Download Keshara`s Super short study guide! -Organelles -

Keshara's Super short study guide!
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-Organelles --> 15 questions
>cells "tiny organs" interdependent
The advantages organelles provide Eukaryotes:
>Advanced compartmentalization
>Decrease time for random collisions
Nucleus: "blue print" Gives code for making proteins/houses DNA
DNA --> gives mRNA the code --> mRNA makes protein
Has double membrane, porous, and is the biggest organelle
Endoplasmic Reticulum: "construction" makes "new" proteins
nucleus-contiguous, reticulating sacs
"rough" has ribosome. "Makes" proteins from mRNA (chaperones "shaped" proteins)
>it addresses via signal peptide
>signal peptide directs protein to a cellular location
1) NH2 terminal --> ER
2) Mid peptide --> Organelles
3) no signal --> cytosol (secreted; made by ER- free ribosome)
"Chaperones" shape peptides into functional proteins
>Smooth E.R has NO ribosome
>makes/shapes lipids and steroids,
Golgi Apparatus: "mailbox/post office"
>puts proteins, lipids, to their workplace
Address via glycosylation (+oligosaccharides)
>works with the endoplasmic reticulum
E.R --> golgi (takes proteins produced/macro molecules) --> sort/label/package into vesicles (goes through
"oligosaccharide-modification" --> sent to lysosome, plasma membrane, extra-cellular matrix
Lysosome: "recycling container"
>Recycles old proteins to new ones.
Pompe's disease - liver cannot break down glycogen into glucose (decrease in acid alpha
glucosidase/increase in lysosomal glycogen ---> increase lysosomal glycogen = cell death)
>symptoms in infants are reparatory
>in adults its musculoskeletal
>treated by daily recombinant enzyme replacement therapy = EXPENSIVE
Tay Sachs disease - brain disease
> lysosome cannot breakdown lipids
>founds a lot in ashkenazi jews
>treated by enzyme replacement/substrate reduction/pryrimenthamine
>Lysosomes are enclosed by a single membrane (lysosomes contain harsh digestive enzymes). They
contain different hydrolytic enzymes, such as proteases, lipases, and nucleases that are capable of breaking
down all types of biological polymers (e.g. proteins, nucleic acids, carbohydrates, and lipids) that enter the
cell or are no longer useful to the cell
>The membrane around a lysosome allows the digestive enzymes to work at the 5 pH they require.
Lysosomes fuse with vacuoles and dispense their enzymes into the vacuoles, digesting their contents. They
are created by the addition of hydrolytic enzymes to early endosomes from the Golgi apparatus.
>Lysosomes function as the digestive system of the cell.
>lysosomes avoid self-digestion by "glycosylation"
>Lysosomes are manufactured into the cytoplasm by the Golgi apparatus with enzymes inside.
>The enzymes that are within the lysosome are made in the rough endoplasmic reticulum
Peroxisome: "garbage can"
>Catalase H2O2 into H2O + O2
>not e.r dervived
Mitochondrion: "refrigerator" ATP
>power house
>glucose (C6H12O6) + O2 --> ATP
>nature selects folded membrane because it increase surface area and subsequent ATP
>Free radical (superoxide O2^-2 mutates Mitochondria-DNA (lone pair electrons) )
>mitochodria reproduction is asexual-binary fission (it can also fuse with other mitochondria. In many
single celled eukaryotes their growth and division is linked to the cell cycle. In multi-cell eukaryotes it
replicated DNA and divides in response to the energy needs of the cell
>to be clear mDNA/mtDNA = Mitochondrial DNA. Its the DNA located in the mitochondria, most other
DNA is located into the nucleus
>it accounts for only 37 genes (inherited from mother)
>transcription --> multi gene transcripts
>translation = E.R
>not all Mitochondria are encoded by its genome
>most are coded by genes in the nucleus and the proteins imported into it
Chloroplast: "generator"
Plasma Membrane: "door" Signal/filter
Cytoskeleton: "wall"
>cell's cytoplasmic support of envelope via actin/myosin
*note:
Muscle, brain are aerobic (O2) and mitochondria rich
Decrease calories = increase life (sirtuin)
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-Parameters on how big a cell can become
Cell Size = Surface area/Volume
"perfect" cell size is 0.6m (animal cell; ie: man/elephant)
Surface area = 0.6um^3
Volume = 10^3 um^3
(as a side note u = micro or 10^-6)
Plant is "cut off"
Cell size = 0.06m
Surface Area = 60,000 um^2
Volume = 10^6 um^3
If the cell size = 0.006
(surface area = 6 X 10^6 um^2 and volume = 10^9)
The cell is "dead" ---> can not exist
You need a HIGH surface area to have a fast import of nutrients, and to export waste.
