Unit 4: Digestion , Absorption , Transport , And Excretion

Question 1

What is the GI Tract

What is its main function

Answer 1

26 foot long tube that starts at the mouth and ends at the anus

Main function is to absorb and digest nutrients from food

Question 2

What are the two main organs of the go tract

Answer 2

• the stomach (Greek: gastr)
• the intestines

The mouth is also important organ of the GI tract because both chemical and mechanical digestion happens here

Question 3

What are the important organs of the digestive system anatomy

Answer 3

Epiglottis

Sphincter

Duodenum

Jejunum

Ileum

Accessory organs that help digestion:
- salivary glands
- liver
- gallbladder
- bile duct
- pancreatic duct
- pancreas

Digestive tract organs that contain the food:
- mouth
- esophagus
- stomach
- small intestine
- large intestine (colon)
- rectum
- anus

Question 4

What is grehlin

Answer 4

A hunger hormone secreted by the stomach that alert your mind to hunger

Question 5

What four basic chemical tastes detected by taste buds

Answer 5

Sweet

Sour

Bitter

Salty

5th:
Umami (mono sodium glutamate, MSG) has a savoury taste

Question 6

What sensory factor is more sensitive than taste and by how much

Answer 6

Smell

1000x

Question 7

Why do people instinctively enjoy sweet salty and fatty foods

Why do people have and aversion to bitter tastes

Answer 7

These food signal sources of essential nutrients and energy :

Sugars for the brain

Fat for energy and nutrients

Salt for na and cl

Bitter tastes:
- the aversion to is is because it discourages consumption of food with bitter toxins

Question 8

What is the problem with the instinctive like to sugar fat and salt

Answer 8

It can lead to drastic overconsumption of these things

The modern food industry adds them to food to increase their appeal and drive overconsumption

Question 9

What labelling changes has health Canada proposed under the healthy eating strategy

Answer 9

The label of oak mage have to highlight higher levels of saturated fat sodium and sugars

Also update the nutrition facts to include % DV for sugar and to group all sugars in the ingredients list

Question 10

What is the digestive system

GI system

Digest

Absorb

Answer 10

Digestive system: the body’s system composed of organs that break down complex food particles into smaller absorabable products, then excrete out the unabsorbed stuff (like fibre)

GI system: the whole digestive system including the pancreas liver and gall bladder

Digest: break down molecules into smaller molecules , main function of the digestive tract in relation to food

Absorb: to take in (ex . Nutrients taken into the intestinal cells after digestion) main function of the digestive tract in relation to nutrients

Question 11

What are mechanical and chemical digestion

Answer 11

For the digestive tract to do the process of digestion and absorption, both chemical and mechanical digestion are used

Question 12

Epiglottis

Sphincter

Duodenum

Jejunum

Ileum

Answer 12

Epiglottis: a flap at the start of the esophagus that prevents food from entering the lungs

Sphincter: circular muscle surrounding and able to close a body opening . The stomach has two , one at the start of it and and one at end

Duodenum:
- the first part of the small intestine, the site where foods are subjected to the action of bile and pancreatic juices and where breakdown of protein’s carbs and fats starts

Jejunum:
-the first 2/5 of the small intestine beyond the duodenum, main function is absorption of digested material

Ileum:
- the last segment of the small intestine that is just before the large intestine and functions in the absorption of nutrients

Question 13

Accessory organs that help digestion:
- salivary glands
- liver
- gallbladder
- bile duct
- pancreatic duct
- pancreas

Answer 13

salivary glands: donate a starch digesting enzyme, donate a fat digesting enzyme

• liver: makes bile which facilitates digestion of fats
• gallbladder : stores bile until it’s needed
• bile duct: transfers, bile to the small intestine
• pancreatic duct: transfers, pancreatic juice to the small intestine
• pancreas: makes enzymes to digest all energy, yielding nutrients. Releases bicarbonate to neutralize stomach acid that enters the small intestine.

Question 14

Digestive tract organs that contain the food:
- mouth
- esophagus
- stomach
- small intestine
- large intestine (colon)
- rectum
- anus

Answer 14

mouth: chews and mixes food with saliva

• esophagus: passes food to the stomach
• stomach: adds acid, enzymes (like pepsin to do protein digestion) and fluid . Churns mixes and grinds food to a liquid mass
• small intestine: secretes enzymes that digest, carbs, fat and protein. the cells lining the intestine, absorb nutrients into the blood and lymph
• large intestine (colon): reabsorbs, water and minerals. Passes waste like unabsorbed nutrients and some water to the rectum.
• rectum: stores waste prior to elimination
• anus: whole rectum closed opens to allow elimination

Question 15

What is mechanical digestion

Answer 15

It starts at the mouth where food peices are teared into shreds and saliva moistens/softens it to ease swallowing througuh esophagus

Question 16

What is peristalsis what happens after

Answer 16

A wavelike muscular squeezing of the esophagus, stomach and small intestine that pushes food along the digestive tract

this happens after the chewing and softening of food has occurred via saliva in the mouth.

