Humans must get basic organic molecules from food for what three reason
1. make ATP
2. build tissues
3. serves as cofactors and coenzymes
carbohydrates, fats, and proteins broken down to building blocks during digestion
polymers
building blocks taken into the bloodstream by absorption
monomers
By what process does digestion break down polymers into monomers?
hydolysis reactions- adding water
Where is the digestive tract considered to be in relation to the body?
outside
indigestible fiber- wood fiber
cellulose
Six functions of the digestive tract
1. motility
2. secretion
3. digestion
4. absorption
5. storage and elimination
6. immune barrier
taking food into the mouth
ingestion
chewing
mastication
swallowing
deglutination
one way automatic rhythmic movement through the GI tract starting at the esophagus after swallowing
peristlasis
churning as in the stomach
segmentation
digestive enzymes, acid, mucus released outside an organ or tract
exocrine
hormones to regulate digestion released within an organ or tract
endocrine
breaking food down into smaller units
digestion
passing broken down food into blood or lymph
absorption
simple columnar epithelium with tight junctions to prevent swallowed pathogens from entering the body
immune barrier
Parts of the GI tract
mouth- stomach- pharynx- esophagus- cardiac sphincter- stomach- pyloric sphincter- duodenum (SI)- jujenum (SI)- ileum (SI)- large intestines- rectum- anus
length of the gastrointestinal tract
30 feet
other organs that help the digestive tract but are not considered directly part of the tract
accessory organs
6 accessory organs
teeth
tongue
salivary glands
liver
pancreas
gallbladder
how many adult teeth do most people have?
32
GI tract layers
tunics
inner secretory and absorptive layer that may be folded to increase surface area
mucosa tunic
layer that contains glands and is very vascular to pick up nutrients
submucosa tunic
smooth muscle layer responsible for peristalsis and segmentation
muscularis tunic
outer binding and protective layer
serosa tunic
stimulates and speeds up esophagus, stomach, small intestine, pancreas, gallbladder, and first part of large intestine by using parasympathetic division of GI tract
vagus nerve
stimulates and speeds up lower large intestine by using the parasympathetic division of the GI tract
spinal nerves in sacral region
slows down and inhibits peristalsis and secretion by stimulating contraction of sphincters
sympathetic division of GI tract
paracrine signals and sensory neurons in gut wall
intrinsic regulation
contains mucus and amylase to start digestion of starch and carbs
saliva
antimicrobial agen in saliva
mucus
How many muscles coordinatedly contract in deglutination?
25 PAIRS
Three parts of deglutination
oral
pharyngeal
esophageal
voluntary part of deglutination where the muscles of mouth and tongue mix food with saliva
oral
initiated by receptors in the posterior oral cavity and oropharynx
pharyngeal
covers the nasopharynx
uvula
covers the vocal cord
esophagus
What relaxes in order to allow deglutination?
upper esophageal sphincter
automatic part of deglutination regulated by the controlled byswallowing center of the brain stem
esophageal
lump of food moving down the esophagus after swallowing
bolus
Mouth, pharynx, and upper esophagus are lined with ___ ____ and innervated by ___ ____ ___.
skeletal muscles; somatic motor neurons
Lower esophagus is lined with ___ ___ controlled by the ___ ____ ____.
smooth muscle; autonomic nervous system
length of the esophagus
10 inches
the esophagus passes through the diaphragm through what structure?
esophageal hiatus
esophagus is lined with what type of cells?
nonkeratinized stratified squamous epithelium
What sphincter allows food to pass into the stomach but not out
lower esophageal/ cardiac
5 functions of the stomach
stores food
churns food to mix with gastric secretions
begins protein digestion
kills bacteria in food with stomach acid
moves food into small intestine
food passing into the small intestines after going through the stomach
chyme
Food is delivered to the ___ region of the stomach.
cardiac
upper region of the stomach
fundus
lower region of the stomach
body
distal region of the stomach
pyloris
end of the pyloris and start of the small intestine
pyloric sphincter
stomach folds in lining
rugae
stomach ulcers most occur in what region?
pyloris
caused by overloading acids on barriers by burning, carbonation, and acidic foods
ulcers
Located at the base of rugae to make secretory cells
gastric pits
secrete mucus to help protect stomach lining from acid
mucus neck cells
secrete HCl acid and intrinsic factor to help small intestine absorb vitamin B12
parietal cells
secrete pepsinogen
chief cells
secrete histamine and serotonin as paracrine signals
enterochromaffin-like (ECL) cells
secrete gastrin hormone
G cells
descrete somatostatin hormone
D cells
primary active transport of H+ takes place through ____
H+/ K+ ATPase pumps
Cl- is transported through what process?
facilitated diffusion
made in G cells and carried to parietal cells in blood to stimulate secretion of HCl
gastrin
Gastrin stimulates ECL cells to secrete ___.
histamine
stimulates parietal cells via H2 receptors
histamine
stimulate parietal and ECL cells
parasympathetic neurons
Main functin of HCl
drops pH to 2
Describe the process by which HCl drops pH level
-Proteins denatured allowing enzyme access.
