BIO12 - unit 3 - digestive system

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digestion def

+ how many functions

digestion def

+ how many functions

process of changing food into small soluble monomers that can be absorbed + used by your cells

-3 main functions:

1. digestion

   • mechanical

   • chemical

2. absorption

3. elimination

digestive SYSTEM functions

1. digestion

   a. mechanical digestion

   • physical breakdown of food

   b. chemical digestion

   • breaking of bonds in polymers to get similar monomers (hydrolysis)

2. absorption

   • movement of monomers/nutrients from digestive system into blood (circulatory) or lymph

3. elimination

   • expulsion (force smth out) of indigestive residues from body (poop)

digestion

2 types

1. mechanical digestion

   • physical breakdown of food

     • increases surface area to be able to attack

2. chemical digestion

   • breaking of bonds in polymers to get monomers (by hydrolysis)

absorption

movement of monomers/nutrients from digestive system into blood (circulatory) or lymph

elimination

expulsion (force smth out) of indigestive residues from body (poop)

• stuff that has never been “in” our body since not absorbed; just gone thru our hole

why physical breakdown of food

to increase surface area so more places to be attacked

alimentary canal

tube that runs from mouth to anus

-food passes through the organs:

• mouth

• pharynx (throat?)

• esophagus

• stomach

• small intestine

• large intestine

• rectum

• anus

accessory organs

• egs and how?

-the organs that assist but the food does not pass through them

• eg. pancreas

• eg. liver

mouth

-order

-type(s) of digestion

-first step

-mechanical digestion

• teeth grinds cuts tears food

• tongue + cheek holds food in to help mix w/ saliva

• saliva

  • contains H2O, mucus for lubrication

-chemical digestion

• saliva (comes from 3 sets of salivary glands)

  • salivary amylase (enzyme that breaks down starch)

salivary amylase

-what

-pH

-which type of digestion

-enzyme that breaks down starch

-pH of 7; same as mouth

-chemical

saliva

-contains

-comes from

-type of digestion(s?)

-contains

• H2O

• mucus

• salivary amylase

-comes from 3 sets of salivary glands

-chemical digestion bc salivary amylase

-physical digestion bc lubricant

mouth

-order

-process

-first

1. teeth physical digestion by tear/cut

2. saliva breaks down starch (chem. digest.)

3. chewed food gets pushed to back of mouth (pharynx) by tongue (now called bolus) + gets swallowed

4. swallowed (3 steps)

   a. soft palate moves back to cover opening of nose

   b. epiglottis (trap door) covers the trachea (air tube/windpipe)

   c. bolus enters the esophagus

how to swallow haha

3 steps

before:

chewed food (bolus) gets pushed to back of mouth (pharynx)

1. soft palate moves back to cover opening of nose

2. epiglottis (trap door) covers the trachea (air tube/windpipe)

3. bolus enters the esophagus

during mouth, what enzyme digests starch into

→ be specific and general

salivary amylase digests starch + H2O into maltose

→polysaccharide → disaccharide

(not into building blocks but rather smaller molecules)

does salivary amylase breaks down carbohydrates

yes, since starch is a carbohydrate

esophagus

-order

-what + contains

-function

-type(s) of digestion

-second (after mouth)

-long muscular tube extending from pharynx to stomach (stack of donuts) + contains cardiac sphincter

-transport

-produces mucus to allow food to travel more easily

-chemical digestion bc salivary amylase

esophagus

-order

-process

-type of digestion

-second (after mouth

-food moved along esophagus by involuntary muscle contractions (peristalsis)

-end of esophagus is cardiac sphincter (trap door)

• muscle that opens to allow food into stomach + closed to prevent “back flow” of acidic stomach contents

peristalsis def

+ when

food (bolus) moving along esophagus by involuntary muscular contractions

heartburn

→ contains

burn in esophagus when there’s “back flow” of acidic stomach contents

→ HCl and pepsin

heartburn vs vomit

heartburn:

-HCl and pepsin in esophagus

-backflow of acid chyme

peristalsis

in esophagus, involuntary muscle contractions that moves food down

cardiac sphincter

-why called

-function

at end of esophagus,

-muscle that opens to allow food into stomach + closes to prevent back flow of acidic stomach contents

• or else heartburn + vomiting

-closest sphincter to heart?

