Final exam (70% new material, 30% from the midterms) Flashcards
What are the 4 basic digestive processes of the digestive system? (simple)
1) Motility
2) Secretion
3) Digestion
4) Absorption
(Digestion) What is Motility? (simple)
Muscular contractions that cause mixing and moving material along the digestive tract.
(eg) smooth muscle helps with this
(Digestion) What is Secretion? (Simple)
Secretion of digestive enzymes
(eg) bile, salt, mucus, hormones, buffers
(Digestion) What is Digestion? (simple)
Chemical breakdown of large food molecules into smaller sub-units for absorption.
(Digestion) What is Absorption? (simple)
Small particles transported from the digestive tract across cells that line the digestive tract, then into the blood or lymph.
What mechanical processes break down food for digestion and why?
Chewing, swallowing, bile.
Turns food into chunks to increase surface area.
(more SA for enzymes to act on for CHEMICAL digestion)
What type of reaction occur when digestive enzymes break the chemical bonds in large molecules?
HYDROLYSIS
(catabolic pathway) breaks down. does not require energy. releases energy actually.
*water is used to break down a large molecule by inserting itself into it and connecting to the functional groups. O and OH on each new molecule)
6 major organs of the digestive system?
1) Oral cavity
2) Pharynx
3) Esophagus
4) Stomach
5) Small intestine
6) Large intestine
What does the oral cavity do for digestion?
- Ingestion
- Mechanical digestion with accessory organs (teeth, tongue)
- Moistening, mixing (creating more SA)
- Salivary secretions
What does the Pharynx do for digestion?
Uses muscular propulsion to push the food (bolus) into the esophagus
What does the esophagus do fro digestion?
Transport materials from the mouth to the stomach
What does the stomach do for digestion?
-Chemical digestion of materials by acid and enzymes
-Mechanical digestion through muscular contractions.
What does the small intestine do for the digestive system?
Enzymatic digestion
Absorption of water, organic substrates, vitamins, ions.
What does the large intestine do for the digestive system?
Dehydration and compaction of indigestible materials in preparation for elimination (POOP)
What are proteins?
Monomer=Amino acid
Multiple amino acids bonded together= peptide
Multiple peptides=polypeptide (large molecule)
What are carbohydrates?
Monomer=monosaccharides (Glucose)
2 monomers= disaccharides
Many monosaccharides together = Polysaccharide (Starch)
What are lipids? (digestion)
Triglycerides = 3 fatty acids 1 glycerol
(often get digested into 2 free fatty acids and 1 monoglyceride) (1 glucerol with 1 fatty acid attached)
What are nucleic acids? (digestion)
Polymer = DNA, RNA. broken down into nitrogenous bases and sugars
How do carbohydrates get digested?
Oral cavity (salivary amylase) (carbs are now disaccharide and trisaccharide)
Stomach (Proenzyme)
Sm Intestines (Pancreatic amylase)
*carbohydrates (polysaccharide), di/trisaccharide, monosaccharide)
How do lipids get digested?
Oral cavity (Lingual lipase)
Stomach (nada)
Sm Intestine (Bile, salts, pancreatic lypase)
-Monoglyceride and fatty acids
How do proteins get digested?
Oral cavity (nada)
Stomach (pepsin)
Sm Intestine (Trypsin, Chymotrypsin, Elastase, Carboxypeptidase)
-short peptides, amino acids
Salivary amylase. Wheres is active, whats its substrate and what are the products?
Oral cavity (salivary glands)
Polysaccharides (starch)
Disaccharides (maltose) and trisaccharide
Lingual lipase. Wheres it active, whats its substrate and what are the products?
Oral cavity (glands on tongue)
Lipids (triglycerides)
monoglycerides + 2 fatty acids
Pepsin. Wheres it active, whats it substrate and what are the products?
Stomach (produced by cheif cells)
Proteins
Small peptides and amino acids
Proteases (Chymotrypsin/ trypsin) Wheres it active, whats its substrate and what are the products?
Small intestine (Secreted by pancreas tho)
Proteins
Short chain peptides
Pancreatic amylase. Wheres it active, whats its substrate and what are the products?
Small intestine (secreted by pancreas tho)
Carbohydrates (polysaccharides -starch)
Di/trisaccharides
Pancreatic lipase. Wheres it active, whats its substrate and what are the products?
Small intestine (secreted by pancreas tho)
Lipids (triglycerides)
Monoglycerides + 2 fatty acids
Disaccharidases (Maltase). Wheres it active, whats its substrates and what are the products?
Small intestine
Disaccharides (Maltose)
Monosaccharides (glucose)
Disaccharidases (Sucrase). Wheres it active, whats its substrate and what are the products?