Then the stomach holds the swallowed food and mashes it into a fine paste and the stomach and intestines add water so the paste becomes more fluid and becomes chyme.

Then segmentation occurs where there is periodic squeezing of the circular muscles I nthe segments of the intestine
- the makes alternating forwards and backward movement which allows greater mixing between the partially digested food and digestive juices/enzymes to help complete digestion and allow better contamct with the intestinal wall for absorption

Question 17

What is the purpose of the sphincter in digestion

What is chyme

Answer 17

It squeezes the opening of the stomach to narrow it and prevent the contents in the stomach from going back up to the oesophagus as the stomach contracts

Chyme is the fluid that results from the actions of the stomach on the food

Question 18

After the chyme is made what happens 

Answer 18

The pyloric valve at the lower end of the stomach controlls the exit of the chyme and let’s only a little squirt at a time go into the small intestine

Then the small intestine contracts to move the contents along its length while also absorbing nutrients then the contents arrive in the large intestine

Question 19

What happens after food arrives in the large intestine 

Answer 19

At this point digestion and absorption are almost complete

The task of the large intestine/colon is to reabsorb the water that was donated to digest the food and to absorb minerals

This leaves a paste of fibre and other undigested materials, which is excreted as faeces

Question 20

Does the digestive tract work better at certain times of the day?

Answer 20

No digestion is continuous and not time dependent, but the timing of meals affects your well-being. Do the bodys needs for regular nutrient replenishment ( can’t digest at certain times because the body needs nutrients to be replenished every few hours)

Question 21

Why would eating late at night affect some people?

What is the best time to exercise in relation to eating?

Answer 21

It could interfere with their normal sleep patterns

A few hours after eating since digestion can inhibit physical activity

Question 22

What is the sallowed food mass called

Answer 22

A bolus

Question 23

What is chemical digestion

Answer 23

Chemical breakdown via digestive enzyme of nutrients into absorbable products

The enzymes are secreted by specialized glands in the mouth stomach and pancreas, and epithelial cells of the small intestine

Question 24

What do digestive juices contain and what is their function

Which organ secrete digestive juices

Answer 24

They contain enzymes that break nutrients down into their component parts for absorption

Salivary glands, stomach, pancreas, liver, and small intestine

Question 25

What is in saliva that helps in digestion and oral health

Answer 25

salivary amylase: It digest starch lingual lipase: initiate digestion of fat, especially milk fat Helps maintain the health of teeth by washing away food particles that may get stuck in the teeth and neutralizing decay promoting acids that are made by bacteria in the mouth

Question 26

How does protein digestion happen in the stomach? Chemical digestion. What’s more acidic, saliva or gastric juice

Answer 26

Protein digestion is the stomach’s main function, Gastric juice made by cells in the stomach (mixture of water enzymes in HCL) activates pepsin using acidic environment Pepsin digests protein Gastric juice is more acidic as lower pH

Question 27

If there are digestive enzymes in the digestive tract, how can the cellular lining of the digestive tract not get degraded along with the food?

Answer 27

There are specialized cells that secrete, thick viscous substance called mucus Mucus coats and protects the stomach and the rest of the digestive tract lining. The digestive tract lining is a mucus membrane.

Question 28

What is the role of the small intestine in chemical digest?

Answer 28

It helps digestion and absorption with the help of enzymes and digestive fluids from the pancreas, liver and gallbladder

Question 29

What is bile and what does it do? What is pancreatic juice and what does it do

Answer 29

Bile is a fluid made by the liver and stored in the gallbladder Once partially digested mixture arrives in the small intestine, hormonal messengers signal the gallbladder to contract and squirt the right amount of bile into the . The bile emulsifies fats to prepare them for digestion Other hormones notify the pancreas to secrete pancreatic juice containing sodium bicarbonate ( an alkaline compound ) which neutralize the stomach acid that reaches the small intestine and make an optimal ph for enzyme activity Pancreatic juice also digest, carbohydrates, fat, and protein

Question 30

What is an emulsifier

Answer 30

A compound that has water soluble and fat soluble portions that attract fat and oils into water and mixes them together Mixes fats and oils with water