-NOT TO: slow down food, rather to not push food back up

stomach

• def

• contains

• types of digestion

• order/location

-thick-walled

-J-shaped organ

-pH of 2 or 2.5 due to HCl

-acidic but won’t digest stomach because mucus (forms a thick protective layer)

-has 3 layers of muscle, running in diff directions to churn + mix

-mechanical digestion → the 3 muscles to churn + mix
→ not break down polymers yet

-chemical digestion of proteins if bolus contains proteins

• if not protein, then no chem. digest.

-order: after esophagus + cardiac sphincter; below ribcage

why does stomach have 3 layers of muscle running in diff directions

so able to churn all parts → not just one
→ physically digestion

stomach

• order

• process

• afer esophagus + cardiac sphincter

-if bolus has peptides (proteins), causes stomach cells to secrete gastric juice (has pepsin; makes proteins into peptides)

-since acidic (pH of 2 or 2.5), kills bacteria + salivary amylase denatures (active site change so substrate can’t bind) + activates pepsin to digest protein

• chem. digestio if protein only
  

-after food churn in stomach for 2-6 hours, pyloric sphincter opens

-bolus is released into duodenum (first part of small intestine) → bolus called acid chyme

secrete meaning

if cell make smth then cell dump out

gastric juice

-where

-contains

-what

-secreted in stomach if bolus has proteins

-contains:

• pepsinogen

  • enzyme in inactive form

• HCl (hydrochloric acid)

• mucus

-process:

• when pepsinogen + HCl combine, result is the active enzyme

  • a type of protease enzyme (these digests proteins → peptides (smaller a.a. chains)

  • enzyme called: pepsin

what are protease enzymes

→ some examples of specific protease enzymes

-active

-these digests proteins

→ pepsin

what do enzymes do when break down/digests

• a term

• always forget what

hydrolysis

• always forgets need to add water as reactant in order to cut

if mucus in stomach breaks, what happen

stomach ulcer

• hole here

why called pyloric sphincter

close to pancreas

why stomach can stay in food for a big range

→ 2 to 6 hours

because depends on what food is

• orange juice quicker bc liquid → less mechanical

• steak longer → lots of protein → pepsin needed lots of time bc limited

what happens to salivary amylase goes from mouth to stomach

denatures (active site changes shape so substrate can’t bind) because pH of mouth 7 to stomach pH 2

emulsify def

breakdown of fats

duodenum

• order

• accessory organs

• def

• contains

• after stomach + pyloric sphincter

• pancreas (and its duct) + gall bladder (with bile duct)

-most of digestion + absorption of nutrients (ehh into monomers)

-is the first 25cm of small intestine

-pH of 8.5 bc of sodium bicarbonate to neutralize stomach pH

-has pancreatic juice (containing sodium bicarbonate + 4 pancreatic enzymes which breaks into monomers)

-has bile (not enzyme), is emulsifier to do mechanical digestion

duodenum

• order

• process

• type of digestion

• after stomach + pyloric sphincter

-acid chyme enters duodenum

-stimulates pancreas to release pancreatic juice (neutralizes + breaks into monomers) thru pancreatic duct

-stimulates the gall bladder to release bile thru bile duct (mechanical digestion)

-goes to rest of small intestine

• mechanical (bile) + chemical digestion (enzymes)

pancreatic juice

-made in + how release

-contains

-produced in pancreas, released into duodenum thru pancreatic duct

-has:

• sodium bicardbonate (NaHCO3)

  • to prevent SI enzymes from being denatured (+…)

  • denatures pepsin

  • prevents bad stuff (see other)

• 4 pancreatic enzymes

  • pancreatic amylase (starch + H2O → maltose)

  • trypsin (peptides + H2O → smaller peptides)

  • lipase (fat droplets after bile breakdown + H2O → glycerol + fatty acids)

  • nuclease (DNA or RNA + H2O → nucleotides)

sodium bicarbonate

-chemical name

-made in

-helps in

-what happen if not enough

-NaHCO3

-made in pancreas bc its in pancreatic juice

-helps in duodenum (small intestine)

-prevents:

• digesting the small intestine

• duodenum ulcer

• denaturing (active site change → can’t bind substrate)

4 pancreatic enzyme

-pH of all

• all have pH of 8.5 (or 8-9)

-pancreatic amylase (works on starch - long chain of glucose)

