3.1.2: Tissue Fluid

Question 1

What is the primary function of capillaries?

Answer 1

Capillaries form capillary beds at exchange surfaces, allowing for the exchange of substances between blood and tissue fluid

Capillaries have a narrow diameter to slow blood flow, maximizing diffusion.

Question 2

What components are forced out of capillaries into tissue fluid?

Answer 2

Water, glucose, amino acids, fatty acids, ions, and oxygen

This occurs due to high hydrostatic pressure at the arterial end of the capillaries.

Question 3

Define hydrostatic pressure.

Answer 3

The pressure exerted by liquid

Hydrostatic pressure is responsible for forcing liquid out of capillaries.

Question 4

Define oncotic pressure.

Answer 4

The tendency of water to move into the blood via osmosis

Oncotic pressure is influenced by large molecules like plasma proteins remaining in the capillaries.

Question 5

What happens to hydrostatic and oncotic pressure at the venule end of the capillaries?

Answer 5

Hydrostatic pressure is low, while oncotic pressure is high, leading to net movement of liquid back into the capillary

This process involves the reabsorption of tissue fluid.

Question 6

True or False: Tissue fluid is formed when blood pressure is lower than osmotic pressure.

Answer 6

False

Tissue fluid is formed when blood pressure is higher than osmotic pressure.

Question 7

Fill in the blank: The remaining liquid in the lymphatic system is called _______.

Answer 7

lymph

Lymph has a similar composition to plasma but contains less oxygen and nutrients.

Question 8

What is the role of large molecules like plasma proteins in capillaries?

Answer 8

They lower the water potential of the blood, resulting in higher oncotic pressure

This helps to draw water back into the capillaries from the tissue fluid.

Question 9

List the substances that tissue fluid bathes the cells in.

Answer 9

• Water
• Glucose
• Amino acids
• Fatty acids
• Ions
• Oxygen

These substances are essential for the cells’ metabolic processes.

Question 10

What occurs once equilibrium of the water potential of the blood is reached?

Answer 10

No more water from the tissue fluid can be reabsorbed back into the blood in the capillaries

The remaining liquid is absorbed into the lymphatic system.

Question 11

What is the composition difference between lymph and plasma?

Answer 11

Lymph does not contain large plasma proteins and has less oxygen and nutrients

This is due to absorption by the cells in the surrounding tissues.

Question 12

Identify the layers of a blood vessel.

Answer 12

• Endothelium
• Smooth muscle
• External elastic lamina
• Adventitia

These layers provide structure and regulate blood flow.

Question 13

What is the function of valves in veins?

Answer 13

To prevent backflow of blood

Valves are essential for maintaining unidirectional blood flow towards the heart.