Human Physiology: Role of Body Fluids

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Questions and Answers

What is the primary role of fluids in the body?

Regulating blood pressure only

Only aiding in digestion

Maintaining balance of salts and proteins (correct)

Facilitating respiration

Which of the following is NOT a role of body fluids?

Transporting oxygen (correct)

Facilitating digestion

Keeping skin moist

Regulating body temperature

What is the total body water volume in an average adult human?

3 liters

25 liters

70% of body weight

40 liters (correct)

What is the role of podocyte cells in the kidneys?

They assist in the filtration of blood in the glomerulus. Signup and view all the answers

Which fluid composes the largest part of extracellular fluid?

Interstitial fluid Signup and view all the answers

Which substances are completely reabsorbed in the proximal convoluted tubules?

Glucose and amino acids Signup and view all the answers

How do kidneys maintain fluid balance in the body?

By controlling excretion of substances Signup and view all the answers

What percentage of the liquid filtered by the kidneys is excreted as urine?

1% Signup and view all the answers

What is the primary function of electrolytes in the body?

To maintain normal cell and organ function Signup and view all the answers

What volume of plasma is considered part of the extracellular fluid?

3 liters Signup and view all the answers

How much blood plasma do the kidneys filter in a 24-hour period?

150 to 180 liters Signup and view all the answers

What primarily causes the coloration of urine?

Urochrome pigment Signup and view all the answers

What term describes the ability of a membrane to allow molecules to pass through it?

Permeability Signup and view all the answers

Which part of the nephron is primarily involved in the regulation of pH?

Distal tubule Signup and view all the answers

The process of tubular secretion is primarily responsible for?

Removing unwanted substances from blood into tubular fluid Signup and view all the answers

Which ion is NOT reabsorbed significantly in the proximal convoluted tubules?

Calcium Signup and view all the answers

What is the primary characteristic of the cell membrane?

It allows only specific substances to pass through. Signup and view all the answers

Which transport mechanism moves ions from low concentration to high concentration?

Active Transport Signup and view all the answers

Which condition is associated with inadequate alveolar ventilation?

Respiratory acidosis Signup and view all the answers

What is a potential cause for respiratory alkalosis?

Anxiety during a panic attack Signup and view all the answers

Which of the following accurately describes metabolic acidosis?

Low pH and low HCO3- Signup and view all the answers

In compensated metabolic alkalosis, what would be the expected pH?

Normal pH Signup and view all the answers

What condition may result from severe pain?

Respiratory alkalosis Signup and view all the answers

What is characterized by a high pH and low CO2?

Respiratory alkalosis Signup and view all the answers

What is the primary function of the kidneys related to fluid?

Filtration of blood plasma Signup and view all the answers

Which waste products are primarily eliminated by the kidneys?

Urea and toxins Signup and view all the answers

How do the kidneys contribute to blood pressure regulation?

By releasing the enzyme renin Signup and view all the answers

What is the physical characteristic of the kidneys?

Dark red and slightly flattened Signup and view all the answers

What is the significance of the renal cortex?

It produces hormones regulating stress and metabolism Signup and view all the answers

Where are the kidneys situated in relation to the vertebral column?

Adjacent to the lumbar region, extending from T12 to L3 Signup and view all the answers

What is NOT a function of the kidneys?

Maturation of red blood cells Signup and view all the answers

What structure sits atop each kidney?

Adrenal gland Signup and view all the answers

What is the primary function of the renal cortex?

Urine filtration Signup and view all the answers

What is the role of the renal pelvis?

Acts as a funnel for urine flowing to the ureter Signup and view all the answers

Which structure prevents urine from flowing back towards the kidneys?

Ureterovesical valves Signup and view all the answers

What is the primary function of the detrusor muscle in the bladder?

To contract during urination to push out urine Signup and view all the answers

Which part of the kidney is responsible for anchoring the renal cortex?

Renal columns Signup and view all the answers

What is the length of the male urethra?

8 to 10 inches Signup and view all the answers

What happens when the bladder is stretched to a certain degree?

The brain is notified to empty the bladder Signup and view all the answers

What is the main purpose of the urethra?

To carry urine from the bladder to the outside of the body Signup and view all the answers

What is the primary function of juxtamedullary nephrons?

To concentrate or dilute urine Signup and view all the answers

Which section of the male urethra is the widest?

Prostatic urethra Signup and view all the answers

What percentage of nephrons in the human kidney are cortical nephrons?

85% Signup and view all the answers

Which of the following correctly describes the glomerulus?

A tuft of small blood vessels Signup and view all the answers

How does the structure of juxtamedullary nephrons differ from cortical nephrons?

Juxtamedullary nephrons have a longer loop of Henle Signup and view all the answers

What role do podocytes play in the nephron?

They wrap around glomerular capillaries Signup and view all the answers

What distinguishes the membranous urethra from the bulbous urethra in males?

Membranous urethra is narrower than bulbous urethra Signup and view all the answers

Which of the following statements about the vasa recta is true?

Vasa recta help maintain the osmotic gradient Signup and view all the answers

Study Notes

Urinary System and Fluid Balance

The urinary system consists of the kidneys, ureters, bladder, and urethra. These structures work together to filter blood, process waste, and regulate fluids.