• starch + H2O → maltose (disaccharide)

-trypsin (works on bigger peptides)

• peptides + H2O → smaller peptides

-lipase (works on lipids) (time: after bile breakdown) (fully digested bc into monomers)

• fat droplets + H2O → glycerol (think HOHOHO) + fatty acids

  • fat droplets are bile breaks down

-nuclease (works on DNA/RNA from foods)(even tho monomers, still has smaller pieces)

• DNA or RNA + H2O → nucleotides

bile

-made in + why/places been in

-function

• produced in liver as a result of RBC destruction

• stores + released from gall bladder through bile duct

-is an emulsifier (big fat → fat droplets)
→ increase surface area → easier to be coated in pancreatic juice + access lipase

-NOT break down bonds

-mechanical digestion

acid chyme

-descr

-where called

where is this

-acidic

-liquid-y

-has: polypeptide + disaccharide from salivary amylase + full form fats

this is when entering to duodenum

small intestine (second part)

• order

• how long

• what makes it small

• what

• contains

• type of digestion

• after stomach + after duodenum

• 6-7m long (including duodenum)

• lumen of it is small

-rest of small intestine after duodenum

-absorption of nutrients

-walls of the SI, secrete 4 enzymes to complete chem digestion by hydrolysis

-walls contain:

• villi

• microvilli on villi

  • both absorb glucose, amino acid, phosphate group, bases to go in blood

• has lots of blood vessels/capillaries within (vascularized)

• intestinal glands (makes SI enzymes)

• lacteal

  • absorbs products of fat digestion (fatty acids + glycerol)

small intestine (after duodenum)

• order

• process

• after stomach and after duodenum

-nutrients absorbed by walls of SI (secretes 4 enzymes to complete all chemical digestion by hydrolysis):

-maltase (works on maltose)

• maltose + H2O → glucose

-lactase (works on lactose)

• lactose + H2O → glucose

-peptidase (works on small pepsides)

• small peptides + H2O → amino acids

-nucleotidase (works on nucleotides)

• nucleotides + H2O → phosphate group, sugar, nitrogen-base

enzymes are pH of 8.5

where are biomolcules fully done digesting (breaking down)

-lipids/fats → in duodenum

-rest in small intestine after duodenum

where nutrients are absorbed?

which nutrients absorbed by x and which by y

walls of small intestine

non-fat nutrients absorbed by villi + microvilli to go to blood

fat products (glycerol + fatty acids) absorbed into lacteal (lymphatic system)

if broken pancreas, what happens/how affect

no pancreatic juice

• sodium bicarbonate not released

• not neutralize

• denatures the enzymes

• 4 enzymes won’t work

-not break down to get nutrients, stops at:

• starch

• big peptides

• fat droplets

• DNA or RNA

pancreas produces hormones

• no or lower production of insulin + glucagon

→ no homeostasis

if liver broken, what happens/how affect

-won’t make bile

→ big fat won’t be broken down into fat droplets

• lipase can’t break them down into glycerol + fatty acids → can’t digest → nutrients not absorbed by lacteal

-food goes into appendix + rots (appendicitis)

-if burst, waste spread to liver area, bad

what allows the small intestine (after duodenum) to do big job

(adaptations)

1. warm

2. long (6-7m)

3. folds to increase surface area = villi (very thin → one cell thin so can diffuse easily)

4. microvilli to increase surface area

5. highly vascularized (lots fo blood vessels/capillaries) → to transport to get nutrients everywhere

small intestine wall

• parts

  • functions

• villi

• microvilli

  • both absorb glucose, amino acid, phosphate group, bases go into blood

• lacteal (lymphatic system)

  • absorbs products of fat digestion (glycerol + fatty acids) into inside villi tube

• intestinal glands

  • make SI enzymes + releases them

• blood vessels/capillaries

  • for transport, so absorbed nutrients can go into blood

liver

• what role in digestion

• functions

-an accessory organ

1. production of bile (then stored in gallbladder)

   • 1.5 L / day

2. production of blood proteins from amino acid

3. produces urea from breakdown of amino acids

   • removing the very toxic amino group from body by converting it to urea (NH2 → urea)

4. converts hemoglobin (quaternary protein; 4 poly-pep; RBC, carry oxygen) from old red blood cells to bile pigments

   • gives bile its greenish-yellow colour)