You need low volume to have an INCREASE in collisions among molecules
(as a side note a small cell size reduces nutrient/waste rate and enzyme/substrate collisions, so plants are
metabolically slower than us
In size Eukaryotes > prokaryotes > viruses > proteins > small molecules > atoms
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- Know plant only organelles
-Vacuole: "reservoir"
Stores H2O, starch, and protein
-Cell wall "structure" surrounds plasma membrane
>made up of cellulose
Plastids: store/synthesize sugar, chlorophyll (photosynthesis). They manufacture and store chemical
compounds used by the cell.
Chloroplast: "generator":
photo-synthesis
LIGHT + CO2 + H2O --> C6H12O6 + O2
>like mitochondria it produces energy/is double membrane. But unlike it, it is endothermic/has mesophyll
cells
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-Know endo-symbiosis
Endo-symbiosis: small, special guy "teams up with" big, simple guy
(DNA)
+
(small special prokaryote)
{
DNA
} =
(big simple prokaryote)
[{(DNA)} DNA]
(Eukaryote [organelles containing prokaryote)
Arguments against endo-symbiosis:
>dependant
>dysfunctional lysosomes
>no inter species fusion
Arguments for endo-symbiosis
>double membrane
>prok-DNA
(no introns)
>independent genes become vestigial
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-Know plasma membrane
>How lipids arrange into a bi-layer
-Know which molecules can diffuse, which need facilitates transport
-Know principles of diffusion/active transport
Membrane is Semi permeable "barrier"
-bi-layer lines up "tail to tail" because of hydrophilic "head" and hydrophobic "tail" (uncharged
hydrocarbon removed from H20 [nonpolar])
(+ out - in)
>evolved from single layer membrane to increase volume
>hydrophobic, neutral, small molecules simply diffuse via cell
>Stuff that simply diffuses: H2O, CO2, O2 = neutral/small
Estrogen = nonpolar
>Stuff that doesn't do through easily
>H+ (charged)
>Glucose = Polar
>Insulin = Polar
Simple diffusion = passive/facilitated transport
1) "down hill" high to low concentration
2) equilibrium
3) ATP free (exo thermic)
Facilitated transport = simple diffusion = passive transport
>like said before, H2O simply diffuses through the cell (nephron has aquaporins to speed up process)
>O2, CO2 simply diffuse through erythorocytes
H+ is facilitates into mitochondrion via ATP synthase
Glucose is facilitated into cells via insulin activated transport
Active transport:
1) molecules move "up hill" from low to high concentrations
2) create a gradient (polarity)
3) cost ATP
Osmosis = simply diffusion of H2O
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-Know what would happen to a cell in a hypo/iso/hyper environment
Isotonic = 90% H2O + 10% solute
Hypo-tonic = 100% H2O + 0% solute
>90% H2O (ISOTONIC)
Hyper-tonic = 80% H2O + 20% solute
<90% H2O (ISOTONIC)
Cell "shrinks" in hyper tonic solution (water follows salts/solute)
Note taking these things:
Sweat, beer, tea (caffeine) = hyper tonic
Salt -- hyper tonic
Water --> hypotonic
Water maintains blood pressure, temperature, cell volume
Starch is too large; size usually is not an issue in your body
(please note starch's bonding is the reason why your body doesn't take it)
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-Know the 3 parts of cell theory
1) Cells are the smallest living functional unit
2) All organelles are composed of cells
3) all living things come from pre-existing cells
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-Know the cellular organization
Cell -->
[life's smallest unit] (myocte cell = muscle ; neuronal cell = nerve)
tissue -->
[10^8/9 cells that have the same function forms a tissue]
organ --> [10^11/13 different functioning tissues form a organ]*
organ system --> [10^12/14 cells organs working toward goal]**
organism
*Specific organs you should remember and the parts.
