3.2.3 exchange at the capillaries

Question 1

hydrostatic pressure

Answer 1

pressure that fluid exerts when pushing against sides of vessel/container

Question 2

lymph

Answer 2

fluid held in lymphatic system, which is system of tubes that returns excess tissue fluid to blood system

Question 3

oncotic pressure

Answer 3

pressure created by osmotic effects of solutes

Question 4

tissue fluid

Answer 4

fluid surrounding cells & tissues

Question 5

name dissolved substances in plasma

Answer 5

• oxygen
• carbon dioxide
• minerals
• glucose
• amino acids
• hormones
• plasma proteins

Question 6

erythrocytes

Answer 6

red blood cells

Question 7

leucocytes

Answer 7

white blood cells

Question 8

platelets

Answer 8

fragments in blood

Question 9

define steps of how is tissue fluid formed

Answer 9

1. blood in artery reaches tissues, branches into arterioles & then capillaries which link with venules
2. arterial end: blood at high hydrostatic pressure & pushes blood fluid out of capillaries through capillary wall
3. fluid contains plasma with dissolved nutrients & oxygen
4. tissue fluid surrounds cells & exchange of gases/nutrients occur across plasma membranes

Question 10

role of tissue fluid

Answer 10

surrounds cells in tissue & supplies them with oxygen/nutrients

Question 11

describe the movement of plasma from capillary into tissue fluid

Answer 11

mass flow

Question 12

how are substances returned to the blood

Answer 12

• blood at venous end at lower hydrostatic pressure
• some tissue fluid returns to capillary carrying carbon dioxide & other waste products

Question 13

what happens to the tissue fluid which doesn’t re-enter the blood

Answer 13

some directed into lymph/lymphatic system

Question 14

describe lymph nodes

Answer 14

swellings found at intervals along lymphatic system & important for immune response

Question 15

hydrostatic pressure in:
- blood plasma
- tissue fluid
- lymph

Answer 15

• high
• low
• low

Question 16

oncotic pressure in:
- blood plasma
- tissue fluid
- lymph

Answer 16

• more negative
• less negative
• less negative

Question 17

cells in:
- blood plasma
- tissue fluid
- lymph

Answer 17

• red blood cells, neutrophils, lymphocytes
• some neutrophils (especially in infected areas)
• lymphocytes

Question 18

proteins in:
- blood plasma
- tissue fluid
- lymph

Answer 18

• plasma proteins
• few proteins
• few proteins

Question 19

fats in:
- blood plasma
- tissue fluid
- lymph

Answer 19

• transported in lipoproteins
• few fats
• more fats (especially near digestive system)

Question 20

role of hydrostatic pressure in movement of fluids between blood & tissue fluid

Answer 20

• hydrostatic pressure of blood pushes fluid out into tissues
• hydrostatic pressure of tissue fluid pushes fluid into capillaries

Question 21

role of oncotic pressure in movement of fluids between blood & tissue fluid

Answer 21

• oncotic pressure of blood pulls water back into blood (negative)
• oncotic pressure of tissue fluid pulls water into tissue fluid

Question 22

which substances aren’t present in tissue fluid & why

Answer 22

• red blood cells
• platelets
• most white blood cells
• plasma proteins
  = too large to fit through capillary wall

Question 23

describe the lymphatic system

Answer 23

• drains excess tissue fluid out of tissues & returns to blood via subclavian vein in chest
• fluid called ‘lymph’
• similar in composition to tissue fluid but contains more lymphocytes

Question 24

where are lymphocytes produced

Answer 24

lymph nodes