5. detoxifies blood by removing + metabolizing poisonous substances (eg. alcohol)

6. stores glucose as glycogen after eating + breaks down glycogen into glucose to maintain blood glucose concentration between meals

large intestine

• order

• made of? / made of

• size

• after duodenum + rest of small intestine

-consists of:

• appendix

• colon

  • ascending colon

  • transverse colon

  • descending colon

• rectum

• anus

• bacteria

  • bacteria (eg. e-coli) are v important for proper functioning of LI

-larger in diameter than small intestine (larger lumen)

• 6.5 cm vs. 2.5cm in diameter

• 1.5 - 2 m vs. 6-7m in length

large intestine

• functions

• process

-functions:

• absorbs water + any soluble nutrients

• stores non-digestible material unit until is defeated at anus

-process

• when acid chyme first enters LI, it encounters the appendix

  → function of organ not clear, + subject to inflammation (appendicitis)

• peristalsis, which began in esophagus occurs along the entire digestion tract

  • moving it along

• poops

feces contains

• nondigestive remains (eg. got cellulose-fiber)

• Bile pigment (colours) - liver makes it

• large quantities of bacteria (swells)

functions of bacteria in large instestine

-bacteria (eg. E.coli) are very important for the proper functioning of your LI

• help breakdown starch (fibre → glucose)

• eats/reduce your amount of feces

• produce usable vitamins, minerals, and amino acids

diarrhea and constipation

• what

-watery fees (diarrhea)

• often caused by infection (food poisonings, contaminated water) that causes small intestine wall to become irritated and increase peristalsis
  → poop more often

→ leads to dehydration +death bc less absorption of water

constipation

• what

-hard., dry feces, - hard to pass

• often caused by ignoring the need to “go”

• can cause. hemorrhoids

how is blood sugar regulated

-by pancreas producing 2 hormones (insulin and glucagon)

-they work together to maintain blood glucose levels = homeostasis

pancreas

-diff types

2 types of cells

1. produces pancreatic juice

2. (cell called islets of Langerhans) produces two hormones

   • insulin

   • glucagon

hormone def

made in one place, travels to another and acts on the other place

feedback inhibition of insulin

-process

-so what

1. after eating, you have high blood sugar

2. pancreas insulin in response

3. insulin travels in blood + targets the liver

4. liver will convert glucose → glycogen and stores it

5. lowers blood sugar since convert glucose to smth else

6. lower blood sugar = inhibits insulin bc pancreas won’t need response

feedback inhibition of glucagon
-process

-so what

1. low blood sugar (after fasting)

2. pancreas responds by releasing glucagon

3. glucagon (a trigger) travels in blood to liver

4. in liver, glycogen → glucose

5. increase blood sugar since smth converted to glucose (sugar)

6. blood sugar increase = inhibits glucagon bc pancreas won’t respond

ppl with diabetes (high blood sugar)

-inject insulin to lower blood sugar (glucose → glycogen) since turn sugar into smth else

the diff types of enzymes

in duodenum..

• sodium bicarbonate (NaHCO3) will neutralize acid chyme to prevent enzymes from denature

  • will denature pepsin to protect duodenum

• 4 pancreatic enzymes work by hydrolysis (using H2O to cut)

• pH of 8.5

  • pancreatic amylase

    • starch + H2O → maltose (disaccharide)

  • trypsin

    • peptides + H2O

      • some alr digested in stomach

      • peptides + H2O → smaller peptides

  • lipase

    • first bile (non-enzyme) helps mech. digest. big fat → fat droplets

    • fat droplets + H2O → glycerol + fatty acids

      • digestion of fats done!

  • nuclease

    • DNA/RNA + H2O → nucleotides

• protein’s second chance at digestion

• fat complete digestion

in small intestine…

• digestion + absorbption

• 4 SI enzymes work by hydrolysis

• pH of 8.5

  • maltase

    • maltose + H2O → glucose

  • lactase

    • lactase + H2O → glucose

  • peptidase

    • smaller peptides + H2O → animo acids

  • nucleotidase

    • nucleotides + H2O → phosphate group, sugar, nitrogen base

• absorption happens in SI walls:

  • villi + microvilli absorb:

    • non-fat nutrients

  • lacteal/lympthatic system absorb:

    • fat products (glycerol + fatty acids)