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DIGESTION What is digestion? DIGESTION What is digestion?

DIGESTION What is digestion? - PowerPoint Presentation

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DIGESTION What is digestion? - PPT Presentation

The process in which food is broken down into smaller molecules that can be absorbed into the body and are usable by cells Five Main Digestive Processes Ingestion Eat Intaking ID: 908739

stomach food intestine digestion food stomach digestion intestine liver small digestive bile cells blood taste tongue esophagus teeth mouth

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Slide1

DIGESTION

Slide2

What is digestion?

The process in which food is

broken down

into smaller molecules that can be absorbed into the body and are usable by cells.

Slide3

Slide4

Five Main Digestive Processes

Ingestion

– Eat;

Intaking of food into Digestive TractMovement – Food travels down digestive tract.

Digestion

– Large molecules

 Small molecules (mechanical or chemical).

Absorption

– Transporting digested nutrients to cells in the body.

Egestion

– Removal of materials (waste) from food that the body cannot digest.

Slide5

The “Taste Map”: All Wrong

Do you taste different components of taste with different parts of your tongue?

Slide6

Tongue Papillae

Circumvallate

papillae

Slide7

Taste Test!

You will be tasting flavoured candies. Yummy

Catch! – You have to PLUG YOUR NOSE!

One student = facilitator, other = taster

Facilitator chooses

1

candy (don’t show the taster!), unwrap it while the taster has their eyes closed and put it in their hands.

60 seconds (keep your nose plugged!) – describe sensations and try to determine the flavour of the candy. Guess again after the min is up. THEN unplug your nose... Switch roles and repeat.

**Remember keep the flavour a secret until the end**

Slide8

Taste

What is the difference between taste and flavour?

Does smell affect taste?

If your sense of taste is impaired, it is possible your appetite might decrease. What things might decrease your sense of taste?Cigarettes, illness, medications, vitamin deficiencies

Slide9

Why do we eat??

Slide10

Nutrients!

Body needs energy to do work.

Nutrients include

CarbohydratesProvide energy (growth, warmth, movement

).

Proteins

For growth of cells and

tissues.

Repair of damaged tissues.

Source of energy if carbohydrates and fats

unavailable.

Slide11

Nutrients cont…

Fats

Provide energy

Two times that of carbohydrates

Nutrients help

in our growth,

by keeping us healthy,

by repairing our cells and tissues,

by giving us energy.

Slide12

Enzymes : their role

Enzymes are used to digest

food.

Carbohydrase / AmylaseCarbohydrates to Simple

sugars.

Protease

Proteins to Amino

acids.

Lipase

Fats to Glycerol and Fatty

acids.

Slide13

A) Importance of the Digestive System

Humans/Animals need a digestive system in order to obtain nutrients for energy.

Digestive system will:

E.g. Cracker (starch) Glucose (used by our cells in the body)

Large Complex Molecules

Small, simple molecules

Breaks down

Slide14

Anatomy of Digestive System

How long do you think the digestive system is?

From mouth to anus, is on average 6-9 meters in length! (that’s 21-23 feet long)

1) Mouth: 15 cm2) Pharynx: 15 cm3) Esophagus: 35 cm4) Stomach: 30 cm5) Duodenum: 25 cm6) Jejunum: 2.5 meters

7) Ileum: 3 meters

8) Colon: 1.5 meters

9) Rectum: 15cm

*How can such a long system fit into our bodies?!

Slide15

B) Organization of Digestive Tract

From mouth to anus, is on average, 6-9 m or 21-23 ft long.

Organs are divided into two categories:

Gastrointestinal Tract (G.I.)Continuous tube from mouth to anus.Includes: Mouth, esophagus, stomach, small intestine, large intestine, rectum, anus.

Accessory Organs

Lie outside the G.I tract.

Produce secretions that help in digesting food.

Include: Teeth, tongue, salivary glands, liver, pancreas, gall bladder, (appendix).

Slide16

Food must be mechanically and chemically reduced before it can be absorbed across the intestinal wall.

Slide17

Two Types of Digestion

Mechanical Digestion:

The physical break down of food into digestible chunks.E.g. Chewing with teeth.Chemical Digestion: Chemical break down of food to a form that can be absorbed (usually by the blood stream).E.g. Enzymes cleaving substrates.

