9.4 Digestion in the mouth and stomach Flashcards
The mouth/oral cavity
-> What process are we starting for digestion? (ingestion -> digestion -> absorbtion -> egestion)
What physical digestion is happening? (indepth)
What chemical digestion is happening? (breif)
Mouth: beginning ingestion: taking in food
Teeth physicall break down food (cutting/crushing)
-> Different types of teeth = different functions of cutting
SHARP TEETH (Incisors/canines)
-> Grabing
-> Piercing through food
(Animals: Carnivores, killing pray)
(Front of mouth)
FLAT TEETH (Molars)
-> Grinding
-> Crushing teeth
(Animals: herbavoirs)
(Back of mouth)
Chemical digestion: Saliva
Saliva
What secrets saliva?
What substances are in saliva?
What does this enzyme break down?
What does saliva + food create?
Salica secreted by salivary glands in the presents of food (when food is in mouth, when u see it, smell it, etc)
Saliva contains:
Mucous
Salivary amylase
Water
Mucous:
Secreted to lubricate the food, helping you swallow.
Salivary amylase
(Begins the breakdown of carbohydrates)
(Polysaccarahids into diassaccarids)
Saliva + food create BOLUS: “wet ball of food”
What is an enzyme?
Any chemical produced by cells to facilitate biochemical reactions
How does your tongue work in digestion?
Swallowing -> what is happening?
USE CORRECT TERMINOLOGY
Where is the food being sent to?
Tongue pushes back food into the back of your mouth, helping you swallow.
While you swallow you temporarily cannot breath.
Why?
1) As food is pushed into your pharynx (throat)
-> soft pallet is raised to prevent food from entering your nasal cavity
2) STIMOUTANOUSLY, epligottis swings DOWN and blocks the entrance of the larynx (voice box), preventing food from entering your trachea (pathway to your lungs).
epliglotis is up: “normal” there is air intake
epliglotis is down: FOOD/”no air”
Epiglotiis is a flap of tissue and the trachea is a long tube connecting your voice box (larynx) to your lungs.
What is happening in the esphagus?
-> What causes the bolus to move down?
What type of muscle is causing this?
Where is the bolus going down to?
Esphoagus is a long, muscular tube that carries the bolus from your pharynx( throat) to your stomach)
–> The food stretches the walls of the esphogus, activiating smooth muscles that causes pristalsis
–> SMOOTH MUSCLES INACT INVOLUNTARY/UNCONCIOUS MOVEMENTS
Peristalsis = rhythemic, wave-like contractiosn to move food in the right path (usually down, however depends on the bodies orientation)
BOLUS GOES DOWN TO YOUR FIRST SPHINCTER (gastroesophageal sphincter)
What are spincters?
What is the first spincter the bolus interacts with?
What is the second shincter bolus interacts with?
Sphincters are circular muscles that contract, opening and closing parts of your body.
Relaxed: allowing thigns to enter
Contracted: preventing things from entering
–> Therefore sphincters are contracted most of the time.
1st sphincter:
Gastroesphageal sphincter
(Between the esphagus and the stomach, joining them together)
–> relaxs = food can enter the stomach
–>cotnracted = food cannot enter the stomach, helps prevent acid reflux (acid going back up the esphagus, ie vomiting or heartburn)
2nd sphincter:
Phyloric sphincter
(Stomach and the small intestine)
–> PEriodically opens and closes (relaxes and contracts) therefore only letting a small amount of chyme pass through
–> Prevents overloading, allowing time for digestion (specifically lipids)
Stomach? What is it?
-> What is it made out of? And how does this help with physical digestion?
How does the stomach chemically digest food?
What hormone is working? and what does it signal? and what does that secret? (name the general term of what it secrets, not the elements)
Muscular organ that continues mechanical and chemical breakdown of food.
-> Made up of many muscles, that help with physical digestion.
–> These muscles contract and relax (periodically) which churns food.
CHEMICALLY:
-> Gastrin begans to signal the stomach to release gastric juices when food enters the stomach
–> Gastrin is a HORMONE.
What is in gastric acid and what is its purpose?
Gastric acid (chemically breakdown of food)
-Mucous
-> Protective slimely substance, ensuring that the stomach does not eat itself
-HCL (Hydrocloric acid)
Kills bacterial/kills harmful organisms, the acidicty stops the production of amylase
-Pesinogen (Inactive) (A digestive enzyme)
What is pepsinogen? and how is it activated? Why is it pepsinogen before the other thing?
A digestive enzyme within gastric jucises secreted by the stomach.
Activiated by HCL
-> Breaks down protiens into seperated amino acids
-> Pepsin is ACTIVE and works in an acidic enviroment
It is activated/first released as pepsinogen because its a safety mechanism to prevent damage to the stomach tissue
–> preventing the stomach from digesting itself
Acid reflux, what is it? Why? and what does it cause the person to experience?
-> Stomach acid entering into the esophagus (going backwards)
Caused by a incomplete closure of the gastroesphaueal sphincter.
–> From an overfilled stomach (overeating) (Vommiting)
–> Smoking, because prolongue smoking makes the sphinters relax and stimulate more stomach acid production
Causes:
Burning sensation
Heartburn
WHat are stomach ulcers?
What is the original beleif that caused stomach ulcers
A lesion/hole/opening in the epithelium (lining) of an oragn, which can happen inb the stomach.
–> This exposure can cause stomach acid to burn through other layers and cause more harm.
Originalled believed to be caused by stress and diet
–> which was disproven by an unethical method by Dr Barry Marshal
(drank a solution with H Plylori bacteria, devolped ucler symptons and treated himself with anti-biotics)
What causes stomach ulcers? What does it lead to?
H pylori bacteria (a bacteria that is able to survive stomach acid)
–> makes a hole in the first layer of the stomach, which prevents mucus producing cells from working and therefore stomach is unprotected. exposed stomach can lead to immense pain/bleeding and in servre casses the bacteria can enter blood stream
Food terminology? When it enters mouth what is it, when it is in stomach?
Food –> Food bolus (physically broken down food mixed with saliva) –> Chyme (Semi-chemically digested and mechanicalled digested food, which is mixed with gastric juices and saliva)
