1. 11.3
Excretory System

2. Definitions Excretion— Osmoregulation—
The disposal of nitrogen-containing waste products of metabolism
Osmoregulation—
How organisms regulate solute concentrations and balance the gain and loss of water

3. Why is excretion important?
Body needs to get rid of waste
Otherwise, waste will build up
Take up space
Prevent metabolic processes
Poison organism

4. What are the two types of waste produced by the body?
Solid waste
Liquid waste (urea)
Where is solid waste processed?
Large intestine
Where is solid waste excreted?
Rectum and anus
Where is liquid waste processed?
Kidney
Where is liquid waste excreted?
Urinary tract

5. Excretory System Overview

6. Overview of Excretory System, Kidney, and Nephron Structure

7. Kidney Structure
Be able to draw: cortex, medulla with pyramids, pelvis, ureter, renal artery, and renal vein

8. Identify the components of a kidney.
cortex
medulla
renal pyramids
pelvis
ureter
renal artery
renal vein

9. Nephron Structure Be able to draw a nephron Must include glomerulus
Bowman's capsule
proximal convoluted tubule
loop of Henle
ascending and descending both labeled
distal convoluted tubule
collecting duct
Ascending portion of Loop of Henle
Descending portion of Loop of Henle

10. Identify the components of a nephron.
glomerulus
Bowman's capsule
proximal convoluted tubule
loop of Henle
ascending and descending
portions of the Loop/Henle
distal convoluted tubule
collecting duct
Ascending portion of Loop of Henle
Descending portion of Loop of Henle

11. How do solutes and water get into the proximal convoluted tubule?
High pressure in arteries/arterioles leading into the nephron
This leads to ultrafiltration in the capillaries of the glomerulus
Water and solutes such as urea, glucose, salts, and amino acids drain into the Bowman's capsule
Water and solutes dumped into the proximal convoluted tubule

12. How are salt, amino acids, and water reabsorbed into blood from the proximal convoluted tubule?
Salt (NaCl), glucose, and amino acids are transported back to the blood by active transport
Water follows in to the blood by osmosis

13. Solute Reabsorption Diagram

14. How are the cells on the wall of the proximal convoluted tubule specially adapted for selective absorption?
microvilli increase the surface area for absorption through active transport
mitochondria produce ATP for active transport

15. What happens after filtration and reabsorption?
3. Secretion
Toxins, excess ions and other substances are actively transported out of the filtrate
4. Excretion
The filtrate is sent out of the nephron and out of the body as urine

16. What are some reasons an individual’s blood solute concentration increase?
vomiting and diarrhea makes the body lose water
increased salt intake (from eating those potato chips...)
drinking alcohol adds ethanol and sugar
drinking coffee adds sugar and caffeine
excess sweating makes the body lose water
if the individual isn’t drinking enough water

17. Anti-Diuretic Hormone (ADH) Function
Osmo-receptors in the brain monitor blood solute concentration
It is a hormone that is synthesized in the brain (hypothalamus)
When solute concentrations are high, ADH is released into the blood stream
ADH travels to the nephrons of the kidney and tell kidney to reabsorb more water
This is a negative feedback control of ADH secretion

18. cortex shown at the edge of kidney;
1. Blood vessels carry blood to and from the kidney. Draw a labelled diagram to show the internal structure of the kidney, including the vessels that are connected to it (5 marks)
cortex shown at the edge of kidney;
medulla shown inside the cortex (with pyramids);
pelvis shown on the concave side of the kidney;
ureter shown connecting with the pelvis
renal artery shown connected
renal vein shown connected
IB Exam Question

19. 2. Draw a labelled diagram of a nephron. (6 marks)
IB Exam Question
glomerulus;
Bowman's capsule;
proximal convoluted tubule;
loop of Henle;
ascending and descending both labeled;
distal convoluted tubule;
collecting duct;

20. IB Exam Question
3. Which part of the nephron shown below is impermeable to water molecules? (1 mark)
A. I
B. II
C. III
D. IV
Correct answer: C

21. high pressure in arteries/arterioles leading into the nephron;
4. Describe how the liquid and solutes that flow through the proximal convoluted tubule are produced. (2 marks)
IB Exam Question
high pressure in arteries/arterioles leading into the nephron;
this leads to ultrafiltration in the capillaries of the glomerulus;
Water and solutes such as urea, glucose, salts, and amino acids drain into the Bowman's capsule which leads to the proximal convoluted tubule;

22. mitochondria produce ATP for active transport;
IB Exam Question
5. Explain how the structure of the proximal convoluted tubule cell is adapted to carry out selective re-absorption (2 marks)
microvilli increase the surface area for absorption / active transport;
mitochondria produce ATP for active transport;

23. 7. Describe how these solutes and water are reabsorbed
IB Exam Question
6. Name three solutes that are selectively reabsorbed back into the blood in the proximal convoluted tubule (1 mark)
glucose
amino acids
salt (NaCl)
7. Describe how these solutes and water are reabsorbed
by the blood from the proximal convoluted tubule.
Salt (NaCl), glucose, and amino acids are transported back to the blood by active transport
Water follows in to the blood by osmosis

24. 8. Where in the kidney does ultrafiltration take place? (1 mark)
IB Exam Question
8. Where in the kidney does ultrafiltration take place? (1 mark)
A. Glomerulus
B. Loop of Henlé
C. Proximal tubule
D. Collecting ducts
Correct answer: A

25. A. The amount of blood flowing to the kidney
9. What can be changed in the kidney over a period of time in order to carry out the process of osmoregulation?(1 mark)
IB Exam Question
A. The amount of blood flowing to the kidney
B. The amount of fluid filtered from the blood in the glomeruli
C. The amount of solutes selectively reabsorbed in the proximal convoluted tubule
D. The amount of water reabsorbed in the collecting ducts
Correct answer: D

26. 10. State three reasons why a person’s blood plasma solute concentration may increase. (3 marks)
IB Exam Question
vomiting / diarrhoea
increase salt intake;
drink alcohol / coffee;
excess sweating / lack of water intake;

27. 11. How does anti-diuretic hormone (ADH) function in osmoregulation.
IB Exam Question
11. How does anti-diuretic hormone (ADH) function in osmoregulation.
It is a hormone that is synthesized in the brain (hypothalamus)
Osmo-receptors in the brain monitor blood solute concentration.
When solute concentrations are high, ADH is released into the blood stream
The hormone travels to the nephrons of the kidney and signal kidney to reabsorb more water.,
This is a negative feedback control of ADH secretion;

28. IB Exam Question
12. Anti-diuretic hormone has its main effect on which part of the nephron? (1 mark)
A. Proximal tubule
B. Bowman’s capsule
C. Loop of Henle
D. Collecting duct
Correct answer: D