Summary of the Urinary System - homeschool.ie

Subject: Leaving Certificate Biology Higher Level

Teacher: Ms. R. Doyle

Week: Week 19

Title: Excretion (kidney)

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Summary of the Urinary System

Definitions of Urinary System

Excretion: removal of waste products of metabolism

Metabolism: sum of all chemical reactions in a living organism

Homeostasis: maintaing a constant internal environment in a living organism

Osmoregulation: maintaing a constant water level in a living organism. Detected by the

hypothalamus

Filtration: removal of materials from the blood

Reabsorbtion: returning of filtered material to the blood

Glomerular filtrate: content of the blood that has passed through the glomerulus

Diffusion: movement of molecules from an area of high molecule concentration to an area of

low molecule concentration across a semi permeable membrane. Passive process; doesnt

require energy (ATP)

Osmosis: movement of water molecules from an area of high water concentration to an area of

low water concentration across a semi permeable membrane. Passive process; doesnt require

energy (ATP)

Osmotic gradient: difference in water concentration between two areas

Semi permeable/ selectively permeable: controls water enters an area based on size of molecule

Active transport: movement of molecules that requires energy (ATP)

Exocrine gland: a gland that has a duct (tube) coming out of it

Endocrine gland: a gland that does not have a duct (tube) coming out of it

ADH: anti- diuretic hormone

Hormone: proteins produced by endocrine glands (ductless glands) that transport chemical

messages around the human body dissolved in blood

Homework Questions

2008 Q13

2006 Q13

DEB 2005

DEB 2015



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Part of the excretory system and is involved in Homeostasis

Urinary System and the kidney have a role to play in homeostasis

Homeostasis: maintaining a constant and balanced internal environment in a living organism

Kidneys role in homeostasis

Excretion: removal of waste products of metabolism from a living organism (not to be confused

with egestion)

Osmoregulation: maintaining a constant water balance in a living organism

Excretion:

Excretory Product Source Site of Excretion How

Urea Protein Kidneys Via filtration in the

nephron

CO2 Carbohydrates/

proteins/ Lipids

Lungs Breathing

H20 Cellular Respiration,

food

Lungs, Skin, kidney Breathing, Sweating

Salts Skin, lungs, kidney Breathing, Sweating



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Kidney

Exocrine gland (has a duct-ureter)

Located in the pelvic cavity

Renal Artery (comes from Aorta/ linked to afferent arteriole): carries O2 and food to the kidney

Renal Vein (goes to the vena cava/ linked to efferent arteriole): carries CO2 and waste products

away from the kidney

Part of kidney Role Part of Nephron structure

Cortex Filtration Glomerulus/ bowman’s

capsule/ distal convuluted

tubule

Medulla Reabsorption Proximal convuluted tubule/

loop of henle/ collecting duct

Pelvis Excretion Collecting duct

Filtration: removal of materials from the plasma part of the blood

Reabsorption: returning of filtered materials to the blood



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Nephron

Kidney is made up of millions of nephron which increase the surface area for filtration

and reabsorption

Aid the filtration and reabsorption process by:

o Having a large surface area (many of them)

o Walls of nephron are one cell thick

o Surrounded by a good blood supply

Structure of the Nephron

Afferent Arteriole (cortex): blood enters the kidney via the afferent arteriole. This

blood comes from the renal artery which is linked to the Aorta. The afferent

arteriole is larger than the efferent arteriole so that it creates pressure and forces

the blood out of the arteriole to enter the glomerulus

Glomerulus (cortex): the content of the blood containing water, salts, amino acids,

triglycerides, glucose is passed through the glomerulus and becomes known as the

glomerulus filtrate. (blood and filtrate will contain the same amount of glucose,

amino acids etc for this reason).Red Blood cells, white blood cells, platelets and

large undigested proteins are not passed through the glomerulus as they are too

large and continue straight on the the efferent arteriole



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Bowman’s Capsule (cortex): glomerulus filtrate collected by the Bowman’s capsule

and passed to the proximal convuluted tuble. The Bowman’s capsule is the part of

the nephron involved in filtration. The glomerulus is not the part of the nephron

involved in filtration. The glomerulus is part of the circulatory system

Proximal Convuluted Tubule (medulla): Majority of reabsorption of all food groups

occurs here as well as some water. Food and salt molecules are reabsorbed by

diffusion. Water molecules are reabsorbed by osmosis

Loop of Henle: For the remainder of the nephron water and salts are reabsorbed

along the loop of henle.