Question 31

What is the final step in chemical digestion before absorption

Answer 31

Enzymes on the intestinal cell surfaces perform last-minute breakdown reactions using the proteases on their surfaces

Question 32

By the time the contents reached, the colon digestion and absorption of which macro nutrients are complete what remains in the digestive tract after macro nutrient absorption

Answer 32

Carbs fats, and proteins broken down and absorbed Water fiber, and some minerals remain in the digestive tract

Question 33

What role do gut bacteria play in digestion

Answer 33

Certain kinds of fibre can’t be digested by human enzymes so these bacteria break down these fibres and make absorbable fat fragments which help in nutrient salvage Then when nutrient salvage happens, these absorbable fat fragments are absorbed by the intestinal cells to get more nutrients

Question 34

Overall, what happens with chemical digestion summary?

Answer 34

It begins in the mouth where food is mixed with enzyme and saliva that acts on carbohydrates . Digestion continues in the stomach where stomach enzymes and acid breakdown protein. Then it continues in the small intestine where the liver and gallbladder make bile that emulsifies fat and the pancreas and small intestine give enzymes that continue digestion so that absorption can occur bacteria in the colon breakdown certain fibres that can’t be digested by the human enzymes.

Question 35

Can the digestive system handle mixed food, combination like fruit and meat?

Answer 35

Yes, it is highly adoptable and can handle any mixture of foods simultaneously

Question 36

Give an example of how the digestive organs sense what nutrients are coming in and respond

Answer 36

Ex. The Pancreas increases secretion of the enzymes needed for the main macro nutrient in that meal, for example increases amylase ouput for a high carbohydrate meal and reduces outputs of other types of enzymes. This make sure that foods of all types are used fully by the body.

Question 37

Summary of chemical digestion page 94

Answer 37

Okay

Question 38

Enzymes Monosaccharide Disaccharide Polysaccharide Disaccharidase Amino acid Dipeptide Try peptide Polypeptide Fatty acid Glycerol Monoglyceride Diglyceride Triglyceride Emulsified fat PH

Answer 38

Enzymes: - proteins that allow conversion of one substance into another without the enzyme being altered important in many chemical reactions in the body digestive enzymes breakdown food into small molecules that can be absorbed Monosaccharide: - single sugar, molecule, glucose or fructose Disaccharide : - Pair of monosaccharides linked together maltose lactose or sucrose Polysaccharide : - many monosaccharides up to thousands linked together starch Disaccharidase - Enzyme involved in hydrolyzing a specific disaccharide into its monosaccharide components Amino acid - building block of proteins - Dipeptide - 2 bonded amino acids Try peptide - 3 bonded amino acids Polypeptide - 10 or more amino acids bonded these polypeptide from proteins Fatty acid : - building block of fats Glycerol : - backbone to which fatty acids are attached to to make a glyceride Monoglyceride : - Glycerol with one fatty acid attached Diglyceride - glycerol with two fatty acids attached Triglyceride : - glycerol with three fatty acids attached. These are the predominant form of fat in the diet and in the body. Emulsified fat : - fat droplets dispersed and stabilized in a watery solution via emulsifiers like bile PH: - measure of how acidic or alkaline a solution is . low pH are acids, 0.5 strong to 4 weak - alkaline solutions have pH from nine weak to 13.5 strong

Question 39

What are the four major classes of digestive enzymes?

Answer 39

Protease lipase amylase disaccharidase

Question 40

What digestive enzymes are in the mouth and what do they do? What all happens in the mouth

Answer 40

Saliva contains amylase which breaks down starch into polysaccharides and Maltose Food is mashed and mixed with saliva , saliva breaks down the starch, swallowing triggers the peristaltic wave that travels the length of the esophagus and carries one chewed bite to the stomach

Question 41

What digestive enzymes are in the stomach and what do they do?

Answer 41

Stomach makes gastric juice which has Pepsin and pepsin breaks protein into polypeptides Starch digestion still happen in the upper stomach but The gastric juice also mixes with the salivary enzymes and stops their function The result is chyme and the carbs and protien rich part of the chyme goes into the small intestine first then slayer of fat follows behind

Question 42

What digestive enzymes are in the pancreas and small intestine and what do they do?

Answer 42

They make pancreatic juice and intestinal juice, which have variety of enzymes Ex Proteases like trypsin break polypeptides to peptides dipeptides, tripeptides, and free amino acids Some sugars require minimal digestion and are absorbed relight after containing the intestinal lining Also the liver donates bile to the small intestine so it can emulsify the fats for better enzyme action The pancreas secreted enzymes to digest fat protien and starch in the small intestine Then the cells of the small intestine make the final digestive enzymes

Question 43

What do lipases do what do analyzes do?

