Module 3 – Cardiovascular and Urinary System 1

Types of Lipids

Triglycerides - neutral fat; account for 90% of lipids, major storage form of fat; energy source.

Phospholipids - essential to building cell membranes; lecithins (soybeans, egg yolks).

Steroids - common chemical structure is steroid nucleus or ring structure; cholesterol most widely known; body makes 75% of needed cholesterol

Lipoproteins

• Carries of lipid molecules.

• Consist of cholesterol, triglycerides, and phospholipids with protein carrier (apoprotein).

• Types: high-density lipoprotein (HDL), low-density lipoprotein (LDL), very low-density lipoprotein (VLDL).

Low-Density Lipoprotein Cholesterol (LDL-C)

• “Bad” cholesterol.

  • Contributes to plaque deposits and coronary artery disease.

• Transports cholesterol from liver to tissues and organs.

• Carries the highest amount of cholesterol.

• Good level (< 2.5 mmol/L)

Very Low-Density Lipoprotein Cholesterol (VLDL-C)

• Primary carrier of triglycerides in blood.

• Through bodily processes, becomes LDL-C.

High-Density Lipoprotein Cholesterol (HDL-C)

• “Good” cholesterol

  • Transport cholesterol for destruction and removal from body.

• Manufactured in liver and small intestine

• Reverse cholesterol transport

  • Assist in transport of cholesterol away from body tissues and back to liver.

• Good level (total cholesterol to HDL ratio < 4.0 mmol/L)

Lipid Disorders

Hyperlipidemia - high levels of lipids in the blood.

Hypercholesterolemia - elevated blood cholesterol.

Dyslipidemia - abnormal levels of lipoproteins.

Drugs for Dyslipidemia

Drugs for lowering LDL levels - statins, bile acid sequestrants, and ezetimibe.

Drugs for lowering triglycerides - omega-3 fatty acids, fibrates, and niacin.

Drugs for treating familial hypercholesterolemia - statins.

Function of the Kidneys

Kidneys regulate:

• Fluid volume

• Electrolytes

• Acid-base balance

Kidneys secrete

• Renin - for blood-pressure regulation

• Erythropoietin - to stimulate red blood-cell production

• Calcitriol - active form of vitamin D for bone homeostasis

Renal Reabsorption and Secretion

• Glucose, amino acids, sodium, chloride, calcium, and bicarbonate reabsorbed.

• Potassium, phosphate, hydrogen, ammonium ion, and some acid drugs secreted into filtrate.

• Hormones can affect the degree of reabsorption in the renal tubule.

  • Aldosterone - stimulate sodium reabsorption.

  • Antidiuretic hormone (ADH) - increase water reabsorption.

Chronic Kidney Disease (CKD)

Also called renal failure

Decrease in kidney’s ability to function.

• Drugs can accumulate to high levels.

Leading causes

• Untreated HTN

• Diabetes mellitus

Diagnosis and Pharmacotherapy

• Urinalysis

• Serum creatinine and BUN

• Glomerular filtration rate (GFR)

  • Best marker for estimating renal function (90 to 120 mL/min)

Diuretics

Increase rate of urine flow.

Excretion of excess fluid used to treat:

• Hypertension, heart failure, kidney failure.

• Liver failure or cirrhosis, pulmonary edema.

Loop diuretics: most effective diuretic, blocks reabsorption of sodium and chloride; ex: Furosemide.

Thiazide diuretics: largest, most common diuretic, block reabsorption of sodium and increases potassium and water excretion; ex: Hypochlorothiazide.

Potassium-sparing diuretic: diuresis without affecting blood potassium levels; ex: Spironolactone.

Body Fluid Compartments

Continuous exchange of fluids across semipermeable membranes between intracellular and extracellular fluid compartments.

Controls water balance.

Role of Electrolytes

• Needed in very small amounts to maintain homeostasis.

• Essential for nerve condition, membrane permeability, and water balance.

• Sodium

  • Essential for maintaining osmolality, water balance, acid-base balance.

  • Normal level: 135-145 mEq/L

• Potassium

  • Essential for proper nerve and muscle function.

  • Normal level: 3.5-5 mEq/L

• Acid-Base Imbalance

  • Acidosis - excess acid (pH below 7.35)

  • Alkalosis - excess base (pH above 7.45)