DS Combined Set

Digestive System

move material from world to blood

-consume high energy molecules

-consume essential amino acids that our body can’t synthesize (specific organics)

Ex. of Specific Organics

sodium, potassium, iron, minerals

-many trace minerals and trace elements

Defenses

we need to have protections along the digestive tract to prevent infection and maintain health

Functions of the Digestive System

secretion, motility, digestion, absorbtion

Secretion

moving materials from body into lumen of tract

(adding water, mucus, acids, enzymes)

-7L/day of fluid moving into the digestive tract (mucus, saliva, dilute, enzymes, electrologist solution)

Motility

smooth muscle contractions to control the movement of material through the digestive tract

-Controlled by enteric nervous system: 2 plexuses- submucosal and enteric plexus

-combination of longitudinal and circular muscles

Digestion

break down food into absorbable forms

increase surface so enzymes can break down better

mechanical vs. chemical

Mechanical Digestion

breaking food into tiny pieces

-first need to use mechanical digestion to increase surface area then can do chemical digestion

-does not break into molecules yet

Chemical Digestion

using enzymes to break down into larger molecules

proteins—> amino acids

polysaccharides—> monosaccharides

breaking food molecules into absorbable molecules

function of lips

suction, allow for facial movement

teeth

grinding, gripping, tearing

humans can do all of those making us adaptable

tounge

gather materials and moving it around during mechanical digestion (unconcons)

type of sensory organ: taste, moves globs of food to oropharynx

swallowing

deglutition

-coordinated contraction of throat, while simultaneously activating the larynx up and epiglottis down to swallow

coordination of larynx, tongue, pharynx, epiglottis

-10s to move down esophagus to stomach

Anatomy of Digestive System

oral cavity—>

oropharynx—>

laryngopharynx—>

esophagus—>

(skeletal muscle 2/3rds and 1/3rd smooth muscle)

lower esophageal sphincter—>

stomach—>

pyloric sphincter—>

The pancreatic duct and the bile duct empty into

duodenum—>

jejunum—>

ileum—>

cecum—>

small intestine—>

large intestine—>

rectum

also

pancreas, liver, gallbladder

liver + gallbladder

bile breakdown of biliruben

bile

emolsifier

-breaks down fat into smaller globs

Stomach

adds strong acids (makes ph around 2)

-adds enzymes and has layers of mucus and bicarbonate

end product is chyme

pancreas

solution of bicarbonate ions, enzymes (make into absorbable pieces)

pyloric sphincter

detects acid through nervous system and hormones

slows down stomach emptying —> little at a time

large intestine

absorbs water, vitamins, house symbiotic bactera

Anatomy of Walls: Stomach Wall

top: epithelium

-with gastric pits

lamina propia

mucosa

-muscularis mucoase

-submucosal plexus

submucosa'

muscularis

-myenteric plexus (ind. branch of the NS)

serosa

Serosa

tough connective tissue that forms the mesentary (holds in place)

-secretes mucus

Anatomy of Walls: Something Wall

villi (has apical membrane with brush boarder)

=increase surface area

-blood vessels

-lacteal (lymph vessels)

Motality Patterns: Peristalsis

contraction wave of movement (circular), moving things from one place to another (along a tract)

-esophagus

-stomach

-intestines

Motality Patterns: Segmental Contractions

different parts are contracting at different times (sloshing) to fully break down material in stomach

-alternating contractions

-small intestine

-makes sure digestive material gets sloshed around so it can be absorbed +

Peristalsis =moves along the intestine and mixes things

Migrating Motor Complex

slow 90 min

-triggered by the stomach being empty

-The job is to move stuff down the intestine/sweeping bacteria into the large intestine

-starts in the duodenum, slow wave travels through the whole small intestine

-if you get bacteria in the small intestine moves back to large intestine.

Topology

mathematics of shapes

-we are one tube

-nothing crosses at a cellular level

Absorbtion

move materials from lumen into body

Secretion Mechanism

movement of H20= cause we actively transport material into lumen—> H20 move solutes and water follows

-you loose half a liter through defication= pooping

Dehydration

don’t have water= will dilute sodium and potassium

=loss of water and salts= needs electrolights

Coordination of Motility

by enteric nervous system

-two layers in wall of digestive tract of neurons

-submucosal plexus

-myenteric plexus

sensory neurons

-motor neurons and inter neurons

All ANS influences these

Enzymes

are proteins

-depend on shape, charge, Ph

denaturing= unfolding protein

Amalyase

take starch—> maltose (Glu+ Glu)

Lipase

triglycerides—> fatty acid+ monoglycerides

nucleases—> break nucleic acids—> nucleotides

Peptidases: Endopeptidase

break down peptide chain into smaller pieces

Peptidases: Exopeptidase

attacks end of chain= breaks into 3 amino acids

smaller pieces of the peptide chain broken down even smaller

Duodenum

1st of 12 inches of small intestine

-before jejunum

-contains brush boarder

(tiny hair like projections)

