Exchange

Question 1

What is ingestion?

Answer 1

Taking food in

Question 2

What is the order of organs in digestion?

Answer 2

Teeth, salivary glands, stomach, small intestine, large intestine, rectum and anus

Question 3

What role in digestion do teeth play?

Answer 3

Mechanical: incisors cut and tear food, molars mash food to increase surface area for enzyme action

Question 4

What role in digestion do salivary glands play?

Answer 4

Produces saliva to lubricate food to swallow and has salivary enzymes such as amylase (amylose to maltose)

Question 5

What role in digestion does the stomach play?

Answer 5

Glands secrete HCl (correct pH for enzymes and sterilises food)

Produces pepsin (endopeptidase)

Mechanical digestion when stomach ‘churns’

Question 6

What are parts of small intestine?

Answer 6

Duodenum (start):

Bile and pancreatic acid are added

Peristalsis occurs

Jejunum (middle)

Ileum (end):

Villi and microvilli lining ileum

Dipeptidases (dipeptides to amino acids) and disaccharidases (disaccharides to monosaccharides) are added

End of ileum monomers are absorbed across small intestine lining into blood in capillaries

Question 7

What part in digestion do large intestines play?

Answer 7

Reabsorbs water into blood

Question 8

What does the rectum do?

Answer 8

Stores undigested food

Question 9

What does the anus do?

Answer 9

Egestion (removal)

Question 10

What are endopeptidases?

Answer 10

Enzymes that break central regions of polypeptide chains

Long chains into smaller chains

Question 11

What are exopeptidases?

Answer 11

Enzymes that break peptide bonds on the ends of polypeptide chains

Question 12

What are dipeptidases?

Answer 12

Enzymes that break dipeptides into amino acids

Question 13

Where is bile produced?

Answer 13

Produced in liver and stored in gall bladder

Question 14

What does bile do?

Answer 14

Emulsifies lipids and neutralises pH

Question 15

What is a chylomicron?

Answer 15

Vesicle to transport lipids

Question 16

Describe lipid absorption

Answer 16

Monoglycerides and fatty acids in lumen of intestine diffuse (simple) across membrane into the epithelial cells

They then go into the smooth ER and are recombined into triglycerides

They then move into the golgi apparatus where they are converted into chylomicrons and lipoproteins and cholesterol are added

They then move out of the cell by exocytosis into lacteal (too big to be absorbed into blood)

They are then absorbed into the blood

Question 17

What is another word for chest?

Answer 17

Thorax

Question 18

What is inspiration?

Answer 18

Breathing in:

External intercostal muscles contract

Pulls ribcage up and out

Diaphragm contracts and flattens

Increases volume in thorax, therefore decreasing the pressure

External air moves down pressure gradient and into lungs

Question 19

What is expiration?

Answer 19

Breathing out:

Internal intercostal muscles contract

Pulling ribcage down and in

Diaphragm relaxes and arcs

Less volume in thorax, therefore increasing pressure

Internal air is forced out of the lungs down the pressure gradient

Question 20

What does COPD stand for?

Answer 20

Chronic obstructive pulmonary disease

Question 21

What are the risk factors that increase the probability of someone suffering from COPD?

Answer 21

Smoking
Air pollution
Genetics
Infections
Occupation (exposure to harmful chemicals/dust)

Question 22

Define correlation

Answer 22

When a change in 1 of 2 variables is reflected in a change of the other variable

Question 23

Define causation

Answer 23

When you can claim that the one variable actually causes the other variable

Question 24

Describe the path of oxygen in humans

Answer 24

Oxygen in the air moves in down the trachea into the bronchi. It then enters the bronchioles and then alveoli, where the oxygen dissolves in the surfactant in the alveoli, allowing it to diffuse over the epithelial and endothelial cells into the blood.

Question 25

Describe the tracheal system of an insect

Answer 25

Oxygen moves into the insect through spiracles, passing through the dust filter

Tracheae are held open by rings of chitin (collapse prevention)

Tracheoles extend throughout the insect’s body tissues, carrying oxygen directly to respiring cells and removing carbon dioxide

There is a short diffusion pathway between the tracheoles and the body cells.

Question 26

What are the key points for countercurrent flow?

Answer 26

Water and blood flow in opposite directions so blood is always meeting water with a higher oxygen concentration

This means concentration/ diffusion gradient is maintained across the whole length of the gill lamella

Therefore diffusion of oxygen into the blood can occur across the whole length of the gill lamella

This ensures maximum possible gas exchange is achieved