Answer 43

Lipases break emulsified fat into monoglycerides , free fat fatty acids and glycerol Amylases breaks starch and polysaccharides down into maltose, disaccharidases break disaccharides into monosaccharides

Question 44

What non-enzymatic secretions are important to digestion

Answer 44

HCL: made in the stomach and helps hydrolysis or chemical breakdown of protein into smaller peptides by making acidic conditions to activate pepsin enzyme HCL is a strong acid (less than two pH) and kills most food born bacteria entering the body Bicarbonate: is secreted by the pancreas and neutralizes stomach acid that reaches the small intestine Bile: made by liver and stored in gallbladder. Gallbladder is stimulated by fat in the diet and then squirts the bile into the duodenum. Bile is an emulsifier which causes fat to form a suspension in the watery medium of the GI tract so that the enzymes can break down the fat. Bike is also need for gst absorption by the intestinal mucosa

Question 45

What is absorption?

Answer 45

After nutrients are broken down into their basic building blocks absorption happens where nutrients pass through the epithelial cells of the small intestine into the bloodstream or the lymphatic system

Question 46

What gets absorbed and broken down and where are they absorbed into?

Answer 46

Carbs, fats, and proteins: broken down into basic building units to be absorbed Vitamin and mineral : absorbed with no change by the digestive enzymes Water and alcohol : absorbed directly into the blood

Question 47

What is transport

Answer 47

Happens after absorption of the nutrients into the mucosal cells of the intestine It involves two circulatory systems: - blood/ vascular system - lymphatic system

Question 48

What types of nutrients enter the blood stream directly from the intestinal cells

Answer 48

Water soluble nutrients: monosaccharides amino acids short and medium chain fatty acids (14 or fewer carbons) water soluble vitamins and minerals Released directly into the bloodstream through capillaries surrounding the small intestine, and then they transported to the liver

Question 49

What is special about the transport of fatty acids with long hydrocarbon chains?

Answer 49

Long hydrocarbon chain (16 or more carbons) and fat soluble vitamins can’t get direct access to the capillaries, unlike water soluble nutrients because they are too big and not soluble So they cluster together in the intestinal cells forming large fat molecules, which special protein carriers are attached to this forms a lipo protein complex called a chylomicron which then get taken up by the lymphatic system

Question 50

What happens after the chylomicrons are taken up by the lymphatic system

Answer 50

Their transported through lymph spaces , reach the thoracic duct, which empties into a vein that leads to the heart

Question 51

Overall, where do all nutrients end up after transport

Answer 51

All nutrients end up in the bloodstream to be distributed to different parts of the body where their metabolize stored or excreted, depending on the needs of the body

Question 52

Where does most water reabsorption occur

Answer 52

In the colon (large intestine)

Question 53

What happens to food residue in the colon before it is excreted as feces What function do bateria in the colon have

Answer 53

The colon has a lot of bacteria the food residue is fermented by the bacteria, This bacterial fermentation causes production of gas Functions of the bacteria : The bacteria also partially digest fiber, giving the body some food energy as a result They also produce some vitamins such as vitamin K, but the body is only able to absorb a fraction of the vitamins made by the bacteria in the colon they prevent growth of pathogenic bacteria

Question 54

What causes diarrhea?

Answer 54

Normally bacterial colon coexist in the body well and don’t harm But the wrong type of bacteria can come in, and the result is diarrhoea

Question 55

What is the term for the population of bacteria in the colon and what is its significance?

Answer 55

The micro biome It influences many disease processes, both positively and negatively 

Question 56

Pages 94-97

Answer 56

Okay

Question 57

Within how many hours does the body digest and absorb how much of the carb fat and protien in a meal

Answer 57

24-48 90%

Question 58

What do these become once broken down carbs Fat Protien Vitamins Minerals

Answer 58

carbs: become glucose and used for immediate energy or stored in the liver and muscles to use when energy is low Fat: become fatty acids to become added to cell membrane to ise for energy, stored in adipose tissue Protien: broken into amino acids used to make enzyme, muscle protiens and other bio molecules Vitamins: support chemical reactions for growth, repair, and energy Minerals: become part of our bones (ex. Calcium and phosphorus) or help in oxygen transport (ex iron)

