Lecture 31 Physio urine composition, functions of kidney, basic nephron processes Flashcards
whats the composition of normal urine?
creatinine urea, uric acid H+, NH3 Na+, K+ Toxins drugs (anti viral, diuretics) 95-98% water (1.5L/day)
whats the composition of pathological urine?
Glucose Protein Blood hemoglobin leucocytes bacteria (infection)
what disease is associated with glucose in urine?
Glucosuria
diabetes
what disease is associated with protein in urine?
proteinuria
what disease is associated with blood in urine?
erthrocytes
hematuria
what disease is associated with hemoglobin in urine?
hemoglobinuria
Normal urine
A. contains amino acids. B. has a volume of 20 L per day. C. does not contain protons (H+). D. contains sodium and potassium. E. tastes sweet.
D. contains sodium and potassium.
what does normal urine look like?
clear, light or dark amber look
what does normal urine taste like?
not sweet
acidic (pH: 5-6)
pH dependent on diet
veggies - pH = 7.2
meat - pH = 4.8
what does normal urine smell like?
unremarkable
what does pathological urine look like?
golden, red, brown, blue
what does pathological urine taste like?
sweet: diabetes mellitus
what does pathological urine smell like?
like fruits: ketosis (fasting), diabetes, chronic alcohol abuse
rotten: infection (bacteria), tumour
what if pathological urine smell like fruits?
ketosis (fasting), diabetes, chronic alcohol abuse
what if pathological urine smell rotten?
infection (bacteria), tumour
whats 9 functions of the kidneys?
- Hormone production (erythropoietin)
- Metabolism
- Gluconeogenesis
- pH-regulation
- Filters blood
- Water homeostasis
- Salt/ion homeostasis
- Re-absorption of nutrients (amino acids, glucose)
- Excretion of drugs, endogenous metabolites and toxins
whats EPO?
stimulates the bone marrow to produce more RBC
low O2 levels are detected by kidneys
kidney releases EPO
what releases EPO?
Kidneys
what causes chronic renal failure?
anaemia (low levels of RBC/haemoglobin → low blood O2 levels)
what ions are involved in salt/ion homeostasis and whats it useful for?
Na+, K+, Ca2+
blood pressure
what nutrients are reabsorbed by kidneys?
Amino acids, glucose
whats water homeostasis important for?
hydration
blood pressure
what drugs, endogenous metabolites, and toxins are excreted from kidneys?
aspirin, anti-viral drugs, urea, uric acid, herbal toxins
what concentration is vital for many processes?
K+ concentration
why is K+ concentration important for all cells?
resting membrane potential is based on K+ gradient (inside/outside) of cells
why is K+ concentration important for neurons and cardiomyocytes?
action potentials, rhythm generation in pacemaker cells, contractility, signaling
what secretes K+ (potassium)?
Kidneys
what happens if have too much K+?
hyperkalemia (death)
Kidney disease/failure
how much grams of K+ in a banana?
0.5g
how much grams do we need of potassium / day dietary need?
5g
how much grams of K+ can kill as 165lb person?
190g
whats lidocaine used for?
local anaesthetic in a practice or hospital
whats lidocaine?
excreted by kidneys after metabolisation in liver due to fat soluble (lipophilic) nature
whats aspirin?
common pain killer
highly water soluble (hydrophilic)
excreted by kidneys
what does pH =?
-log[H+]
what does bicarbonate (HCO3-) do?
main buffer of blood
neutralise acids from metabolism, food, drinks
maintain blood pH of 7.4
how is HCO3- concentration in the blood controlled?
by Lungs (exhale of CO2) and kidneys by reabsorption of HCO3- or secretion of H+ ions
Which of the following processes is NOT a function of the kidney?
A. gluconeogenesis B. secretion of glucose C. filtration of blood D. K+ reabsorption E. drug secretion
B. secretion of glucose
What are the basic nephron processes of the kidney?
- filtration
- secretion
- re-absorption
whats Filtration of the nephron?
creates a plasma-like filtrate of the blood
whats Reabsorption of the nephron?
removes useful solutes from the filtrate and returns them to the blood
whats secretion of the nephron?
adds additional wastes from the blood to the filtrate
what determines the way a particular substance is handled in the kidneys?
balance of:
- filtration
- secretion
- re-absorption
where are many substances filtered with a constant rate and whats the exception?
renal corpuscle (glomerulus);
exception: substances bound to protein
To be filtered with a constant rate at the renal corpuscle what do some substances need to be?
partly (Na+, K+)
entirely (glucose) re-absorbed; entirely secreted (PAH: represents many drugs)
what are the nephron different parts?
glomerulus
proximal tubule
distal tubule
collecting duct
what does the glomerulus do?
filtration
what does the proximal tubule do?
bulk reabsorption of electrolytes (Na+, K+),
secretion of metabolites, drugs and toxins
what does the distal tubule do?
fine-tuning of electrolytes/water reabsorption
what does the collecting duct do?
fine-tuning electrolyte/water reabsorption
wheres glucose (only) reabsorbed?
only in proximal tubule;
wheres K+ reabsorbed or secreted?
different parts of tubule (depends on diet!!);
wheres water reabsorbed?
most parts of tubule
how is penicillin (drugs and toxins) mostly excreted?
by active secretion, not filtration;
are big molecules (such as albumin) filtered?
No
The renal proximal tubule facilitates:
A. fine tuning of electrolyte/water reabsorption B. secretion of K+ (potassium) C. reabsorption of drugs D. filtration of blood E. secretion of drugs and metabolites
E. secretion of drugs and metabolites
summary
whats normal urine made of?
mostly water, electrolytes (K+, Na+), drugs/toxins, metabolites and acids
summary
The kidney has a variety of functions
what are they?
filtration, excretion, salt and water homeostasis, pH regulation, hormone synthesis
summary
how do kidneys achieve their functions?
basic nephron processes:
filtration, reabsorption, secretion
