3017 Patho Exam 3 (Renal System, Endocrine System)

Renal and Urinary Systems Anatomy Review

Structures:

■ Kidneys

■ Ureters

■ Bladder

■ Urethra

Internal Structure of Kidney and Blood Supply

• Renal Capsule: outermost layer of kidney → protect kidney

• Renal Cortex: directly beneath renal capsule

• Medulla: innermost layer kidney, composed of multiple pyramids

• Pyramid : separated by renal columns

• Papillae: narrow tips of renal pyramids → empty urine to calyx

• Calyx: larger collection sac → empty urine into renal pelvis

• Renal Pelvis: store small amount of urine → empty urine to ureter → bladder

Functions of the Kidney

1) urine formation and excretion of wastes

2) regulation of fluid and electrolyte balance and acid–base balance

3) hormonal functions: regulate blood pressure, regulate RBC production, activation of vitamin D, production and release of bradykinin and prostaglandins (PGs).

Anatomy of a Nephron

Nephron: filter blood to remove wastes and produce urine

Each nephron has:

• Glomerulus: collection of capillaries → filter blood

• Bowman’s capsule: structure surrounding each glomerulus

• Tubular system include:

→ Proximal convoluted tubule (PCT)

→ Loop of Henle: reabsorb different substances in urine formation

→ Distal convoluted tubules (DCTs)

→ Collecting tubule

Urine Formation

Urine is formed through the continuous processes of:

1. Filtration (Glomerulus filter blood = don’t allow RBC and protein to pass through membrane) → force electrolytes, glucose, water across membrane into Bowman’s capsule → then into PCT

2. Reabsorption (PCT & DCT reabsorb water and solutes back into blood; ADH and aldosterone control permeability of the DCT membrane)

3. Secretion (solutes move from blood to filtrate)

4. Concentration (Loop of Henle reabsorbs additional water to concentrate urine)

Action of antidiuretic hormone (ADH)

Purpose: Water Balance

• Excess water is taken into body → ADH is suppressed → kidneys produce more dilute urine to rid body of excess water

• Dehydration → ADH stimulated → kidney increase water reabsorption → reduce urine volume

Action of aldosterone secretion

Purpose: Electrolyte Balance

• Sodium decreases (hyponatremia) → Aldosterone released → increase reabsorption of sodium in distal tubule → increase serum sodium level

• Elevated potassium (hyperkalemia) → aldosterone secreted → increase excretion of K+ in renal tubules → more K+ in urine

Renin-angiotensin-aldosterone system (RAAS)

Purpose: Acid-Base Balance → keep blood pH between 7.35 - 7.45

• With acidosis, kidney tubules excrete H+ and reabsorb bicarbonate ions (HCO3–) to increase serum pH to a normal level

• With alkalosis, kidney tubules reabsorb H+ and excrete HCO3– to decrease pH to a normal level.

Hormonal Function of Kidney

Kidney produces hormones renin, erythropoietin, activated vitamin D, bradykinin, prostaglandins

• Decrease in blood pressure → Renin released + angiotensinogen released → produce angiotensin I + ACE → form angiotensin II → constricts blood vessels → increase blood pressure

• Decreased renal blood flow and hypoxia → Erythropoietin released → stimulates bone marrow to produce RBCs

• Prostaglandins trigger vasodilation → resulting in increased blood flow to kidneys

• Bradykinin increases permeability of capillary membrane to certain solutes

Terms

• Anuria: < 100-ml urine output/24 hr

• Oliguria: < 400-mL urine output/24 hr

• Polyuria: > 2,000-mL urine output/24 hr

• Dysuria: Pain with urination

• Enuresis: Involuntary urination at night

• Frequency: Increase in voiding

• Hematuria: Blood in urine

• Hesitancy: Difficulty starting the flow of urine

• Incontinence: Inability to control urinating

• Nocturia: Frequent urination at night

• Retention: Unable to empty bladder

• Urgency: Urge to void immediately

Diagnostic Studies

Blood Tests

• Serum creatinine: waste product, normal 0.5 - 1.2 mg/dL, increase in serum creatinine → renal dysfunction

• BUN: waste product, normal 8 - 21 mg/dL, increased BUN → renal dysfunction

• Electrolytes:

→ Sodium: normal 135 - 145 mEq/L

→ Potassium: normal 3.5 - 5.3 mEq/L

→ Phosphorus (PO4): normal 2.5 - 4.5 mEq/L

→ Calcium: 8.2 to 10.2 mg/dL

Urinalysis

• Color/Turbidity/Odor

• pH (changes in renal function)

• Protein (normally not in urine but presence → infection, inflammation)

• Glucose (diabetes)

