topic 8 - exchange and transport

Question 1

how do you find surface area to volume ratio?

Answer 1

SA : V simplifies

Question 2

what substances do we need to get rid of?

Answer 2

waste (e.g. urea), CO2, water to prevent cell lysis

Question 3

how is urea removed from the body?

Answer 3

-via skin through sweat
-via kidneys in urine after having diffused from cells in the blood plasma for removal

Question 4

how does exchange occur in single-celled organisms?

Answer 4

-gases + dissolved substances can dissolve into / out of cell across membrane
-large SA:V

Question 5

where does gas exchange occur in mammals?

Answer 5

alveoli of lungs

Question 6

how are alveoli’s adapted for their function?

Answer 6

-large SA
-good blood supply
-thin walls (1 cell thick) - short diffusion pathway
-in clusters

Question 7

what are the factors affecting the rate of diffusion? (4)

Answer 7

surface area of membrane, concentration gradient, diffusion distance and temperature

Question 7

how does the surface area of a membrane affect the rate of diffusion?

Answer 7

-larger it is - more space for particles to move - faster rate of diffusion

Question 8

how does the concentration gradient affect the rate of diffusion?

Answer 8

-bigger the difference, steeper the conc. - faster the rate of diffusion

Question 9

what is the concentration gradient?

Answer 9

difference between 2 concentrations

Question 10

how does diffusion distance affect the rate of diffusion?

Answer 10

-blood supply is in closer contact
-shorter/thinner it is = faster rate of diffusion

Question 11

how does the temperature affect the rate of diffusion?

Answer 11

-higher the temp. - higher the Ke, therefore faster rate of diffusion

Question 12

what is fick’s law:?

Answer 12

rate of diffusion ∝ SA x conc. difference / thickness of membrane

Question 13

what are the 4 main components of blood?

Answer 13

1. red blood cells
2. white blood cells
3. platelets
4. plasma

Question 14

what is the function of blood?

Answer 14

transport such as (Oxygen, Carbon dioxide etc.)

Question 15

what are red blood cells (erythrocytes) role?

Answer 15

-rich in haemoglobin (iron-containing bio-molecule) - binds to oxygen
-develop in bone marrow
-circulate for 100-120 days - recycled by macrophages afterwards

Question 16

what is the reversible reaction for haemoglobin and oxygen?

Answer 16

haemoglobin + oxygen ⇌ oxyhaemoglobin

Question 17

how are red blood cells adapted for their function?

Answer 17

-no nucleus
-small and flexible
-biconcave shape - maximise SA
-thin - short diffusion distance

Question 18

what are the 2 types of white blood cells?

Answer 18

phagocytes and lymphocytes

Question 19

what are phagocytes?

Answer 19

white blood cells that engulf and destroy unwanted micro-organisms through phagocytosis
-produced in bone marrow
-lifespan of 4 - 15 days

Question 20

what are lymphocytes?

Answer 20

-produced in bone marrow and thymus
-produces antibodies - bind and destroy pathogens, clump pathogens for phagocytosis, release chemical signals
-release antitoxins
-create memory cells

Question 21

what are platelets?

Answer 21

cell fragments produced by giant cells in bone marrow

Question 22

how do platelets stop bleeding? (2 ways)

Answer 22

1. proteins on their surface - enable them to stick to breaks in a blood vessel and clump
2. secrete proteins - result in formation of a blood clot - plug a would (converts fibrinogen to fibrin)

Question 23

what is plasma and what is its role?

Answer 23

-straw-coloured substance
-carries blood cells around body and glucose, salts and waste

Question 24

what type of circulatory system for mammals have?

Answer 24

double circulatory

Question 25

what is a double circulatory system?

Answer 25

-blood flows in 2 circuits
1. pulmonary - heart to lungs
2. systemic - heart to rest of body

Question 26

what are the 3 main blood vessels?

Answer 26

arteries, veins and capillaries

Question 27

what do arteries do?

Answer 27

carry blood AWAY from the heart (generally oxygenated - except pulmonary artery)

Question 28

how are arteries adapted?

Answer 28

-no valves
-small lumen, thick, muscularly walls - to withstand high pressure

Question 29

what do veins do?

Answer 29

carry blood IN TO the heart (usually deoxygenated - except pulmonary vein)

Question 30

how are veins adapted?

Answer 30

-have valves - prevent backflow
-thinner walls, large lumen
-under low pressure

Question 31

what do capillaries do?

Answer 31

carry deoxygenated AND oxygenated blood from arteries to veins (connect them) -

Question 32

how are capillaries adapted?

Answer 32

-no valves
-thinnest walls - 1 cell thick and very permeable
-large SA - due to tiny vessels in close contact
-under low pressure for slow exchange

Question 33

what muscle is the heart made of?

Answer 33

cardiac muscle

Question 34

what type of pump is the heart?

Answer 34

double pump
1st - pumped to lungs (right side - technically left in diagrams)
2nd - pumped to rest of body (left side - technically right in diagrams)

Question 35

how many chambers are in the heart and what are they?

Answer 35

right and left atriums, and right and left ventricles

Question 36

explain how blood enters and leaves the heart?