(For brain)
>Medulla --> Involuntary
> Cerebullum --> voluntary
>Cerebrum --> Thinking
(for liver)
>emulsifies and packages diet-fat
>detoxifies alcohol
**Specific organ systems include:
Digestive: Stomach, liver, pancreas, small/large intestine
Cardio-Pulmonary: Lungs, heart, artery, capillaries, veins
>the endothelium is the smooth interior lining of more than 60,000 miles of blood vessels.
>this tissue, if removed from the body and flattened would cover over 6 tennis courts. called "brain of
arteries"
> it acts as a smart barrier to control which substances can pass from the blood into the arterial wall.
>it also releases molecules that help regulate blood pressure, fight off disease, and control blood clotting
(so we have fine-tuned blood so fluid can flow easily enough)
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>Microscope
>Know everything about the microscope and the relationship of magnification and field of view
>Know how to calculate total magnification
>Know basic lab application
>Know the type of lens to start out with
-Start out with 10x lens
Lens refracts light magnifies, inverts image
-resolution = detail
Compound light microscope:
magnify 100x --> resolve >= 200nm
Fluorescent microscope
magnify: 1000x
resolves: >= 10nm
Electron microscope:
magnify: 500,000x
resolves: >= 1nm
Total magnification = ocular X objective
Field of view = circular area under microscope is inversely related to magnification
SO if
TOT mag = 10x FOV = 16nm
TOT mag = 40x FOV = 4nm
TOT mag = 100X FOV = 1.6nm
TOT mag = 400x FOV = 0.4nm
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-How paper chromatography works and how it separates stuff
>isolates, identifies a molecules based on its interaction with solvent (solubility)
>polarity also (more soluble molecule = higher up)
>chlorophyll goes up (type A is more polar than type B)
-Know differential centrifugation
> is density based isolation of organelles via centripetal force
>heavy = fast
>light = slow
-Blender separates tissue's cells
>detergents opens (solubilizes) cell's plasma membrane
-Then you pour the homogenate (the uniform substance) onto a density gradient
So how would you isolate ribosome?
1) Centrifuge @ 100,000g
2) transfer "supe" into fresh tube
Supernatant = liquid
"light organelles stay in solution (at equal densities)
Pellet = solid
"heavier" organelles precipitate out of solution
Assay - test for presence, activity of organelles
Precipitate --> salt neutralizes DNA (less hydrophillic)
Alcohol shields DNA from H2O
-Spectrotography: identify, quantify a molecule via absorbing a unique wavelength of light
DNA = 260 nm
Protein = 280 nm
Chlorophyll A = 450 nm/650nm
-Know beers law (concentration and absorbance reading)
Beer's law
Absorbance = [molecule]
Ie:
5mg molecule = 50% absorbance @650 nm
A) 10mg = 100% ABS
B) 1mg = 10% ABS
C) 0.001 = 0.1% ABS (directly proportional)
Want to pipette out 1/1000 th of a stock solution?
Use serial dilution!
>A serial dilution is the stepwise dilution of a substance in solution. Usually the dilution factor at each step
is constant, resulting in a geometric progression of the concentration in a logarithmic fashion. A ten-fold
serial dilution could be 1 M, 0.1 M, 0.01 M, 0.001 M... Serial dilutions are used to accurately create highly
diluted solutions/
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-(10 question) in digestion.