• Ketones (diabetic ketoacidosis, high-protein diet)

• Bilirubin (liver disease)

• RBC/WBC

• Bacteria (UTI )

Gerontological considerations

• Older adults susceptible to kidney injury r/t decreased blood flow, decreased GFR, altered tubal function and acid-base balance

• Incomplete emptying of bladder

• Decreased drug clearance

Risk factors for renal disorders

• Age -> Incomplete emptying of bladder → UTI

• Benign prostatic hyperplasia → Obstruction of urine flow

• Diabetes/Hypertension → Chronic kidney disease

• Gout/hyperparathyroidism/Crohn’s disease → Kidney stone formation

• Immobilization → Kidney stone formation

• Sclerosis/Tumors/Parkinson Disease → Incontinence

Terms

• Acute Kidney Injury: rapid loss of renal function

• Chronic Kidney Disease: kidney damage or decrease in GFR > 3 months

• Acute Nephritic Syndrome: kidney disease with glomerular inflammation

• Acute Tubular Necrosis: kidney injury r/t damage of kidney tubules

• End-stage Kidney Disease: final stage of chronic kidney disease → retention of waste products → need for renal placement

• Glomerulonephritis: inflammation of glomerular capillaries

DIABETES

Glossary terms

Diabetes: defects in insulin secretion → hyperglycemia

Diabetic ketoacidosis (DKA): Type 1 diabetes → deficiency of insulin → liver breaks down fatty acids → highly acidic ketone formed → acidocis

Fasting plasma glucose: blood glucose from fasting for 8 hours

Gestational diabetes: diabetes during pregnancy

Glycated hemoglobin (HgbA1C): glucose molecule attach to hemoglobin for the life of of red blood cell (120 days)

Hyperglycemia: elevated blood glucose level

Hyperglycemic hyperosmolar syndrome (HHS): Type 2 diabetes → insulin deficiency by an illness that raise demand for insulin

Hypoglycemia: low blood sugar level

Impaired fasting glucose (IFG) or Impaired glucose tolerance (IGT): prediabetes

Insulin: hormone secreted by beta cells of pancreas → metabolism of carbohydrates, proteins, fats

Insulin pump: continuous subcutaneous insulin infusion device delivers insulin on 24-hours basis

Ketone: highly acidic, formed when liver breaks down free fatty acid in the absence of insulin

Latent autoimmune diabetes of adults (LADA): subtype of diabetes

Nepthropathy: damage of kidney

Neuropathy: damage of nerve

Retinopathy: damage of small blood vessels that nourish retina in eye

Type 1 diabetes: absence of insulin production and secretion from genetic, immunologic, environmental factors that destroy beta cells in pancreas

Type 2 diabetes: deficiency of insulin production

Risk factors of Type 1 vs Type 2 Diabetes

Type 1

• Early-onset (younger population)

• Genetic/Familial

• Viral or toxins factors

Type 2

• Age (older population)

• Obesity

• Prediabetic

• HTN > 140/90 mmHg

• HDL < 35 mg/dL

• Triglycerides >250 mg/dL

• History of gestational diabetes or babies born weighing over 9 lbs

Insulin

• Hormone secreted by beta cells in islets of Langerhans in pancreas

• Insulin is anabolic, storage hormone

• Transports, metabolizes glucose for energy

• Stimulates → storage of glucose in liver, muscle (as glycogen) → storage of dietary fat in adipose tissue → transport of amino acids into cells

• Inhibits breakdown of stored glucose, protein, fat

During Fasting Periods

• Pancreas continuously releases a small amount of insulin (basal insulin)

• When blood glucose levels decrease → Pancreas releases glucagon (secreted by alpha cells) → breaks down glycogen to make glucose (glycogenolysis)

→ breaks down amino acids to make glucose (gluconeogenesis)

Type 1/Type 2/Gestational Diabetes

Type 1 diabetes: absence of insulin production and secretion from genetic, immunologic, environmental factors that destroy beta cells in pancreas

Type 2 diabetes: deficiency of insulin production

Gestational diabetes: diabetes during pregnancy due to secretion of placental hormones → causes insulin resistance

Clinical manifestations of Diabetes

• Polyuria

• Polydipsia

• Polyphagia

• Fatigue

• Vision changes

• Tingling or numbness in hands or feet

• Dry skin, skin lesions or wounds that are slow to heal

• Recurrent infections

• Type 1 may have sudden weight loss

Diagnostic findings

• Fasting plasma glucose

• HbA1c

→ A normal A1C level is below 5.7%

→ 5.7% - 6.4% indicates prediabetes

→ 6.5% or higher indicates diabetes

Criteria for Diagnosis of Diabetes