urinary system 4

Question 1

urea

Answer 1

Nitrogenous waste products (urea, uric acid, creatinine):

Are poorly reabsorbed by kidney tubules.

This is because tubule cells lack many membrane carriers for them.

So, they stay in the filtrate and are excreted in urine in high concentrations.

Their origins:

Urea: From protein breakdown → amino acids used for energy → liver converts waste to urea.

Uric acid: From nucleic acid metabolism (DNA & RNA).

Creatinine: From creatine metabolism in muscles.

Ions and blood balance:

The kidneys actively reabsorb or excrete ions (like Na⁺, K⁺, H⁺, etc.) as needed.

This helps maintain blood pH and electrolyte balance, adjusting based on body needs.

If you’re studying for an exam, a good way to test understanding is to ask yourself:

Why isn’t creatinine reabsorbed?

What role does urea play in urine concentration?

How do kidneys adjust for blood pH?

Question 2

diffrence between urine and filtrate

Answer 2

Volume filtered:
Kidneys filter 150 to 180 liters of blood plasma through the glomeruli daily.

Processing filtrate:
The filtrate moves through the tubules, where:

Reabsorption: Necessary substances like water, nutrients, and ions are taken back into the blood.

Secretion: Additional wastes or excess ions are added into the filtrate.

Urine volume:
Despite the huge volume filtered, only about 1.0 to 1.8 liters of urine are produced in 24 hours.

Filtrate vs. Urine:

Filtrate: Similar to blood plasma but without proteins; contains everything dissolved in plasma.

Urine: Contains nitrogenous wastes (like urea, uric acid, creatinine) and unneeded or excess substances. It has lost most water and nearly all nutrients and necessary ions by the time it reaches collecting ducts.

Homeostasis:
Healthy kidneys regulate blood composition, maintaining a stable internal environment, despite changes in diet or cell activity.

Question 3

freshley voided urine colour

Answer 3

Normal urine is usually clear and pale to deep yellow.

The yellow color comes from urochrome — a pigment formed from the breakdown of hemoglobin (from old red blood cells).

Urine color depends on solute concentration:

More solutes = deeper yellow

More diluted (from drinking lots of water) = pale, straw-colored

Unusual urine colors can happen due to:

Certain foods (like beets or asparagus)

The presence of blood, bile, or certain medications

Question 4

urine ordor

Answer 4

Urine Odor — Key Points:
Freshly formed urine is sterile and has a slightly aromatic (mild) smell.

If urine stands too long, bacteria begin to act on the solutes, and it develops a strong ammonia odor.

Certain foods (like asparagus), medications, or diseases (such as diabetes mellitus) can change the smell of urine.

Question 5

the ph of pee

Answer 5

Urine pH Overview:
Normal urine pH is around 6 — meaning it’s slightly acidic.

Urine pH can change based on:

Diet

Body metabolism

Health conditions

🥚🍞 What makes urine more acidic?
High-protein diets (e.g., eggs, cheese)

Whole wheat products

These foods produce acidic byproducts, so the kidneys excrete more acids → urine becomes more acidic.

🥦🌿 What makes urine more alkaline (basic)?
Vegetarian diets (lots of fruits and vegetables)

These foods produce more alkaline byproducts, so the kidneys excrete excess bases → urine becomes more alkaline.

Urinary tract infections (UTIs) caused by certain bacteria can also make urine alkaline.

Question 6

the weight of pee

Answer 6

Urine Specific Gravity (SG) Overview:
Urine is water + solutes, so it is denser (heavier) than pure distilled water.

Specific gravity compares the weight of urine to distilled water.

Distilled water = 1.0

Urine usually ranges from 1.001 (very dilute) to 1.035 (very concentrated).

When Urine Is Dilute (Low Specific Gravity):
Drinking excessive fluids

Using diuretics (drugs that increase urine output)

Having chronic renal failure (kidneys lose ability to concentrate urine)

✅ When Urine Is Concentrated (High Specific Gravity):
Inadequate fluid intake (not drinking enough water)

Fever (causes dehydration)

Kidney inflammation (called pyelonephritis)

Question 7

things that are supposed to be in pee

Answer 7

Normal Solutes Found in Urine:
Sodium ions (Na⁺)

Potassium ions (K⁺)

Urea

Uric acid

Creatinine

Ammonia

Bicarbonate ions (HCO₃⁻)

Other ions, depending on blood composition

🩺 Why Urinalysis Is Important:
Certain diseases change urine composition dramatically.

Finding abnormal substances in urine helps diagnose health problems.

That’s why routine urinalysis is a key part of physical exams.

Question 8

things not supposed to be in pee

Answer 8

Substances NOT Normally Found in Urine:
Glucose

Blood proteins

Red blood cells (RBCs)

Hemoglobin

White blood cells (pus)

Bile

🩺 Why This Matters:
Presence of these substances usually indicates a health problem or disease.

For example, glucose in urine can suggest diabetes.

Blood or proteins might signal kidney damage or infection.