digestive system.....

i aint memorizing allat :(

Functions of digestive system

1. ingest food

2. digest food

3. absorb nutrients and monomers

4. eliminate undigested remains

Saliva is secreted from?

salivary glands

Saliva contents + functions

water (adds moisture), mucus (lubricates mouth), HCO3 (bicarbonate, keeps pH of mouth neutral), salivary amylase (enzyme)

chemical rxn for saliva

starch (through salivary amylase under neutral pH) → maltose

Swallowing in five steps 

1. tongue pushes food to back of the mouth where reflex action is triggered

2. food enters pharynx

3. epiglottis covers glottis (top of trachea)

4. soft palate covers nasopharynx region

5. peristalsis squeezes food down esophagus 

gastric juice contents + functions

mucus (secreted by goblet cells of the gastric gland), HCL (kills most microbes, exposes peptide bonds, activates pepsin), pepsinogen (inactive enzyme which turns into pepsin)

chemical rxn for pepsin

protein (under pH 2.5-3) → peptide fragments

food leaving stomach is called? 

chyme 

food leaving mouth is called?

bolus

liver and gallbladder contents + functions

bile (bile salts and pigments) to emulsify fats to make them small droplets to be digested 

Pancreatic juice contents 

NaHCO2 (sodium bicarbonate), pancreatic amylase, trypsin, lipase, pancreatic nuclease

chemical rxn for pancreatic amylase

starch (under pH 7.1-8.2) → maltose

chemical rxn for trypsin

protein (under basic pH) → peptide fragments 

chemical rxn for lipase

emulsified fat (under basic pH) → glycerol and fatty acids

chemical rxn for pancreatic nuclease 

nucleic acids (under basic pH) → nucleotides 

intestinal juice contents 

peptidase, maltase, intestinal nuclease 

chemical rxn for peptidase

peptide fragments (under basic pH) → amino acids

chemical rxn for maltase

maltose (under basic pH) → glucose

chemical rxn for intestinal nuclease

nucleotides (under basic pH) → sugar, phosphate, base

three main functions of stomach

1. mechanical digestion

2. chemical digestion

3. storage of food (2-6 hours)  

physical design of stomach

sac is made of smooth muscle which allows peristalsis (mechanical digestion) 

function of liver 

produce bile to emulsify lipids 

2 functions of the pancreas

1. product pancreatic juice (exocrine function since secretion goes directly to the small intestine without going into the blood

2. produce & secretes insulin to maintain homeostasis (endocrine function since secretion goes straight into blood

three sections of the small intestine

duodenum, jejunum, ileum

function of folds

increase number of epithelial cells

function of villi

increase number of epithelial cells

function of microvilli

increases cell membrane/surface area of epithelial cells 

what allows absorption in the small intestine?

1. warm and moist

2. intestine is very long

3. intestinal wall is folded

4. intestinal wall has villi 

5. villus have microvilli

6. each epithelial cell has extra mitochondria

which two macromolecules go down the polar monomer pathway?

glucose and amino acids

which two macromolecules go down the non-polar monomer pathway?

glygerol and fatty acids

polar monomer pathway

1. pass through epithelial cells by active transport

2. enter blood capillaries

3. pass through hepatic portal system to be processed by the liver

4. enter circulatory system and go to body cells

non-polar monomer pathway

1. pass through epithelial cells by diffusion

2. enter lacteals to be processed by lymphatic system

3. enter circulatory system and go to body cells 

what is the hepatic portal system?

a special blood vessel that takes blood from small intestine to liver 

Large intestine/colon functions

1. absorbs water and salt

2. produce and absorb vitamins via bacteria

3. formation and expulsion of feces 

physical features of the large intestine

1. cells have many channel proteins to maximize water absorption

2. no folds

gastrin 

1. stimulated by peptides and amino acids in stomach, sight, smell, and taste

2. source: pyloric end of stomach

3. target organs: cardiac end of stomach - causes release of gastric juice

secretin

1. stimulated by HCL in the duodenum

2. source: duodenum

3. target organs: pancreas (releases pancreatic juice) and liver (produces extra bile)

CCK

1. stimulated by fats and proteins in duodenum

2. source: duodenum

3. target organs: gallbladder (causes concentrated bile to enter duodenum) and pancreas (continue secretion of pancreatic juice)