Small intestine
Disacchardies (Sucrose)
Monosaccharides (glucose/fructose)
Disaccharidases (Lactase). Wheres it active, whats its substrates and what are the products?
Small intestine
Disaccharides (lactose)
monosaccharides (galactose and glucose)
Peptidases and Dipeptidases. Wheres it active, whats its subtrate and what are the products?
Small intestine
Short peptides
Amino acids
What are the 3 main types of disaccharidases?
Maltase
Sucrase
Lactase
What is Emulsification?
Physically breaking down fats (lipids) into into small enough droplets in order for digestion to be effective.
Done by BILE (produces in the liver, secreted from the GALLBLADDER)
*Takes place in the small intestine
What is absorption? (Digestion)
How molecules from the the outside of the body to the digestive tract across and through cells. (into cells)
**for absorption to occur molecules need to be broken down (digested) first
What is transport? (Digestion)
How molecules are moved/ circulated around the body (lymph or blood)
What substances can be absorbed WITHOUT being broken down first? (Digestion)
Vitamins
Minerals
Water
Where does most absorption occur?
Small intestine
-The Duodenum and Jejunum
*1st and 2nd part of small intestine
How are carbohydrates absorbed once theyve been broken down into monosaccharides? (Digestion)
They enter capillaries in the villi (plr villus) in the small intestine
*via Secondary active transport (into epithelial) & Facilitated diffusion (out of epithelial into blood)
How are proteins absorbed once they’ve been broken down into amino acids? (Digestion)
They enter capillaries in the villi (plr villus) in the small intestine
*via Secondary/ Tertiary active transport (into epithelial cell) & facilitated diffusion (out of epithelial into blood)
How are lipids absorbed once they’ve been broken down? (Digestion)
They’re packed as CHYLOMICRONS and enter the LACTEAL in the villi (plr villus) in the small intestine
*Diffuse into intestinal cell. EXOCYTOSIS out of the cell in lymph
How do the monosaccharides GLUCOSE, GALACTOSE and FRUCTOSE enter the intestinal epithelium ?
Glucose/ Galactose: Secondary active transport
Fructose: Facilitated diffusion
What do intestinal epithelial cells have on their apical surface?
Peptidases
Break down small peptides into amino acids
What are broken down lipids called in the small intestine?
Micelles (small hydrophobic molecules surrounded by bile and salts)
*lipid portions of micelles pass through membrane by simple diffusion
*(in epithelial cell) Chylomicrons form (lipids coated with proteins) move out of cell via exocytosis
How is water absorbed in the digestive system?
Osmosis dummy.
In the small intestine and colon
Name 3 types of electrolytes (ions) and where are they absorbed?
Na+ (passively and actively)
K+ (passively)
Ca2+ (actively)
Small intestine and colon
How do water soluble vitamins get absorbed? (Digestive)
Diffuse across digestive epithelium.
*B12 must be bound to intrinsic factor and then gets absorbed via Active transport
How do lipid soluble vitamins get absorbed? and list some lipid soluble vitamins aswell (Digestive)
(absorbed with other digested lipids)
A D E K
Tell me the pathway of water soluble molecules (carbs/ proteins) take in the digestive system?
Digested into intestinal epithelial cell then into blood capillary
carried in the blood stream to the liver via the hepatic portal system
Then back to the heart and around the body
Can fats pass directly into the blood stream?
No you fucking idiot
They pass into the intestinal epithelial cells then into a lacteal cell of the lymphatic system
What are the 6 main hormones that regulate digestive functions?
1) Gastrin
2) Secretin
3) Gastric Inhibitory Peptide (GIP)
4) Cholecystokinin (CCK)
5) Vasoactive Intestinal Peptide (VIP)
6) Enterocrinin
Go Suck Garys Cock. Very Entertaining
Tell me some shit about Gastrin? What is it, wheres it secreted, what stimulates it?
-Digestive hormone
-Its secreted from cells in the stomach and duodenum.
-Stimulated by: Arrival of food and stretching of stomach. As well as the VAGUS VIII (ANS nervous system) and arrival of Chyme (in duodenum) with large amounts of protein
What does Gatrin cause in the digestive system?
It causes MORE gastric secretions (acids and enzymes) and increased gastric motility (muscle activity in the stomach)
Tell me some shit about Secretin? What is it, wheres it secreted, what stimulates it and what does it do
-Digestive hormone
-Secreted from cells in the duodenum
-Stimulated by: Arrival of acidic chyme in small intestine.
-Causes the pancreas to release bicarbonate ions (to neutralize the chyme) which stimulates the liver to secrete bile
-It inhibits gastric secretion and decreases gastric motility
Pathway of secretin?