>Mouth/teeth/salvia
>stomach and what contractions it has
>when mechanical and when is chemical
-function of esophagus
-stomach and what’s gastric
>Know pepsin to pepsinogin (+ feedback)
>know negative feedback aspect of gastric juice (turns itself off)
-know bile
-pancreas (and the -ogen non active enzymes it releases)
-liver also releases stuff
>both release stuff to small intestine
>small intestine is associated with absorption
>know the physical features that maximize absorption into the blood
-know cecum (large intestine)
-big cecum = plant eater (Koala)
Digest
1) break-down
Mechanical, chemical
2) Absorb
Monomers into blood, cells
3) Excrete
Remove waste
1st tude -- digestive tract
2nd tube - body
Mouth, stomach, liver, pancreas, and small intestine contribute to breakdown
-hydro-lytic enzymes break polymers into monomers
Smooth muscle line digestive tract, is involuntary
Teeth mechanically digest food.
Incisors: shear
Canines: long pointed, "grip/rip"
Molars: large surface area, to grind
Mechanical (teeth) increase of surface area so it aids in chemical digestion
Molars helped man go from meat -- > plant.
Mouth chemically digests food through the salivary glands
>mucin: lubricates/neautralizes
>amylase: hydro-lyzes starch
>lysozyme: hydrolyzes bacterial wall
On tongue
taste buds: identify food
Bolus: partially digested food; is easy to swallow
Epiglottis: cartilage-flap that keeps food out of the trachea
Esophagus: mouth to stomach
Peristalsis: is the weak, slow "wave-like" contractions done by the SMC lined esophagus
(moves foward so bolus moves forward)
Tracheotomy: making a incision in the trachea and inserting tube into the stoma to create airway
Stomach is a hallow smooth "j" shaped pouch which is sphicter paced
Protease hydrolyzes protein
Mucous buffers acid
ulcer: cause by increase stomach acids/ decrease in sodium bicarbonate relased/mucus lining the stomach
wall
Stomach (mechanical) - J pouch churns/squeezes
Sphincter - ringed muscules pace digestion
Chemical
No food (less pH of 4)
decrease in gastrin secretion = decrease in gastric juice
Yes food (> pH 4)
Increase in gastrin secretion = increase in gastric juice
HCl + pepsinogen + mucus
Negative feedback:
Gastrin --> HCl + pepsinogen
pepsingogen is a zymogen (an inactive enzyme)
An increase in HCl causes a decrease in gastrin = gastric juice
So there will be a limited amout of gastric juice in your stomach at any one time
Positive feedback:
HCl + Pepsinogen --> Pepsin
Pepsin protease hydrolyze-activates zymogen
>basically Pepsin helps makes more pepsinogen
Gastrin --> HCL + Pepsinogen --> Pepsin
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( - ) feedback
( + ) feeback
Chyme = acidic slurry enters small intestine
Ghrelin = appetite stimulant
Leptin = appetite suppressant
Pancrease is exo-crine "feeds" small intestine
Endo-crine "feeds" blood
Pancreatic juice:
1) has sodium bicarbonate (NaCO3^-)
2) nuclease, lipase, amylase, protease
Pancreas proteases/activates zymogens
Liver - produces bile
Gallbladder- "paces' bile small intestine
Bile - emulsifies (breaks-up) fat
Small intestine hydrolyzes and absorbs
1) a decrease in chyme cause a release in pancreatic juice
2) increase in bile
3) turns polysaccharides into monosaccharide's
Small intestine aborbs monomers into blood/cells
Helped by villi, finger like projections that increase furface area.
Micro-villi: "finger like" projections on each cell
For absorption:
endo-cytosis into small intestine
exo-cytosis into capillaries
Excrete -- large intestine
Colon - removes waste and re-absorb H2O
Fiber or "roughage" attracts water and create pressure to induce bowerl movements
Cecum is used to digest cellulose.
