Physiological Roles of the Kidney Flashcards
What are the functions of the urinary system?
- Regulator
- Excretor
- Producer
How does the urinary system act as a regulator?
- Electrolyte balance
- Regulation of water
- Inorganic ion balance
How does the urinary system act as an excretory?
- Removal of metabolic wastes (from the blood)
- Removal of foreign chemical from body
How does the urinary system act as a producer?
- Gluconeogenesis (production of glucose from non carbohydrate source)
- Production of hormones
What does electrolyte imbalance leads to?
Disease
What happens if there is 1/3 decrease of K+ concentration?
Nerves unable to generate action potential
What happens if there is 1/2 decrease in Ca2+ concentration?
Tetanic skeletal muscle concentration
What does homeostasis require?
Maintenance of water, pH and electrolytes with narrow range to be conductive to life
Where is sodium largely located?
In extracellular fluid
What does changes in plasma Na+ affect?
- Plasma volume = blood pressure
- Intracellular fluid composition and volume
What is a role of sodium in the kidney?
Determinant in controlling extracellular fluid volume and water distribution
What can an imbalance in sodium lead to?
- Hyponatraemia
- Hypernatraemia
Where is 98% of potassium located?
Intracellularly
How much of potassium is in skeletal muscle?
70%
What is vital in the maintenance of potassium balance?
Kidney
What is the main role of potassium in the cell
Forms basis of the RMP and excitability of nerve and muscle cells
What can occur of an imbalance of potassium?
- Hypokalaemia
- Hyperkalaemia
What does alteration of the amount of excretion/reabsorption of key electrolytes do?
- Alter plasma concentration
- Alter interstitial concentration
- Influence cellular function
How many different types of aquaporins are there?
8+ sub-types
What produces ADH?
Posterior pituitary gland
What produces aldosterone?
Adrenal cortex
Is ADH or aldosterone a long term effector?
Aldosterone
Is ADH or aldosterone a short term effector?
ADH
Why does ADH act a short-term effector in response to dehydration?
- Increase in plasma osmolarity
- Increased body loss of water
- Reduced intake of water
Why does aldosterone act a long-term response to decrease body fluid volume?
-Loss of both water and salt results in no change of osmolarity
Where is atrial natriuretic peptide produced?
Atrial tissue
How does atrial natriuretic peptide work?
Inhibits reabsorption of Na+
Inhibiting H20 reabsorption
Urine becomes more dilted
What is acidosis?
pH<7.35
What is alkalosis?
pH>7.45
What happens to the CNS + PNS if pH>7.45?
Over excitability
- Sensory neurone fire absence of stimulation
- Motor neurons cause muscle twitches
Are metabolic acids continually produced?
Yes
What controls acid-base balance?
- Respiratory system
- Kidney
Describe acidosis: In terms of -H+ secretion -H- excretion -HCO3- -pH of urine -Compensatory chang in plasma membrane
- H+ secretion = increase
- H- excretion = increase
- HCO3- = zero
- pH of urine = acidic
- Compensatory change in plasma membrane = alkalisation towards normal
Describe alkalosis: In terms of -H+ secretion -H- excretion -HCO3- -pH of urine -Compensatory chang in plasma membrane
- H+ secretion = decrease
- H- excretion = decrease
- HCO3- = increase
- pH of urine = alkaline
- Compensatory change in plasma membrane = acidification towards normal
Within which part of the nephron does the following process
mainly take place: reabsorption of water and nutrients
A. Renal corpuscle
B. Proximal tubule
C. LoH descending limb
D. Distal tubule
E. Collecting duct
B
Within which part of the nephron does the following process
mainly take place: reabsorption of water by ADH A. Renal corpuscle B. Proximal tubule C. LoH descending limb D. Distal tubule E. Collecting duct
E
Collecting ducts are located within which part of the kidney?
A. Cortex B. Medulla C. Renal pyramids D. Renal columns E. Renal pelvis
C
Which of the following statements relating to ADH is correct? A. It increases the permeability of the collecting ducts to water. B. It is secreted in response to low potassium ion in the blood. C. It causes the kidneys to produce a larger volume of very dilute urine. D. It is secreted by the anterior pituitary. E. Its release is insensitive to the osmolarity of interstitial fluid.
A
In response to increased levels of aldosterone, the kidneys produce…
A. a larger volume of urine. B. urine with a higher concentration of sodium ions. C. urine with a lower concentration of potassium ions. D. urine with a lower concentration of sodium ions. E. urine with less glucose.
D
Which of the following statements relating to the RAAS is correct?
A. Renin is released from the
macula densa in response to
an increase in the GFR
B. The macula densa is located within the proximal tubule and monitors filtered Na +
C. Juxtaglomerular cells release renin in response to a
decrease in filtered Na +
D. Renin is released into the
filtrate where it increases Na+
and water reabsorption
C
A drug that inhibits angiotensin converting enzyme (ACE) may lead to: A. less secretion of aldosterone B. increased urinary loss of sodium C. reduction of blood pressure D. B and C only E. A, B, and C
E
The process of filtration is driven by:
A. active transport B. blood osmotic pressure C. blood hydrostatic pressure D. renal pumping E. solvent drag
C
Measurement of the functions of a nephron reveals a glomerular capillary pressure of 55 mm Hg, and a pressure in the Bowman’s space of 15 mm Hg. Assuming that the Oncotic pressure is 28 mm Hg, and the glomerulus pressure is 2mmHg.
What is the net filtration pressure in this case?
A. 40 mm Hg B. 14 mm Hg C. 30 mm Hg D. 26 mm Hg E. 100 mm Hg
B
Autoregulation of the GFR is best described by the following?
A. Myogenic vasoconstriction of afferent arteriole B. Maintains GFR over a wide range of blood pressures C. Depends on changes in the efferent arteriole D. All of the above E. A and C only
D
