Lecture 14 - Renal system I Flashcards
What is plasma?
The fluid component of the blood, and usually represents about 55% of the blood by volume.
What is haematocrit?
A measure of the proportion of the blood occupied by cells (usually around 45%)
How do we measure body fluid compartments?
Inject a substance which is known to distribute in a given compartment, then calculate the ‘volume of distribution’ (Vd)
What is volume distribution?
The volume of fluid required to contain the total amount of drug in the body at the same concentrations that present in the plasma.
How do you calculate volume distribution (Vd)?
Vd=Q/Cp
Volume distribution = amount of drug/ plasma concentration fo
of drug
What is osmotic pressure?
The force (per unit area) required to oppose a new movement.
What are some examples of osmotic changes?
- Fall in plasma albumin caused by liver failure, protein malnutrition, renal failure.
- Effects of such include oedema, including peripheral, pulmonary, ascites and cerebral oedema.
What is the role of the kidney?
- Elimination fo endogenous and exogenous compounds.
- Maintenance of chemical homeostasis, including pH.
- Maintenance of volume status.
- Endocrine signalling.
What is the role of the lower urinary tract?
- Storage of urine
- Urination ot a socially appropriate time and place.
- Maintenance of continence
What is the interaction between the renal and gastrointestinal system?
- While the gut mostly regulates input, the kidney regulates output; equilibrium is the balance between the two systems.
- The gut can be a source of rapid water, K+, H+ or HCO3- loss; there are no infrequently high inputs from the gut; the kidney is key to returning equilibrium.
- Hepatic failure; through hypoalbuminemia, causes large changes in renal fluid handling.
What is the interaction between the renal and cardiovascular system?
- Maintenance of blood pressure through a regulation fo volume and hence filling pressure.
- Regulating the tight ionic composition required for appropriate cardiac muscle function.
- Regulation of volume required for vascular filling|: adaptation of hypovolemic shock.
What is the interaction between the renal and respiratory system?
- Regulation pH; metabolic and respiratory acidosis /alkalosis.
- Joint metabolic pathways for the regulation fo the renin/angiotensin system.
What is the interaction between the renal and endocrine system?
- Through the renin-angiotensin system, it regulated the secretion of aldosterone from the adrenal cortex, hence renal Na+, K+ and water regulation.
- Vitamin D regulation, and hence regulation of Ca2+
- Is the target of central hormonal control by vasopressin.
- Diabetes; the kidney is a common target organ and ultimate cause of death in many with diabetes. It is the commonest cause of end stage renal failure.
What is the interaction between the renal and autonomic nervous systems?
- Kidneys receive an afferent innervation and efferent nerve controlling blood flow in the kidney. This interaction is currently the target of new clinical therapies for hypertension, particularly renal denervation.
- Autonomic innervation of the bladder and urethra are essential for controlling the storage of urine and micturition.
What is the interaction between the renal system and haematology?
- Through erythropoietin, the kidneys regulate the production fo erythrocytes.
- Many haematological malignancies lead to renal disease, through the deposition of antibodies (e.g., myelomas, leukaemia, etc).
