LAB 7- Digestive System Flashcards
Digestive System Function
- Ingestion
- Mechanical processing
‒ Chewing - Chemical digestion
‒ Secretion of digestive enzymes - Absorption
- Compaction into feces
- Defecation
Digestion Activities
-Digestive enzyme action
‒ Bile emulsification
Organs of
Digestive tract
(alimentary
canal)
Mouth
- Oral cavity with
teeth and
tongue
- Pharynx
- Esophagus
- Stomach
- Small intestine
- Large intestine
- Anus
Accessory
digestive
organs
Salivary
Glands
- Liver
- Gallbladder
- Pancreas
Peritoneum
-Retroperitoneal organs: Pancreas,
Duodenum, Rectum
-Serous membrane:
Parietal peritoneum
Visceral peritoneum =Serosa
Peritoneal cavity =potential space
between layers
Duodenum is
the first part of the small intestine
seruos membrane is
largest membrane that lines cavity
Mesentery
-Double sheets of peritoneum that suspend the organs and hold them in
place
Two Types:
Dorsal: mesentery proper, small intestine, greater omentum, colon, liver, stomach
ventral: lesser omentum, falciform ligament
Oral Cavity (Mouth) Digestive Functions
Ingestion
Secretion: Saliva
Mechanical digestion: Mastication = Chewing, Mixing
Chemical digestion: Salivary amylase
Propulsion
control muscle vs no control muscles
control- skeletal
no control- smooth
oral phase
-tongue forms a food bolus and pushes it into the laryngopharynx
Pharynx (Throat) Digestive function
Propulsion: Swallowing or Deglutition = Skeletal muscle propels food into
the esophagus
Esophagus anatomy
-Collapsible tube passageway
Esophageal hiatus:
‒ Opening in diaphragm for
esophagus
Lower esophageal
sphincter:
– Controls food entry and
movement back into
esophagus
Esophagus function
Digestive function:
Peristalsis: pushes food forward with contractions
-Solid food takes 4 to 8
seconds to get from
mouth to stomach
Liquid takes ~ 1 second
GERD =
gastroesophageal reflux disease – chronic heartburn
– can lead to esophageal cancer
Stomach Anatomy
Four regions in stomach:
– Cardia
– Fundus
– Body
– Pylorus
Lesser curvature
Greater Curvature
Rugae (wrinkles)
– Large folds in
mucosa
Pyloric sphincter
Stomach Digestive Functions
-temporary storage of food
Chemical digestion - secretes gastric
juice: Pepsin, HCl, Intrinsic factor, Gastric lipase
Mechanical digestion - body and
pylorus: Peristaltic mixing waves, Maceration, Chyme = creamy liquid mix of gastric juice and food
Absorption (small amount)
‒ Water, ions, short fatty acids and some drugs
intestine wall layers
Four layers in order:
- Mucosa: lamina propria, strat sqad, epi, smooth muscle
- Submuscosa: connective tissue, blood vessels, lymphatic vessels, glands, enteric nervous system
- Muscularis externa: inner and outer layer
- Serosa: visceral peritoneum
Small Intestine anatomy
three Components:
Duodenum
Jejunum (empty)
Ileum
Structures that ↑ surface area of the
mucosa:
– ridges of mucosa
– Villi
– Microvilli
= brush border
Small Intestine Digestive Functions
Secretion
– Mucus
– Intestinal juice
– Bile from liver
Mechanical digestion and mixing
– Segmentation
– Bile emulsification of lipids
Chemical digestion
– Digestive enzymes break down
carbohydrate, lipid and protein
Absorption
– nutrient
– water
Propulsion
– Peristalsis 19
large intestine anatomy
Cecum
Vermiform appendix
Colon
Taeniae coli:
leocecal valve
Fatty appendices
Rectum
Anal canal
external/internal sphincter
Large Intestine Digestive Function
Digestion by intestinal bacteria
- secretes mucus only, no enzymes
Formation and absorption of vitamin Kand B
Consolidation and propulsion of unusable fecal matter toward anus
Elimination
Large intestine dysfunction
Diarrhea: many causes, occurs with any condition that reduces transit time of food through the LI decreasing time to absorb water
Constipation: many causes, occurs with any condition that results in food residue sitting in the LI for extended periods so too much water is absorbed
Accessory Digestive Organs –
Salivary Glands
saliva three parts:
-parotid gland
-submandibular gland
-sublingual gland
Saliva components:
-Mucin- moistens food &
binds it into a
“bolus” (sticky)
- Serous clear fluid
-salivary
amylase = enzyme
that initiates starch
digestion
Teeth
-20 Primary teeth= temporary
-32 Secondary teeth =
Adult or Permanent
Accessory Digestive Organs – Liver &
Gallbladder
-liver: produces bile, bile emulsifies fat
-gall bladder- stores and concentrates bile, gallstones
jaundice
-yellowing of skin
-Liver dysfunction or
blockage
Accessory Digestive Organs – Pancreas
Exocrine gland = Secretes pancreatic juice from pancreatic duct to duodenum
-digests carbs, lipids, nucleic acids, protein
Endocrine gland:
Produces insulin and glucagon (hormones)
Starch is
a polysaccharide consisting of long chains of glucose.
Amylase is
an enzyme found in saliva
that breaks down polysaccharides into smaller oligosaccharides and disaccharides such as maltose and glucose
Benedict solution is
used to identify monosaccharides and some disaccharides.
T or F : pH affects the way enzymes such as amylase function
true
A positive result for the Benedict test occurs anytime
the reagent changes from its original blue color
Benedict reagent reacts with high levels of maltose, creating a
solution an orange color
A weak reaction with just a little maltose, or other simple sugars
turns Benedict reagent green
Enzymes are active _______and their activity is decreased below and above that range.
within a certain pH range,
Enzymes serve as
biological catalysts that decrease the amount of energy required to
initiate a reaction
activation energy
energy required to convert a substrate (for example starch) into a product (in this case: glucose)
substrates
The specific molecule or molecules that are acted upon by an enzyme
products
released from the surface of the enzyme
Enzymes do not change the
thermodynamic equilibrium of a reaction; they merely increase the rate of a reaction and
speed up the approach toward chemical equilibrium
when heat is added to an enzyme its
denatured
Lugol’s and Benedict’s solutions
are indicators
for starch and monosaccharides (such as glucose)
Lugol’s solution: colors for absence of starch and presence of starch
-dark yellow
-black/purple
Benedict’s solution color for absence and presence of disaccharides
-blue
-orange
Bile salts
-amphipathic molecules made by the liver.
-hydrophobic and a hydrophilic
-aid the body in lipid digestion, but they are not enzymes
Litmus is a pH indicator color for acid and base
-pink/red
-blue/lavendar
