Bio

Question 1

Define excretion.

Answer 1

Excretion is the removal of metabolic waste products produced by cells in the body.

Question 2

List the five metabolic waste products of the human body.

Answer 2

Carbon dioxide
Water
Urea
Salts
Heat

Question 3

Why is feces not considered a metabolic waste product of the human body?

Answer 3

Feces is undigested food, not produced by cellular metabolism. Metabolic waste comes from chemical processes inside cells.

Question 4

Write the equation for cellular respiration. Which products of cellular respiration are “wastes”?

Answer 4

Equation:
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP
Wastes: Carbon dioxide (CO₂) and water (H₂O)

Question 5

List the three major organs responsible for excretion.

Answer 5

Kidneys
Lungs
Skin

Question 6

What is nitrogenous waste and what does it include?

Answer 6

Nitrogenous waste contains nitrogen and comes from protein breakdown. It includes:

Ammonia
Urea
Uric acid

Question 7

How does the body get rid of ammonia?

Answer 7

The liver converts ammonia (toxic) into urea (less toxic), which is excreted by the kidneys in urine.

Question 8

What does the skin excrete and how does it do this?

Answer 8

Skin excretes water, salts, and urea through sweat glands via perspiration.

Question 9

What do the lungs excrete and how do they do this?

Answer 9

Lungs excrete carbon dioxide and water vapor during exhalation.

Question 10

How is the liver involved in excretion?

Answer 10

The liver detoxifies harmful substances, breaks down amino acids (producing urea), and processes drugs and alcohol.

Question 11

How does the liver link the excretory system and the digestive system?

Answer 11

The liver produces bile (for digestion) and breaks down toxic substances (for excretion). It converts ammonia to urea and sends it to the kidneys.

Question 12

List the main components of the urinary system and the function of each

Answer 12

Kidneys: Filter blood and produce urine
Ureters: Carry urine from kidneys to bladder
Bladder: Stores urine
Urethra: Carries urine from bladder to outside the body

Question 13

Through what structure does urine exit the body and what is this process called?

Answer 13

Urine exits the body through the urethra. This process is called urination or micturition.

Question 14

What two structures (sphincters) are responsible for controlling the flow of urine?

Answer 14

Internal urethral sphincter (involuntary)
External urethral sphincter (voluntary)

Question 15

Identify the structures of the nephron and the function of each.

Answer 15

Bowman’s capsule: Surrounds the glomerulus and collects filtrate
Glomerulus: Filters blood under pressure
Proximal tubule: Reabsorbs water, nutrients, and ions
Loop of Henle: Concentrates urine by reabsorbing water and salt
Distal tubule: Further reabsorption and secretion
Collecting duct: Collects urine and sends it to the renal pelvis

Question 16

Identify and describe the function of the vessels that are involved with blood supply of the nephron.

Answer 16

Renal artery: Brings blood into kidney
Afferent arteriole: Brings blood to glomerulus
Glomerulus: Filters the blood
Efferent arteriole: Carries blood away from glomerulus
Peritubular capillaries: Surround the nephron for reabsorption/secretion
Renal vein: Returns filtered blood to circulation

Question 17

What are the three processes associated with urine formation?

Answer 17

Filtration
Reabsorption
Secretion

Question 18

Define filtrate and identify the substances that are part of its makeup.

Answer 18

Filtrate is the fluid filtered from blood into Bowman’s capsule. It includes water, glucose, salts, amino acids, and urea.

Question 19

Discuss filtration in terms of the location in the nephron and what substances are filtered out of the blood.

Answer 19

Location: Glomerulus into Bowman’s capsule
Filtered out: Water, glucose, salts, urea, amino acids (but not large proteins or blood cells)

Question 20

Discuss reabsorption in terms of location in the nephron and what substances are reabsorbed.

Answer 20

Location: Mostly in the proximal tubule, also in the loop of Henle and distal tubule
Substances reabsorbed: Water, glucose, amino acids, salts

Question 21

Discuss secretion in terms of location in the nephron and what substances are involved.

Answer 21

Location: Mainly distal tubule
Substances secreted: Drugs, excess ions (e.g., H⁺, K⁺), and toxins from blood into nephron

Question 22

What is ADH? (Be able to fill in a negative feedback loop to help explain this hormone)

Answer 22

ADH (Antidiuretic Hormone): Regulates water balance by making the collecting duct more permeable to water
Negative feedback:

Dehydration → hypothalamus signals pituitary → release ADH → kidneys reabsorb more water → more concentrated urine
Overhydration → less ADH → more water excreted → diluted urine

Question 23

What is aldosterone

Answer 23

A hormone from the adrenal glands that increases sodium (Na⁺) reabsorption in the kidneys, which helps retain water and increase blood pressure.

Question 24

How do the kidneys regulate water balance? What is water balance called?

Answer 24

By adjusting the amount of water reabsorbed using ADH and aldosterone.
This regulation is called osmoregulation.

Question 25

Describe the negative feedback mechanism in terms of hydration and dehydration.

Answer 25

Dehydration: Triggers ADH → kidneys reabsorb water → urine becomes concentrated Hydration: ADH decreases → less water reabsorbed → urine becomes dilute

Question 26

Identify the five tests associated with urinalysis and describe the purpose of each.

Answer 26

Color: Indicates hydration Clarity: Cloudiness may indicate infection pH: Acidic or basic; abnormal pH may suggest diet or kidney issues Glucose: Presence may indicate diabetes Protein: May indicate kidney damage

Question 27

Identify specific disorders related to the kidney and excretory system. (That urinalysis can test for...)

Answer 27

Urinary tract infection (UTI) Kidney disease Diabetes Dehydration Kidney stones

Question 28

Explain kidney failure and the need for a kidney transplant.

Answer 28

Kidney failure occurs when kidneys can no longer filter blood. Waste builds up, causing serious health issues. Treatment includes dialysis or a kidney transplant to restore function.

Question 29

Be prepared to label all the parts of the kidney and identify which areas of the kidney nephrons are found in.

Answer 29

Nephrons are located in: Cortex: Contains glomerulus and tubules Medulla: Contains loops of Henle and collecting ducts Key kidney parts: cortex, medulla, renal pelvis, ureter

Question 30

Be prepared to describe the path of blood, and urea through the kidneys and nephron. Include the term filtrate and as many parts of the circulatory system and urinary system as you need.

Answer 30

Blood path: Renal artery → afferent arteriole → glomerulus → efferent arteriole → peritubular capillaries → renal vein Filtrate path: Bowman’s capsule → proximal tubule → loop of Henle → distal tubule → collecting duct → renal pelvis → ureter → bladder → urethra Urea: Filtered out in glomerulus → part of filtrate → some reabsorbed, most excreted in urine