Distal Convuluted Tubule: this is the site of action of Anti- Diuretic Hormone (ADH)

which affects the permeability of the nephron wall and will determine the amount

of water that is reabsorbed at this stage

ADH (after intense/vigorous excercise, after eating salty foods or on a warm day)

o Water level in the blood is low detected by the hypothalamus of the brains

o sends a message to the pituitary gland (endocrine gland-ductless gland that

produces hormones) in the brain to produce a large amount of ADH

o Travels in the blood to the distal convuluted tubule/ collecting duct of the

nephron in the blood

o ADH increases the permeability of the nephron wall

o Large volume of water is reabsorbed by the nephron back into the blood

o Volume of urine is low

o Has a high salt concentration

o Dark yellow/ brown in appearance

Collecting Duct: any water which is not reabsorbed back into the blood is

transported via the collecting duct to the ureter and transported to the bladder.

ADH can also act in the collecting duct

Functions of water (following reabsorbtion): solvent, medium for chemical

reactions, transport, temperature regulation, formation of plasma



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Urinary System

Revision Diagram of Nephron



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Urinuary System Revision Questions

1. Where in the nephron structure does filtration take place

2. Name 3 substances that do not pass through the glomerulus. Give a reason for this

3. When the content of the blood is passed through the glomerulus what does it become known as

4. In what part of the structure of the kidney does filtration occur

5. In what part of the structure of the kidney does reabsorption take place

6. List 3 ways in which the nephron has adapted to its role in absorption

7. What is excretion. How does it differ to egestion

8. Name three products that must be excreted from the body and state the location of excretion

9. Where in the structure of the nephron does reabsorption of food molecules occur

10. Name 3 types of food molecules reabsorbed at the location named in Q9

11. By what transport mechanism is 1. Water 2. Salt reabsorbed in the nephron

12. State a location in the nephron where 1. Water 2. Salt is reabsorbed

13. Name the blood vessel that supplies the kidney with food and oxygen. From what major blood

vesel in the body is blood vessel derived

14. Name a hormone which controls the amount of water reabsorbed into the body from the

nephron

15. Where is this hormone produced

16. Where is the site of action of this hormone in the nephron

17. What effect does this hormone have on the structure on the nephron that influences

reabsorption

18. Explain the role of ADH in water reabsorption from the kidney after a period of excercise

19. Describe the appearnace and volume of urine after excercise

20. What group of biomolecules do hormones belong to

21. How do hormones travel around the body

22. Draw and label a structure of the nephron

23. Is the kidney an example of an endocrine or an exocrine gland.give a reason for your answer

24. Draw and label the strucutre of a nephron

25. In what section of the kidney is the Bowman’s capsule located

26. Where in the structure of the nephron are Amino Acids reabsorbed

27. Large proteins are not passed throught the glomerulus. Given a reason for this

28. State two situations which may result in a drop in the water level of the blood

29. The kidney has a role to play in homeostasis. What is homeostasis

30. Why is glucose absent from urine

31. Why is the concentration of glucose the same in the plasma and glomerular filtrate

32. Is it normal to find proteins in urine. Give a reason for your answer

33. Why is the afferent arteriole larger than the efferent arteriole



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The Urinary System Exam Paper Question 2018-Q6



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2011 Q12

(a) (i) What is meant by the term excretion?

__________________________________________________________________________________

(ii) Mention one method of excretion in flowering plants.

__________________________________________________________________________________

(b) (i) Draw a large labelled diagram of a vertical section through a human kidney.

Label the following parts of your diagram: cortex, medulla, pelvis.

(ii) Indicate clearly on your diagram where re-absorption takes place.

