Chapter 21: Nutrition and Digestion

Question 1

What is a calorie

Answer 1

Describes the potential energy of food; a measure of how much cellular work can be powered by the energy released from breaking down foods.

Question 2

Macronutrients and micronutrients

Answer 2

Macronutrients are nutrients that our body requires in large amounts:
* Carbohydrate
* Proteins
* Fats

Micronutrients required in small amounts:
* Vitamins
* Mineral

Question 3

Explain the glycemic index (GI), and the type of information it provides

Answer 3

A scale that ranks a carbohydrate-containing food or drink by how much it raises blood sugar levels after it is eaten or drank; differentiates between high GI foods (quickly digested and converted to blood sugar) and low GI foods (digestes more slowly → slower rise in blood sugar).

Question 4

Undernourished and malnourished

Answer 4

Deficient in one or more essential nutrients = malnourished.
Deficient in calories = undernourished.

Question 5

What is the difference in function between HDL and LDL cholesterol?

Answer 5

Both are types of dietary cholesterol. Low-density lipoprotein delivers cholesterol to cells; correlated with blocked blood vessels, high blood pressure etc. High-density lipoprotein brings excess cholesterol from blood to liver for recycling; may decrease vessel blockage

Question 6

What are essential nutrients and different classes?

Answer 6

nutrients that can’t be made by animal and must be supplied through diet:
1. Essential amino acids
1. Essential fatty acids
1. Minerals
1. Vitamins

Question 7

Vitamins and minerals, functions

Answer 7

An organic compound essential for body funtion:
* Required in small amoutns
* Humans don’t have enzymes to make most vitamins
* Most function as coenzymes that assist metabolic reactions

Inorganic elements essential for body function:
* Required in different amounts

Question 8

Fat-soluble and water-soluble vitamin and its function

Answer 8

Fat-soluble vitamins are absorbed along with fats in our diet and stored in body’s fatty tissues and liver:
* Vitamin D increases absorption of calcium in small intestine

Vitamin C (water-soluble)
* Required for collagen synthesis

Question 9

Minerals and functions

Answer 9

• Iron (Fe) is the oxygen-binding component of hemoglobin.
• Calcium (Ca) and phosphorus (P) are components of bone tissue.
• Magnesium (Mg) support enzyme function.
• Sodium (Na), potassium (K), and calcium are important for nerve and muscle activity.

Question 10

Why and in what situation do fat-soluble vitamins present a greater toxicity risk than water-soluble vitamins?

Answer 10

Excess fat-soluble vitamins are stored in liver, spleen, and adipose tissue, which could lead to toxicity if ingested in improper amounts from supplements. Excess water-soluble vitamins are eleminated in urine.

Question 11

Give 2 reason why water is important part of our diet

Answer 11

• Carries nutrients to your cells
• Required for cellular metabolism
• Provides moist environment for ear, nose, and throat
• Allows kidneys to expel toxins and wastes
• Prevents kidney stones and constipation
• Improves digestion
• Helps maintain a healthy weight

Question 12

obesity and possible causes

Answer 12

Excessive accumulation of fat that has a negative impact on health.
Could be due to issues that involve genetics and lifestyle factors:

• Mutations in leptin, a hormone produced by adipose cells to suppress appetite
• Diet of red meat, sweets, processed foods

Question 13

Why do organisms have to eat? :(

Answer 13

1. Animals eat to obtain energy for body activities, which can be stored as ATP.
2. Obtain building blocks to assemble new molecules
3. Obtain essential nutrients (e.g. vitamins and minerals) that can’t be synthesized

Question 14

What is a healthy diet? :/

Answer 14

One that must contain:
* Fuel
* Raw materials
* Essential nutrients

Question 15

(Aerobic) cellular respiration (number of ATP produced, oxygen requirement, and by-products)

Answer 15

*Preferred by cells, but requires O2.

3 stages:
1. Glycolysis (makes 2 ATP)
2. Citric acid cycle (2)
3. Oxydative phosphyration (28)

32 ATP per glucose molecule consumed.
CO2 and H20 as waste products

Draw out reaction

Question 16

Fermentation (anaerobic) (number of ATP produced, oxygen requirement, and by-products

Answer 16

Done when oxygen isn’t available.

2 steps:
1. Glycolysis
2. Fermentation (lactic acid or alcohol)

Lactic acid fermentation:
Glucose converted to lactate.
Alcohol fermentation:
Glucose converted to CO2 and ethanol

2 ATP per glucose molecule consumed.
CO2, lactic acid, and alcohol as waste products.

Question 17

The 4 stages of food processing and where they occur in the
human body.

Answer 17

1. Ingestion: . . . eating.
2. Digestion: breaking down (chemical and mechanical) food into molecules small enough for the body to absorb.
3. Absorption: taking up products of digestion, usually by cells lining the digestive tract.
4. Elimination: removing undigested materials from digestive tract.

