Result: clumping which allows the milk to stay in the stomach for a longer time so the pepsin can break it down more easily and not pass through quickly

Trypsinogen (inactive) → Trypsin

Source: lining of the duodenum (changes in the presents of enterokinase)

Substrate: Peptide bonds in proteins

Result: individual amino acids

Enterokinase

Source: brush boarder of small intestine (lining of duodenum) when there is a release of CCK and secretin

Substrate: Trypsinogen

Result: The change of Trypsinogen to trypsin

Pancreatic Lipase

Source: Pancreas

Substrate: Fats (Lipids)

Result: glycerol and fatty acids

Pancreatic Amylase

Source: Pancreas

Substrate: Carbohydrates

Results: monosaccharides (small enough to absorb)

Maltase:

Source: Lining of the small intestine

Substrate: Maltose

Result: 2 glucose molecules (converts a disaccharide to a monosaccharide)

Lactase

Source: small intestine

Substrate: Lactose

Result: 1 glucose molecule and 1 galactose molecule

Sucrase

Source: lining of the small intestine, the tips of the villi

Substrate: Sucrose

Result: Glucose and Fructose

Erepsin (mixture of protein digesting enzymes, peptidases)

Source: ileum and pancreas

Substrate: proteins

Result: proteins and peptones to amino acids

Chemical Secretions (NOT ENZYMES)

HCl

very low PH (2-3) that helps to breakdown food and kill pathogens
PARIETAL cells from the stomach lining (Only found in the stomach)
triggers the change of Trypsinogen to Trypsin (helps with the digestion of proteins)
Makes the folded proteins denature to allow for more surface area to be reached by the Pepsin
when in the small intestine it triggers CCK

Mucus

is a protective layer to the stomach against the HCl (Prevents self digestions
created by the Stomach lining
is extremely basic and has a high concentration of BICARBONATE (neutralizes the HCl)

Bicarbonate

Stomach

in the mucus to help to neutralize the HCl

Small Intestine

released when Secretin is triggered in the DUODENUM which neutralizes the stomach acids that is let out when the chyme is pushed through from the stomach
allows for the increase in pH
SECRETED BY THE PANCREAS

Bile

is part of the MECHINCAL DIGESTION (just emulsifies fats to increase surface area for lipase to break it down chemically)
is released into the SMALL INTESTINE (Duodenum)
- reacts to the CCK when the gall bladder is squeezed which releases the bile from the GB
Helps to neutralizes chyme so not to harm the small intestine
is produced by the LIVER then moves through the COMMON BILE DUCT and stored in the gallbladder
MAKE UP:
- Bile salts
- phospholipids
- cholesterol
- bile pigments (bilirubin)

Hormones

is a chemical messenger that has a target tissue that would change something and is carried in the blood, which bring about a particular change or effect. (They are used up in metabolism, which is different hen enzymes)

Gastrin (MOST IMPORTANT)

Source: secreted into the blood by G-cells by STOMACH LINING, response to proteins entering the stomach or stretch, smell, thought, or taste

Target Tissue: Chief cells (to produce pepsinogen and Parietal cells to produce H+ ions to make HCl)

Effect: to produce pepsinogen and Parietal cells to produce H+ ions to make HCl.

Cholecystokinin (CCK)

Source: Small intestine lining (when the Chyme and the HCl is present)

Target: Gall bladder (to release the bile into the DUODENUM) and the pancreas (to release digestive enzymes (see above) into the DOUDENUM)

Effect: Gall bladder → to release the bile into the DUODENUM)

pancreas → to release digestive enzymes (see above) into the DOUDENUM

Pro-secretin to Secretin (Inactive to Active)

Source: Small intestine lining (HCl is present)

Target: Pancreas

Effect: to make the Bicarbonate be released into DUODENUM which neutralizes stomach acid so the small intestine does not get burnt through

Structures and Functions:

Mouth and Teeth:

the start of the entire digestive system
THEY ARE ONLY PART OF MECHINAL DIGESTION
- they will grind the food and break it apart to allow for it to be easier
Contains the tongue
- push the food around and the food down the pharynx (turns into bolus)
- is an very strong muscle
- taste buds allow us to figure out different flavors
Contains Saliva
- BOTH MECHINAL AND CHEMICAL DIGESTION
- Chemical Salivary Amylase (see above)
- Moistens the food (allows for it to swallow)
Contains Uvula (protects the nasopharynx)

Pharynx

where the food goes before the esophagus
separation between the trachea and the esophagus (has 3 parts)

Epiglottis

the flap of cartilage that covers the trachea when you are swallowing which prevents the food from entering the larynx

Esophagus

tube that brings the bolus from the mouth to the stomach
Made of 2 layers of muscle (both smooth muscle)

Peristalsis

Involuntary movement (is made because of contractions of the smooth muscle)
how the food moves through the full GI Tract (starts in the esophagus)
is uses in the stomach to flip the food and move it to allow more areas to be exposed to enzymes and HCl
how the chyme is moved in the small and large intestine

Cardiac Sphincter

Sphincter at the top of the stomach (controls the HCl release into the esophagus, if it is open then there is a chance of gastric reflux)
FUNCTION: to prevent chyme and other stomach content from going back up to the esophagus.

Stomach and Muscles

3 Muscles: longitudinal, circular and oblique (Superficial to Deep) which allow for the food to be turned in everyway and are very strong muscles
continues the MECHINAL DIGESTION of the bolus and turns it into chyme
all smooth muscle
Contains enzyme (Pepsin, which is starts the chemical digestion of Proteins)

Pyloric Sphincter

is the sphincter at the small intestine side of the stomach
is controls what can come in and out of the stomach (closes off the stomach before the chyme is made so it does not leak out before properly digested)

Duodenum

where 80% of digestion happens (also has absorption)
this is where the majority of enzymes and bile is secreted

Jejunum

second part of the small intestine
absorption of the vitamins, proteins, fats etc.
there is less villi and they are smaller

Ileum

the longest portion of the small intestine
has the ileocecal junction at the end of it (last part of the small intestine)
has erepsin in it and secretes it

Liver

is an accessory organ
products bile and sends it through the common bile duct to the gall bladder
all the nutrients that the small intestine just received goes through the HEPATIC PORTAL VIEN (this is too allow for them to refined and processed some are carbs, fatty acids, amino acids, monosaccharides, glycerol)
refines all the raw nutrients
PROCESSES, FILTERS, DETOXIFIES
stories vitamins (B12)
produces plasma proteins
converts carbs to fats when glycogen storage is full
breaks down amino acids (creates urea)

Gall Bladder