GIT Physiology

• Digestion

• Absorption

• Defacation

functions of the digestive system.

• Alimentary Canal

• Accessory Digestive Organ

two parts of the digestive system.

• Salivary glands

• Tongue

• Teeth

• Pancreas

• Liver

• Gallbladder

accessory digestive organs.

Salivary Glands

secrete saliva into the mouth.

• 99.5% water

• .5% solutes (Na, K, Cl)

• Immunoglobulin A

composition of saliva.

Immunoglobulin A

component of the saliva that protects the mouth from bacteria.

1000-1500 mL

normal amount of saliva.

• Serous secretion - secretes starch digestive enzymes

• Mucus secretion - secretes mucin

2 types of protein in the saliva.

Salivary Amylase/Ptyalin

“starch digesting enzyme”

• Parotid gland

• Submandibular

• Sublingual

three salivary glands.

Parotid Gland

- salivary gland found anterior and inferior to the ears, between the skin and the masseter

- the largest

Submandibular Gland

salivary glands found beneath the base of the tongue in the posterior part of the floor of the mouth.

Sublingual

salivary glands found superior to the submandibular gland.

Decrease production of saliva

result of sympathetic stimulation to the salivary glands.

Increase production of saliva

result of parasympathetic stimulation to the salivary glands.

Extrinsic Muscles of the Tongue

part of the tongue that is concerned with the movement of the tongue side to side, in and out.

Instrinsic Muscle of the Tongue

part of the tongue that is concerned with the altering the shape of the tongue (during speech)

Taste Buds

receptor for the taste.

Deciduous Teeth

- 20 in number

- aka “milk, temporary, baby teeth”

6-12 years old

age where you lose your deciduous teeth.

Lower Central Incisors

first teeth to erupt.

32

number of permanent teeth.

Pancreas

- an organ that acts both as an exocrine (secretes enzymes) gland and an endocrine (secretes hormones) gland

- secretes pancreatic juices

- consists of head, neck, body, and tail

Greater Curvature of the Stomach

location of the pancreas.

1200-1500 mL

normal amount of pancreatic juice

• Carbohydrate-digesting enzyme (pancreatic amylase)

• Protein-digesting enzyme (trypsinogen)

• Triglyceride-digesting enzyme (pancreatic lipase)

enzymes in the pancreatic juice.

Enterokinase

- trypsin passes through this to become trypsin (active form)

- found the the duodenum

Pancreatic Duct

- passageway of pancreatic juice in the pancreas

- duct of Wirsung

• Smaller pancreatic duct

• Larger pancreatic duct

birfurcation of the pancreatic duct results in?

Hepatopancreatic Ampulla

the connection between the larger pancreatic duct and the common bile duct.

Spinchter of Odi

other name for the spinchter of the hepatopancreatic ampulla.

• Release of cholecystokinin

• Peristaltic wave in the common bile duct

• Intestinal wave

factors that activate the relaxation of the sphincter of Odi.

Liver

heaviest and second-largest organ that contains hepatocytes.

Lobule

functional unit of the liver.

Hepatocytes

part of the liver that is responsible for the production of bile.

Bile

fluid produced in the liver that helps with the emulsifaction of fats.

• Water

• Cholesterol

• Bile salts

• Bile pigments

composition of bile.

800-1000 mL

normal amount of bile.

Gall Bladder

serves as the storage of bile and is located inferior to the liver.

Common Hepatic Duct

the combination of the (R) and (L) hepatic duct.

Cystic Duct

passageway of bile in the gall bladder.

Common Bile Duct

the combination of the cystic duct and the common hepatic duct.

• Lateral wall: cheeks

• Roof: hard palate (anterior) and soft palate (posterior)

• Floor: tongue

boundaries of the buccal/oral cavity.

• Nasopharynx

• Orophrynx

• Laryngopharynx

parts of the pharynx.

Deglutition

movement of food from mouth to stomach.

• Voluntary stage

• Pharyngeal stage

• Esophageal stage

stages of deglutition.

Voluntary Stage

stage of deglutition wherein bolus passes into the oropharynx.

Pharyngeal Stage

- stage of deglutition where the bolus is seen in the oropharynx, which will trigger the sending of information to the deglutition center.

- fastest stage

• Medulla oblongata (main)

• Lower pons

the deglutition center is found here.

• Soft palate and uvula: moves superiorly to close the nasopharynx

• Larynx: moves forward and upward

• Epiglottis: moves backward and downward

the movement of the soft palate, uvula, larynx, and epiglottis during the pharyngeal stage.

Esophageal Stage

stage of deglutition wherein the bolus is seen/already in the esophagus.

25 cm

how long is the esophagus?

Esophagus

- composed of a smooth muscle

- passageway of the bolus

- has two sphincters

• upper esophageal sphincter

• lower espohageal sphincter

- (-) digestive enzymes

Gastroesophageal Reflux Disease

- affects the lower esophageal sphincter by causing it to weaken or fail to close completely, allowing stomach contents to flow back into the esophagus

- (+) heartburn

- management: antacids

• Cardia

• Fundus

• Body

• Pylorus

• Greater curvature

• Lesser curvature

parts of the stomach.

4 liters

how many liters of food can a stomach store?

