Physiology of renal introduction Flashcards
(20 cards)
What is the intake of water?
2.4L per day, but variable.
From drinking, food, and metabolism.
What is the output of water?
Exhale air and water vapour.
Skin - sweating
Faeces
Urine -has the greatest independent control to maintain water body balance. Other factors are highly variable, depending on temperature, metabolic rate and diet.
What are the body fluid compartments?
Plasma is made up of blood, exchanges with interstitial space, which exchanges with intracellular compartments.
Water can cross into cells if there are aquaporins and osmotic gradient.
Water and fats do not mix.
What is plasma?
The fluid component of blood.
The rest of the blood volume is occupied by cells.
What is haematocrit?
A measure of the proportion of the blood occupied by cells.
Usually around 45%.
What is volume of distribution?
The volume of fluid required to contain the total amount of drug in the body at the same concentration as that present in the plasma.
Vd =Q / Cp
Q = amount of drug
Cp = plasma concentration of blood
What is osmotic pressure?
The force per unit area required to oppose movement of water across the interface of two solutions with different solute concentrations.
The interface is a semi-permeable membrane.
What is the relationship between osmotic pressure and water potential?
Inversely proportional
High water potential = low osmotic pressure.
What is the importance of osmotic pressure?
A fall in plasma albumin causes a fall in oncotic pressure.
This is caused by liver failure, protein malnutrition, renal failure - loss of protein due to leaky membrane.
It causes oedema.
What is oedema?
Peripheral oedema - limb swelling
Pulmonary oedema - affecting gas exchange and breathing.
Ascites - in the abdominal cavity.
Cererbral oedema - swellings causes the brain pressure to increase and compress.
What is the role of the kidney?
Elimination of 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 at a specific time and place.
Maintenance of continence.
What is the balance between GI and kidney?
The gut regulates input, the kidney regulates output.
Equilibrium is the balance between these systems.
The gut can be a source of rapid water, K+, H+, or HCO3- loss.
There are no infrequently high inputs from the gut e.g. water poisoning, the kidney is important for returning to equilibrium.
Hepatic failure, through hypalbuminaemia - , causes large changes in renal fluid handling.
What is the interaction of the cardiovascular system and renal system?
The kidney is important for regulating total body volume.
The CVS needs the fluid to maintain blood pressure.
If too low, heart cant generate force of contraction.
When kidneys go wrong, blood pressure is affected.
Hypotension - high BP, caused by kidney problem, excessive activation of renin angiotensin system, drives BP up.
What is the interaction of the renal system with the respiratory system?
Respiratory system controls carbon dioxide input
CO2 levels are a determinant of pH.
So lungs and kidneys work together to maintain pH.
Also have joint metabolic pathways for the regulation of the renin/angiotensin system.
What is the interaction of the renal system with endocrine system?
Renin-angiotensin system.
Vitamin D regulation - Ca2+ regulation.
Target of central hormonal control by vasopressin - antidiuretic hormone ADH.
Kidneys are affected by diabetes mellitus
What is the interaction of the renal system with the ANS?
Kidneys receive afferent innervation and efferent nerves controlling blood flow in the kidney.
Autonomic innervation of the bladder and urethra are essential for controlling the storage of urine and micturition.
What is the interaction of the renal system with haematology?
Kidneys are location of signalling molecule erythropoietin, EPO which stimulates RBC production in body.
So RBC count are determined by kidney function.
What is the interaction of the renal system with haematology?
Kidneys are location of signalling molecule erythropoietin, EPO which stimulates RBC production in body.
So RBC count are determined by kidney function.
Many hamatological malignancies lead to renal disease through deposition of antibodies.
What is the interaction of the renal system with the musculoskeletal system?
Pelvic floor, supports base of bladder, important for continence
Damage leads to incontinence.
Damage can also release toxins into circulation - myoglobin, and high K+ from crushed cells.
Skeletal muscle controls the external urethral sphincter.