Intestinal Phase Enzymes

duodenal signals:

-bile

-pancreatic enzymes

-brush boarder enzymes

Duodenal Signals: Acid

produce secretin—>

-slows stomach motility

-also triggers bicarbonate release from the pancreas

-neutralizes acid

Duodenal Signals: Carbohyrates

makes gastric inhibitory peptide (GIP)

glucagon-like peptide 1 (GLP-1)

-both tell the pancreas to make insulin

-ensure there is not too much glucose in blood (prepares for carbohydrates)

Duodenal Signals: Fats

cholecystokinin (CCK)

-triggers contraction of gallbladder

-delivers bile into duodenum

-also tells pancreas to release digestive enzymes

Pancreas

takes C02 and sending bicarbonate out and proton bacj into blood—> reserves what stomach does= makes more acidic

Ghrelin

is an appetite stimulus by stomach= increase appetite

Bile

accumulates in gallbladder

-digest fats

Bile Salts

=amphipathic

(hydrophilic and lipophilic)

-water gets out between/ fat molecules in water (lipophilic)

become cluster—> bile salts split fat molecules —> into smaller balls of fat= emulsification

Pancreatic Zymogens

lipases, amylases, nucleases, peptidases- trypsinogen (protein digesting enzyme)

-all made in inactivated form—> get peptidase and get activated later

Enteropeptidase in Pancreas

brush border has this enzyme that works to break the safety cap of trypsinogen

trisinogen + enteropeptidase

=

activation of lipase, amylases, nuclease, and peptidase

Gallstone

Enzymes cant get out of the pancreas —> enzymes can’t activate an get acute pancreatis

(inflammation)

Brush Boarder Continued

Maltose (Glu+ Glu)

Sucrose (Glu+ Fru)

Lactose (Glu+ Gal)

can’t absorb any—> need enzymes sucrase, maltase, lactase

Na+ based symports

as disaccharides pass through duodenum—> brush boarder enzymmes break maltose into seperate glucose, sucrose into fructose, and lactose into glucose and galactose.

Absorption: Carbohydrates

monosaccharides SGLT and GLUT transporters

Absorption: Proteins

amino acids (Cl-3) Na+ symporters

Absorption: Nucleic Acids

nucleotides—> transport proteins

Absorption: Fats

gets broken down into glycerol + 2 fatty acids—> move into enterocyte—> get put back together into triglycerides—> gather into chylomicrons( protein+ fats) export from cell—> lacteals take it out through lymph—> into blood

Cephalic Phase

sensory or cognitive aspects of food

-activity in parasympathetic NS on the Vagus nerve to abdominal cavity to the stomach

think and hunger is activated

“long vagal reflex”

increased motility and secretion (gets ready for food)

-prepares for food and opens slightly

Saliva

secretion of salivary glands

-mostly, water, mucus, antibodies (disinfectant)

-one of first defenses

-lysosome, anti-bacteria

-salivary amylases, lingual lipase -both work best at ph of (6-7) salivary Ph

Amalyse

enzymes in which break up polysacharides (starch)—> can break down to level of maltose

Lapase

enzyme which breaks down fats—> triglycerides—> monoglyerides+ fatty acid

Gastric Glands

G cells—> gastrin

Parietal Cells

produce hydrochloric acid & intrinsic factor

Hydorchloric Acid

kills microorganisms

denatures proteins

makes Ph of stomach 2

Intrinsic Cells

protects vitamin b-12 from acid, enables b12 absorbtio inintestine

ECL Cells

secrete histamine

Chief Cells

pepsinogen—> (with acid)= endopeptidase

gastric lipase,

Gastric Phase System

sensory stimuli food from stomach—> G cells—> gastrin

can activate ECL cells to make histamine—→ parietal cells

OR

gastrin—> parietal cells—> acid—> make chief cells

OR

parietal cells—> intrinsic factor

chief cells—> make intrinsic factor

or gastric lipase

Peptidase

enzyme which breaks down proteins

Intestinal Phase

stomach being emptied into the duodenum

acid in the duodenum—> duodenum secretes secretin

—> causes the pancrease to release bicarbonate and pancreatic enzymes into the duodenum

=slow stomach emptying

Carbohydrates in duodenum

duodenum secretes GTP—> slows + GLP-1

GTP- slows down stomach emptying

GLP-1 - slows down the stomach, suppressing appetite, triggers insulin production

Fats in duodenum

duodenum secretes CCK—> powerful appetite suppressant and stimulates gallbladder contraction to release bile for fat digestion.

Proteins

= peptidase —>

1-3 amino acids

—>

Na+ based symports

Nucleic Acids

=nucleases —>

nucleotides—>

Na+ based symports

Carbohydrates

starches or disaccharides—>

starches, maltose, sucrose, lactose