Fluid Balance

Question 1

What 3 major factors does blood composition depend on? (3)

Answer 1

1. Diet
2. Cellular metabolism
3. Urine output

Question 2

What are the 4 major roles that kidneys have in keeping the blood constant? (4)

Answer 2

1. Excretion of nitrogenous wastes
2. Ensuring proper blood pH
3. Maintaining the water balance of the blood
4. Maintaining the electrolyte balance of the blood

Question 3

In a young, healthy adult, how much does water account for in women and in men? (2)

Answer 3

1. Women - 50% water

2. Men - 60% water

Question 4

How many main locations does water occupy and what are the locations called all together? (2)

Answer 4

1. Three main locations

2. Fluid components

Question 5

How much of the body fluid is intracellular fluid?

Answer 5

2/3 of the body fluid

Question 6

What does it mean when fluid is “intracellular”?

Answer 6

The fluid is contained within living cells

Question 7

What does it mean when fluid is “extracellular”?

Answer 7

The fluid is contained outside of living cells

Question 8

How much of the body fluid is extracellular?

Answer 8

1/3 of the body fluid

Question 9

What is included in extracellular fluid? (4)

Answer 9

1. Blood plasma
2. Interstitial fluid
3. Cerebrospinal fluids
4. Serous fluids

Question 10

What does plasma serve as while it circulates through the body delivering substances?

Answer 10

A highway that links the internal and external environments

Question 11

What links the internal and external environments?

Answer 11

Plasma

Question 12

Where does most of our body fluid come from?

Answer 12

Fluids and foods we ingest in our diet

Question 13

How much water is produced during cellular metabolism?

Answer 13

About 10% of the water in our body

Question 14

What is the driving force for water intake?

Answer 14

Thirst mechanism

Question 15

Describe the thirst mechanism. (2)

Answer 15

1. Highly sensitive cells in the hypothalamus (osmoceptors) are excited by an increase in plasma solute content
2. Osmoreceptors activate the hypothalamic thirst center

Question 16

How much of an increase in plasma solute is required to excite the osmoreceptors?

Answer 16

An increase in plasma solute content of just 2-3% is enough

Question 17

Why does the mouth become dry when the thirst mechanism is active?

Answer 17

The salivary glands are obtaining the water that they rewire from the blood

Question 18

List the 3 routes by which water leaves the body. (3)

Answer 18

1. Vapourize out of the lungs
2. Lost in perspiration
3. Leaves the body by stool

Question 19

What is reabsorption of water and electrolytes by the kidneys primarily regulated by?

Answer 19

Hormones

Question 20

What happens when blood volume drops? (2)

Answer 20

1. Arterial blood pressure drops

2. → decreases the amount of filtrate formed by the kidneys

Question 21

What does antidiuretic hormone (ADH) do?

Answer 21

Prevent excessive water loss in the urine

Question 22

How does ADH prevent excessive water loss in the urine?

Answer 22

ADH travels to the kidneys’ collecting ducts and causes the duct cells to reabsorb more water

Question 23

Define: electrolytes

Answer 23

Charged particles (ions) that conduct an electrical current in an aqueous solution

Question 24

What are 2 effects of electrolyte movement? (2)

Answer 24

1. Alters blood volume and blood pressure

2. May severely impair the activity of irritable cells like nerve and muscle cells

Question 25

Define: aldosterone

Answer 25

Hormone that helps to regulate blood composition and blood volume by acting on the kidney