The order is Mouth Pharynx Esophagus Stomach Small intestine Large intestine Rectum Anus Ingestion and mastication Mouth aka Oral cavity Both physical chewing food and chemical digestion occur salivary amylase ID: 779888
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Slide1
Alimentary Canal
Aka the gastrointestinal tract (G.I. tract)
The order is:
Mouth
Pharynx
Esophagus
Stomach
Small intestine
Large intestine
Rectum
Anus
Slide2Slide3Ingestion and mastication
Slide4Mouth (aka Oral cavity)
Both physical (chewing food) and chemical digestion occur (salivary amylase)
It contains multiple structures for breaking down food:
Teeth
Tongue
Salivary glandsHard Palate Soft Palate
Slide5Slide6Slide7Teeth
Primary teeth vs. secondary teeth
Slide8Anatomy of a Tooth
Slide9Tooth
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.
Slide10Dental Caries (aka Cavities)
500 species of bacteria inhabit the mouth.
Certain bacteria thrive on sugar, and produce lactic acid which destroys tooth enamel.
Streptococcus
mutans
Slide11Teeth 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.
Slide123 Types of teeth
Incisors:
These
teeth are excellent for
biting
and cutting food.Canines (cuspids): Being pointed in shape they are used to
tear or shred food.Premolars and Molars: Both are flattened on the upper surfaces and are used for
grinding and chewing food.
Slide13Root Canal
https://
www.youtube.com/watch?v=jHHn52KhBkQ
https://
www.youtube.com/watch?v=YDs-848-u-U
Slide14Tongue
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
Slide15Slide16Tongue continued
The top layer of the tongue is covered with a layer of bumps called papillae
Papillae
helps grip
food and contains taste buds
People are born with ~10 000 taste buds, which decline as we age
Slide17Slide18Taste buds
Can detect the following tastes:
Sweet
Salty
Sour
Bitter Umami
Slide19Why 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 dangers
Example: Natural poisons and spoiled foods tastes bitter
Slide20The “Taste Map”: All Wrong
Do you taste different components of taste with different parts of your tongue?
Slide21Tongue Papillae
Circumvallate
papillae
Slide22Taste 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**
Slide23Taste
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
Slide24Babies response to sour taste
http://
www.dailymail.co.uk/news/article-2392574/Photographers-April-Maciborka-David-Wile-capture-toddlers-reactions-trying-lemon-time.html
Slide25Check 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.
Slide26Salivary Glands
There are three types of salivary glands:
1. Parotid Glands
2. Submandibular Glands
3. Sublingual Glands
Slide27Salivary Glands continued
Serous
cells produce
amylase – splits starch and glycogen into
disaccharides
Slide28Salivary Glands continued
Mucous cells produce mucus – lubrication during
swallowing
Saliva is 99% water, the rest is mucus, salts, and enzymes
The water in saliva moistens and dissolves particles of food, aiding chemical digestion, the ability to taste, and the chewing process
Slide29Exocrine glands
Are glands that produce and secrete substances onto an epithelial surface by way of a duct
For example: Salivary Glands
Slide30Swollen parotid gland
in child with viral
mumps
. This virus can also infect the testes.
Slide31Parasympathetic
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.
Slide32Check Your Understanding!
Describe the chemical digestion that occurs in the mouth
Mucus is found in saliva. What might its function be?
Slide33Movement!!
Slide34Swallowing
Voluntary
Tongue pushes bolus to back of throat (Pharynx)
Soft palate closes off nasal passage
Epiglottis closes off the trachea and food travels down esophagus
Slide35Pharynx
The junction between nasal and oral cavity, part of the throat
Slide36Can you drink upside down?
Slide37Can 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?
Slide38Esophagus
Esophagus is made of
smooth muscle
that becomes stretched to help food bolus move along
.Inside is covered in a thick lining of mucus
Causes a wavelike contraction called PERISTALSIS.
Reverse peristalsis = Vomiting
Slide39The wall of the
esophagus
contains both
circular
and
longitudinal muscle.
Slide40Slide41Slide42Slide43Slide44Movement cont.
Smooth muscle contractions also move food through the rest of the digestive tract.
Slide45Digestion / Absorption
Slide46Sphincter
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
Slide47At the junction of stomach and duodenum is the pyloric sphincter. Regulates movement of stomach contents from stomach
small intestine.
Slide48Slide49Draw This!
Slide50Heart 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!)
Slide51The 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
Slide52Gastric Pits
Slide53Gastric 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)
Slide54Pepsin breaks down proteins into short amino acid chains
Slide55G cells – secretes gastrin, a hormone. Gastrin stimulates the secretion of
HCl
and aids in stomach motility.
Gastrin is 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??
Slide56Slide57The 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.
Slide58Absorption
Some water, specific vitamins and alcohol
Slide59Stomach Composition
The stomach has four layers that surrounds the space called the lumen.
Mucosa
Submucosa
Muscle layer
Serosa
The stomach has folded membranes on the inside called Rugae
allows stomach to expand
Slide60Why doesn’t the stomach digest itself?
Mucous 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)
Slide61Peptic Ulcers
Slide62Peptic Ulcer
Most commonly caused by bacterial infection
Helicobacter pylori
NSAIDS (
non-steroidal anti-inflammatory drugs
) aspirin and IBProfenSmoking
AlcoholGenetics
Slide63A Very Famous Stomach!
Alexis St. Martin, 1822
https://
www.youtube.com/watch?v=pqgcEIaXGME
Slide64Mechanical vs
Chemical recap
Mechanical – churning of stomach
Chemical :
HCl
denatured proteins and kills ingested bacteriaPepsin begins protein digestion
Slide65Check 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 stomach