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Organs of the Digestive Tract - Coggle Diagram
Organs of the Digestive Tract
MOUTH
Functions: Injestion. To begin mechanical & chemical digestion.
Structures: Teeth, salivary glands, tongue
Starch amylase - Salivary amylase - maltose.
Lubricates & softens the bolus of food. Enzymes in saliva kill bacteria.
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TEETH
Begins mechanical digestion to increase surface area of food for enzymes to act.
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SALIVARY GLANDS
Salivary glands: Ducted glands that produce saliva which:
Contains salivary amylase & begins chemical digestion (optimal @ pH of 6.8).
Liquefies food.
TONGUE
3 functions:
Contains taste buds.
Moves the food in the mouth.
Pushes the bolus to the back of the throat to the "swallow reflex centre."
A taste bud: is a chemical sense involving detecting chemicals turning the response into a nerve impulse & then sending it to begin.
PHARYNX
Structure: the back of the throat. Opens to respiratory & digestive system.
Function: Swallowing - when food is placed on the "reflex centre", the following things happen.
The soft palate covers the nasopharynx.
The epiglottis covers the trachea.
Peristalsis of the esophagus begins.
ESOPHAGUS
Structure: 30 cm long muscular tube. Connects phraynx to stomach.
Function: Bolus moves through the esophagus by peristasis (a slow, rymphic contraction that pushes the bolus along).
ESOPHAGUS
Structure: 30 cm long muscular tube. Connects phraynx to stomach.
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Function: Bolus moves through the esophagus by pertalisis (a slow, rymphtic contraction that pushes the bolus along).
STOMACH
Structure: a 'j' shaped organ with 3 layers of muscle. Inner layer has rugae (ridges). Begins & end with sphictors that relax to allow substances to pass.
At the begginning of stomach, there's a ring of muscle called the layer esophagagel sphintor (aka cardic sphinctor) which stops food from re-entering the esophagus.
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Functions: Churns food & lidifies it (mechanchal digestion).This process is aided by the rugae in the stomach layer. Begins the chemical digestion of proteins with gastric glands secretions.
Gastric juices:
Pepsinogen
3M HCI
Mucous
Hydrochloric acid (HCI): released when proteins enter the stomach.
Creates a pH of 2.5 which kills bacteria.
Transforms pepsinogen into an active hydrolyic enzyme pepsin which begins protein digestion.
Pepsinogen - HYDROCHLROYIC - pepsin.
Protein -
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Protein - PEPSIN - smaller polypeptides.
Mucous secretions help protect the stomach wall from the HCI. An ulcer can result if acid gets through the mucus layer & pepsin begins to digest stomach cells.
The bolus leaves the stomach as an acidic liquid called chyme.
The pyroric stomach @ the base of the stomach will meter out of the chyme into the duodemum @ a slow, controlled rate.
Heartburn is caused by the backing of the HCI (acid) into the esophagus from the stomach (when the cardic sphinctor allows some through).
Called heartburn in english because the burning is located behind the sternum (by the heart).
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SMALL INTESTINE
Callled the small intestine becuase of it's small diameter.
There are 3 regions:
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Duodenum: Chemical digestion from the pancreatic & intestinal juices.
Jejunum: absorbtion.
Ileum: absorbtion.
Villi contains:
Blood capillaries for nutrient absorption (sugars & amino acids).
Lacteals (lymph capillaries) for glycerol & fatty acids.
Absorption through microvilli involves active transport.
Structures:
Long muscular tube.
Folds in layer of small intestine called villi.
Villi also has a smaller folds called microvilli.
Function:
To complete digestion of nutrients & to begin absorbtion of the nutrients.
Walls of the duodenum contain glands that produce & release intestinal juices.
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Pancreatic juices
Chyme pH 2.5 - SODIUM BICARBONATE - pH 8
Starch - PANCREATIC AMYLASE - maltase.
Fat droplets - LIPASE - glycerol & 3 fatty acids.
Proteins -TRYSPIN - peptides.
Dna/rna - NUCLEASES - nucleoides.
Can remember "SALT + N" for the enzymes.
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The function of the jejunum & ileum is solely absorption.
Chyme moves through the small intestine via pertaslis.
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Intestinal juices
dipeptides - PEPTIDES - amino acids.
Nucleotides - NUCLEOSIDASE - sugar, phosphate, & N-base.
Maltose - MALTASE - glucose + glucose.
Sucrose - SUCRASE - glucose + fructose.
Lactose - LACTASE - glucose + galactose
Secretions from the liver & pancreas enter the duodenum via the common bile duct.
Bile: not an enzyme but breaks fat into smalller far droplets so they are easier to digest.
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Large intestine
Structure: The large intestine is large in diameter but shorter length muscleualr tube.
It consists of....
Colon (ascending, transverse, descending, & sigmoid colon).
Rectum
Anus
Function:
Absorption of water & salts.
Stores indigestiable material until it can be elimanted.
Has anaerobic bacteria, E-coli that...
Breaks down indigestable material
Inhibit invasion by patthogens
Produce vitamins (Vitamin K) & other molecules (such asgrowth factors).
Produces waste (methane gas).
Rectum
By the end of large intestine wastes are transformed into pasty "feces" which build up in the rectum until message is sent to central nervous system to stimulate bowel movement.
Anus
Spinctor muscle through which feces exits the body.
The entire process of digestion from the mouth to the anus last - 24 hours.