Mass Transport in Animals

Question 1

What is digestion?

Answer 1

Where large biological molecules are hydrolysed by enzymes into smaller molecules that can be absorbed across cell membranes

Question 2

Digestion of carbohydrates

Answer 2

• Amylase produced by salivary glands hydrolyses starch into maltose
• Maltose hydrolysed by maltase into glucose
• Membrane bound disaccharides attached to the ileum also help hydrolyse maltose into glucose

Question 3

Digestion of lipids

Answer 3

• Bile salts produced by liver emulsify lipids, increasing SA:V of lipid droplets
• Lipase hydrolyses lipid droplets into micelles
• Micelles contain bile salts and fatty acids
• Micelles make fatty acids soluble and bring to cell lining the ileum
• Fatty acids absorbed by diffusion
• Triglycerides reformed in cells
• Vesicles move to membrane

Question 4

Digestion of proteins

Answer 4

• Endopeptidase hydrolyse peptide bonds within polypeptide
• Exopeptidase hydrolyses peptide binds at ends of polypeptide
• Membrane bound dipeptidase hydrolyse peptide bonds between dipeptides

Question 5

Amino acid absorption

Answer 5

• Co-transport with Na+
• Na+ pumped out, creating low concentration of Na+
• Na+ diffuses in via co-transport
• Amino acids co-transported in too against concentration gradient

Question 6

What is haemoglobin?

Answer 6

A protein with a quaternary structure found in red blood cells. Oxygen binds forming oxyhaemoglobin

Question 7

Oxyhaemoglobin dissociation curve

Answer 7

• Oxygen loads onto haemoglobin at high partial pressure of oxygen
• Haemoglobin becomes saturated with oxygen
• Oxygen unloads at the cells where partial pressure of oxygen is low

Question 8

The Bohr shift

Answer 8

• Oxyhaemoglobin curve shifts to the right
• Organisms respire, increasing concentration of carbon dioxide in blood
• Increased blood acidity decreases haemoglobin affinity for oxygen
• Oxygen unloads more easily at respiring cells, becoming less saturated with oxygen

Question 9

Organisms in low oxygen environments oxyhaemoglobin curve

Answer 9

• Lower partial pressure of oxygen in lungs
• Haemoglobin has a higher affinity for oxygen
• Able to load oxygen at lower partial pressure of oxygen

Question 10

Organisms in high oxygen environments oxyhaemoglobin curve

Answer 10

• Higher partial pressure of oxygen in lungs
• Haemoglobin has a lower affinity for oxygen
• Unload more oxygen at cells
• Useful for animals with high rate of respiration (eg. Small SA:V animals loose more heat per gram)

Question 11

Arteries structure (+ function)

Answer 11

• Narrower lumen (blood at high pressure)
• Elastic tissue and folded endothelium (stretch and recoil, maintaining smooth pressure)
• Thick muscle (contract and change flow of blood)

Question 12

Vein structure (+ function)

Answer 12

• Wide lumen (blood at low pressure)
• Smooth endothelium (reduce friction)
• Thin muscle (can’t contract)
• Valves (prevent backflow of blood)

Question 13

Capillaries structure (+ function)

Answer 13

• One cell thin endothelium (short diffusion distance)
• High surface area (fast rate of diffusion)
• High hydrostatic pressure at start of capillaries (outward pressure forces fluid out capillaries)

Question 14

Heart structure (+ function)

Answer 14

• Aorta (oxygenated blood to body)
• Pulmonary vein (oxygenated blood from lungs)
• Left atrium (pimps blood to ventricle)
• AV valves (open when pressure is greater in atria)
• Left ventricle (thicker muscle, pumps blood around body)
• Pulmonary artery (deoxygenated blood to lungs)
• Vena Cava (returns blood from body)
• Right atrium (pumps blood to ventricle)
• SL valves (open when pressure is higher in ventricles)
• Right ventricle (pumps blood to lungs)

Question 15

Cardiac cycle

Answer 15

• Atria contracts
• Pressure higher in atria than ventricles
• AV valves open and SL valves close
• Ventricles contract
• Pressure higher in ventricles
• AV valves close and SL valves open
• Atria and ventricles relax
• Pressure higher in atria than ventricles
• AV valves open and SL valves close

Question 16

Cardiac output formula

Answer 16

Cardiac output = stroke volume x heart rate

Question 17

Atheroma formation

Answer 17

• Build up of fatty plaque on inside of artery
• Can lead to thrombosis (blood clot) or aneurysm (swelling)
• Blocked coronary arteries can lead to myocardial infarction (heart attack)
• Reduces flow of oxygen and glucose to heat and can’t respire

Question 18

Risk factors for cardiovascular disease

Answer 18

• High blood pressure
• High blood cholesterol / poor diet
• Cigarette smoking

Question 19

What is pressure filtration?

Answer 19

The way a substances move out of the capillaries into the tissue fluid

Question 20

Tissue fluid formation

Answer 20

• Hydrostatic pressure higher in blood than tissue fluid
• Water and small molecules forced out
• Large molecules stay inside capillary
• Pressure drops along capillary bed as water moves out

Question 21

Tissue fluid return

Answer 21

• Water potential in blood becomes lower than tissue fluid as proteins remain in blood
• Water moves into capillary by osmosis
• Water moves down pressure gradient so hydrostatic pressure drops in capillary
• Tissue fluid drains into the lymph