• Gastric gland

• Pyloric gland

two tubular glands of stomach.

Gastric Gland

produces gastric juice.

2000-3000 mL

normal amount of gastric juice.

Mucus Neck Cells

cell in the gastric gland that secretes mucus.

Chief Cell

cell in the gastric gland that is responsible for the production of pepsinogen.

Pepsin

- a protein-digesting enzyme found in the stomach

- active form of pepsinogen

Parietal Cell

cell in the gastric gland responsible for the production of the intrinsic factor and hydrochloric acid.

Intrinsic Factor

responsible of the vitamin B12 in the ileum.

Hypochloric acid

activates the pepsinogen into pepsin.

G Cell

releases gastrin.

Gastrin

- stimulates parietal cells to secrete hydrochloric acid

- promotes gastric motility, and aids in the growth of the gastric mucosa.

Small Intestine

- longest alimentary canal where major events of absorption happens

- major digestive organ

• Duodenum

• Jejunum

• Ileum

parts of the small intestine.

Enterogastric Reflex

reflex responsible for tightening of the pyloric sphincter.

Secretin

hormone that stimulates the liver to produce bile and the pancreas to produce pancreatic juice.

Cholecystokinin

stimulates the contraction of the gallbladder, leading to the release of bile into the small intestine to aid in fat emulsification and digestion.

Chyme

- is the semi-fluid, pulpy mass of partly digested food and gastric secretions that is expelled (2-3 tsp) by the stomach into the duodenum.

- is formed in the stomach through the mechanical and chemical breakdown of food, mixing bolus with gastric juices

- white cream

3-6 hours

how long does the journey of the chyme in the looping coils of small intestine take?

Large Intestine

- produces haustral contractions, which are slow, segmenting movements that mix the contents and aid in water absorption

- largest alimentary canal.

• Cecum

• Colon

• Rectum

• Anal canal

• Anus

parts of the large intestine.

• Ascending

• Transverse

• Descending

• Sigmoid

parts of the colon.

Iliocecal Spinchter

connection of small and large intenstine.

500 mL

normal amount of methane gas in the large intestine.

Stercobili

responsible for the color of stool.

Hirshsprung Disease

- is a congenital condition characterized by the absence of ganglion cells (nerve cells) in a segment of the large intestine, typically the sigmoid colon and rectum.

- this lack of innervation prevents the affected bowel segment from relaxing, leading to functional obstruction, accumulation of stool, and colonic distension (megacolon) proximal to the affected segment. It causes severe constipation and feeding difficulties in newborns and infants.

Myentric/Auerbach Plexus

part of the enteric nervous system that controls movement of GIT.

Submucosa/Meissner’s Plexus

part of the enteric nervous system that controls secretions and blod flow in GIT (mucus).

Monosaccharide

- simple sugar

- can easily penetrate the cell membrane due to its small size

- e.g. glucode, galactose, fructose, and ribose

Disaccharide

- double sugar

- e.g. sucrose, maltose, and lactose

• 1 glucose

• 1 fructose

components of sucrose.

• 2 glucose

components of maltose.

• 1 glucose

• 1 galactose

components of lactose.

Polysaccharide

- many sugar

- e.g. starch and glycogen

In the Mouth:

• Salivary amylase/Ptyalin digests starch (polysaccharide) into maltose.

In the Stomach:

• Pepsin digests protein into large polypeptides.

In the Small Intestine:

• Trypsin digests large polypeptides into peptides (the smallest fragments of protein).

• Pancreatic lipase combined with bile breaks down triglycerides into monoglycerides, fatty acids, and amino acids.

• Pancreatic amylase and brush border villi enzymes further break down carbohydrates:

  • Sucrase breaks down sucrose into 1 glucose and 1 fructose.

  • Maltase breaks down maltose into 2 glucose molecules.

  • Lactase breaks down lactose into 1 glucose and 1 galactose.

discuss the digestion process.

• (R) kidney

• Liver

• Gallbladder

• Pancreas (head and neck)

contents of the (R) upper quadrant of the abdomen.

• (L) kidney

• Stomach

• Spleen

• Pancreas (body and tail)

contents of the (L) upper quadrant of the abdomen.

• Cecum

• Appendix

• (R) Ovary

contents of the (R) lower quadrant of the abdomen.

• Sigmoid colon

• (L) ovary

contents of the (L) lower quadrant of the abdomen.

• Location of pain: epigastric region

• Referred pain: (R) shoulder/lateral border of the (R) scapula

location of pain and referred pain of stomach

• Location of pain: umbilical region

• Referred pain: low back area

location of pain and referred pain of small intestine.

• Location of pain: suprapubic region

• Referred pain: sacrum

location of pain and referred pain of large intenstine/colon.

• Location of pain: (R) upper quadrant or (R) hypochondrium

• Referred pain: (R) shoulder/scapula

location of pain and referred pain of liver and gall bladder

• Location of pain: (L) upper quadrant or (L) hypochondrium

• Referred pain: (L) shoulder

location of pain and referred pain of spleen.

• Location of pain: (L) upper quadrant or (L) hypochondrium

• Referred pain: (L) shoulder

location of pain and referred pain of pancreas.