotic c) Hyper-osmotic with the filtrate Why
Iso-osmotic
We reabsorb salt and water in equal portions so there is not change in the concentration of things in the proximal tubule
What are some substances that are reabsorbed in the Proximal tubule
sugars amino acids phosphate sulphate lactate
What are some substances that are secreted i the proximal tubule
H+ Hippurates Neurotransmitters Bile pigments Uric acid Drugs Toxins
What is transcellular reabsorption
Substances that are to be reabsorbed into the blood via a number
What are the tight junctions and what do they do
Protein junctions
Help to separate the apical luminal membrane and the basement membrane
What determines the amount of the substance that is reabsorbed back into the blood
Whether a cell junction is tight or leaky
What are the 3 ways in which substances can be moved across the membrane
Primary active transport
Secondary Active Transport
Facilitated division
Describe what happens in primary active transport
Energy is directly required to operate the carrier and move the substrate against its concentration gradient - hydrolysis of ATP is required
Describe what happens in secondary active transport
The carrier molecule is transported coupled to the concentration gradient of an ion (usually Na+)
Sodium comes from outside to inside the cell and with this moves another molecule either in the same direction (symporter) or second
What happens in facilitated diffusion
Passive carrier-mediated transport of a substance down its concentration gradient to get a molecule to move a substance from one side of the membrane to the other. The concentration gradient already exists
Give an example of primary active transport
Na/ K pump
Give an example of secondary active transport
Na/ glucose
What are some other ways in which molecules can move in or out of a cell
Diffusion through the lipid layer (O2 and CO2)
Diffusion through channels (ions)
Where is the sodium potassium pump found
lateral membrane of the epithelial cells
For every 1 ATP molecule used in the K/Na transporter, how many of each ion would be moved
3Na out of the cell
2K in of the cell
What does the K/Na pump do
helps to keep the concentration the same