Functions of the Urinary Tract

Filtration: Kidneys filter gallons of fluid from the bloodstream. Approximately 20% of the plasma volume passing through the glomerulus at any given time is filtered.
Waste Processing: Kidneys process about 200 quarts of blood to remove about 2 quarts of waste products and excess water. Waste products include urea, creatinine, toxic wastes, and drug metabolites.
Elimination: Kidneys eliminate nitrogenous wastes (ammonia, uric acid, urea, creatine, creatinine, and amino acids), excess salts, water, and other toxins from the body. Carbohydrates are broken down into CO2 and H2O, fats into CO2 and H2O, and proteins and nucleic acids into NH2 groups.
Regulation: Kidneys maintain acid-base balance by excreting acid and conserving bicarbonate. They also regulate blood pressure through the renin-angiotensin system, which involves renin from the kidneys, angiotensinogen from the liver, angiotensin I and II, ACE from the lungs, and aldosterone from the adrenal gland.
Conversion: Kidney cells convert vitamin D to its active form.

Kidney Structure and Characteristics

Physical Characteristics: Kidneys are dark red, slightly flattened bean-shaped organs with an average weight of 120 to 170 grams.
Dimensions: They are 10-12 cm long, 5-6 cm wide, and 2-3 cm thick.
Location: They extend from the T12 to L3 vertebrae, lying in the retroperitoneal position (behind the parietal peritoneum) in the superior lumbar region. They are slightly asymmetrical.
Outer/Inner Surface: The outer surface of the kidney is concave, and the inner surface is convex.
Adipose Tissue: The kidneys are surrounded by a layer of adipose tissue, which helps hold them in place and protects them from physical damage.
Layers: The kidney has three layers: renal fascia (fibrous outer layer), perirenal fat capsule (thick layer of adipose), and renal/fibrous capsule (inner layer of connective tissue).
Other Structures: An adrenal gland sits atop each kidney, and is part of the endocrine system. The renal cortex is the light-colored outer region; the renal medulla contains the darker reddish-brown renal pyramids, which are triangular in shape. The renal pelvis is a medial basin-like cavity where urine collects from the major renal calyces (extensions of the pelvis).

Nephron and Urine Formation

Nephrons are filtering units of the kidneys. There are millions of nephrons in each kidney.
Two Types of Nephrons: Cortical nephrons and juxtamedullary nephrons. Cortical nephrons are more numerous, with short loops of Henle, while juxtamedullary nephrons have longer loops of Henle, and a crucial role in concentrating urine.
Glomerulus: A tuft of small blood vessels that filter blood.
Filtration: The pressure of blood forces water and small molecules out into the Bowman's capsule.
Proximal Convoluted Tubule: Reabsorbs ions, water, nutrients, and adjusts filtrate pH.
Loop of Henle: Reabsorbs water and solutes into the interstitial fluid.
Distal Convoluted Tubule: Selectively secretes and absorbs ions to maintain blood pH and electrolyte balance.

Ureters

Two slender tubes that transport urine from the kidney to the urinary bladder, each 25-30 cm long and 6 mm in diameter.
Ureterovesical valves are located at the bladder entry to prevent backflow.

Bladder

A sac-like hollow organ for urine storage.
Walls of the bladder stretch to hold 600-800 ml of urine.
Trigone: Smooth, triangular region of the bladder base where infections often persist.
Detrusor Muscle: Smooth muscle in the bladder wall; contracts during urination to expel urine into the urethra.

Urethra

Thin-walled tube that carries urine from the bladder to the exterior of the body via peristalsis.
In males, the urethra is longer, divided into four sections (prostatic, membranous, bulbourethral, and pendulous), and also part of the reproductive system.
In females, the urethra is shorter, opening anteriorly to the vaginal opening.

Urine

Normal urine is transparent, yellow, or amber in color, slightly odorous, and has a pH of 4.6-8.0. Specific gravity measures 1.001 –1.035.
Other characteristics: In 24 hours, the kidneys filter 150-180 liters of blood plasma into the tubules. Daily urine production is approximately 1.0-1.8 liters in adults at rest.

Fluid Balance

Fluids are essential for maintaining a proper balance of salts, proteins, and other blood components (e.g., electrolytes).
Body fluids help regulate temperature, aid blood circulation, assist digestion, and keep the skin moist.
The composition of body fluids varies across different age groups (e.g., fetal, infant, adult, elderly) and factors like water, proteins, fats, and minerals.

Electrolytes

Electrolytes are present to maintain a balance for normal cell function, including chloride and phosphate.

Homeostasis

The kidneys maintain homeostasis by controlling the excretion of substances from the body. This includes regulating water and electrolyte balance.

Tonic Solutions

Isotonic solutions have the same solute concentration as another solution, causing no net movement of water particles across cell membranes.
Hypertonic solutions have a higher solute concentration than the cell interior, causing water to move out of the cell, potentially shrinking it.
Hypotonic solutions have a lower solute concentration than the cell interior, causing water to move into the cell, potentially causing swelling.

Buffer Mechanism

Buffers prevent significant changes in pH. The most important buffer system in blood is the bicarbonate system.
Other buffer systems are located in other fluids in the body.

Acid-Base Balance

Interpretations: The interpretation of ABGs involves analyzing values for pH, PaCO2, and HCO3 to identify whether a patient has respiratory acidosis, respiratory alkalosis, metabolic acidosis, or metabolic alkalosis. Using the ABG interpretation table can aid this process.
Causes: This can result from various factors, such as respiratory depression, anxiety, and metabolic issues.

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Description

Test your knowledge on the vital roles of body fluids in human physiology. This quiz covers topics such as kidney functions, fluid balance, and the essential contributions of electrolytes. Dive in to see how well you understand the importance of fluids in maintaining health.