Kidney Structure and Function

What functions of the kidney are involved in urine formation?

homeostasis and elimination of waste

What is included in the homeostasis function of the kidney?

fluid balance/blood pressure, electrolyte balance, acid-base status

What is included in the elimination of waste function of the kidney?

metabolic waste and drugs

What is included in the endocrine function of the kidney?

regulation of red blood cell production, vitamin D, and blood pressure

Due to the important functions the kidney is responsible for, it is very metabolically active and receives 22% of the bodies blood supply. How is this done?

arteries and veins branch off/into major main vessels (aorta and caudal vena cava)

What parts of the nephron are located in the cortex?

glomeruli, proximal convoluted tubule, distal convoluted tubule

What parts of the nephron are located in the medulla?

loop of Henle and collecting ducts

How many nephrons do cat kidneys contain?

170,000-190,000

How many nephrons do dog kidneys contain?

400,000-500,000

How many nephrons do horse and cow kidneys contain?

10,000,000

What is unique about the number of nephrons?

fixed during gestation so we are born with the number of nephrons we will have for life, these nephrons can die off but DO NOT regrow/are not replaced

What is the renal hilum?

where everything enters or leaves the kidney

How is the renal cortex supplied by blood?

blood enter at the hilum via the renal artery which divides into smaller and smaller branches traveling up the connective tissue between renal pyramids to enter the cortex

Where does the glomerulus get plasma?

the small vessel that branches of the renal artery forms a bundle of capillaries in the glomerulus where it will keep 20% in plasma to filter and excrete as urine while the rest of the filtered blood drains into the renal vein and exits via hilum

Where are the most significant amount of changes made to the filtered plasma?

renal cortex; change in electrolyte composition, pH, reabsorption of some filtered products and secretion of waste products

Where is the urine concentration determined?

renal medulla where the loop of henle provides mechanism to concentrate while the collecting duct is where concentration itself occurs

What gives the renal medulla its “striped” appearance?

loops of henle and collecting ducts of millions of nephrons running next to each other

Each renal pyramid ends in a ________.

papilla that drains into a minor calyx

When will the kidney produce concentrated urine to regulate hydration status?

dehydrated

When will the kidney produce dilute urine to regulate hydration status?

hydrated/overhydrated

When will the kidney reabsorb water and create concentrated urine to regulate blood pressure?

decreased blood pressure

When will the kidney excrete excess water and create dilute urine to regulate blood pressure?

increased blood pressure

What are the consequences of being unable to concentrate urine?

increased urination (polyuria), increased thirst (polydipsia) to keep up, risk of hypotension

What are the consequences of being unable to dilute urine?

hypertension, fluid overload, pulmonary and/or peripheral edema and ascites

What is the result of severe hypokalemia?

decrease in action potentials in skeletal muscle causes extreme muscle weakness

What is the result of severe hyperkalemia?

hyperpolarization of cardiac myocytes with prolonged periods between action potentials causes arrhythmia and slow heart rate (bradycardia)

What is one of the most important components of blood osmolarity?

sodium

What is the normal pH for the body?

7.3-7.4

How can the kidney regulate the bodies pH?

reabsorption of H+ or HCO3-

What is toxic about primary waste products?

nitrogenous waste forms ammonia (NH3)

How does the kidney excrete ammonia toxic?

liver combines two ammonia to form urea and the kidney excretes it

Due to poor kidney function the elimination of uremic toxic is decreased, what are clinical signs that show this?

ulceration of mucosal surfaces, neurologic effects, high blood pressure, decreased cardiac function, altered clotting ability, nausea

What allows the kidney to detect changes as an endocrine organ?

stretch receptors for pressure and chemoreceptors for electrolytes/pH

Kidneys are very sensitive to blood oxygen, what do they do when they detect a drop in blood oxygen?

produce erythropoietin (EPO) to signal bone marrow to make more RBCs

Kidneys are very sensitive to blood oxygen, a low blood pressure can correlate to less oxygen. What do they do to regulate the blood pressure?

release renin to reabsorb more sodium which will cause more reabsorption of water and constriction of blood vessels

How do the kidneys regulate calcium levels?

release vitamin D in response to low calcium

What are common problems with chronic kidney disease?

increased thirst and urination, dehydration, hypokalemia, anemia, increased uremic toxins

What are common problems with acute kidney injury?

inability to urinate, fluid overload, hyperkalemia, arrhythmia, hypernatremia, acidosis, and increase in uremic toxins