Slide18

Slide19

Teeth

Primary teeth vs. secondary teeth

Slide20

Anatomy of a Tooth

Slide21

Tooth

Enamel –

White outer

part of the tooth. Is mostly made of calcium phosphate, a rock-hard mineral.Dentin – has living cells, is porous, and is like bone (softer than enamel)Pulp – the softer, living inner structure of teeth. Blood vessels and nerves run through the pulp.

Slide22

Cementum

– connective tissue (bone like) that binds the root of the tooth to the gums and jawbone.

Crown – area of tooth that is visible (enamel)

Neck – Where the crown meets root. Covered by gingiva (gums)Root – the anchor of the tooth

Slide23

Tooth aches

500 species of bacteria inhabit the mouth.

Certain bacteria thrive on sugar, and produce lactic acid which destroys tooth enamel.

Streptococcus mutans

Slide24

Teeth Questions

What are three types of teeth? What are they used for?

Why do Cavities Hurt?

Analyzing the teeth of animals is a good indication of their diet. Explain why. SciShow Videos Why do we have baby teeth? Why is flouride good for our teeth?Why do we have to brush our teeth? List the two main reasons.

Slide25

Root Canal

https://

www.youtube.com/watch?v=jHHn52KhBkQ

https://www.youtube.com/watch?v=YDs-848-u-U

Slide26

Ingestion and mastication

Slide27

Mouth (aka Oral cavity)

Only part of the alimentary canal involved in ingestion

Mechanical digestion (chewing) and chemical digestion (enzymes in saliva) start here

Slide28

Slide29

Tongue

Made up of groups of muscles that run in different directions. This gives the tongue its flexibility.

Mixes food with saliva to form a mass of wet food called a bolus.

Initiates swallowing by pushing bolus towards the pharynx

Slide30

Slide31

Tongue continued

The top layer of the tongue is covered with a layer of bumps called papillae

Papillae helps grips food and contains taste buds

Slide32

Slide33

Taste buds

C

an detect the following tastes:

Sweet SaltySour Bitter Umami

Slide34

Why is the tongue important in choosing the kinds of food you eat?

Tastes has a homeostatic function

Promotes the intake of nutritious foods that your body needs

Protects you body from possible dangersExample: Natural poisons and spoiled foods tastes bitter

Slide35

Babies response to sour taste

http://

www.dailymail.co.uk/news/article-2392574/Photographers-April-Maciborka-David-Wile-capture-toddlers-reactions-trying-lemon-time.html

Slide36

Check Your Understanding!

What is the tongue? What function does it perform?

How many different tastes can the tongue detect? What are the tastes?

What kind of homeostatic function does your tongue serve? Explain.

Slide37

Salivary Glands

There are three types of salivary glands:

1. Parotid Glands

2. Submandibular Glands3. Sublingual Glands

Slide38

Salivary Glands continued

Serous cells produce amylase – splits starch and glycogen into

disaccharides

Slide39

Salivary Glands continued

Mucous cells produce mucus – lubrication during swallowing

Slide40

The

submandibular

salivary glands

are

the

squirters

used in “

gleeking

”!

Slide41

Gleeking

with

submandibular

gland at base of lingual

frenulum

Slide42

Swollen parotid gland

in child with viral

mumps

. This virus can also infect the testes.

Slide43

Parasympathetic

innervation

stimulates

salivary gland secretion (anticipation of tasty food).

Sympathetic stimulation

inhibits

normal secretion, which is why

people

who are frightened experience the sensation of a dry mouth.

Slide44

Check Your Understanding!

Describe the chemical digestion that occurs in the mouth

Mucus is found in saliva. What might its function be?

Slide45

Movement!!

Slide46

Swallowing

Voluntary

Tongue pushes bolus to back of throat (Pharynx)

Epiglottis closes off the trachea and food travels down esophagus

Slide47

Pharynx

The junction between nasal and oral cavity, part of the throat

Slide48

Esophagus

Esophagus is made of

smooth muscle

that becomes stretched to help food bolus move along.Causes a wavelike contraction called PERISTALSIS.

