Lecture 10 Flashcards
Briefly describe the cellular signalling/signal transduction pathways in epithelia
There is a stimulus which causes a ligand to be released. This binds to the receptor in the membrane or intracellularly. There is signal transduction through a 2nd messenger or other wats. We then need to be able to turn it off and so there is negative feedback
Where are receptors location and what sorts of things bind to them?
Water soluble ligands bind to plasma membrane receptors and lipid-soluble ligands bind to cytoplasmic or nuclear receptor
What is an example of a lipid soluble ligand that binds to a receptor inside the cell?
a steroid
Lipid soluble ligands tend to alter what?
they alter gene expression
Which is faster at causing an effect, water-soluble or lipid-soluble ligands. Why is this?
The water soluble ones because lipid soluble ligands alter gene expression and so there needs to be time for the genes to transcribe, translate and for there to movement of the required genes
Briefly describe G-protein coupled receptors
There is a receptor and a G-protein which is made up of an α, β, and γ subunit. When the ligand binds to the receptor, the G-protein becomes associated with the receptor. GTP is converted to GDP and then there is dissociation of these subunits and they can go off and do stuff
What is the function of the kidney?
it filters blood removing wastes and extra water to make urine
What does the kidney control?
blood pressure
What are the three main hormones that regulate NaCl and water transport pathways in the kidney tubules?
- angiotensin II and aldosterone
- atrial natriuretic peptide (ANP)
- antidiuretic hormone/vasopressin
What is the purpose of angiotensin II and aldosterone?
to increase the NaCl and water reabsorption to increase blood pressure
What is the purpose of atrial natriuretic peptide?
to decrease NaCl and water reabsorption
What is the purpose of antidiuretic hormone/vasopressin?
to mainly increase water reabsorption
Briefly describe the angiotensin II signal transduction in the adrenal cortex stimulating aldosterone release
In response to a low blood pressure, angiotensin || acts on the adrenal glands which release aldosterone which causes an increase in the Na+ uptake from the kidney tubules and increase blood pressure
What stimulates angiotensin II signal transduction in the adrenal cortex?
low blood pressure
Describe the angiotensin II signal transduction in the adrenal cortex
In response to low blood pressure (sensed via low perfusion pressure in the kidneys and a decrease in NaCl to the macula densa) renin is released from the kidneys and this cleaves angiotensinogen (from the liver) to form angiotensin I which is further cleaved by ACE to form angiotensin II. Angiotensin II binds to the AT1 receptor on the zona glomerulosa cells of the adrenal cortex
How does the kidney know that there is low blood pressure?
there is low perfusion pressure in the kidneys and a decrease in NaCl to the macula densa