Summary Renal Physiology

Renal Physiology
Functions of the kidney
Homeostasis
 Body’s ability to maintain a stable and constant internal environment.
 Despite changes.
 This includes:
o Regulation of blood volume
o Regulation of blood pressure
o Regulate osmolarity (ion levels)
o Acid-base balance
Excretion
 Remove metabolites.
 E.g., urea which is a product of protein metabolism
 Excretes chemicals and therapeutic drugs.
Endocrine System
 The kidneys also play a part in the endocrine system and the production of new red
blood cells.
 Known as erythropoietin.
 The kidneys produce erythropoietin (EPO)
 This stimulates the bone marrow to produce new red blood cells.
 Low oxygen means the kidneys secrete more EPO.

 When blood pressure drops, renin is secreted by the kidneys.
 This acts on angiotensin to form angiotensin II.
 This is a vasoconstrictor.
 To increase blood pressure.
Renal Function
 Vasa rector: capillaries after the bowmans capsule
 Refer to diuretics lecture.

Drugs and renal Physiology
 Drugs are highly bound to plasma proteins.
 Making it unlikely to be filtered effectively.
 So, remains in the bloodstream and lasts longer in the body.

GFR and creatinine clearance
 Glomerular filtration rate
 The rate at which kidneys filter the plasma.
 Indicates kidney health.
 Can be estimated using eGFR by measuring blood creatinine levels.
 Muscles use creatinine as a energy source
 Creatine is converted to creatinine.
 And creatinine is removed from the body by the kidneys.
 This is usually constant and the rate it is cleared depends on kidney function.