D4.3 - Maintaining the Excretory System

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Questions and Answers

What hormone stimulates the reabsorption of Na+ when blood Na+ concentration drops?

Cortisol

Glucagon

Aldosterone (correct)

Insulin

What is the normal pH of body fluids in humans?

8.0

7.4 (correct)

6.8

7.0

Which of the following actions occurs if blood becomes too acidic?

H+ ions are reabsorbed

HCO3- is secreted

HCO3- is excreted

H+ ions are excreted (correct)

Which factor does NOT affect the balance of materials in urine?

Genetic makeup Signup and view all the answers

Which condition specifically involves only the urethra during a urinary tract infection?

Urethritis Signup and view all the answers

What is a common symptom of a urinary tract infection?

Frequent urination Signup and view all the answers

Which of the following is a potential complication of untreated urinary tract infections?

Permanent kidney damage Signup and view all the answers

What is one preventative measure against urinary tract infections?

Maintaining hygiene Signup and view all the answers

What are the two important characteristics of blood influenced by the amount of water reabsorbed from filtrate?

Volume and concentration of plasma solutes Signup and view all the answers

What triggers the release of antidiuretic hormone (ADH)?

Increased osmotic pressure in blood plasma Signup and view all the answers

What effect does excessive water consumption have on the kidneys?

Allows more water to enter urine Signup and view all the answers

Which structure in the brain regulates the release of ADH?

Hypothalamus Signup and view all the answers

What happens when blood plasma becomes too dilute?

Osmoreceptors stop the release of ADH Signup and view all the answers

What is diabetes insipidus primarily characterized by?

Excessive thirst and urination Signup and view all the answers

What is the primary function of a diuretic?

Increase volume of urine Signup and view all the answers

How does ADH affect the kidneys?

Increases water reabsorption in distal tubules Signup and view all the answers

What is the primary cause of kidney stones?

Excess calcium in urine Signup and view all the answers

Which treatment method is used for kidney stones larger than 20 mm?

Surgery Signup and view all the answers

Which of the following conditions can lead to nephron damage?

Kidney infection Signup and view all the answers

What percentage of nephrons must be destroyed to cause inadequate urine output?

75% Signup and view all the answers

What is a key feature of hemodialysis?

Utilizes an external device Signup and view all the answers

What is the function of the dialysate in hemodialysis?

To facilitate diffusion of wastes Signup and view all the answers

What does peritoneal dialysis utilize as its membrane?

Lining of intestines Signup and view all the answers

What is a common source of kidneys for transplantation?

Close family members Signup and view all the answers

Which of the following indicates a risk for kidney failure?

High blood pressure Signup and view all the answers

What is one consequence of kidney damage due to high blood pressure?

Reduced ability to filter wastes Signup and view all the answers

Study Notes

Maintaining the Excretory System

The amount of water reabsorbed from the filtrate affects blood volume and plasma solute concentration.
The excretory system is crucial for homeostasis.
Disorders in the excretory system can impact other body systems.

Water Balance

Osmotic pressure is the force generated by osmosis and affects the exchange of materials between blood and cells.
Solute concentration in blood usually remains constant despite variations in water intake.
If a person drinks a lot of water, kidneys allow more water into urine.
If water is scarce, kidneys conserve water by producing concentrated urine.

Regulating ADH

Antidiuretic hormone (ADH) regulates osmotic pressure in kidneys to enhance water absorption.
Release of ADH leads to more concentrated urine.
ADH makes the upper part of the distal tubule and collecting duct permeable to water.
Osmoreceptors are cells sensitive to osmotic pressure located in the hypothalamus.
The hypothalamus regulates hunger, thirst, blood pressure, body temperature, fluid balance, and salt balance.

Regulating Reabsorption of Water

High blood plasma concentration (increased osmotic pressure) triggers the release of ADH from the pituitary gland.
ADH increases the permeability of the distal tubules and collecting ducts, allowing more water to be reabsorbed and lowering the osmotic pressure.
Low blood plasma concentration (decreased osmotic pressure) stops ADH release, reducing water reabsorption, and increasing urination.