-Pepsinogen converted to active pepsin digests proteins.
-Drops pH level
Optimum pH for pepsin activity
2
Two things that could eat the stomach lining
acid and pepsin
Three defenses prevent eroding of the stomach lining
-adherent layer of mucus with bicarbonate
-tight junctions between epithelial cells
-rapid epithelial mitosis that replaces epithelium every three days
Stomach is the site of beginning digestion for which molecule?
proteins
Starches begin digestion in __
mouth
Starch digestion ends in the ___. Why?
stomach because salivary amylase is not active at pH 2
Only common substances absorbed in the stomach
alcohol and NSAIDs
erosions of the mucosa of the stomach or duodenum
peptic ulcers
bacterium that reduces mucosal barriers to acid
helicobacter pylori
treatment for ulcers is a combination of ___ and ___.
K+/H+ pump inhibitors and antibiotics
inflammation of the submucosa caused by erosion from acid
gastritis
needed to stimulate protective alkaline mucus production
prostaglandins
Tagamet and Zantac inhibit ___ receptors.
H2
big folds of the small intestine's mucosa and submucosa
plicae circulares
three sections of the small intestine in order from top to bottom
duodenum
jejunum
ileum
mucosa of the small intestine has smaller folds called __?
villi
epithelial plasma membranes are folded into ___
microvilli
Site of complete digestion of carbs, proteins, and fats
small intestine
Part of the small intestine that absorbs sugars, lipids, amino acids, calcium, and iron
duodenum and jejunum
part of the small intestine that absorpbs bile salts, vitamin B12, water, and electrolytes
ileum
columnar epithelium with goblet cells
villi and microvilli
what absorbs sugars and amino acids?
capillaries
absorbs fatty acids
lacteal
Lacteal is part of the ___ system.
lymphatic
have microbial properties and secrete antibacterial molecules
Paneth cells
Paneth cells and mitotic stem cells make up ___.
intestinal crypts
intestinal enzymes located on villi
brush border enzymes
Brush border enzymes break 2, 3, 4 carbs apart to make ___.
monosaccharides
Monosaccharides are absorbed by ___.
microvilli
Active sites of brush border enzymes are exposed to ___.
chyme
Intestinal peristalsis is week because of pressure where?
pyloric end
What upsets autonomic peristalic rhythms?
toxins in small intestine
Stronger function of small intestines and its purpose
segmentation- to mix the chyme
___ ___ contractions occur automatically.
smooth muscle
graded depolarizations produced by pacemaker cells that cause action potentions in muscle cells
slow waves
What causes smooth muscle to contract automatically?
slow waves
pacemaker cells of the smooth muscles
interstitial cells of Cajal
Depolorization fromt he interstitial cells of Cajal opens ___ gated __ channels
voltage; Ca2+
___ ___ nervous system stimulates or inhibits cells of Cajal.
autonomic enteric
Two things of the parasympathetic system that combine to increase amplitude and duration of slow waves
-absorptin of water, electrolytes, vitamin K, and some B vitamins
-production of vitamin K and B vitamins via microbial organisms
-storage of feces
-minimal break down of Beta 1, 4 (cellulose) linkages by bacteria
several hundred different species of bacteria that live in the large intestines
microbial biota
Two categories of intestinal bacteria
commensal and mutualistic
bacteria that benefit while not harming the host
commensal
bacteria that benefit while also benefiting the host
mutualistic
Four benefits of microbes
- make vitamin K and some B vitamins
-make fatty acids from cellulose for energy
-aid absorption of electrolytes and salts
-outcompete harmful bacteria
IBS is caused by disruption of normal ___.
microflora
How much water is excreted with feces per day?
200 mL
Stimulates greater salt and water absorption
aldosterone
what secretes aldosterone?
adrenal gland
Controls defecation voluntarily
external anal sphincter
contract to increase pressure as the anal sphincters relax
longitudinal rectal muscles
As material passes to the rectum, PRESSURE ___ and the internal sphincter ___.
increases; relaxes
largest abdominal organ
liver
first stop for blood from intestines
liver
regenerative liver cells
hepatocytes
capillaries that separate hepatic plates
sinusoids
True or False: The liver is very permeable.