Question 59

What is in the large Intestine and it’s purpose

Answer 59

Gut microbiota are in the large intestine (colon) They have role in metabolism, vitamin production, and immune function The colon absorbs digested fibre fragments, fluids, some water soluble witmins, bio active compounds , some minerals The undigested fibre in the colon is fermented by bacteria, partially digested, with some products absorbed and the rest excreted as feces

Question 60

What’s absorbed through the walls of the small intestine

Answer 60

Monosaccharides Amino acids Fatty acids Vitamins Minerals And other nutrients Whcih are then absorbed into the blood and lymph

Question 61

How do intestinal cells adapt to to dietary deficiency like low calcium intake

Answer 61

They increase absorption efficiency to for nutrient in short supply like calcium

Question 62

What are villi and microvilli

Answer 62

Villi: finger like projections of the intestinal lining the increase the surface area for abroptions Microvilli: tiny hairlike projections on each villus cell that even greatly increase surface area of absorption and trapping of nutrients

Question 63

How large is the surface area of the small intestine

Answer 63

If flatten 1/3 of football field

Question 64

Where do nutrients in the lymphatic system go first

Answer 64

The nutrients in the lymphatic vessels enter the thoracic duct then reach the blood stream near the heart

Question 65

What happens to the intestinal surface during severe malnutrition

Answer 65

The surface shrinks sometime to 1/10 or its original size to reduce nutrient absorption Also fibre usually provides the bulk that the intestinal muscles use for contraction which help to maintain muscle strength, if fibre is gone muscles become weak from lack of excericise

Question 66

Why is malnutrition considered a self perpetuating problem fkr digestion

Answer 66

Malnutrition impairs digestion Impaired digestion worsens malnutrition This is a cycle

Question 67

What are cells

Answer 67

The smallest units in which independent life can exist All living things are single cells or organisms made of cells

Question 68

What are the most basic needs of body cells

Answer 68

Energy Oxygen Water Building blocks Control systems Essential nutrients from food

Question 69

How often do digestive tract cells and red blood/skin cells replace themselves Muscle cells Liver cells Brains cells

Answer 69

Digestive tract cells: every three days Red blood/skin cells: every 10-120 days Muscle cells: once everyd few years Liver cells: quickly whenever repairs to the liver are needed Brain cells: some brain cells don’t reproduce at all, they’re lost forever is injured by disease or damage

Question 70

What is an enzyme What is a fat cell

Answer 70

Enzyme: working protiens that speed up specific chemical reactions without being changed themselves Fat cells Liver cells: cells that store gst and form fat tissue. The make enzymes needed to metabolize fat and hormone for appetite and energy balance

Question 71

What special about the genes Kd cells

Answer 71

Specific genes for the specific cell type are active in the cell Ex fat cell has genes for enzymes that metabolize fat

Question 72

What is nutrigenomics

Answer 72

The science of how nutrients affect gene activities and how genes affect activity of nutrients Ex. Concentration of certain vitamins/minerals influence the genes production of nutrient metabolizing protien

Question 73

How are cells organized in the body

Answer 73

Soecialized Cells are organized into tissues that do special tasks (ex muscle tissues) Tissues form organs (ex heart has muscle and nerve tissues) Organs form body systems (ex. Heart lungs and blood vessel work together as the cardiovascular system)

Question 74

Describe the cardiovascular system

Answer 74

Consist of the heart blood and blood vessels (arteries, veins, capillaries). It delivers oxygen, nutrients and water to the body’s tissues and removes carbon dioxide and other wastes Blood circulated through the lungs for gas exchange and through the digestive system for nutrient absorption The blood and the lymph are the main circulating fluids

Question 75

Describe the immune system

Answer 75

Defends the body against infections and foreign invaders Includes white blood cells, lymph nodes, and other components in the lymphatic system

Question 76

Describe the hormonal (endocrine) system

Answer 76

This system uses chemical messengers (hormones) produced by glands (li

Question 77

Describe the hormonal (endocrine) system

Answer 77

This system uses chemical messengers (hormones) produced by glands (like the thyroid and pancreas) to regulate growth metabolism and appetite The key glands in this are the : pancreas (insulin, glucagon hormones) Stomach (gastrin) Small intestine (secretin) Fat tissue (appetite regulating hormones)

Question 78

Describe the nervous system

Answer 78

Controls and coordinates body activities by sending electrical signals between the brain spinal cord and body Hypothalamus: montiers nutrient levels and triggers hinder signals

Question 79

Excretory system

Answer 79

Removes wastes and helps maintain fluid and chemical balance Ex. Kidneys filter the blood and remove nitrogenous wastes excess minerals and water to make urine