Regulating Reabsorption of Water (continued)

If blood plasma is too dilute, osmotic pressure decreases.
Osmoreceptors stop/prevent the release of ADH which makes the distal tubule and collecting duct less permeable to water.
More water is excreted in the urine.

Diabetes Insipidus

Diabetes insipidus happens when ADH activity is insufficient, causing excessive urination.
This leads to intense thirst, dehydration, and ion imbalances.
Treatment includes synthetic ADH to restore water and ion balance.

Diuretic

A diuretic increases urine volume by reducing ADH release.
This causes decreased permeability of the tubules and collecting ducts.
Diuretics, such as alcohol, coffee, tea, or carbonated drinks, increase water loss and can lead to dehydration.

Reabsorption of Salts

Kidneys control salt balance by regulating the excretion and reabsorption of ions.
Aldosterone is a hormone that stimulates the reabsorption of Na+ when blood Na+ concentration drops.
Chloride (Cl-) ions follow Na+ due to charge attraction.
Water follows by osmosis.
Excess K+ in the blood signals aldosterone to increase excretion of K+ in the distal tubules and collecting ducts.

Maintaining Blood pH

Body fluids maintain a pH of 7.4.
Acid-base buffer systems in the blood adjust H+ ion concentrations.
If the blood becomes too acidic, H+ ions are excreted, and bicarbonate ions are reabsorbed.
If the blood is too basic, H+ ions aren't excreted, and bicarbonate ions aren't reabsorbed.
The bicarbonate buffer system, which combines carbon dioxide, water, and carbonic acid, regulates the pH.

Balance of Excretory System

The balance of substances in urine depends on several factors, including diet, physical activity, stress, and fatigue.
Healthcare professionals consider many factors when analyzing urine to detect diseases like diabetes.

Urinary Tract Infection (UTI)

Cystitis is a bladder infection caused by bacteria or viruses.
Urethritis is a urethra infection.
UTIs are more common in women than men due to anatomical differences.
UTIs can cause permanent kidney damage.

UTI Symptoms

UTI symptoms include painful urination, frequent urination, even when no urine is produced, bloody or brown urine, and tenderness, chills, fever, nausea, and vomiting.

UTI Treatment

UTI treatment primarily involves antibiotics.
In severe cases, surgery might be necessary.

Kidney Stones

Kidney stones are crystalline formations caused by excess calcium in urine.
Treatment options include medications to dissolve the stones, ultrasound shock waves for smaller stones, or surgery for larger stones.

Problems with Kidney Function

Renal insufficiency is when kidneys can't maintain homeostasis.
Nephrons can be damaged due to high blood pressure, kidney infections, trauma, poisoning, and atherosclerosis.
Complete nephron destruction (greater than 75%) leads to inadequate urine output to maintain homeostasis.
Kidney transplants and artificial kidneys (performing dialysis) are possible solutions.

Dialysis

Dialysis uses a semipermeable membrane to remove waste products from the blood.
Involves diffusion of substances across the membrane, from high to low concentration.
Dialysate (a solution similar to clean blood plasma) is on the other side of the membrane.
Two main types of dialysis are hemodialysis and peritoneal dialysis.

Hemodialysis

Uses an artificial membrane (machine) to filter waste products from blood.
Filtered blood (dialysate) is returned to the patient.
Typically takes 2-5 hours, 3x per week.
Patients need a regulated diet to avoid toxin buildup.

Peritoneal Dialysis

Uses the lining of the abdomen (peritoneum) to filter waste products.
Dialysis solution is introduced into the abdominal cavity.
The solution contains capillaries that slowly filter the blood.

Kidney Transplants

Kidney transplants replace damaged kidneys with healthy ones, often from a living donor.
Recipients must maintain a healthy diet and lifestyle to care for the transplanted kidney.
Kidneys can also be obtained from deceased donors who have completed the necessary paperwork.

Kidney-Coronary Connection

High blood pressure can damage blood vessels in the kidneys.
This can lead to kidney failure.
Damage from high blood pressure might go unnoticed initially.

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Description

Explore the key components of the excretory system and its role in maintaining homeostasis. This quiz covers water balance, osmotic pressure, and the regulation of antidiuretic hormone (ADH). Test your understanding of how these elements affect blood volume and overall body function.