Maintaining Water and Nitrogen Balance

Question 1

Describe how the kidneys produce urine

Answer 1

Blood enters the kidneys through the arteries
The blood passes through the capillaries.in the kidneys
The kidneys filter out and remove glucose, water, ions and urea from the blood into tubules (it doesn’t filter large molecules like protein)
After this all the glucose molecules,and the some of the small water and ion molecules are reabsorbed back into the blood in selective reabsorbtion, the glucose by active transport and the water by osmosis
The urea and excess water and ions are removed from the kidneys as urine.
The urine is stored in the bladder

Question 2

What is urine made out of?

Answer 2

Urea
Water molecules

Ions

Question 3

What is selective reabsorbtion?

Answer 3

When glucose and some water and ion molecules are reabsorbed back into the blood after being filtered out by the kidneys- glucose by active transport and water by osmosis

Question 5

What is deamination?

Answer 5

When the liver breaks down amino acids to produce ammonia

Question 6

What is a tubule?

Answer 6

A very small tube

Question 7

Where does deamination take place?

Answer 7

In the liver

Question 8

Name three ways in which water is lost from our body

Answer 8

Sweat
Exhalation
Urinating

Question 9

Name two uncontrolled ways in which water is lost from the body

Answer 9

Sweating
Exhalation

Question 10

What is lost from the body during sweat?

Answer 10

Water
Ions
Urea

Question 11

What is lost from the body during exhalation?

Answer 11

Water vapour

Question 12

What is lost from the body durng urination

Answer 12

Water

Ions

Urea

Question 13

Name a homeostatically controlled way in which water is lost from the body

Answer 13

Urination

Question 14

Is urea toxic or untoxic?

Answer 14

Toxic

Question 15

Which part of the body detects changes in water levels in the body?

Answer 15

Hypothalamus

Question 16

Is blood concentrated or dilute when blood water levels are too low?

Answer 16

Concentrated

Question 17

Is blood dilute or concentrated when blood water levels are too high?

Answer 17

Dilute

Question 19

Explain how negative feedback controls blood water levels when blood is dilute

Answer 19

Blood becomes dilute when the body absorbs water from food and drinks

The high blood water levels are detected by the hypothalamus which transmits the information to the coordination centre.
This inhibits the secretion of ADH from the pituitary gland into the blood stream
This decreases the permeability of the kidney tubules to water, decreasing the amount of water which is selectively reabsorbed back into the blood.
This increases the amount of excess water which is released from the kidneys, resulting in a large volume of dilute urine

Question 20

What molecules are too large to be filtered into the kidney tubules in the production of urine

Answer 20

Proteins

Question 21

Which molecules are too large to pass through the semi-permeable membrane in kidney dialysis

Answer 21

Protein
Blood cells

Question 22

A person with kidney failure has _ _ _ _ _ _ concentrations of water, ions and urea in their bloodstream

fill in the blank

Answer 22

A person with kideny failure has higher concentations of water, ions and urea in their bloodstream

Question 23

Describe the proccess of kidney dialysis

Answer 23

1. A person with kidney failure has a high concentration of water, ions and urea in their blood
2. This is treated with kidney dialysis. The patient’s blood is seperated from a dialysis fluid by a semi-permeable membrane
3. The dialysis fluid contains no urea, so the urea in the person’s blood diffuses from an area of high to low concentration to the dialysis fluid, to remove the urea from the patient’s blood- the dialysis fluid is being constantly refreshed to maintain a large concentration gradient for the urea
4. The dialysis fluid also contains normal levels of water and ions, this causes onlysome of the water and ions in the patient’s blood diffuses from an area of high to low concentration to the dialysis fluid.
5. This reduces the water and ion levels in the patient’s blood back to normal levels

Question 24

Name different treatments for kidney failure

Answer 24

Kidney transplant

Kidney dialysis

Question 25

**What happens** in a **kidney transplant**?

Answer 25

A **diseased kidney** is **replaced** by a **healthy kidney** from a **donor**

Question 26

**Compare** the **advantanges** and **disadvantages** of **kidney dialysis** and **kidney transplants**

Answer 26

Dialysis vs Transplant **No shortage**of **dialysis machines** so they are **readily available** vs **shortage of kidney donors** **Expensive** for the **NHS** in the **long term** vs **only expensive** in the **short term** **Patient must** misist hospital **three times a week** and **eat** a **controlled diet** to **control urea levels** in blood from being **too high** vs **Patient** can lead a **normal life** ... vs **Risk of rejection** by **immune system** and **anti-rejection drugs must** be **taken everyday**, patient may forget to take them, this creates a major **health risk** | Sh.E.L.D

Question 27

**How** does **water enter** the **body**?

Answer 27

Water is **absorbed** from **food** and **drink**

Question 28

**How** do **ions enter** the **body**?

Answer 28

Ions are **absorbed** from **food** and **drinks**

Question 29

**What happens** if there is an **excess** of **water** (too much water) in the **blood**

Answer 29

The water travels into the **cells** by **osmosis** from an area of **high** to **low concentration** along a semi-permeable membrane, when there is **too much water** in the **cells** this can cause the cells to **burst**

Question 30

**What happens** if there is **too little water** in the **blood stream**?

Answer 30

Water in the cells travels into the **blood** by **osmosis** from an area of **high to low** concentration across a **semi-permeable membrane**, when the cells **lose too much water** this can cause them to **shrivel**

Question 31

**Which molecules** are **too large** to be **filtered** from the **blood** into the **kidney tubules**?

Answer 31

**Blood cells** **Proteins**

Question 32

**What** is **active transport**?

Answer 32

The **net movement** of **molecules** from an area of **low** to **high concentration**, **active transport requires energy**

Question 33

**Name two unnatural diuretic substances**

Answer 33

**Alcohol** **Caffiene**

Question 34

**How** do **alcohol** and **caffiene** make someone **dehydrated**

Answer 34

**Alcohol** and **caffeine** are **diuretic**. This **surpresses** the **secretion** of **ADH**, this means in response, the natural process of less ADH happens unnaturally and the **kidney tubules** become **less permeable** to water and so **less water** is **selectively reabsorbed** into the **bloodstream** and there is a high amount of **excess water** being **released** from the **kidneys** as **urine** so more water is lost- causing **dehydration**

Question 35

Alcohol and caffeiene are **diuretic**. What is the meaning of **diuretic**?

Answer 35

**Diuretics increase** the **release** of **urine** from the **kidneys** by **inhibiting** the **secretion** of **ADH**

Question 36

**Name** the **risk** of **not removing excess ions** and **water** in the **bloodstream**

Answer 36

**Death**