Reverse peristalsis

= Vomiting

Slide49

The wall of the

esophagus

contains both skeletal and smooth

muscle.

Slide50

Slide51

Slide52

Can you drink upside down?

Slide53

Can you drink upside down?

Questions:

Is gravity needed to make fluids come down the

esophagus?Can we drink while we stand on our head?How does food go down the esophagus into the stomach?

Why did the fluid not flow out of the mouth when drinking upside down?

What is the muscle action called, which pushes food into the stomach?

Slide54

Movement cont.

Smooth muscle contractions also move food through the rest of the digestive tract.

Slide55

Slide56

Movement cont.

Smooth muscle contractions also move food through the rest of the digestive tract.

Slide57

Digestion / Absorption

Slide58

Sphincter

A sphincter is a ring of muscle that controls the passage of material.

Relaxed = open, Contracted = closed

At the junction of esophagus and stomach is the cardiac sphincter (AKA Lower Esophageal Sphincter). Stops stomach contents from going into esophagus

Slide59

At the junction of stomach and duodenum is the pyloric sphincter. Regulates movement of stomach contents from stomach

 small intestine.

Slide60

Slide61

Draw This!

Slide62

Heart Burn

Caused by a cardiac sphincter that doesn’t tighten as it should

stomach acid into esophagus

Often

happens when

too much food in the stomach (overeating) or to much pressure on the stomach (obesity, pregnancy)

Certain foods act as a trigger (relaxes the sphincter or causes more acid production

 smoking causes both!)

Slide63

The Stomach

Site of initial protein digestion and food storage.

Smooth muscle contractions cause ingested food to be crushed, ground, and mixed, liquefying it to form

Chyme

Slide64

Gastric Pits

Slide65

Gastric Pits

Stomach contains GASTRIC PITS that have

GLANDS

and MUCUS cells.Glands contain:Parietal cells – secrete HCl (hydrochloric acid)Chief cells – secrete pepsinogen, the zymogen (inactive) form of the digestive enzyme pepsin.(Pepsinogen

 Pepsin under

low pH)

Slide66

Pepsin breaks down proteins into short amino acid chains

Slide67

G cells – secretes gastrin, a hormone.

Gastrin stimulates the secretion of

HCl

and aids in stomach motility. It’s released in response to stomach stretching or the presence of proteins in the stomach. It is inhibited by HCl in the stomach. What kind of feedback is this??

Slide68

Slide69

The J-shaped

stomach

stores food (the

semi-digested

mass is called

chyme

), initiates the digestion of proteins, has only

minimal

absorption, and moves materials on to the small intestine.

Slide70

Absorption

Some water, specific vitamins and alcohol

Slide71

Stomach Composition

The stomach has four layers that surrounds the space called the lumen.

Mucosa

SubmucosaMuscle layer

Serosa

The stomach has folded membranes on the inside called

Rugae

 allows stomach to expand

Slide72

Why doesn’t the stomach digest itself?

Mucus cells in the gastric pits secrete a thick layer of mucus which protects the walls of the stomach

also secrete bicarbonate solution which neutralizes stomach acid (acid base reaction)

Slide73

Peptic Ulcers

Slide74

Peptic Ulcer

Most commonly caused by bacterial infection

 Helicobacter pylori

NSAIDS (non-steroidal anti-inflammatory drugs)  aspirin and IBProfen

Smoking

Alcohol

Genetics

Slide75

A Very Famous Stomach!

Alexis St. Martin, 1822

https://

www.youtube.com/watch?v=pqgcEIaXGME

Slide76

Mechanical vs Chemical recap

Mechanical – churning of stomach

Chemical :

HCl  denatured proteins and kills ingested bacteriaPepsin  begins protein digestion

Slide77

Slide78

Liver & Gall Bladder

Liver produces Bile

 mainly water and some bile salts

Bile is stored in the Gall Bladder  the gall bladder absorbs water making the bile more concentratedBile releases into duodenum via bile duct

Slide79

Bile Salts

Emulsify Fats (Emulsify -

To

make a suspension of small globules of one liquid in a second liquid in which the first will not mix)

Slide80

Bile continued

Mechanical digestion:

Emulsification – bile salts break down fat globules into smaller droplets so that they can be digested by enzymes.

