Week 11: Renal and Endocrine Disorders

Practice flashcards covering renal anatomy, nephron function, glomerular disorders, and endocrine system pathologies including diabetes and thyroid dysfunction.

Nephron

The functional unit of the kidney; each kidney contains about $1$ million of these units, consisting of a glomerulus and a tubule.

Glomerular capillaries

Highly permeable capillary beds within the nephron that serve as the site of filtration.

Peritubular capillaries

Highly permeable capillary beds within the nephron characterized by a high rate of reabsorption.

Kidney Hormones

The kidneys produce renin, erythropoietin, and activated Vitamin D.

Total Body Fluid Distribution

Approximately $2/3$ is intracellular fluid and $1/3$ is extracellular fluid (interstitial fluid and plasma).

Renal Blood Flow (Gross)

The kidneys typically receive a volume of approximately $1\text{ Liter per minute}$.

Cortical nephrons

The most common type of nephron, accounting for approximately $90\%$ of all nephrons.

Juxtamedullary nephrons

Nephrons that make up approximately $10\%$ of the total and utilize vasa recta for their blood supply.

Descending loop of Henle

The specific segment of the nephron tubule responsible for water reabsorption.

Thick ascending limb of loop of Henle

The segment of the nephron tubule responsible for the reabsorption of sodium, potassium, and chloride.

Juxtaglomerular apparatus

The structure responsible for nephron regulation.

Collecting duct

The final segment of the nephron responsible for the reabsorption of sodium and water.

Glomerular Filtration Barriers

A three-part barrier consisting of fenestrated capillary endothelial walls, a basement membrane that repels plasma proteins, and podocytes with slit membranes.

Glomerular Filtration Rate (GFR)

The primary indicator of global kidney function, representing the sum of filtration by all functioning nephrons, measured in $mL/min$.

Renal Clearance

The volume of blood completely cleared of a specific solute in a defined time; for glucose and albumin, this value is typically zero in healthy kidneys.

Diabetic nephropathy

Kidney damage resulting from persistent elevations in glucose levels that promote glycated protein formation and distortion of the mesangial matrix.

Autoregulation

The property of the kidneys to maintain relatively constant renal blood flow and GFR despite changes in systemic blood pressure.

Myogenic Mechanism

A renal autoregulation process where arteries vasodilate when blood pressure falls and vasoconstrict when blood pressure rises.

Macula densa

Specialized tubular cells that detect the rate of sodium and chloride flow; they stimulate renal autoregulation via tubuloglomerular feedback.

Renin–angiotensin–aldosterone system (RAAS)

A system activated by macula densa cells that promotes renal sodium reabsorption and sustains GFR.

Prerenal failure

Kidney failure resulting from a lack of perfusion, often occurring if a critical hypotensive state is sustained for hours.

Proximal Tubule Reabsorption Sums

By the end of this segment, $100\%$ of nutrients (glucose, amino acids), $85\%$ to $90\%$ of bicarbonate, and $60\%$ to $70\%$ of sodium, chloride, potassium, and water are reabsorbed.

Chronic Kidney Disease (CKD) Stage 3

The stage where most patients are diagnosed, characterized by a GFR below $60\,mL/min$.

Glomerulosclerosis

A common death pathway for nephrons involving injury that starts at the podocytes and the parietal epithelial cells lining Bowman’s capsule.

Acute Glomerulonephritis (AGN)

A renal disorder where an immunological response (often post-GABHS infection) triggers inflammation that damages glomerular membranes.

Nephrotic Syndrome

A clinical combination of findings including massive albuminemia and edema, occurring when damaged glomeruli become hyperpermeable to proteins.

Anasarca

Severe, generalized edema often associated with conditions like Nephrotic Syndrome.

Autosomal dominant polycystic kidney disease

The most common hereditary cause of renal disease, characterized by fluid-filled cysts that enlarge the kidneys and may rupture.

Hydrophilic Hormones

Water-soluble hormones such as epinephrine, norepinephrine, peptides (vasopressin, insulin), and proteins (ACTH, TSH).

Hydrophobic Hormones

Lipid-soluble hormones including steroid hormones (cortisol, aldosterone, estrogen) and thyroid hormones (T3, T4).

Thyroxine (T4)

The less biologically active form of thyroid hormone and the precursor to T3.

Triiodothyronine (T3)

The form of thyroid hormone with greater biological activity.

Infundibulum

The pituitary stalk that connects the hypothalamus to the pituitary gland.

Posterior Pituitary

The site of secretion for vasopressin (AVP) and oxytocin (OT).

Anterior Pituitary

The site containing endocrine cells that secrete ACTH, TSH, LH, FSH, GH, and PRL.

Cushing Disease

A state of hyperpituitarism often caused by a benign corticotroph adenoma, leading to elevated ACTH and cortisol.

Secondary Endocrine Disorder

Dysfunction of an endocrine gland caused by an abnormal pituitary gland.

Sheehan’s syndrome

Hypopituitarism caused by pituitary ischemia, trauma, or infarction following hemorrhage in the post-partum period.

Prolactinoma

The most common pituitary adenoma, which can cause amenorrhea/galactorrhea in females and hypogonadism/decreased libido in males.

Acromegaly

A condition caused by excessive GH secretion in adults, resulting in the overgrowth of the jaw, hands, feet, and organs.

SIADH

Syndrome of Inappropriate Antidiuretic Hormone, leading to hyponatremia and hypoosmolarity due to excess water reabsorption.

Hyperparathyroidism Mnemonic

'Bones, Stones, Groans, Moans'—referring to painful bones, renal stones, abdominal GI symptoms, and psychiatric effects.

Addison’s Disease

Primary adrenal insufficiency caused by autoimmune destruction of the adrenal glands, leading to cortisol and aldosterone deficiency.

Hashimoto Thyroiditis

The most common cause of hypothyroidism; an autoimmune destruction of the thyroid gland.

Cretinism

A congenital form of hypothyroidism due to hormone deficiency in utero, resulting in short stature and intellectual disability.

Grave’s Disease

The most common cause of hyperthyroidism; an autoimmune stimulation of the thyroid gland characterized by exophthalmos and T3/T4 excess.

Glycogenesis

The process of glycogen formation from glucose.

Glycogenolysis

The breakdown of stored glycogen into glucose, which can sustain a well-nourished person for $12-24\text{ hours}$.

Gluconeogenesis

The conversion of amino acids and fats into energy, which can result in the accumulation of ketoacids (ketones).

Type 1 Diabetes Mellitus

A form of DM characterized by T-cell mediated autoimmune destruction of pancreatic beta cells, often presenting as ketoacidosis in children.

Type 2 Diabetes Mellitus

A condition defined by insulin resistance and eventual beta cell exhaustion, strongly associated with obesity.

Metabolic Syndrome Criteria

Defined by at least 3 of: Waist circumference ($M \ge 40\,in$, $W \ge 35\,in$), BP ($\ge 130/85\,mm\,Hg$), Fasting glucose ($\ge 100\,mg/dl$), Triglycerides ($\ge 150\,mg/dl$), or reduced HDL.