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Biology > Nutrition in Humans > Flashcards

Nutrition in Humans Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is the alimentary canal?

A

A series of hollow organs joined in a long twisting tube from the mouth to the anus

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2
Q

Define ingestion

A

The process of taking food into the body via the mouth

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3
Q

Define digestion

A

The process whereby large and complex food molecules are broken down into smaller and soluble molecules (physical and chemical means) that can be absorbed into the bloodstream

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4
Q

Define absorption

A

The process whereby soluble food molecules pass through the intestinal walls into the bloodstream

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5
Q

Define assimilation

A

The process of transporting and utilising absorbed foods

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6
Q

Define egestion

A

The process of removing undigested food in the form of faeces from the body via the anus

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7
Q

Egestion vs excretion

A

Egestion: Removal of undigested foods
Excretion: Removal of unwanted matter as a result of digestion

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8
Q

Define peristalsis

A

The rhythmic wave-like contractions of the muscular walls of the oesophagus, stomach, small and large intestines

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9
Q

Describe

Peristalsis in the movement of food in the oesophagus

A

Antagonistic muscles in the oesophagus, the circular and longitudinal muscles, work antagonistically to push food down the oesophagus. One relaxes while the other contracts

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10
Q

Describe

The role of peristalsis in digestion

A

Peristalsis moves food forwards so that different nutrients in the food can be digested by the different organs with the specific pH and enzymes

Food can also be churned (stomach) to bring substrates and enzymes closer and also physically broken down to increase surface area for catalysis

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11
Q

What is the substrate that amylase digests?

A

Starch

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12
Q

What enzymes are present in pancreatic secretions and what do they digest?

3 enzymes

A
  1. Pancreatic amylase: starch to maltose
  2. Trypsin: proteins to polypeptides
  3. Pancreatic lipase: fats to fatty acids and glycerol
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13
Q

What enzymes are present in intestinal juices and what do they digest?

5 enzymes

A
  1. Maltase: maltose to glucose
  2. Sucrase: sucrose to glucose and fructose
  3. Lactase: lactose to glucose and galactose
  4. Lipase: fats to fatty acids and glycerol
  5. Erepsin (a peptidase): polypeptides to amino acids
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14
Q

Describe the function of the mouth

A

Food is chewed and mixed with saliva. Chewing facilitates swallowing and increases SA:V ratio of the food for enzymes to work on. Saliva contains salivary amylase, breaks down starch into maltose. It also moistens the food; acts as a lubricant to help roll food into a bolus

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15
Q

Describe the function of the oesophagus

A

It transports boli downwards from the mouth to the stomach with peristaltic contractions

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16
Q

Describe the functions of the stomach

3 functions

A
  1. Breakdown of food (physical: churning action (peristalsis); chemical: use of pepsin to digest proteins
  2. Kill bacteria (low pH- pH 2- kills bacteria present)
  3. Absorption (certain vitamins are absorbed here)
17
Q

What are the substances secreted by the stomach and how are they secreted?

2 Substances

A
  1. Pepsin
  2. Hydrochloric acid
    They are secreted through numerous gastric pits lined by secretory cells
18
Q

What is the name of the final mixture leaving the stomach and a property of the mixture

A

Chyme. It is very acidic.

19
Q

What are the functions of hydrochloric acid in the stomach?

4 functions

A
  1. Digestion: It activates pepsin from its inactive form, pepsinogen
  2. Anti-bacterial
  3. Denaturation of salivary amylase
  4. Optimal pH for pepsin to work
20
Q

What are the portions of the small intestine and their functions?

3 sections

A
  1. Duodenum (25 cm): Receives chyme, pancreatic juices and bile. Chyme is neutralised by alkali chyme and pancreatic juices. Digestion mainly occurs here to produce the final products of all classes of nutrients
  2. Jejunum (250 cm): Specialises in absorption. Villi are much longer here
  3. Ileum (300 cm): Absorbs any remaining nutrients, vitamin B12 and bile salts
21
Q

What are some features of the small intestine that aid in absorption?

5 features

A
  1. Very long: More time for digestion and absorption to happen
  2. Presence of millions of villi; microvilli: Increase SA:V ratio
  3. Villi have a rich network of blood capiliaries
  4. Villi have lacteals: Fats are absorbed into these
  5. Villi have one cell thick walls: Diffuse quickly; short distance
22
Q

Describe the assimilation of glucose

A
  1. Glucose absorbed by the small intestine is transported to the liver through the hepatic portal vein
  2. Most would be converted to glycogen and stored in the liver and muscles
  3. Some would leave the liver and be transported around the body for usage (respiration)
  4. Excess would be converted to glycogen as well
23
Q

Describe the assimilation of amino acids

A
  1. Amino acids will pass through the liver to the rest of the body
  2. Excess will be deaminated as there is no storage
24
Q

Describe the assimilation of fats

A
  1. Absorbed fatty acids and glycerol will form fat globules again after absorption
  2. They would be absorbed by lymphatic capiliaries first before being passed to larger veins prior to usage
25
Q

State

The function of the large intestine

A
  1. Absorbs any remaining water and mineral salts
  2. Site for bacterial fermentation of food to faeces that releases vitamins that are absorbed
26
Q

What are the functions of the liver

7 functions

A
  1. Regulation of blood glucose conc.
  2. Secretion of bile
  3. Storage of iron from destroyed RBCs
  4. Metabolisation of amino acids and deamination
  5. Manufacturing of plasma proteins
  6. Breakdown of alcohol: detoxification
  7. Breakdown of hormones
27
Q

How does the liver regulate blood glucose concentration?

A
  • When blood glucose is above normal: More insulin is secreted by Islets of Langerhans; stimulates liver to convert excess glucose to glycogen at a faster rate; conc. decreases
  • When blood glucose is below normal; more glucagon is secreted by Islets of Langerhans; stimulates liver to convert glycogen to glucose at a faster rate; conc. increases
28
Q

How does the liver help in fat digestion?

A
  • It secretes bile
  • Released in the duodenum
  • Bile salts emulsify fat globules to produce fat droplets; higher SA:V ratio
  • Higher rate of fat digestion
29
Q

What role does the liver play in red blood cell production?

A

After RBCs are destroyed in the spleen. haemoglobin is transported to the liver and broken down, producing iron that is stored in the liver. This is used to synthesise new RBCs

30
Q

Describe the process of deamination as amino acids pass through the liver

A
  1. Amino groups are removed from excess amino acids and converted to urea
  2. Remaining section is converted to glucose
31
Q

How does the liver break down alcohol?

A

The liver converts alcohol to acetaldehyde using alcohol dehydrogenase enzymes

32
Q

What happens to hormones in the liver?

A

They are broken down or metabolised after they have done their work in the body to ensure that hormones are not always present

33
Q

What are the effects of excessive consumption of alcohol on the body?

3 main areas

A
  1. Effects on digestive system: gastric ulcers (alcohol stimulates acid secretion in the stomach); liver cirrhosis (liver tissues damaged and replaced with fibrous tissue which are less able to function; can cause patients to haemorrhage, leading to liver failure or death)
  2. Effect on nervous system: reduced self control (affects brain that controls judgement, concentration, coordination, behaviour and emotions), depressant (slows down some brain functions) increased reaction times (slurred speech, blurred vision, poor muscular coordination
  3. Alcoholism (social issues; addiction)
34
Q

What is the mouth also known as?

A

Buccal cavity

Biology (10 decks)

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