Absorption, Assimilation and Teeth

Question 1

Define absorption

Answer 1

movement of digested food molecules through the wall of the intestine into the blood or lymph

Question 2

Define assimilation

Answer 2

movement of digested food molecules into the cells of the body where they are used, becoming part of the cells

Question 3

Adaptations of villi

Answer 3

• It contains blood capillaries: amino acids, water and minerals can enter the blood stream to be taken to the liver and then around the body
• It contains lacteal which fat can be abosorbed
• Only 1 cell thick so nutrients can be absorbed easily
• Projections that increase the surface area for absorption

Question 4

State the role of the hepatic portal vein in the transport of absorbed food to the liver

Answer 4

Transports absorbed food from the small intestine to the liver. After a meal =>high concentrations of glucose and amino acids in blood.The liver reduces levels backs to normal (glucose to glycogen by insulin)

Question 5

Identify the role of the small intestine and colon in absorption of water

Answer 5

the small intestine absorbs 5–10 dm3 per day

the colon 0.3–0.5 dm3 per day

Question 6

Describe the role of the liver as a part of assimilation

Answer 6

• stores glucose by removing it from blood and storing it as glycogen (homeostasis)
• uses amino acids to make proteins, such as those involved blood clotting
• breaks down excess amino acids
• converts fatty acids and glycerol into fat which is stored around the body

Question 7

Define deamination

Answer 7

removal of the nitrogen-containing part of amino acids to form urea, followed by release of energy from the remainder of the amino acid

Question 8

Role of liver

Answer 8

breaks down toxins such as drugs, alcohol and paracetamol

Question 9

Identify the types of human teeth and describe their structure and functions

Answer 9

• Incisors: biting and cutting
• Canine: tearing
• Molar and premolar: grinding and chewing

Question 10

State the causes of dental decay and describe

the proper care of teeth

Answer 10

• Sugary food left between teeh => bacteria in plaque change sugar into acid because it is respiring anaerobically => acid attack on enamel => when enamel worn away, attacks the dentine
• Brushing regularly, avoid sugary foods, visit dentists

Question 11

Describe how fluoride reduces tooth decay
and explain arguments for and against the
addition of fluoride to public water supplies

Answer 11

Reduce the incidence of tooth decay because it makes the enamel more resistant to acid. Some people oppose since they feel that they should be given a choice + unknown long term health effects