TRUE
delivers products of digestion absorbed in intestines to the liver
hepatic portal vein
blood leaves the liver after circulating through its capillaries through the ___
hepatic vein
formed by hepatocytes and arranged as liver lobules with hepatic arteries, hepatic portal veins, and a central vein
hepatic plates
bile secreted by hepatocytes is released into the __ ___
bile canaliculi
Five functions of the liver
detox of blood
carbohydrate metabolism
fat metabolism
protein synthesis
secretion of bile
Where are molecules in bile reabsorbed to be returned to the liver?
small intestine
How much bile does the liver make per day
250-1500 ml
Five components of bile
bile pigments (bilirubin)
bile salts
phospholipids (lecithin)
cholesterol
inorganic ions
breaks large fat down into small beads of fat
emulsifier
what acts as an emulsifier
bile
color of bilirubin
red
a not water-soluble component derived from hemoglobin and produced in spleen, liver, and bone marrow
bilirubin
Bilirubin IS OR IS NOT directly filtered by kidneys and secreted by bile?
is not
conjugates with bilirubin to make the bilirubin water soluble
glucuronic acid
color of biliverdin
green
When can bilirubin be secreted in bile?
when it is water soluble and conjugated
component that makes feces brown and is converted from bilirubin by bacteria in the small intestine
urobilinogen
percentage of urobilinogen absorbed and taken to liver
30-50%
Some urobilinogen can be used in the blood and kidneys to make )).
bile
made from bile acids conjugated with glycineortaurine
bile salts
derived from cholesterol and contain four polar groups on each molecule
bile acids
Two examples of bile acids
cholic acid and chenodeoxycholic acid
most bile acids is recycled through ___ ___.
enterohepatic circulation
How much cholesterol is broken down and lost in feces?
1/2 gram
bile salts form ___ with polar groups toward water
micelles
functional bile salts contain __
amines
Three ways for the liver to detox the blood
secreted into bile
phagocytized by Kupffer cells in sinusoids
chemically altered by hepatocytes
converted into urea
ammonia
returned to the blood to be filtered by the kidneys
urea
altered and secreted into bile
steroids
Two things the liver stores blood glucose as and the processes by which it is done
glycogen- glycogenesis
triglycerides- lipogenesis
What happens to glucose that the liver breaks down to glycogen?
stored or release into blood
can be made by liver from glucose by process of ___.
amino acids; guconeogenesis
__ can be made from fatty acids by the liver by the process of ___.
Ketones; ketogenesis
stores and concentrates bile from the liver
gallbladder
tract of the gallbladder
liver- bile ducts- hepatic duct- cystic duct- gallbladder- cystic duct- common bile duct- duodenum
sphincter located in duodenum
sphincter of ampulla
make insulin and glucagon in pancreas
Islets of Langerhans cells
make pancreatic juice to be delivered to the duodenum
acini cells
Endocrine or Exocrine? insulin and glucagon of the pancreas
endocrine
Endocrine or Exocrine? pancreatic juice of pancreas
Exocrine
bicarbonate + 20 digestive enzymes
pancreatic juice
made from CO2 from the blood by cells lining ductules
bicarbonate
Process by which bicarbonate is made
-carbonic acid made
-carbonic acid dissociates to form H+ and bicarbonate
Bicarbonate is ___ into ___, and H+ is ___ into ___.
secreted; pancreatic juice; absorbed; blood
Bicarbonate is countertransported with __.
Cl-
condition in which a person has trouble secreting bicarbonate, thus destroying the pancreas
cystic fibrosis
inactive until they reach the small intestine
pancreatic enzymes
activates trypsinogen
enterokinase
activated enzyme to digest protein
trypsin
primary stage of digestion
mastication
starch digestion continues in small intestines with ___ ___
pancreatic amylase
Two components of brush border cells
tripsin and enzymes
Two ways monosaccharides are absorbed across the epithelium
- secondary active transport with sodium
- facilitated diffusion with high glucose
formed from pepsin in stomach during digestion of proteins
short-chain polypeptides
Five enzymes to finish protein digestion
-pancreatic trypsin
-chymo trypsin
-elastase
-carboxypeptidase
-aminopeptidase
Digestion of proteins end in the ...?
duodenum and jejunum
During the absorption of proteins, ____________ are cotransported with sodium
free amino acids
Dipeptides and tripeptides cross via what?
secondary active transport
Aids dipeptides and tripeptides in active transport
H+ gradient
pH range needed for protein digestion
6-8
Fat digestion begins where?
duodenum
breaks down or emulsifies fat
bile
breaks fat down into fatty acids
lipase
stripped to have two molecules outside of the gradient and one inside
glycerol
Fatty acids and monoglycerides are transported to ___
brush border cells
Fatty acids and monoglycerides in epithelial cells are turned into what three things?
