Ch 5 Nutrition in Humans

Question 1

Definition of Nutrition?

Answer 1

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

Question 2

Feeding/ingestion is?

Answer 2

Food is taken into the body.

Question 3

Digestion is?

Answer 3

1. Large insoluble food molecules are broken down into smaller soluble molecules that can be absorbed into the bloodstream.
2. Physical: Mechanical breakdown of food substances to increase SA:V to speed up chemical digestion.
3. Chemical: Involves enzymes to digest food into small soluble molecules that can be absorbed.

Question 4

Absorption is?

Answer 4

1. Glucose and amino acids are taken into the blood capillaries.
2. Fats are taken into the lacteal
3. Both take place in the villi in the small intestine.
4. These digested food molecules are taken into the villus of the small intestine by diffusion or active transport.

Question 5

Assimilation is?

Answer 5

1. Absorbed products of digestion
2. Are used as an energy source/converted into new protoplasm
3. Which are needed for growth and repair of body parts.

Question 6

Egestion is?

Answer 6

Undigested matter excreted out of the body as faeces through the anus.

Question 7

Ingestion takes place in the?

Answer 7

1. Mouth

Question 8

Chemical digestion takes place in the?

Answer 8

1. Mouth
2. Stomach
3. Small intestine

Question 9

Absorption takes place in the?

Answer 9

1. Small intestine
2. Large intestine (water)

Question 10

Assimilation takes place in the?

Answer 10

1. Liver

Question 11

Egestion takes place in the?

Answer 11

1. Anus

Question 12

Functions of the mouth?

Answer 12

Teeth
- Break large pieces of food into smaller pieces
- Increases SA:V of food so enzymes can act on it more efficiently

Salivary glands
- Secrete saliva containing salivary amylase into the mouth

Tongue
- Mixes food with saliva
- Moves food to the back of the mouth during swallowing

Question 13

Functions of the oesophagus?

Answer 13

1. Narrow, muscular tube that passes through the chest and diaphragm
2. Connects mouth and stomach
3. Consists of a layer of longitudinal muscles and a layer of circular muscles

Question 14

Peristalsis is?

Answer 14

Rhythmic wave-like muscular contractions in the wall of the alimentary canal.

Question 15

Function of peristalsis?

Answer 15

1. Enables food to be mixed with digestive juices
2. Helps to push or propel the food along the gut

Question 16

Describe how the muscles work together during peristalsis. (Action of muscles, effect on gut, effect on food bolus.)

Answer 16

1.Circular muscles contract, longitudinal muscles relax.
2. Gut becomes narrower (constricts) and longer.
3. Food is squeezed or pushed forward.

1. Longitudinal muscles contract, circular muscles relax
2. Gut becomes wider (dilates) and shorter.
3. Food enters the lumen.

Question 17

Function of the stomach?

Answer 17

1. Contains gastric glands which secrete gastric juice for digestion.

Question 18

Parts of the small intestine? (From front to end)

Answer 18

1. Duodenum
2. Jejunum
3. Ileum

Question 19

How is the small intestine adapted for absorption?

Answer 19

Adaptation 1: Has numerous finger-like projections called villi.
Function: Increased SA:V for increased rate of absorption.

Adaptation 2: The cells of the epithelium have many microvilli.
Function: Increased SA:V for increased rate of absorption.

Adaptation 3: The epithelium wall of the villus is one-cell thick.
Function: Provides a shorter distance for nutrients to diffuse through, increasing rate of absorption.

Adaptation 4: Each villus has many blood capillaries.
Function: Capillaries allow blood to continually transport the absorbed glucose and amino acids away to maintain a steep diffusion gradient.

Adaptation 5: Each villus contains a lacteal.
Function: Allows the continual transport of absorbed fats away to maintain a steep diffusion gradient.

Adaptation 6: The epithelial cells contain many mitochondria.
Function: The mitochondria release energy for active transport of nutrients into the villus.

Adaptation 7: The small intestine is long.
Function: Provide sufficient time for absorption.

Question 20

How does the small intestine absorb?