Purpose – To increase surface area!

Slide81

Slide82

Check your understanding

What is the function of the 2 sphincters in the stomach

What role does each cell in the gastric pit play?

Describe the chemical digestion that occurs in the stomachWhat is the main purpose of bile salts. Explain.

Slide83

Other Liver Functions

Regulate blood glucose levels (stores glycogen)

Breakdown and synthesis of lipids and fats

Protein breakdown and amino acid synthesisStores vitamins (A, B12, D) and ironBreaks down hormones, antibiotics, and other toxic substances (detoxifier)Breaks down the by-products of RBC recycling

Note** these are main functions. Liver is thought to do about 500 separate functions

Slide84

Gall Stones

Crystalline mass formed from bile pigments, cholesterol, and calcium salts.

Cause severe pain and blockage of bile duct

Slide85

Slide86

Slide87

Liver Cirrhosis

Most commonly caused by alcohol,

hepatits

B, hepatits C, and fatty liver disease. Gradual build up of scar tissue that replaces normal tissueLeads to liver failure

Slide88

Ethyl alcohol is toxic to the liver

Slide89

Healthy Liver

Slide90

Liver cirrhosis

Note extensive scarring

Slide91

Cirrhosis of the liver

Chronic alcoholism

will typically lead to damage of the liver characterized by

scarring. The

damaged liver often turns an orange color. This damage of the liver is called “

cirrhosis

”.

Slide92

Jaundice

One of the by-products of RBC destruction is bilirubin (yellow color)

The liver filters out bilirubin from blood, and excretes in bile.

If liver is failing, or bile duct is blocked, bilirubin builds up in body, causing jaundice  a yellowing of skin and whites of eyes.

Slide93

Slide94

Slide95

Gastrointestinal Disorder Project

So now that you know (almost) a lot about the normal functioning of the digestive system, it’s time to investigate some disorders!

Slide96

Plagiarism

Source all the materials you use!

In University if caught plagiarizing you will automatically receive a zero on the assignment with the potential of receiving a failing grade in the course or a suspension from the University!

Slide97

http://www.youtube.com/watch?v=yQHx9WEfT-Y&safe=active

Slide98

Small Intestine

Small Intestine is 7 meters in length

Three

parts to small intestine:Duodenum – first 25-30 cm. - Area of most digestion.Jejunum Ileum

Slide99

When

chyme

enters the small intestine it stimulates the release of secretin and

cholecystokinin by the duodenum walls.Secretin regulates pH  inhibits gastric HCl production and stimulates bicarbonate ion secretion (pancreas) Cholecystokinin causes release of bile (gall bladder) and digestive enzymes (pancreas).

Slide100

Pancreas

Secretes pancreatic juice into the duodenum

Slide101

Slide102

Pancreatic juice contains:

Bicarbonate

changes pH of chyme from highly acidic (pH 2) to weakly basic (pH 8)

Important pH for pancreatic enzymes to function

Slide103

Enzymes

lipase - breaks

down triglycerides into fatty acids and glycerol.

Slide104

Protease – to digest proteins

Amylase – to digest carbohydrates

Slide105

Insulin

Glucagon

Regulation of

blood glucose levels

Slide106

Check your understanding!

What accessory gland produces a secretion with no digestive enzymes

?

What kinds of foods are broken down by the pancreas?Most enzymes are secreted as zymogens (inactive), why do you think that is?

Slide107

Check your understanding!

Explain two functions of pancreatic fluid.

Someone recently has had a cholecystectomy, a surgical procedure to remove his gall bladder. Now he must take medication to prevent diarrhea. Why would the removal of the gall bladder cause diarrhea?

Slide108

Mesentery

Tissue that supports the intestinal tract.

A double layer of connective tissue in which blood vessels, nerves, lymphatics and other structures are contained.

Slide109

Mesentery

Thin walls of small intestine with

blood

supply.

Slide110

Slide111

Slide112

Adhesions

often form following abdominal surgery or after an abdominal infection (peritonitis).