Secretin gets stimulated (by chyme)
Presence of Secretin causes pancreas to release bicarbonate ions to neutralize the acidic chyme.
and caused liver to produce bile
What is the other name for the GIP (gastric inhibitory peptide)?
Glucose-dependent Insulinotropic hormone (GIP)
Tell me about GIP hormone. Where is it secreted, what stimulates it, what does it do? (Digestion)
-Secreted by cells in the duodenum
-Stimulated by Fatty acids and glucose in chyme
-Stimulates the release of insulin from pancreas and lipid synthesis glucose use.
-Inhibits acid production and peristalsis in the stomach (slows rate of chyme being dumped into small intestine)
Tell me about Cholecystokinin (CCK) hormone. What is it, what secretes it, what stimulates it?
-Secreted by cell in the duodenum
-Stimulated by arrival of chyme with fatty acids and partially broken down proteins in it.
-CCK stimulates the gallbladder to release bile as well as the pancreas releasing digestive enzymes.
-Inhibits gastric secretion.
Vasoactive intestinal peptide (VIP) hormone. What secretes it, what stimulates it?
-Secreted by cells in the duodenum
-Stimulated by arrival of chyme
-Stimulates secretions in the small intestine and INHIBITS acid production in the stomach and dilates intestinal capillaries to aid in removal of absorbed nutrients.
Enterocrinin hormone. What secretes it and what stimulates it?
-Secreted in the duodenum when chyme is there.
-Stimulates mucin production by submucosal glands
How does the Nervous system play a role in digestion?
Responds to sight, smell, taste and thought of food.
Stimulates the release of salivary amylase
Signals the stomach to release acid and gastrin.
What are the 3 phases of gastric sectretion?
1) Cephalic phase
2) Gastric phase
3) Intestinal phase
Cephalic phase (1). What is it?
Starts with sight, smell, taste and thought of food.
CNS sends signals to stomach to prepare for arrival of food. (Vagus VIII nerve)
Overall effect of the cephalic phase: Increased production of gastric juices (pepsin, mucus, HCI)
Gastric phase (2). What is it?
Starts when food arrives in the stomach. Distension (stretching of stomach walls).
Increase of stomach pH (more basic)
Stimulates an increase of gastric secretions (enzymes, acids) aswell as gastrin hormone release
Contracts the muscularis externa (churning).
Intestinal phase (3). Tell me about it?
Starts with arrival of chyme in the duodenum. (detected by stretch and chemoreceptors)
Slows down stomach activity so the small intestine has time to process chyme efficiently. (*Enterogastic or Local reflex)
Increase of mucus production in small intestine.
Uses GIP, CCK and Secretin hormone
Do local reflexes involve the CNS?
NOPE
What local reflexes are there during the Gastric phase (2)?
Stretch receptors and chemoreceptors.
*stimulate myenteric and submucosal plexuses….wtf. Leads to increased gastric activity
What local reflexes are there during the Intestinal phase (3) ?
Stretch receptors and chemoreceptors. (in duodenum + stomach)
*they inhibit activity in the myenteric plexus. Leads to decreased gastric activity. also stimulates secretion of mucus
**this is an ENTEROGASTRIC reflex
Do central reflexes involve the CNS?
YES
How do central reflexes work?
They are triggered by the stimulus of stretch receptors in stomach wall and send signals to the CNS.
What is the gastroenteric reflex?
Central reflex (uses CNS)
Receptors in stomach send signal to CNS and it sends signals to small intestine.
Increases motility and secretion along small intestine.
What is the Gastroileal reflex?
Central reflex (use CNS)
Receptors in stomach send signal to CNS and it sends signals to ileum (ileocecal valve)
Stimulates the opening of ileocecal valve which moves materials from small intestine into large intestine to make room for the new material the stomach is digesting.
What is metabolism?
The sum of all chemical reactions that occur in an organism.
What is cellular metabolism?
Chemical reactions within cells that produce energy.
4 things your cells need energy for?
1) Metabolic turnover (repair and cell maintenance)
2) Growth and cell division
3) Secretion, contraction, active transport
4) Storage and nutrient reserve
What is catabolism?
Breaking down organic molecules (cats break shit)
Release energy (exergonic)
*40% used by cell. 60% lost
What is anabolism?
Building up organic molecules.
Store energy
Requires energy (endergonic)
*usually have “coupled” reactions. (Energy released by one reactions fuels another)
What is the equation for photosynthesis?
6CO2 + 6H2O + light energy ———> C6H12O6 + 6O2
What is the equation for Glucose metabolism? (cellular respiration)
C6H12O6 + 6O2 —–> 6H2O + 6CO2 + energy (ATP)