Appendix - cullulase-like enzymes; vestigial organ (not needed)
Herbivores have an increase cecum (like Koalas)
-> Amoeba are eukaryotic protist
>they use phago-cytosis via surface receptions (have actin/polymerize and lysososme function)
>a phagocyte (ligand) binds surface receptor (triggers phagocytosis) --> triggers phagocytosis
>bound receptors cluster
>phagocyte is endocytosed
Pseudopodie: extend/contract of actin subunits into microfilaments
>actin interacts with myosin to cause movement
Hydra (chindarian) is considered advance (eukaryote)
It has differentiated cells
It uses its Cnidocyte "tentacles" /takeshi/ to catch or defend against prey
For birds
1) Mouth "bill" is made out of keratin
2) esophagus connects mouth to stomach
3) crop is for storage
4) gizzard is for stomach (has dirt kept there)
5) cecum (colon) houses microbes
6) pellet (regugitated ingestibles)
Ruminants for cow/sheep/goat
Rumen = 1st stomach
Reticulum = 2nd stomach
"CUD" regurgitated food
Omasum = 3rd stomach
Abomasum = 4th stomach
-Know functional unit of kidney
-know filtration and what gets dumped into nephrons and know what gets absorbed into the blood
-know role of active transport on blood and what aquaporins are
-Know how ADH works
-know how diaretics works
-Know raas
-Know urea
Renal artery: O2, waste, nutrients, H2O
Renal vein: nutrients, H2O
Cortex "outside"
Nephrons are Kidney's functional unit
Medulla is the "inside" nephrons extend into collecting ducts
Collecting ducts: "feed' ureter
Ureters "feed" bladder
Dietary protein = excess amino acids
NH3 (ammonia) is toxic (released from using amino acid)
Liver combines this with Carbon dioxide and this forms Urea
(NH2)2CO = urea not toxic
>kidneys concentrate urea into urine
Nephron is multi cellular
Glomerulus is porous capillaries that filtrate nephron.
Filtrate diffuses from blood into nephron.
Glomerulus ----urea, toxins, h2o, salt, nutrients --> nephron
<---- salt, nutrient, h20 -----------------Bowman's capsule "houses" glomerulus and recieves filtrate
Proximal tubule reabsorbs nutrients into blood via active transport
Loop of henle "pumps out" Na+; H2O follows into blood
Dital tubule "pumps in" toxins
Collecting tube H2O permeable; osmo-regulation target
Aquarons INCREASE osmosis.
Antiduretic hormone (ADH; also called vasopressin)
Increases H2O reabsorption (especially helpful during the summer months)
Renin-angiotensin algosterone system (RAAS)
loss of blood --> nephron's renin
Increase H2O in BLOOD ->
1) contracts arteries
2) "on" tubule Na+ pumps
3) "on" ADH"
"ON aquaporins"
Alcohol/coffee are diuretics = cause dehydration
>decrease brain's ADH
"off" aquaporins
Caffeine "off" Na+ pump
How different animals keep water:
Camels - long collecting tubules
Kangaroo Rat - long loop of henle
Birds, repties: reduced glomerulus
Birds, reptiles: excrete uric acid
Amphibian: contricutered arterioles; long intestine
Man: mixed sizes of loop of henle
Hemo-dialysis: acts as artifical kidney
Heparin = anti-coagulant
Gout - "rich man's disease" caused by purine-rich foods (meat/seafood/alchohol)
Kidney stones = caused by protein rich foods
*notes from book*
Mouth
Amylase (salivary glands) breaks down starch into disaccharides
Mucus, water (salivary glands) lubricates, dissolves food
Stomach
Hydrochloric acid (cell lining stomach) allows pepsin to work, kills bacteria, solubilizes minerals
Pepsin (cell lining stomach) breaks down proteins into large peptides
Mucus (cell lining stomach) protects stomach
Small intestine
Sodium Bicarbonate (Pancreas) Neutralizes acidic chyme from stomach
Amylase (Pancreas) Breaks down starch into disaccharides
Peptidases (Pancreas) Split large peptides into small peptides
Trypsin (Pancreas) Breaks down proteins into large peptides
Chymotrypsin (Pancreas) Breaks down proteins into large peptides
Lipase (Pancreas) breaks down lipids into fatty acids and glycerol
Bile (liver) Emulsifies lipids
Peptidases (cells lining small intestines) split small peptides into amino acids
Disaccharidases (cells lining small intestines) split disaccharides into monosaccharides
After the food is pulverized by teeth, salvia kicks in *contains the enzyme amylase* which breaks down
starches into sugar. With the help of the tongue the food mass (Bolus) is pressed into the pharynx (muscular
cavity connecting the mouth with the esophagus). Epiglottis is a flap of tissue which blocks off the
respiratory passages so the food is directed to the esophagus and not the trachea.