triglycerides
cholesterol
phospholipids
Fatty acides combine with proteins to make __.
chylomicrons
main source of muscle energy
fatty acids
Two components of fat molecules
free fatty acids and glycerol
___ ___ drops chylomicrons into the bloodstream at the ___ ___.
lymphatic system; thoracic duct
agent that allows chylomicrons to bind to receptors on the capillary epithelium within muscles and adipose tissue
apolipoprotein
releases free fatty acids for use by muscle cells or storage by fat cells
lipoprotein lipase
Formed from the combination of cholesterol and triglycerides with apolipoproteins
very-low-density lipoproteins (VLDLs)
removed triglycerides which transport cholesterol to organs
low-density lipoproteins (LDLs)
cholesterol is excess returned to the liver
high-density lipids (HDLs)
primary function of the kidneys
blood pressure regulation
Four functions of the kidney
plasma volume/ BP
waste products in blood
electrolyte balance
plasma pH
functional unit of the kidney responible for forming urine
nephron
how many nephrons per kidney?
> one million
Three functions of nephrons
filtration
reabsorption
secretion
Made up of the glomerulus and Bowman's capsule
renal corpuscle
What is and is not secreted from the Bowman's capsule?
plasma is and blood is not
Function of the renal corpuscle
filtration
filtration slits of the kidney
glomerular capsule
Volumes of filtrate produced by BP
men- 125mL/min
women- 115mL/min
totals- 180L/day
connected to Bowman's capsule for reabsorption
proximal convoluted tubule (PCT)
returns most filtrate to peritubular capillaries
reabsorption of PCT
How much urine excreted in 24 hours maximum?
1-2 L
Minimum amount of urine that must be excreted per day
400 mL
Sodium goes out of filtrate by
active transport
Two things that passively follow sodium out of PCT
chlorine and water
part of Loop of Henle that is permeable to water; impermeable to salt
descending limb
part of Loop of Henle that is impermeable to water' permeable to salt
ascending limb
allow descending and ascending limbs of Loop to increase osmolality in medulla
countercurrent flow and proximity
An increase in osmolality in ___ ___ causes more filtrate to be delivered to ___ ___.
descending loop; ascending loop
Pumping sodium out of ascending loop __ osmolality causing increased ___ to diffuse out of ___ ___.
increases; water; descending loop
__ filtrate causes more sodium transport, which results in __ osmalality around ___ ___.
increased; increased; descending loop
covering of Loop of Henle for secretion
vasa recta
important component of countercurrent multiplier
vasa recta
Vasa recta recirculates salt trapping some in the ___.
medulla
what reabsorbs water coming from where on the loop of henle?
ascending loop; descending loop
hyperosmotic urine produced due to maintenance of solute gradients
urea
contributes to osmolality in medulla
urea
urea diffuses to __ __.
descending loop
plays important role in water conservation because it is impermeable to salt in the medulla and permeable to urea
collecting duct
permeability of water in the collecting duct varies because of
antidiuretic hormone (ADH)
Three components of urine
95% water
urea and uric acid
trace amino acids
causes regulation and secretion of urine
creatine and urea
imparied ability to excrete wastes and regulate blood volume, pH, and electrolyes- resulting from atherosclerosis, inflammation of tubules, kidney ischemia, or NSAIDs
acute renal failure
inflammation of glomeruli caused by an autoimmune attack against glomerular capillary basemen membranes and leakge of protein into urine
glomerulonephritis
nephrons destroyed causing salt and water retenion and uremia
renal insuffienciency
condition with high plasma H+ and K+ levels
uremia
inability to regulate ammonia or urea flow
gout
How to solve many urinary problems
drinking water
How much fluid does the average person need per day?
men- 3 liters (13 cups)
women- 2.2 liters (9 cups)
procedure used to shatter simple stones in the kidney or upper urinary tract
extracorporeal shock wave lithotripsy (ESWL)
bacteria enters the bladder or kidneys
cystitis
cystitis is more common in ___ because the urethra is shorter.
women
common name for cystitis
bladder infection
Symptoms of a urinary tract infection
frequent need to urinate
pain in abdomen
burning sensation during urination
cloudy, bad smelling urine
blood in urine
leaking urine
low back pain
fever
chills
nausea
poor appetite
A UTI can be an infection of what two things?
bladder or kidneys
tube that can be inserted into a body cavity (such as the bladder), duct, or vessel
catheter
process of inserting a catheter
catheterization
sudden contractions of the bladder produce sensation of urgency, more common in women
overactive bladder
inability to control urination or defecation
incontinence
synthetically removing, cleansing, and putting blood back through tubing of various passage sizes
dialysis
waste product of protein digestion
creatine
inadequate rate when kidneys fail to filter that causes an increase in creatine