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Biology 1 > Chapter 7- Nutrition in man > Flashcards

Chapter 7- Nutrition in man Flashcards

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1
Q

What is nutrition? Define it.

A

Nutrition is the process by which organisms obtain food and energy, for growth, repair, and maintenance of the body.

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2
Q

What are the four processes that food goes through during digestion?

A
  1. Ingestion
  2. Digestion
  3. Absorption
  4. Egestion
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3
Q

Explain what happens in the buccal cavity.

A
  1. Teeth- physical digestion. The teeth help break down food molecules into smaller molecules, increasing surface area to vol. ratio.
  2. Saliva- contains mucin, which softens food. Salivary amylase helps break starch down into maltose.
  3. Tongue- rolls the food into slippery round masses called boli.
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4
Q

What happens to the epiglottis during respiration vs during swallowing of food substances?

A
  1. During breathing- air passes into the trachea, and the larynx moves downwards. The glottis is kept open for air to pass through.
  2. During swallowing- larynx moves upwards and the epiglottis covers the glottis, preventing the food particle from entering the trachea.
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5
Q

What happens if food molecules pass down the trachea?

A

When this happens, the person will start coughing violently. Coughing is automatically induced to force the food particle out of the trachea.

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6
Q

Describe the function and structure of the oesophagus.

A

It is a narrow and muscular tube that extends to the stomach. It is made up of mainly two muscles- the longitudinal and the circular muscle. Peristalsis occurs here, all the way to the large intestine. Food goes down the oesophagus to the stomach.

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7
Q

Describe the movement of the longitudinal and circular muscles.

A
  1. The circular muscles contract first, and the longitudinal muscles will relax. This causes the walls of the oesophagus to constrict and become narrower and longer, pushing the food molecules forward.
  2. The longitudinal muscles then contract while the circular muscles relax, causing the walls to dilate and become wider and shorter. This widens the lumen for food to enter.
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8
Q

Describe the function and how peristalsis works.

A

Peristalsis is a wave like, rhythmic muscular contractions in the walls of the alimentary canal. It helps enable food to be mixed with digestive juices, and pushes or propels food along the gut.

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9
Q

Describe the function and the structure of the stomach.

A

The stomach is a thick, muscular and distensible muscular bag. It helps to digest and liquefy food particles, specifically proteins.

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10
Q

Describe the composition and function of gastric juices.

A

Composition- dilute sol. of hydrochloric acid, pepsin and mucus.
1. Denatures salivary amylase- no more digestion of starch.
2. Provides acidic medium for pepsin to function.
3. Converts pepsinogen to pepsin.
(Pepsinogen + HCL > Pepsin (active form)).
4. Kills harmful microorganisms in food.

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11
Q

What happens after digestion in the stomach?

A
  1. Food usually stays there for 3-4 hours.
  2. Food becomes partially liquefied, aka chyme.
  3. Passes in small amounts into the duodenum when the pyloric sphincter is relaxed and opens.
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12
Q

What is the structure and function of the small intestine?

A
  1. Duodenum, jejunum, ileum (highly coiled- small space).
  2. Up to 6m long in adults.
  3. Walls secret digestive juices from glands, which contains enzymes. (Digests starch, fats and proteins).
  4. Adapted to absorb digested food particles (ileum).
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13
Q

Chyme enters the duodenum and stimulates the release of ___________.

A
  1. Pancreatic juices
  2. Bile
  3. Intestinal juices
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14
Q

How is trypsin oven activated, and what does it act on?

A
  1. Trypsinogen + enterokinase > trypsin.
  2. Proteins + trypsin > polypeptides.
  3. Polypeptides + peptidases > amino acids.
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15
Q

What is the pancreatic juice made up of?

A
  1. Pancreatic amylase, to digest starch to glucose.
  2. Pancreatic lipase, to digest fats to fatty acids and glycerol.
  3. Trypsinogen, an inactive enzyme.
    (pH > 7, to neutralize the acidic chyme and provide and alkaline medium for prancreatic enzymes)
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16
Q

What does bile contain? What does it do?

