Renal Physiology & Related Systems – Exam Review

Comprehensive Q&A flashcards covering kidney anatomy & physiology, hormonal control, nitrogenous wastes, adaptive immunity basics, and clinical correlations emphasized in the lecture.

What is the functional unit of the kidney?

The nephron.

Where are the kidneys located in relation to the peritoneum?

Retroperitoneal – behind the peritoneum.

Which arteriole is larger in diameter and helps create glomerular pressure?

The afferent arteriole (larger than the efferent).

What percentage of filtrate is normally re-absorbed by the nephron?

Approximately 99 %.

List the correct order of filtrate flow starting at the glomerular capsule.

Glomerular (Bowman’s) capsule → Proximal convoluted tubule (PCT) → Nephron loop (loop of Henle) → Distal convoluted tubule (DCT) → Collecting duct → Papillary duct → Minor calyx → Major calyx → Renal pelvis → Ureter → Bladder → Urethra.

Which part of the nephron performs the majority of reabsorption?

The proximal convoluted tubule (PCT).

What is the role of the vasa recta surrounding juxtamedullary nephrons?

Allows production of very concentrated urine when water must be conserved.

Define glomerular filtration rate (GFR).

The volume of filtrate formed per minute by both kidneys; a key measure of renal function.

How much urine is typically produced in a day?

About 1–2 L.

Which hormone is released from the posterior pituitary to increase water reabsorption in the kidney?

Antidiuretic hormone (ADH).

What triggers ADH release?

Increased plasma osmolarity (dehydration) sensed by hypothalamic osmoreceptors.

Name the hormone released from the adrenal cortex that increases Na⁺ reabsorption.

Aldosterone.

Water follows which ion during aldosterone-mediated reabsorption?

Sodium (Na⁺).

Where is erythropoietin (EPO) produced and what triggers its release?

Produced by the kidneys in response to hypoxia (low blood O₂).

What enzyme is released by juxtaglomerular cells when renal blood pressure drops?

Renin.

What does renin ultimately generate that raises blood pressure?

Angiotensin II (via ACE in the lungs).

List three major actions of angiotensin II.

1) Vasoconstriction, 2) Thirst stimulation, 3) Aldosterone release.

What class of antihypertensive drugs blocks the conversion of angiotensin I to angiotensin II?

ACE inhibitors (e.g., lisinopril).

Which cardiac hormone lowers blood pressure by promoting Na⁺ and water loss?

Atrial natriuretic peptide (ANP).

Give two similarities between B cells and T cells.

Both are lymphocytes and provide specificity & memory in adaptive immunity.

In adaptive immunity, what do B cells differentiate into to produce antibodies?

Plasma cells.

Which lymphocyte provides cellular immunity by directly killing infected cells?

Cytotoxic T cells (CD8⁺).

Define passive immunity.

Protection via externally supplied antibodies; no immunological memory is generated.

Define active immunity and give its two forms.

Body produces its own antibodies (with memory); can be natural (infection) or artificial (vaccination).

What nitrogenous waste is produced by the liver’s urea cycle?

Urea (non-toxic).

Excess uric acid crystals in joints cause which disorder?

Gout (gouty arthritis).

What is creatinine and why is it measured clinically?

A nitrogenous waste from muscle creatine phosphate; blood creatinine levels assess renal function.

What simple blood test provides a snapshot of kidney function by measuring nitrogenous wastes?

BUN – Blood Urea Nitrogen test.

Which gas primarily regulates respiration rate?

Carbon dioxide (CO₂).

Elevated CO₂ levels are termed what and cause what respiratory response?

Hypercapnia; trigger faster, deeper breathing.

What happens to renal blood flow during sympathetic ‘fight-or-flight’ activation?

Afferent arterioles constrict, dramatically reducing GFR and urine formation.

State Starling’s principle for autoregulation when systemic BP rises.

Afferent arteriole constricts and efferent dilates to lower glomerular pressure.

What structure senses tubular fluid salinity for tubuloglomerular feedback?

The macula densa in the distal convoluted tubule.

Low salinity (due to high GFR) causes macula densa to induce what change?

Paracrine signaling to juxtaglomerular cells ⇒ constriction of afferent arteriole ⇒ GFR decreases.

Define transport maximum (Tm).

The maximum rate at which a substance can be reabsorbed due to saturation of its carrier proteins.

Why does untreated diabetes mellitus lead to glycosuria?

Blood glucose exceeds Tm, carriers saturate, excess glucose remains in filtrate and appears in urine.

Explain polyuria and polydipsia in diabetics.

Glucose in urine osmotically drags water (polyuria); water loss triggers excessive thirst (polydipsia).

What is diabetes insipidus caused by?

ADH deficiency or renal insensitivity to ADH (not glucose related).

Give the normal pH range of urine and what acidic urine may indicate.

Urine pH ≈ 4.5–8; very acidic urine suggests high acid load or metabolic acidosis.

Name two primary types of nephrons and their main difference.

Cortical (shallow) and juxtamedullary (deep with long loops for concentrating urine).

Which renal capillary bed wraps around the nephron loop of juxtamedullary nephrons?

The vasa recta.

Trace renal blood flow from the aorta to the glomerulus.

Aorta → Renal artery → Segmental & smaller arteries → Afferent arteriole → Glomerulus.

After filtration, blood leaves the glomerulus via what vessel?

The efferent arteriole.

Where does blood from the renal vein ultimately drain?

Into the inferior vena cava, then the right atrium.

What percentage of cardiac output is normally directed to the kidneys at rest?

Approximately 20 % (one-fifth).

Name three common diuretic mechanisms.

1) Inhibit Na⁺ reabsorption (loop/thiazide), 2) Block aldosterone, 3) Reduce ADH activity (water diuresis).

Why are diuretics prescribed in congestive heart failure?

To reduce excess fluid volume that backs up into lungs or tissues due to weak ventricular pumping.

What kidney complication is life-threatening in septic shock?

Acute renal failure when BP drops too low to sustain GFR.

Presence of protein (albumin) in urine often indicates what chronic condition?

Long-standing hypertension damaging glomerular filtration slits.

Presence of red blood cells in urine (hematuria) can suggest what two possibilities?

Urinary tract infection or glomerular damage from severe hypertension.

Which respiratory organ removes CO₂ from the body?

The lungs via ventilation.

Which organ system is the strongest regulator of long-term pH balance?

The kidneys (through H⁺ secretion and bicarbonate handling).

Define azotemia.

Elevated nitrogenous wastes in blood due to inadequate renal filtration.

What is polyuria?

Excessive urine output (> 2 L/day).

What is the effect of aldosterone on K⁺?

Promotes K⁺ secretion into tubular fluid in exchange for Na⁺ reabsorption.

Give two key laboratory indicators of early kidney dysfunction.

Decreased GFR and elevated BUN/creatinine.

What simple visual cue can suggest hydration status?

Urine color (light = well-hydrated; dark = concentrated/dehydrated).

Why is EPO abuse attractive to endurance athletes?

It stimulates red blood cell production, increasing oxygen-carrying capacity.

Which blood cells predominate in a UTI urinalysis?

Neutrophils (elevated WBC count).

Why does blocking Na⁺ reabsorption increase urine volume?

Water osmotically follows Na⁺ into the tubular fluid, increasing diuresis.