**4.6 Transfer between the circulatory system + cells**

Question 1

What does the formation of tissue fluid assist in the delivery of?

Answer 1

• Nutrients to cells + removal of waste products.

Question 2

What is tissue fluid comprised of?

Answer 2

• Watery fluid containing glucose, amino acids, O2 + other nutrients.
• Supplies these to cells while removing waste products.

Question 3

How is tissue fluid formed?

Answer 3

• Blood pumped through increasingly smaller vessels.
• Hydrostatic pressure greater than oncotic pressure ∴ fluid moves out of capillaries.

Question 4

What happens to excess fluid tissue?

Answer 4

• Removed through vessels into lymphatic system, then returned to blood near heart (subclavian vein).

Question 5

What substances enter lymph capillaries?

Answer 5

• Tissue fluid.
• Molecules too large to enter blood capillaries.

Question 6

How is liquid moved through lymph capillaries?

Answer 6

• Compression due to body movements.
• Backflow prevented by valves.

Question 7

Where does lymph drain back into blood circulation?

Answer 7

• Veins close to heart.

Question 8

What are produced in lymph nodes?

Answer 8

• Lymphocytes.

Question 9

Where does the lymph system transport proteins?

Answer 9

• From intestines to bloodstream following digestion.

Question 10

What types of pressure influence formation of tissue fluid?

Answer 10

• Hydrostatic pressure: higher at arterial end than venous end.
• Oncotic pressure: changing water potential of capillaries as water moves out.

Question 11

What is hydrostatic pressure?

Answer 11

• Pressure exerted by blood on blood vessel walls.

Question 12

What is oncotic pressure?

Answer 12

• Pressure difference in blood due to plasma proteins + surrounding fluid tissue.

Question 13

What happens with lower water potential of blood?

Answer 13

• Lower water potential of blood causes water to enter blood vessels from tissue fluid at venule end of capillary bed.