A
  1. Bile emulsifies fats by breaking fat globules to small fat droplets which are suspended in water. (Emulsification- increases surface area to volume ration = only physical digestion.)
  2. These small fat droplets are then broken down by pancreatic lipase.
  3. Alkaline, greenish-yellow substance.
17
Q

What does intestinal juice contain?

A

Intestinal juices are secreted from intestinal glands.

  1. Maltase
  2. Sucrase
  3. Lactase
  4. Peptidases
  5. Intestinal lipase
18
Q

How is the small intestine adapted for absorption?

A
  1. Thin walls of villi- easy diffusion into bloodstream.
  2. Length of the intestine (>6m)- increases time for absorption.
  3. Many blood capillaries- carry the nutrients away quickly.
19
Q

What methods of transport are used to transport the food into the blood capillaries?

A 
1. Active transport- glucose, amino acids
(Lumen to epithelial to blood cells)
2. Diffusion- glucose, amino acids
3. Diffusion- glycerol and fatty acids
(Lacteal / lymphatic capillaries)
20
Q

What is the structure of the large intestine?

A
  1. Colon
  2. Rectum
  3. Caecum and appendix
  4. Anus
    It is shorter, but broader than the large intestine. It is about 1.5m long.
21
Q

What are the functions of the large intestine?

A

Colon- Absorb mineral salts and water from undigested food material?
Rectum- Stores faeces temporarily.
Anus- expels faeces (egestion).
General- absorption of water and mineral salts.

22
Q

State the function and structure of the pancreas.

A

The pancreas is a gland connected to the duodenum via the pancreatic duct. It secretes insulin, which regulates blood glucose levels, as well as glucagon, which stimulates the liver to release glucose. Pancreatic juice also comes from the pancreas.

23
Q

Define assimilation.

A

Assimilation is the process whereby some substances are converted into new protoplasm or used to provide energy for the body.

24
Q

What is the function and structure of the hepatic portal vein?

A

The hepatic portal vein consists of blood capillaries that supply the small intestine which unite to form the vein. It transports sugars, fats and amino acids to the liver. Proteins are distributed for new growth and repair in cells, as well as to form enzymes and hormones. These nutrients leave the liver via the hepatic vein.

25
Q

What are the functions of the liver?

A
  1. Regulates blood glucose levels.
  2. Production of bile.
  3. Recycling and storing of iron.
  4. Detoxification.
  5. Synthesis of proteins.
26
Q

How is the blood glucose concentration kept constant?

A

(Normal sugar levels are at 60-70mg/100cm3)

  1. When there is too much sugar, the pancreas secretes insulin, which stimulates the liver to store glucose in the form of glycogen.
  2. When there is too little sugar, the pancreas secretes glucagon, which stimulates the liver to convert glucagon back to glucose, hence increasing the blood glucose level.
27
Q

How is protein synthesis carried out?

A
  1. Liver uses amino acids to synthesize the proteins.
  2. Breakdown of proteins: Amine group gets removed from the amino acids, where it gets converted into urea in the liver. Carbon residues are converted into glucose in the liver. (Deamination)
28
Q

What happens during the storage and breakdown of iron?

A
  1. Red blood cells are destroyed in the spleen.
  2. The iron from the red blood cells are stored in the liver,
  3. Haemoglobin is also recycled in the liver.
  4. These two components are recycled for synthesis of new RBCS.
  5. Bile is also produced in the process.
29
Q

How is detoxification carried out?

A

Detoxification is the process of converting harmful substances into harmless products. An example would be the conversion of alcohol to acetaldehyde, via the enzyme alcohol dehydrogenase. Acetaldehyde becomes a new source of energy for the cells, and can also be broken down further into compounds that can be used during respiration, for cellular activities.

30
Q

What are the harmful effects of alcohol consumption?

A
  1. Slows down brain function
  2. Reduced self control | bipolarity
  3. Symptoms of drunkenness
  4. Addiction
  5. Increased risks of gastric ulcers
  6. Liver cirrhosis
31
Q

Explain what happens during liver cirrhosis.

A
  1. It’s a disease which destroys liver cells.
  2. The liver cells are replaced by fibrous tissue (less functionable)
  3. Hemorrhage / bleeding in the liver.
  4. This can lead to liver failure and eventually death.

Biology 1 (9 decks)

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