The esophagus is the muscular tube that propels food from the mouth to the stomach. Circular muscles
contract in sequence, this muscular action is called PERISTALSIS (which also occurs in the stomach and
intestines). [mucus -- secreted by the cell lines up on the esophagus so it helps lubricate it]
The stomach is a expandable muscular sac which can hold 2-4 L (1 gallon) of flood/liquid. Food is retained
by a ring of circular muscles that separate the lower portion of the stomach from the upper small intestine.
>this muscle is called the "pyloric sphincter" which regulates the passage of food into the small intestine
Stomach has 3 major functions
1) the stomach stores food and gradually releases it into the small intestine at a rate which is proper for
digestion/absorption
2) assists in mechanical breakdown of food
3) glands in the stomach secrete enzymes and other substances that facilitate the chemical breakdown of
food. This includes
>gastrin, HCl, pepsinogen, and mucus
>Gastrin (hormone) helps secretion of HCL by specialized stomach cells
>other cells release pepsinogen an inactive form of the enzyme pepsin (which is protein-digesting)
>pepsin is a protease, an enzyme that breaks down proteins into peptides
>pepsin must be secreted in the inactive form to prevent it from destroying the cells that produce it
>highly acidic conditions in the stomach (pH of 1 to 3) convert pepsinogen to pepsin
Food in the stomach gradually form a thick acidic liquid called chyme
>peristaltic waves then propel chyme toward the small intestine
>pyloric sphincter allows around a teaspoon of chyme to be expelled in each contraction (20 seconds long)
The small intestine a narrow tube (3 meters/10 feet long) has 2 major functions
1)digest food into small molecules
>>this is accomplished with the aid of digestive secretion from the liver, pancreas, and cells of the small
intestine itself
2) and to absorb these molecules, passing them into the blood stream
The liver
>stores fats and carbs for energy
>regulates blood glucose level (glycogen comes from here)
>synthesis of blood proteins
>storage of iron and certain vitamins
>conversion of toxic ammonia (released from break down of amino acids) into urea
>detoxification
>the role of the liver in digestion is to produce "bile" a liquid stored in the gallbladder and released into the
small intestine through a tube called the bile duct
Bile is a complex mixture composed of bile salts, water, other salts, cholesterol, and amino acids.
>bile salts are synthesized in the liver from cholesterol and amino acids.
>even though they are involved in the break down of lipids, bile salts are not enzymes (they act as
detergents/emulsifying agents) dispersing globs of fat in the chyme into microscopic particles
>these particles expose a large surface area for attack by LIPASE a lipid digesting enzyme produced by the
pancreas
Pancreas (lies between the stomach and small intestine) has 2 major types of cells
1) one type produces hormones involved in blood sugar regulation (insulin come from here)
2) other produces a digestive secretion called pancreatic juice
>which is released into the small intestine
>it neutralizes the acidic chyme producing a slightly basic pH
Pancreatic digestive enzyme break down 3 major types of food
1) amylase breaks down carbs
2) lipase digest lipids
3) several proteases seperate proteins and peptides (trypsin, chymotrypsin, carboxypeptidase)
Trypsin and chymotrypsin break proteins and peptides into shorter peptide chains.
