nutrition in humans

What is the function of the mouth in the digestive system?

Ingestion, where food enters the body through the mouth leading to the buccal cavity.

What occurs during physical digestion in the mouth?

Teeth break down large pieces of food into smaller pieces to increase surface area for salivary amylase to act more efficiently.

What is the role of salivary glands in digestion?

They secrete saliva that contains salivary amylase to digest starch into maltose.

What happens in the oesophagus during digestion?

No digestion takes place; the bolus formed by the tongue is swallowed and enters the oesophagus.

What is the function of gastric juice in the stomach?

It aids chemical digestion by containing HCL, mucus, and pepsin.

What effect does HCL have in the stomach?

It denatures salivary amylase, provides a low pH environment for protease, and kills harmful microorganisms.

What type of digestion is facilitated by peristalsis in the stomach?

Physical digestion, as it churns and breaks up food mixing it with gastric juice.

What occurs in the duodenum during digestion?

Chemical digestion, where chyme stimulates the pancreas and gall bladder, releasing enzymes that neutralize acidic chyme.

What is the purpose of bile in digestion?

Bile, released from the gall bladder, emulsifies fats to speed up their digestion.

Describe the function of the pancreas in digestion.

It secretes pancreatic juice containing enzymes to digest starch, proteins, and fats.

What is the role of the liver in the conversion of glucose to glycogen?

Insulin converts excess glucose to glycogen for storage when blood glucose levels are high.

How does the liver assist in fat digestion?

The liver secretes bile to aid in the digestion of fats.

What is the process of deamination in the liver?

Excess amino acids are converted to urea, and the remainder is transformed into glucose.

What is the function of the hepatic portal vein?

It transports blood rich in absorbed nutrients from the small intestine to the liver.

How are villi structured to maximize absorption?

Villi have a large surface area, are one cell thick, and contain capillaries and lacteals for nutrient transport.

What happens in the ileum regarding absorption?

Glucose and amino acids are absorbed by diffusion or active transport; glycerol and fatty acids enter lacteals.

What is the function of the colon in the digestive system?

It absorbs remaining water from undigested food.

What occurs during egestion at the rectum?

Undigested and unabsorbed material is stored before being discharged as feces.

What effects does alcohol consumption have on the brain?

It reduces self-control and reaction time, leading to impairments such as slurred speech and poor coordination.

What is the long-term effect of excessive alcohol consumption on the brain?

It can lead to 'Wet brain' (dementia) and shrinkage of brain volume.

What social implications arise from alcohol addiction?

Neglect of work and family, violent behavior, and potential criminal activities.

What is the role of maltase in digestion?

Maltase digests maltose into glucose.

What is the role of protease in digestion?

Protease breaks down proteins into polypeptides and further into amino acids.

What is the function of lipase in digestion?

Lipase digests fats into fatty acids and glycerol.

What are the components of the digestive system that help neutralize chyme?

Pancreatic juice, intestinal juice, and bile are all alkaline to neutralize the acidic chyme.

What is the significance of the one-cell-thick epithelium in the villus?

It provides a short diffusion distance for nutrients to pass through easily.

What happens to deaminated amino acids in the liver?

They are converted into glucose and excess glucose is stored as glycogen.

What is the effect of alcohol on the digestive system?

Alcohol stimulates acid secretion in the stomach, increasing the risk of gastric ulcers.

How does peristalsis function in the alimentary canal?

It consists of rhythmic wave-like contractions of circular and longitudinal muscles to mix and propel food.