Renal Function Flashcards
Explain the role of the juxtaglomerular apparatus in regulating sodium content and its impact on the release of renin and ADH.
Explain the role of ADH in regulating water balance and maintaining the body’s internal environment. How does ADH production respond to changes in blood osmolarity?
Discuss the function of central osmoreceptors in monitoring and regulating the body’s internal fluid balance. How do central osmoreceptors initiate hormonal responses?
Analyse the effects of ADH on the kidneys and its role in maintaining fluid and electrolyte balance. How does ADH increase water reabsorption in the renal tubules?
- When low blood volume or high blood osmolarity is detected, central osmoreceptors
— in the posterior pituitary are triggered to secrete ADH
— from the hypothalamus - ADH regulates water reabsorption in the distal convoluted tubule and collecting duct
— by Increasing water permeability of the collecting duct
— Results in more water being reabsorbed into the bloodstream - more ADH = more water reabsorption = blood volume increases, and blood osmolarity decreases = lower sodium concentration in the blood.
What are the effects of Hypo- and Hyper-natremia on ADH?
hypo-natremia:
- low Sodium in the blood
- ADH release is suppressed - less ADH release from hypothalamus
- distal CT and collecting duct are now less permeable to water
- less water reabsprption
- more dilute urine and less water conservation in the blood
- helping to conserve sodium concentration in the blood and make the blood less dilute
Hyper-natremia:
- High sodium in the blood
- central osmoreceptors in the posterior pituitary trigger more ADH release from the hypothalamus.
- ADH increases water permeability in the Distal CT and Collecting duct
- More water reabsorption
- more concentrated urine
- helping to dilute the blood and reduce sodium concentration
explain the function of ADH
- ADH regulates water reabsorption in the distal convoluted tubule and collecting duct
- Increases water permeability of the collecting duct
- Results in more water being reabsorbed into the bloodstream
- Helps to concentrate urine and reduce water loss
What is albumin?
a protein found in the blood that maintains fluid balance
Where is albumin produced?
in the liver
Define oncotic pressure (colloid osmotic pressure)
Oncotic pressure, or colloid osmotic-pressure, is a type of osmotic pressure induced by the plasma proteins, notably albumin, in a blood vessel’s plasma that causes a pull on fluid back into the capillary.
helps to retain water within blood vessels
How does albumin impact on fluid balance?
creates oncotic pressure
- prevent water from leaving capillaries
- water is retained within blood vessels and blood is more dilute
It is also a carrier protein
- has a binding capacity to transport hormones, drugs, and ions in the blood
What is Edema?
accumulation of excess fluid within tissues
How does albumin prevent Edema?
What can cause hypoalbuminemia (low albumin levels)?
- Liver Disease
- Malnutrition
- Kidney Disease
- Gastrointestinal Disorders
- increased sweating / severe wounds
- inflammatory conditions
- pregnancy
- Medications
Explain why hypoalbuminemia is harmful
what is meant by fluid balance?
maintenance of blood pressure and blood volume
what electrolytes are regulated by the renal system?
sodium and potassium
what is the optimum concentration range of osmotic particles in the bloodstream to maintain cell function?
280-320 mmol/kg or mOsm/L
what do renal tests measure?
the kidney’s ability to filter, reabsorb, secrete and excrete water, electrolytes, and foreign substances
what are the 3 types of renal tests?
- concentration test
- retention test
- clearance test
concentration test
measure renal ability to concentrate/dilute urine using specific gravity and osmolarity tests performed on a urine sample
specific gravity is measured using the mass of particles in a given volume of urine
what is the normal range for urinary specific gravity?
1.003-1.035 g/ml
(optimal is 1.020)
what would a low specific gravity indicate of the patient?
hypothermia or that the patient is using diuretics
what would a high specific gravity indicate of the patient?
dehydration, diabetes, mellitus, congestive heart failure
what does a retention test measure?
how much a specific substance is being retained in the blood by the kidneys
- substances tested for include uric acid, creatinine, and BUN (blood urea nitrogen)
What does a clearance test measure?
the renal capacity to filter out certain subtances in the blood via glomerular filtration, filtration, and tubular secretion.
in what 3 ways can the kidneys decrease the concentration of substances in the blood?
glomerular filtration, filtration, and tubular secretion.
what are the substances that can be clearance tested?
creatine, and urea
