BIOL 2252: Unit #4 Urinary System

What percentage of body weight is water in adult males?

Approximately 60%

Which tissue has the least water content?

Adipose tissue

Which compartment contains most of the body’s fluid?

Intracellular fluid (ICF)

What are the two components of extracellular fluid (ECF)?

Plasma and interstitial fluid

What happens when ECF osmolality increases?

Water leaves the cells

What is sensible water loss?

Measurable water loss through urine and feces

What is insensible water loss?

Unmeasurable water loss through lungs and skin

What hormone is released when osmolality increases?

Antidiuretic hormone (ADH)

What triggers the thirst mechanism?

Increased blood osmolarity, decreased blood pressure/volume

What hormone increases water reabsorption in kidneys?

ADH

Which hormone increases sodium reabsorption in kidneys?

Aldosterone

What hormone decreases blood pressure by increasing urine output?

Atrial natriuretic peptide (ANP)

What is the effect of dehydration on cells?

Cells shrink as water leaves

What is hypotonic hydration?

Water intoxication; cells swell due to low ECF osmolality

What is edema?

Abnormal accumulation of interstitial fluid

What is the main cation in ECF?

Sodium (Na⁺)

What is the main cation in ICF?

Potassium (K⁺)

What hormone regulates ECF calcium levels?

Parathyroid hormone (PTH)

What is acidosis?

Blood pH below 7.35

What is alkalosis?

Blood pH above 7.45

What are the organs of the urinary system?

Kidneys, ureters, urinary bladder, urethra

What is the functional unit of the kidney?

Nephron

What structure filters blood in the kidney?

Renal corpuscle (glomerulus + Bowman’s capsule)

What part of the nephron reabsorbs the most substances?

Proximal convoluted tubule (PCT)

Which nephron type has long loops for concentrated urine?

Juxtamedullary nephrons

What hormone is released by the kidney to raise blood pressure?

Renin

What is the role of the collecting duct?

Collects urine and responds to ADH

What are podocytes?

Cells in Bowman’s capsule that form filtration slits

What arteriole carries blood into the glomerulus?

Afferent arteriole

What arteriole carries blood away from the glomerulus?

Efferent arteriole

What is glomerular filtration?

Passive process where plasma is filtered into the nephron

What is tubular reabsorption?

Process of reclaiming substances from filtrate into blood

What is tubular secretion?

Movement of substances from blood into the tubular fluid

What part of the nephron is responsible for fine-tuning salt and pH?

Distal convoluted tubule

What does the juxtaglomerular apparatus regulate?

Filtration rate and blood pressure

What cells release renin?

Juxtaglomerular (granular) cells

Where is the macula densa located?

Wall of the distal convoluted tubule

What does the macula densa detect?

Sodium chloride concentration in the filtrate

What is the normal daily urine output?

1.5 L per day

How does alcohol affect ADH?

Inhibits ADH, increasing urine output

What is the role of vasa recta?

Maintains concentration gradient in juxtamedullary nephrons

What are major calyces?

Structures that drain urine into the renal pelvis

What part of the brain regulates thirst?

Hypothalamus

What is the filtration membrane made of?

Fenestrated endothelium, basement membrane, podocytes

What condition results from high ECF sodium?

Hypernatremia

What condition results from low ECF sodium?

Hyponatremia

What is the driving force for glomerular filtration?

Blood hydrostatic pressure

In the kidney, a concentration of 1200 mOsm would be found in which of the following areas (select all that apply):

Medulla, Bend of the nephron loop/hairpin turn, Bottom of the vasa recta/hairpin turn

Blood pressure would decrease due to the release of which of the following:

Atrial natriuretic peptide (ANP)

Blood volume would increase due to the release of which of the following (select all that apply):

Aldosterone, Antidiuretic hormone (ADH)

If HPgc = 52 mmHg, HPcs = 12 mmHg, and OPgc = 32 mmHg, what is the Net Filtration Pressure (NFP)?

NFP = HPgc − (HPcs + OPgc)

NFP = 52 − (12 + 32)

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Which of the following could increase GFR (select all that apply):

Dilated afferent arteriole with a normal diameter efferent arteriole, Constricted efferent arteriole with a normal diameter afferent arteriole, Stimulation of the macula densa cells

In which part of the nephron does most reabsorption take place?

