BIO12 - unit 3 - digestive system

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digestion def

digestion def

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

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 of indigestive residues from body (poop)

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

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

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

heartburn

→ contains

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

→ HCl and pepsin

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 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

-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; 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

-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 into peptides (smaller a.a. chains) → 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

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

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 enzymes (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

-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 red blood cell 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

acid chyme

-descr

-where called

-acidic

-liquid-y

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

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

where are biomolcules fully done digesting

-lipids/fats → in duodenum

-rest in small intestine after duodenum

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

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

-6 main functions]

• production of bile (then stored in gallbladder)

  • 1.5 L / day

• production of blood proteins from amino acid

• produces urea from breakdown of amino acids

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

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

  • gives bile its greenish-yellow colour)

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

• 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:

• 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 or 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

• 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