Complete Solutions
Trace the RAA system and how it affects blood volume and
blood pressure.
1. BP falls, the kidneys release renin into the bloodstream.
2. Renin splits angiotensinogen (secreted by liver) into pieces.
One piece becomes angiotensin I.
3. Angiotensin I is split into pieces by angiotensin converting
enzyme (ACE) - high levels found in the lung. Angiotensin II is
very active.
4. Angiotensin II (hormone) causes muscular walls of arterioles
to constrict, increasing BP.
5. Angiotensin II triggers release of aldosterone from the adrenal
glands.
6. Aldosterone causes kidneys to retain sodium and excrete
potassium. Sodium causes water to be retained which increases
blood volume and blood pressure
Name two hormones that the kidneys produce.
Renin & Erythropoietin
Function of Renin
Controls production of aldosterone
Erythropoietin
,Stimulates RBC production
Edema
Occurs when patients have kidney disease; decrease of albumin
in the blood and increase in the urine can cause fluid build up
Anemia
Occurs when a patient has kidney disease - kidneys cannot make
enough erythropoietin (EPO); low levels of EPO cause the RBC
count to drop and anemia develops
Uremia
Sign of end stage renal disease; build up of toxins in the blood
because the kidneys have stopped filtering
Hypertension
HBP can cause arteries around the kidneys to narrow, weaken,
or harden
Acidosis
Build up of acid in body because of kidney disease (or failure);
kidneys are not filtering the blood well enough
Hypocalcemia:
Low calcium levels make the patient reach kidney failure faster
Hyperkalemia
,Kidneys cannot remove extra potassium causing it to stay in the
blood - impaired urinary potassium excretion
Name the main contributor to serum osmolality
Sodium is the main contributor to serum osmolality
The effects of aldosterone
Aldosterone regulates whether or not sodium is retained or
released from the adrenal cortex whenever the serum sodium
becomes too low.
The main functions of the glomerulus, the proximal tubule, the
Loop of Henle, the distal tubule, and the collecting duct
-Glomerulus: filtration Proximal
-Tubules: reabsorption
-Loop of Henle: concentration
-Distal Tubule & Collecting Duct: secretion and fine tuning
The importance of and the normal values for the glomerular
filtration rate
-The eGFR is a formula that is used to determine the "estimated"
amount of blood passing through the kidneys each minute.
-GFR is normal at 120 - 130 mL/min.
-When eGFR is less than 60, this means that only half the
nephrons are working
The response of blood flow to the kidneys when stimulated by
the SNS.
, -The sympathetic afferents of the kidneys are activated when
there is a short-term, but large, drop in the systemic arterial
pressure.
-They reduce blood flow to the kidneys, but boost the resorption
of water and salt. [This helps redirect blood to more critical
organs.]
The three main lab indicators of renal function
1. Estimated GFR
2. Creatinine
3. BUN
eGFR is the most important!
Normal values for a urinalysis
Microscopic Exam - pH normal = 4.5 - 8
- Specific gravity = 1.030 - 1.040 → depends on hydration status
- Negative for RBC, WBC, epithelial cells, casts, crystals,
bacteria, ketones, nitrates, glucose
-Gross Exam: color, clarity, odor, sediment
-Urine Protein: should be negative (large particles - should not
be filtered out)
Normal urinary output
60 mL/hr or 1.5 L/day for an adult
Polyuria
Increased volume of urine voided