Question 18

Difference between mechanical and chemical digestion

Answer 18

Mechanical: physically breaking down food substances into smaller particles to more efficiently undergo chemical digestion.

Chemical digestion: process by which macromolecules are split into their components
* Requires enzymes that catalyze the hydrolysis of covalent bonds.

Question 19

Identify digestive organs and compartments in animals that are not present in the human digestive tract and briefly describe their functions

Answer 19

Simple animals: gastrovascular cavity (single sac with 1 opening)
Humans: alimentary canal (tube that run between 2 openings).
Some animals also have specialized compartments that aren’t present in humans:
* Crop: pouch that softens and stores food
* Gizzard: grinds up food

Question 20

Oral cavity: teeth, salivary glands, tongue functions

Answer 20

Teeth (incisors, canines, molars) break up food.
Salivary glands produce saliva:
* Moistens and lubricates food
* Buffers neutralize acids
* Antimicrobial agents
* Salivary amylase begins hydrolysis of starch

Tongue pushes the chewed food (bolus) into the pharynx.

Question 21

Pharynx: epiglottis

Answer 21

Covers the opening to the trachea and prevents entry of food into airways during swallowing

Question 22

Esophagus

Answer 22

Esophagus transports food to the stomach
* Peristalsis: smooth (involuntary) muscles contract to move bolus through the alimentary canal.

Question 23

stomach, gastric juice

Answer 23

• Located under the diaphragm
• Stretches to store food
• mechanical and chemical digestion:

Bolus mixed with gastric juice to form chyme.

Secretes gastric juice containing:
* Mucus (secreted by mucous cells): protects stomach.
* HCL (pH 2, secreted by parietal cells): kills bacteria and denatures protein (which increases SA for enzymes to act on).
* Pepsin (secreted by chief cells as pepsinogen): stomach enzyme that breaks covalent bonds between amino acids - protein → peptides.

Question 24

small intestines, sections, epithelium

Answer 24

• Major organ for chemical digestion and nutrient absorption.
• Non-ciliated simple columnar epithelium lining the small intestine synthesize digestive enzymes (maltase, sucrase, lactase, peptidases etc.).

Duodenum
* Mixes chyme with secretions from pancreas and liver.

Jejunum
* Continues chemical digestion and nutrient absorption

Ileum
* Nutrient absorption

Question 25

Large intestines. large intestinal bacteria

Answer 25

Water absorption.

Feces (undigested materials (e.g. cellulose) + bile salts + bacteria) passes to.
Large intestinal bacteria produce:
* Vitamin K
* Folic acid
* B vitamins

Question 26

Rectum and anus

Answer 26

Rectum: a muscular organ at end of large intestine; stores feces.
Anus: consists of internal (involuntary) and external (voluntary) sphincters.

Question 27

Acessory organs: pancreas

Answer 27

Pancreas produces alkaline solution (neutralizes acidic chyme) and digestive enzyme (pancreatic amylase, trypsin, pancreatic lipase, chymotrypsin, nucleases).

Question 28

Acessory organs: liver

Answer 28

Liver: Produces bile, which is then stored in gallbladder.
* Bile emulsifies fats (large fat droplets → smaller droplets; increase SA for pancreatic lipase to act on)

Question 29

Sphincters

Answer 29

Layers of muscle that constrict to regulate food from one location in the digestive tract to another.
In 5 locations:
Esophageal sphincter relaxes (opens) to allow bolus into esophagus.
Cardiac sphincter (lower esophageal sphincter) regulates the passage of food from the esophagus into the stomach.
Pyloric sphincter:through which chyme passes to enter small intestines.

Question 30

Microbial causes of gastric ulcers

Answer 30

Gastric ulcers are open sores in stomach lining.
* Bacterium can infect stomach lining - protective mucus erods and lining is damaged.

Question 31

Trace the digestion of carbohydrates, the locations where each process occurs, and the chemicals responsible for catabolism

Answer 31

Digestion of carbs starts in mouth and ends in small intestines.
Mouth: salivary amylase (starch → maltose) Small intestine: pancreatic amylase (polysaccharide → maltose), maltase (maltose → glucose).

Question 32

Trace the digestion of protein, the locations where each process occurs, and the chemicals responsible for catabolism

Answer 32

Starts in stomach and ends in small intestine.
Stomach: pepsin (polypeptide chains → smaller polypeptides)
Small intestines: trypsin, chymotrypsin (→ smaller polypeptides), peptidases (→ amino acids).

Question 33

Trace the digestion of fat, the locations where each process occurs, and the chemicals responsible for catabolism

Answer 33

Small intestine: bile emulsifies fat (fat globules → fat droplets), lipase ( → fatty acids + glycerol).