Renal Function

Question 1

Explain the role of the juxtaglomerular apparatus in regulating sodium content and its impact on the release of renin and ADH.

Question 2

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?

Question 3

Discuss the function of central osmoreceptors in monitoring and regulating the body’s internal fluid balance. How do central osmoreceptors initiate hormonal responses?

Question 4

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?

Answer 4

• 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.

Question 5

What are the effects of Hypo- and Hyper-natremia on ADH?

Answer 5

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

Question 6

explain the function of ADH

Answer 6

• 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

Question 7

What is albumin?

Answer 7

a protein found in the blood that maintains fluid balance

Question 8

Where is albumin produced?

Answer 8

in the liver

Question 9

Define oncotic pressure (colloid osmotic pressure)

Answer 9

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

Question 10

How does albumin impact on fluid balance?

Answer 10

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

Question 11

What is Edema?

Answer 11

accumulation of excess fluid within tissues

Question 12

How does albumin prevent Edema?

Question 13

What can cause hypoalbuminemia (low albumin levels)?

Answer 13

• Liver Disease
• Malnutrition
• Kidney Disease
• Gastrointestinal Disorders
• increased sweating / severe wounds
• inflammatory conditions
• pregnancy
• Medications

Question 14

Explain why hypoalbuminemia is harmful

Question 16

what is meant by fluid balance?

Answer 16

maintenance of blood pressure and blood volume

Question 17

what electrolytes are regulated by the renal system?

Answer 17

sodium and potassium

Question 18

what is the optimum concentration range of osmotic particles in the bloodstream to maintain cell function?

Answer 18

280-320 mmol/kg or mOsm/L

Question 19

what do renal tests measure?

Answer 19

the kidney’s ability to filter, reabsorb, secrete and excrete water, electrolytes, and foreign substances

Question 20

what are the 3 types of renal tests?

Answer 20

• concentration test
• retention test
• clearance test

Question 21

concentration test

Answer 21

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

Question 22

what is the normal range for urinary specific gravity?

Answer 22

1.003-1.035 g/ml
(optimal is 1.020)

Question 23

what would a low specific gravity indicate of the patient?

Answer 23

hypothermia or that the patient is using diuretics

Question 24

what would a high specific gravity indicate of the patient?

Answer 24

dehydration, diabetes, mellitus, congestive heart failure

Question 25

what does a retention test measure?

Answer 25

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)

Question 26

What does a clearance test measure?

Answer 26

the renal capacity to filter out certain subtances in the blood via glomerular filtration, filtration, and tubular secretion.

Question 27

in what 3 ways can the kidneys decrease the concentration of substances in the blood?

Answer 27

glomerular filtration, filtration, and tubular secretion.

Question 28

what are the substances that can be clearance tested?

Answer 28

creatine, and urea