Nutrition in Humans

Question 1

Where is the Circular and Longitudinal muscle in the alimentary canal located and what do they do?

Answer 1

The 2 muscles are antagonistic. The CM is inside and the LM is outside.
CM contract and LM relax, contracting the canal and food is squeezed forward.
LM contract and CM relax, widening lumen for food to enter.

Question 2

What are the various enzymes in the body and where are they secreted?

Answer 2

Amylase- Mouth/Pancreas
Pepsin- Stomach
Lipase/Protease- Pancreas

Question 3

What is the role of the liver in fat digestion?

Answer 3

Bile salts secreted by the liver emulsify fats, causing the fats to break into tiny fat droplets, increasing their surface area to volume ratio, speeding up their digestion by lipase.

Question 4

What are the various adaptations of the small intestine?

Answer 4

1. The SI is 7m long. This is to allow sufficient time for absorption as food takes a longer time to pass through it.
2. The villi of the SI has a one cell thick epithelium, decreasing diffusion distance for a faster rate of diffusion.
3. The SI contains villi, finger-like projections to increase surface area.
4. The villi have numerous capillaries that continuously carry blood away to maintain a steep concentration gradient for a faster rate of diffusion.
5. Villi have numerous microvilli that further increase surface area.

Question 5

Where does blood rich in nutrients travel?

Answer 5

Via HEPATIC PORTAL VEIN to the LIVER.

Question 6

What are the 6 functions of the liver?

Answer 6

1. Regulation of blood glucose concentration.
2. Production of bile
3. Iron Storage. The red blood cells of the body become worn out and destroyed by the spleen. Their haemoglobin is brought to the liver. It is broken down by the liver, it stores iron released in the process.
4. Protein synthesis,
5. Deamination of amino acids. Excess amino acids are transported to the liver. The amino groups are removed and converted into urea in a process known as deamination.
6. Detoxification. Harmful substances may be absorbed into the blood from the gut. Alcohol is broken down. Liver cells contain enzyme alcohol dehydrogenase, breaking down alcohol to a compound called acetaldehyde.

Question 7

What are the effects of alcohol on your digestive system?

Answer 7

Alcohol stimulates acid secretion in the stomach, increasing risk of gastric ulcers.
Prolonged alcohol abuse leads to liver cirrhosis- where liver cells are destroyed and replaced with fibrous tissue, making the liver less able to function- liver failure+death.

Question 8

What are the effects of alcohol on the nervous system?

Answer 8

Depressant- slows down some brain functions
Self Control- A person becomes carefree as alcohol takes away their inhibities.
Rxn time- Slurred speech, Blurred vision. Poor co-ordination. Clumsy and unsteady walking judgement deteriorates and under estimates speeds.
Social- They may affect their work and families/ exhibit violent behaviour.