Digestion

Question 1

What is Digestion?

Answer 1

A process used to obtain energy (calories) nutrients & resources to build & repair body tissues

Question 2

What are the Four Stages of Digestion?

Answer 2

Ingestion (taking stuff in)
Digestion (break stuff into smaller molecules)
Absorption (moving molecules to the blood)
Egestion/Elimination (removal of waste/toxin)

Question 3

What is the Alimentary Canal?

Answer 3

Tubes and chambers food passes through

Question 4

What do the Accessory Organs do?

Answer 4

Make secretions to help digest food and regulate processes

Question 5

What is the Anatomy to do with Digestion? (14)

Answer 5

Oral Cavity
Salivary Glands
Pharynx
Esophagus
Cardiac Sphincter (LES)
Stomach
Pyloric Sphincter
Liver
Gall Bladder
Pancreas
Small/Large Intestines
Appendix (cecum)
Rectum
Anus

Question 6

What is Mechanical Digestion?

Answer 6

Starts in the Oral Cavity

Physical Breakdown of solid food into smaller bits (squishing/grinding) to increase surface area of food materials

Question 7

How does Mechanical Digestion work?

Answer 7

Oral Cavity
Tongue moves and crushes food, teeth masticate (chew) food

Stomach
3 layers of muscle tissue to twist & crush food

Question 8

What are the types of teeth, and what does it mean if you have more variety?

Answer 8

More types of teeth = more variety in diet

Incisors
    (flat front teeth) - nipping, biting,
    Pulling
Canines
    (pointy) - grabbing/stabbing
Premolars
    Shearing (carnassials, scissor teeth)
Molars
    Grinding & crushing plant matter

Question 9

What is Dental Formula

Answer 9

Distribution (# of teeth types)

Question 10

What is the Human Dental Formula?

Answer 10

2:1:2:3

Incisors, Canines, Premolars, Molars

Question 11

What does Chemical Digestion do?

Answer 11

Breaks biomolecule polymers back into their monomers

Question 12

Where does Chemical Digestion start and what happens there?

Answer 12

It starts in the Oral Cavity

The salivary glands secrete saliva which contains H2O (which dissolves some nutrients), enzymes like Amylase (which breaks starch into smaller chains)
Mucous (to lubricate the food bolus)

Question 13

What is Peristalsis what organism performs it?

Answer 13

The smooth muscle of the Esophagus performs Peristalsis to move the bolus to the stomach
Also the Small Intestine

Question 14

What happens when food arrives at the stomach?

Answer 14

A signal from the Vagus Nerve & the hormone Gastrin tell the stomach glands to produce Gastric Juice

Question 15

What materials are in Gastric Juice?

Answer 15

HCl (to decrease the pH of the stomach, to dissolve some materials& kill pathogens)
Pepsin (enzyme to digest proteins it is secreted as pepsinogen and is activated at a low pH)
And some lipases to digest fat

Question 16

What does partially digested food exit the stomach as?

Answer 16

Chyme. When chyme enters the Small Intestine, the pH decreases, so the hormone Secretin is released
Secretin targets the Pancreas, which releases Bicarbonate Ions (which neutralize Chyme)

Question 17

Apart from Bicarbonate Ions, what does the Pancreas secrete? ATEN

Answer 17

Amylase -> to digest polysaccharides -> which make monosaccharides
Trypsin -> to digest polypeptides
Erepsin -> to digest polypeptides
Nuclease -> to digest nucleic acid

Question 18

What does the Liver do?

Answer 18

It breaks down red blood cells. A byproduct of this is a pigment called Bilirubin. Bilirubin is turned into bile the liver & stored in the Gall Bladder

Question 19

What does the Small Intestine do?

Answer 19

Carries out Fat Digestion

If you eat fat and it appears in the Small Intestine, Cholecystokin (CCK) is released. CCK acts on the Gallbladder. The Gallbladder releases Bile into the Small Intestine to emulsify (increase SA) the fat

Pancreatic Lipase then digests the fat

Question 20

What affect does CCK have on Peristalsis in the Small Intestine and why?

Answer 20

It slows it down, to increase absorption

Question 21

Why is Digestion regulated?

Answer 21

So only the necessary secretions are made. And so those secretions only act on the intended target

Question 22

What three factors stimulate digestive secretions?

Answer 22

Sensory Input (sight, smell, taste of food)
Dissension (stretching) of the stomach
Chemical receptors in the gut

Question 23

What two things direct secretion to be released and what are they released by?

Answer 23

The Vagus Nerve & hormones, secretions are released by the Alimentary Canal

Question 24

What is the formula for Digestion?

Answer 24

Nutrient. ————> Organ ——-—> Gland ———-—> Enzyme
^ Acts on Secrets a Secretes. I
I Receptors. Hormone. l
I ____________________________________________________________________I
Digests

Question 25

How is Peristalsis regulated?

Answer 25

Hormones
Gastrin increases contraction in stomach
CCK (& enterogastrone) slow peristalsis in the intestine to increase absorption

Question 26

What happens when blood sugar is high?

Answer 26

The Pancreas secretes Insulin
Cells absorbs glucose in the blood
The liver stores glucose as glycogen (&fat)
Muscles store glycogen

Question 27

What happens when blood sugar is low?

Answer 27

The Pancreas secretes Glucagon, which makes the liver break Glycogen (& fat) down into Glucose

Question 28

Where does Absorption occur?

Answer 28

The stomach (medications, alcohol)
Most happens in the Small Intestine (very high surface area)
    Long & narrow in diameter 
    Entire inner surface is covered in villi
Some in the Large Intestine
    Water (to make food more solid)
    Electrolytes & ions
    Vitamins

Question 29

Villi structure

Answer 29

Capillaries 
    Absorbs sugar, and amino acids
Microvilli
    On Epithelial cells
Lacteal
    (Lymph duct) Absorbs fat

Question 30

What is Egestion?

Answer 30

When muscle contract (anal sphincters under voluntary control), waste is eliminated

Question 31

How is hunger controlled?

Answer 31

The Hypothalmus in the brain. It directs your desire to eat & influences your choices

Several hormones interact w/ the brain to tell it if you need food

Question 32

What are the hormones that interact with the brain? GLP

Answer 32

Ghrelin (released by stomach if it’s been empty for a bit) - if the stomach is contracted
Leptin (release by fat cells, makes you feel satisfied)
PYY (released by the small intestine if there’s food in it, slows peristalsis. Makes you feel satisfied)

Question 33

Six different Disorders of the Digestive system UCJGDA

Answer 33

Ulcers: damage to the stomach lining (H. Pylori)
Cirrhosis: damage to the liver tissue
    Alcohol
    Hepatitis
    Viruses
    High fat consumption

Jaundice: failure to break down RBCs (toxin build up)
Gallstones: bile salt build up in the Gallbladder (really high fat diet & genetics)
Diverticulitis: bacteri pockets in the colon
Appendicitis: appendix gets swollen/irritated