(iii) 1. Name the blood vessel that supplies blood to a kidney. ________________________________

2. From which blood vessel does the blood vessel referred to in (iii)1 arise? _____________________

(iv) In which cavity of the body are the kidneys located? ____________________________________

(v) Name one substance, other than water, excreted in the urine.______________________________

(vi) Give a feature of the kidney which indicates that it is an exocrine gland.

__________________________________________________________________________________

(b) (i) The diagram

(c) above shows the structure of a nephron and its associated blood supply.

1. Name the parts numbered 1 to 6.

1. __________________ 2. _________________ 3. ________________ 4. _________________

5. _________________ 6. ________________ 7. __________________



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2. Indicate clearly by number where filtration takes place. ____________________

3. Name the hormone associated with changing the permeability of the structure at 7. _____________

(ii) A sample of urine was found to contain protein.

1. Would you consider this to be normal? __________________________________

2. Explain your answer.

_________________________________________________________________________________

(iii) A sample of urine was found to contain glucose.

1. Would you consider this to be normal? _______________________________________________

2. Explain your answer. ______________________________________________________________

Homework 2008-Q13

(a) (i) What is meant by excretion?

_________________________________________________________________________________

(ii) Urea and carbon dioxide are excretory products of the human body. In the case of each

product name a substance from which it is derived.

Carbon Dioxide ___________________________________________________________________

Urea _____________________________________________________________________________

(b) The diagram shows the structure of a nephron and its associated blood supply.

(i) Name the parts A, B, C, D, E and F.

A _______________________ B________________ C________________ D __________________

E ____________________F__________________

(ii) From which blood vessel is A derived? ______________________________

(iii) Where in the kidney is B located? __________________________________

(iv) Give the part of the nephron in which each of the following takes place:

1. filtration, _____________________________________________________

2. reabsorption of amino acids. _________________________________________

(v) Give two features of the nephron that aid filtration.

1. ________________________________________________________________

2. ________________________________________________________________

(vi) Name a group of biomolecules in the blood which are too large to pass through the filtration system

of the nephron. ______________________________________________________



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(b) (i) Suggest two situations which may result in a drop in the water content of the blood.

1.__________________________________________________________________________

2.__________________________________________________________________________

(ii) When the water content of the blood drops a hormone is released. Name this hormone and the

endocrine gland from which it is secreted.

Hormone _________________________ Gland ______________________

(ii) Give a precise target area for this hormone. How does the hormone reach the target area?

Target Area ________________________________________

How it reaches target area ____________________________

(iv) Explain the role of the hormone at its target area, when the water content of the blood is

low.

_____________________________________________________________________________________

_____________________________________________________________________________________

____________________________________________________________________________

Homework- 2006-13 (b)

(b) Use your knowledge of the human vascular and excretory systems to answer the following.

(i) Explain the terms, plasma, glomerular filtrate.

Plasma ___________________________________________________________________________

Glomerular Filtrate _________________________________________________________________

(iii) Explain why red blood cells are normally absent from glomerular filtrate.

_________________________________________________________________________________

(iii) The concentration of glucose is the same in plasma and glomerular filtrate. Why is

this? ____________________________________________________________________________

(iv) Why is glucose normally absent from urine?

__________________________________________________________________________________

(v) Following a period of heavy exercise an athlete may produce only a small volume of

concentrated urine. Explain this observation and give an account of the process that

concentrates the urine

_____________________________________________________________________________________

_____________________________________________________________________________________

____________________________________________________________________________



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2004 12 (a) and (b)

(a) What is homeostasis? State the role of the kidneys in homeostasis.

Homeostasis ______________________________________________________________________

Role of Kidney in Homeostasis _______________________________________________________

(b) (i) Draw a labelled diagram of a nephron. Include blood vessels in your diagram.

(ii) Filtration and reabsorption are vital processes that take place in the nephron. Describe how

each of these processes occurs.

Filtration

_____________________________________________________________________________________

_______________________________________________________________________________

Reabsorption

_____________________________________________________________________________________

________________________________



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Homework- DEB 2005



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Homework – DEB 2015

Summary of the Urinary System - homeschool.ie

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