Chapter 4 Nutrition in Humans Flashcards
State two short and two long-term effects of alcohol consumption [4] (2014/A2)
Short-term
1. Behavioural traits such as reduced self-control [1]
2. Slow down brain functions such as blurred vision, poor muscular coordination and poor judgement and longer reaction times. [1]
Long-term [max:2]
1. Prolonged alcohol abuse can lead to liver cirrhosis which can lead to liver failure and death. [1]
2. Alcohol affects the digestive system by stimulating acid secretion in the stomach leading to gastric ulcers. [1]
3. It may lead to addiction which leads to withdrawal symptoms as side effects. [1]/depression
Gallstones are made of cholesterol, bile salts and other substances. These stones may become large enough to block the bile duct.
Suggest how gallstones may affect digestion of fat. [3] (2015/A1c)
Reduced flow/ less of bile into duodenum [1]
Less fats is emulsified, lowering the surface area of fat globules exposed for lipase to digest [1]
Thus rate of digestion of fats decreases. [1]
Reject: no digestion of fats occurs
State the meaning of the term: digestion [3] (2011/B10 OR)
- Digestion is the process where large, insoluble molecules are broken down into small, soluble molecules [1] that can be absorbed into the body cells.
- Digestion can be a physical process which involves the mechanical breakdown of food into smaller pieces through chewing. [1]
- Digestion can be a chemical process which involves the breaking of bonds in molecules through the action of enzymes. [1]
State the meaning of the term: absorption [3] (2011/B10 OR)
Absorption is the process by which products of digestion such as glucose and amino acids [1]
will be taken into the bloodstream [1] through the wall of the ileum of the small intestine by processes of active transport and diffusion [1]
Describe the functions of the liver. [4] (2011/B10)
- Produces bile which emulsifies fats [1]
- Haemoglobin is transported to the liver after red blood cells are destroyed in the spleen. The liver breaks down the haemoglobin released and stores the iron released [1]/ Breakdown of red blood cells to form bile pigments from haemoglobin and iron released is stored. [1]
- Excess amino acids are deaminated where their amino groups are removed and converted to urea [1]
- Detoxification of harmful substances such as alcohol and breaking them down into harmless substances [1]
- Regulates blood glucose level with the aid of insulin and glucagon [1]
[Any 4]
Describe the digestion of protein in the body. [3] (2012/B10 OR
- Pepsin in the stomach, with the aid of hydrochloric acid which provides an acidic pH, digests proteins into polypeptides [1]
- Trypsin from the pancreatic juice digests proteins into polypeptides in the alkaline environment of the small intestine [1]
- Peptidase/Erepsin found in intestinal juice from the intestinal glands digests polypeptides to amino acids. [1]
Villi are found in the digestive system.
Describe the function of a villus. [3] (2012/B10 OR)
- The villus is a long finger‐like projection on the surface of the small intestine. This increases the surface area to volume ratio, allowing for greater absorption of digested food substances.
- The epithelial layer of the villus helps in the absorption of digested food substances as it is one cell thick. This helps to reduce the distance travelled by digested substances and hence increases the rate of diffusion.
- The surface layer of the villus comprises epithelial cells, which have microvilli to further increase the surface area to volume ratio for absorption. Thus increasing the rate of diffusion.
- Beneath the layer of epithelial cells, there is a network of blood capillaries to quickly transport
away food substances that have diffused though the epithelium. This help to maintain a steep concentration gradient for absorption of food substances by diffusion. - The lacteal absorbs and transports fats.
Describe the role of the liver in the metabolism of carbohydrates [4] (2012/B10 OR)
- The liver is responsible for the regulation of blood glucose levels.
- When blood glucose level rises above the norm, insulin released by the pancreas reaches the liver. [1]
- This promotes the liver cells to be more permeable to glucose. Glucose enters the liver cells and is converted into glycogen for storage. [1]
- When blood glucose level drops below the norm, glucagon released by the pancreas reaches the liver [1]
- and stimulates liver cells to convert glycogen to glucose and release glucose back into the
bloodstream. [1]
Fig 3.1 shows the effect of different blood alcohol concentrations on a person’s reaction times.
Explain why it is not advisable to drink drive
[4] (2015/B9b)
(Graph shows: < concentration, < reaction times.)
- As blood alcohol concentration increases to 70 mg per 100 cm3, reaction time increases by 30 milliseconds. [1]
- When a person drinks, alcohol is absorbed into
the blood and causes the blood alcohol content to rise. [1] - The more a person drinks the higher the resultant blood alcohol content, causing longer reaction times. Blurred vision, poor muscular coordination and impaired judgment may also result. [1]
- This may result in a person being unable to react adequately to changes in the road when driving, thus causing accidents. [1]
Define Nutrition (self)
Nutrition is the process by which organisms obtain food and energy for growth, repair and maintenance of the body.
Define peristalsis (self)
Peristalsis is the rhythmic, wave-like muscular contractions in the wall of the alimentary canal
In the gastrointestinal track, which type of muscles are on the outside? (Self)
The longitudinal muscles
CIrcular- Inner
LOngditudinal - Outer
The circular and longitudinal muscles are __ __. This means when one set of muscles contracts, the other set relaxes. (Self)
Agnostic Muscles
There is a ring of muscle called the __ __ located at the place where the stomach joins the small intestine. (Self)
Pyloric sphicter
Name the three parts of the small intestine in the order which food passes through. (Self)
Duodenum
Jejunum
Ileum