Slide113

Slide114

Peritonitis

can also follow

a penetrating

abdominal

injury.

Slide115

Small Intestine

Made up of three parts:

Duodenum

JejunumIleum

Slide116

Slide117

Slide118

Segmentation

Smooth muscle contractions

in both

directions that mix and further break down contents of small intestine (chyme)Is this mechanical or chemical digestion?

Slide119

Absorption

The small intestine absorbs the majority of nutrients

such as

The breakdown products of CarbohydratesProteinFatsVitamins

by active and passive mechanisms

Slide120

Intestinal

villi

Slide121

Slide122

Each

villus

contains blood capillaries and a lymph capillary (lacteal). Each villus is covered with microvilli.

Slide123

Villi – tiny, finger-like projections on the walls of the small intestine

Microvilli – “brush border”

further increases surface area

Slide124

Within villi structures are blood vessels that carry the absorbed nutrients to the rest of the body

Also contain in the villi are structures called lacteal, which absorbs fats to be delivered into the bloodstream

Slide125

The Colon (AKA large intestine)

Slide126

Main Functions of the Large Intestine

Water

absorption

Absorption of vitamins produced by bacteriaMass movements (defecation) – removes undigested food

Slide127

Chemical Digestion

Indigestible food matter (e.g. cellulose) is digested by enteric

bacteria (ex. E. Coli)

that thrive in the large intestine. These bacteria produce vitamin K and some B vitamins.

Slide128

Appendix

Vestigial organ

 has lost function but retained structure

However, some scientists now think it does serve a function stores good bacteria to help repopulate gut after infection.

Slide129

http://www.flickr.com/photos/moonjazz/3530268320/

Slide130

Endoscopic view of appendix

Cecum

Slide131

Rectum

Connected to the sigmoid colon of the large intestine

Damp Mass of indigestible food remaining in large intestine is called FECES.

Temporarily stores feces before elimination (egestion)

Slide132

Anus

The ending portion of the gastrointestinal tract in which feces (undigested food matter) leaves the body

Anal sphincter controls opening of anus.

Slide133

Bowel Movement

Receptors in the walls of the large intestine give the central nervous system (brain) signals when a

bowel movement

is needed.Some substances stimulate the bowel movements like caffeine.

Slide134

Defecation

to eliminate

feces.

Slide135

Summary

Slide136

Digestion Time Summary

Digestion takes different lengths of time depending on the food being consumed. F

or healthy adults, it's usually between 24 and 72 hours.

Mouth

(

20 sec

)

Starch

is digested to maltose by carbohydrase /

amylase.

Esophagus

(

10 sec

)

Muscles squeeze

food along the canal.

Stomach (

2-6 hours

)

Gastric juice mixes

food when stomach churns.

Small intestine (5 hours)

Intestinal juice contains enzymes that complete the digestion process.

Large intestine and anus (min of 24 hours)

Undigested food reaches the large intestine

Lots of water is removed and taken back into the body

Slide137

Washing your hands is essential!

(Return to regular notes booklet for this)

BacteriaFood poisoningParasitesWorms (Tapeworms)* All can be transferred through the mouth!

Slide138

Slide139

The Bacteria in your Gut?

Good, bad or ugly?

Good √

E.coli helps you digest food that you could not digest otherwise.

Bad √

 The bacteria that help you out, also produce

flatulence

as a by-product. Gas is a normal part of digestion.

Ugly

 Some bacteria cause

food poisoning

, resulting in severe stomach cramps, vomiting and diarrhea.

Slide140

Slide141

More important stuff...

Our bodies make two hormones that contribute to homeostasis.

GASTRIN: Releases gastric juice (

HCl) and relaxes gastric sphincter.SECRETIN: Help release bicarbonate ions that neutralize HCl.Our pancreas also helps with homeostasis in regulating blood glucose.

Slide142

Slide143

Insulin and Glucagon in Digestive System

Two hormones secreted by pancreas.

Work with liver to control level of glucose in body (blood).

Insulin released after meal  allows cells to become permeable to glucose. Excess glucose stored by liver as glycogen.

Can change back to

glucose

if blood glucose becomes too low  Glucagon