Nutrition in humans: answers

What is the consequence of iron deficiency and why are women more susceptible than men?

Iron is needed for our bodies to form haemoglobin, so if we don’t get enough iron in our diets our bodies can’t make enough red blood cells and less oxygen is transported around our blood. This results in anaemia which is characterised by tiredness and lethargy because our cells can’t respire as much as usual. Women are more susceptible to anaemia because they lose blood every month during menstruation, so need to produce more red blood cells compared to men.

What three factors influence the amount of energy a person needs?

The age of a person, the amount of activity they do and whether they are pregnant affects the amount of energy a person needs. Energy requirements increase with age, then fall again as the person approaches old age. Pregnant women and people who carry out a lot of physical activity also need a higher calorie intake.

In what organs of the digestive system are carbohydrates broken down?

Carbohydrates are broken down into simpler sugars by carbohydrase enzymes such as amylase and maltase. Amylase is released by the salivary gland and digests food in the mouth. Amylase is also secreted by the pancreas where it digests food in the small intestine.

What are the functions of the liver and gall bladder during digestion?

The liver produces bile and the gall bladder stores bile before releasing it into the small intestine. The function of bile is to make the food leaving the stomach less acidic, otherwise the acidic food would damage the small intestine and denature the enzymes in the small intestine.

How are villi adapted for absorbing digested food molecules into the bloodstream?

Villi have an extremely large surface area to maximise the area for absorption to take place. There is a short distance for molecules to diffuse from the small intestine to the bloodstream and any molecules which have not diffused into the bloodstream will be actively transported through the villi by carrier proteins. There is a large network of capillaries for absorption to take place and a lacteal branch in the centre for lipid absorption.

Describe how the movement of different muscles helps to push food through the digestive system.

Circular and longitudinal muscles in the digestive system work together to push food through the gut. The circular muscles reduce in diameter during contraction whereas the longitudinal muscles get shorter when they contract. These two movements creates a squeezing movement to push food along the alimentary canal.

What is the term for the movement of food through the gut.

Peristalsis is the technical term for the movement of food through the digestive system.

Explain what is meant by the term ‘balanced diet’?

A ‘balanced diet’ means a diet which contains all of the food groups in appropriate proportions.