Proximal convoluted tubule

Juxtaglomerular cells of the juxtaglomerular complex secrete ________________ when ___________:

Renin; blood pressure drops

Which of the following does NOT explain the high pressure within the glomerular capillaries?

The volume of plasma in the efferent arteriole is higher than in the afferent arteriole

The macula densa cells respond to ________.

Changes in sodium content of the filtrate

What is the most direct function of the juxtaglomerular apparatus?

Help regulate blood pressure and the rate of blood filtration by the kidneys

pH = 7.47, HCO₃⁻ = 28

Metabolic alkalosis

pH = 7.50, CO₂ = 50; HCO₃⁻ = 31

Metabolic alkalosis

pH = 7.31, HCO₃⁻ = 19

Metabolic acidosis

pH = 7.5, CO₂ = 29

Respiratory alkalosis

pH = 7.32, CO₂ = 49

Respiratory acidosis

pH = 7.29, CO₂ = 28; HCO₃⁻ = 17

Metabolic acidosis

HCO₃⁻ = 19 plus coma

Metabolic acidosis

Increased HCO₃⁻ plus paresthesia

Metabolic alkalosis

Decreased H⁺ and HCO₃⁻ = 29

Metabolic alkalosis

Increased H⁺ and CO₂ = 48

Respiratory acidosis

Increased pH and CO₂ = 30

Respiratory alkalosis

CO₂ = 50 plus lethargy, confusion, stupor

Respiratory acidosis

Uncontrolled diabetes mellitus

Metabolic acidosis

Extreme anxiety and fear

Respiratory alkalosis

Kidney failure

Metabolic acidosis

Hyperaldosteronism

Metabolic alkalosis

Prolonged emesis (vomiting)

Metabolic alkalosis

Scoliosis

Respiratory acidosis

Pneumonia

Respiratory acidosis

Prolonged exercise

Metabolic acidosis

Starvation/severe dieting

Metabolic acidosis

Excessive diarrhea

Metabolic acidosis

Prolonged anesthesia

Respiratory acidosis

Excessive consumption of Maalox

Metabolic alkalosis

How can the lungs help fix metabolic alkalosis?

Decrease breathing rate and depth, causing carbon dioxide to accumulate in the blood which helps to lower blood pH

How does the body correct metabolic acidosis?

Increase breathing rate and depth

How does the body correct respiratory acidosis in COPD (Chronic Obstructive Pulmonary Disease)?

Increase H⁺ excretion into the urine

How do kidneys fix metabolic alkalosis?

🩺 How do the kidneys respond?

1. Increase excretion of HCO₃⁻ (bicarbonate):

   • The kidneys filter out and eliminate excess base in the urine.

   • This lowers the amount of bicarbonate in the blood, helping to bring pH down.

2. Decrease H⁺ (acid) secretion:

   • The kidneys stop actively secreting as much H⁺ into the urine.

   • This helps retain acid in the blood, bringing pH back toward normal.

3. Urine becomes more alkaline (higher pH):

   • Because bicarbonate is being excreted and fewer H⁺ are secreted, urine pH rises.

Body water content is greatest in the elderly.

False

Potassium, magnesium, and phosphate ions are the main intracellular electrolytes.

True

Tubular reabsorption involves the movement of substances from the

renal tubule to the peritubular capillaries

The process by which fluid passes through the capillary membranes of the glomerulus is called:

filtration

What is the role of atrial natriuretic peptide (ANP)?

reducing blood volume and sodium levels

Which of the pressures that determine net filtration pressure (NFP) is regulated by both intrinsic and extrinsic controls of glomerular filtration rate (GFR) by essentially regulating blood pressure?

Hydrostatic pressure in glomerular capillaries (HPGC)

Which vessel directs blood into the glomerulus?

afferent arteriole

Which of the following is an abnormal constituent of urine?

hemoglobin

Filtrate in the glomerular capsule empties into which structure?

proximal convoluted tubule

What would happen if the amount of glucose in the kidney tubule is greater than the transport maximum?

glucose will be excreted in the urine

Within the renal tubule, two hormones play a role in determining the final volume and sodium concentration of the urine. The hormone ____ regulates

sodium reabsorption, while ______regulates water reabsorption.

aldosterone; antidiuretic hormone (ADH)