>carboxypeptidase completes protein digestion by seperating individual aimo acids from the end of the
peptide chains. These proteases are secreted in an inactive form and become activated once in the small
intestine.
The wall of the small inestine completes the digestive process by absorbing in all the nutrients in the blood
(by using several protease listed above to break down amino acids into peptides and absorbs lipids)
Small intestine is a major site of nutrient absorption into the blood.
>the small intestine has numerous folding and projections that give it a huge internal surface. Covering the
entire surface area are fingerlike projections called villi. They move gently back and forth in the chyme that
passes through the small intestine.
>this movement increases their exposure to the molecules to be digested/absorbed
>each villi have microvilli
"segmentation movements" rhythmic unsynchronized contraction of the circular muscles of the intestine
slosh the chyme back and forth brining nutrients into contact with the absorptive surface.
>when absorption is complete, coordinated peristaltic waves conduct the leftovers into the large intestine
>nutrients diffuse out of the intestinal cells into the intersititial fluid, where they enter the bloodstream
>each villus (plural of villi) is provided with a rich supply of blood capillaries and a single lymph capillary
called a lacteam which carry off absorbed nutrients and aborb them throughout the body.
>most nutrients enter the body throught the capillaries but fat subunits take a different router.
>after diffusing into the epithelial cells they resynthesize into fats, combined with other molecues, and then
released as droplets into the intersitial fluid.
The large intestine in an adult human is about 1.5 meters long (smaller than the "small" intestine in lenght)
>has two part
1) Colon
2) rectum
>cell linining absorb B vitamins made by bacteria in the large intestine
>also absorb leftover water and salt
--> rectum pushed out food through peristaltic movements
>digestion is controlled by the nervous system and hormones
When food comes into the stomach it triggers the second phase of digestion. Stimulation of the stomach
wall causes the production of a large quantity of mucus which protects the stomach.
>acidity of stomach converts pepsinogen into pepsin
>begins protein digestion
>however presence of protein in food reduces the concentration of stomach acids
>as protein is broken down, acidity drops, and the release of gastrin is no longer inhibited
>gastrin is then released again and stimulates further acid production
>cells secreting stomach acid are also activated by expansion of the stomach and by presence of peptides
produced by protein digestion
>liquid chyme is gradually released into small intestine
>its acidity stimulates the release of a second hormone called SECRETIN into the bloodstream by cells in
the upper intestine.
>secretin causes the pancreas to pour sodium bicarbonate into the small intestine
>sodium bicarbonate neutralizes the acidity of the incoming chyme, creating an environment in which the
pancreatic enzyme can function.
>3rd hormone called cholecytokinin is produced by the cells of the upper small intestine as a response to
the presence of chyme,
>this hormone causes pancreas to release various digestive enzymes into the small intestine
>causes the gallbladder to contract, squeezing bile through the bile duct to the small intestine. (bile assist in
bile breakdown)
Gastric inhibitory peptide, a hormone secrete by the small intestine in response to the presence of fatty
acids and sugar in chyme inhibits acid products and peristalsis in the stomach.
>this slows the rate at which chyme is dumped into the small intestine, providing additional time for
digestion an absorption to occur
Charts that summarizes the paragraph above:
( ) = site of production
[ ] = stimulus for production
{effect}
Hormones
Gastrin (stomach) [food in mouth/peptides in stomach] {stimulates acid secretion by cells in stomach}
Secretin (small intestine) [acid in small intestine] {stimulates bicarbonate production by pancreas and liver;
increases bile output by liver}
Cholecystoksin (small intestine) [amino acids, fatty acids in small intestine] {stimulates secretion of
pancreatic enzymes and release of bile by gallbladder}
Gastric Inhibitory Peptide (small intestine) [fatty acids and sugar in small intestine] {inhibits stomach
movements and release of stomach acid}
pg594-603 if you want more stuff about kidneys
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