Answer 20

1. Glucose and amino acids diffuse into the blood capillaries in the villi. (Glucose and amino acids are also absorbed by active transport when conc of digested food substances in capillary < than in small intestine lumen.)
2. Glycerol and fatty acids diffuse into the epithelium.
3. They combine to form fat globules that enter the lacteal.

Question 21

What happens to undigested and unabsorbed matter?

Answer 21

1. Stored temporarily in the rectum.
2. Discharged as faeces through the anus.

Question 22

Function of the hepatic portal vein?

Answer 22

Transports nutrients from the small intestine to the liver.

Question 23

Functions of the liver?

Answer 23

1. produce Bile - Emulsify fats
2. deAmination - Excess aa -> urea (to be excreted)
3. Detoxification - alcohol broken down into CO2 and H2O
4. breakdown of HOrmones (after they have served their purpose)
5. regulate blood Glucose level
   - Blood glucose > normal - glucose to glycogen by insulin
   - Blood glucose < normal - glycogen to glucose by glucagon
   (BADHOG)

Question 24

Substrate: Starch
Enzyme and product?

Answer 24

Amylase, maltose

Question 25

Substrate: Maltose
Enzyme and product?

Answer 25

Maltase, glucose

Question 26

Substrate: Protein
Enzyme and product?

Answer 26

Protease, polypeptide

Question 27

Substrate: Polypeptide
Enzyme and product?

Answer 27

Protease, amino acids

Question 28

Substrate: Fats
Enzyme and product?

Answer 28

Lipase, fatty acids and glycerol

Question 29

Process of blood glucose concentration regulation? (Higher and lower than normal)

Answer 29

Higher than normal:
1. Islets of Langerhans in pancreas secrete more insulin into the liver.
2. Excess glucose gets converted into glycogen.
3. Blood glucose concentration decreases back to normal.

Lower than normal:
1. Islets of Langerhans in pancreas secrete more glucagon into the liver.
2. Glycogen gets converted into glucose.
3. Blood glucose concentration increases back to normal.

Question 30

What happens to amino acids after absorption?

Answer 30

1. Amino acids that enter the cells are converted into protoplasm for the growth and repair of worn-out body parts.
2. Used to form enzymes and hormones.
3. in the liver, excess amino acids are deaminated into urea for excretion. Urea is removed through the urine.
4. The remaining amino acids are converted into glucose in the liver.

Question 31

What happens to fats after absorption?

Answer 31

1. Fats are absorbed into the lymphatic capillaries which join to form larger lymphatic vessels which discharge fats into the bloodstream.
2. When there is not enough glucose, fats are used to build protoplasm like cell membranes.
3. When there is not enough glucose, fats are broken down to provide energy needed for the body’s vital activities.
4. Excess fat is stored in adipose tissues beneath the skin and around the heart and kidneys, acting as shock absorbers which protect the organs.

Question 32

How does excessive alcohol consumption negatively affect the digestive system?

Answer 32

1. Alcohol stimulates acid secretion in the stomach. Excess stomach acid increases the risk of gastric ulcers.
2. Too much alcohol may lead to liver cirrhosis (Liver cells are destroyed and replaced with fibrous tissue aka scar tissue, making the liver less able to function.)
3. Alcoholic liver cirrhosis may lead to bleeding in the liver, liver failure and then death.

Question 33

How does excessive alcohol consumption negatively affect the nervous system?

Answer 33

1. Depressant
   - Slows down some brain functions.
2. Reduced self-control
3. Effect on reaction time
   - Slurred speech, blurred vision, poor muscular coordination
   - Judgement deteriorates, underestimate speed
   - Drive faster and with less caution, slower reaction

Question 34

Negative long-term impacts of excess alcohol consumption on the brain?

Answer 34

1. Wet brain (A type of dementia)
2. Shrinkage of brain volume
3. Life-long physical, mental and behavioural problems in child - heavy consumption of alcohol during pregnancy

Question 35

Negative social impacts of excessive alcohol consumption?

Answer 35

1. Neglecting work and families
2. Violence
3. Higher risk of committing crimes