Exam 3- Digestion Flashcards
What are the functions of the digestive tract?
- Ingestion 2. Motility 3. Secretion 4. Digestion 5. Absorption 6. elimination
Mastication/chewing, churning, denaturation is ________ digestion and enzymes used to break covalent bonds is _______ digestion
- Mechanical
- Chemical
What are the accessory organs for digestion?
- Teeth
- Tongue
- Salivary glands
- Liver
- Gallbladder
- Pancreas -Anything not directly in the digestive tract
True or False: if food passes through it then it is an accessory gland?
False- food does not pass through accessory glands
Put the mucosa in order from innermost to outermost
- Epithelium
- Lamina propria
- Muscularis mucosa
What is contained in the submucosa?
Connective tissue/blood vessels
Lymphatic vessels/nerves
What two layers does the Muscularis externa have?
Inner circle M.
Outer longitudinal M
Visceral peritoneum in abdominal cavity describes what?
The serosa
This is located in the thorax and around rectum/anus; covering of retroperitoneal parts in abdomen?
Adventitia
True or false: the enteric system can function independent of CNS?
True this is the submucosal plexus and myenteric nerve plexus
What influences the extrinsic salivary glands? (PSNS or SNS)
PSNS
True or false: intrinsic salivary glands need to be turned on to secrete juices whereas extrinsic secrete at a constant rate?
False: its the opposite
Intrinsic secrete at constant rate, they are single cells in mucosal lining of the mouth including lingual, labial, and buccal
What are the extrinsic salivary glands?
Parotid, Sublingual, submandibular
Match the following
A. Clear watery serous fluid, rich in salivary amylase
B. Some serous fluid with some mucous more viscous than A
C. Primarily thick stringy mucus
- Submandibular gland
- Parotid gland
- Sublingual gland
A with 2
B with 1
C with 3
What are the three phases of deglutition?
- Voluntary phase
- pharyngeal phase
- esophageal phase
Main function of the stomach?
Storage (4L capacity) exits via 3 ml portions
What three layers of the stomach allow it to twist?
Longitudinal layer
Circular layer
Oblique layer
Match the following
A. Goblet cell
B. Mucous neck cell
C. Parietal Cell
D. Chief cell
E. G-cell
- secretes Pepsinogen and gastric lipase
- secretes intrinsic factor and hydrochloric acid
- Secretes alkaline fluid contain mucin
- secrete gastrin into the blood via enteroendocrine cells
- secretes acid fluid containing mucin
A with 3
B with 5
C with 2
D with 1
E with 4
What converts pepsinogen to pepsin?
Gets converted when in the presence of hydrochloric acid -pepsin is protein splitting enzyme
What does gastric lipase split up?
Fat
what is required for vitamin b-12 absorption?
A. Pepsin
B hydrochloric acid
C. Intrinsic factor
D. Extrinisic factor
C. Intrinsic factor
What protects the stomach wall?
A. Gastrin
B. Mucus
C. Pepsin
D. all of the above
B. Mucus
Which of the following is a positive feedback loop?
A. Cephalic phase
B. Gastric phase
C. intestinal phase
B. Gastric phase
Describe the cephalic phase?
- Receptors: special senses pick up smell or taste or sight
- Sensory input: increased nerve signals relayed from the cerebral cortex and hypothalamus to the medulla oblongata
- The medulla figures out all of the input from the higher brain centers
- Motor Output: increased nerve signal relayed from medulla oblongata to stomach
- Effector: stomach stimulated to both increase force of contraction and release of secretions
Describe the gastric phase?
Food is now in stomach score!
- Receptors: Baroreceptors in stomach wall detect stretch. Chemoreceptors detect protein or higher PH
- Sensory input: signal relayed to medulla oblongata
- Medulla figures out whats going on
- Motor output: increased nerve signal relayed from oblongata to stomach
- Effector: Stomach is stimulated to both increase force of contraction and release secretions (gastrin)
What 3 effects does gastrin have?
- Increase stomach force of contraction
- Release HCL
- Stimulate contraction of pyloric sphincter
If chyme never leaves the stomach will the gastric phase continue?
Yes- this phase continues till chyme leaves the stomach
Might as well do the intestinal reflex too. So describe this?
- Receptors- chemoreceptors in intestinal wall detect acidic chyme or low PH in stomach contents
- Sensory input: decreased nerve signals relayed to medulla oblongata
- Medulla oblongata integrates
- Motor output: Decreased nerve signals relayed from medulla to stomach
- Effector: stomach stimulated to both decrease force of contraction and release less secretions
What causes the release of CCK?
The presence of fatty chyme in the duodenum
What causes the release of secretin and what does secretin do?
- The presence of acidic chyme
- Secretin tells the stomach to secrete less/inhibits secretions
What gland located in the small intestine secretes a specialized thick alkaline mucus in response to low PH chyme in stomach
Brunners Glands
What enzymes are located in the microvilli?
- Peptidase- breaks down peptides into aa
- Sucrase, maltase, lactase- breaks down disaccharides into mono
- Lipase- breaks down fats into fatty acids and glycerol
What hormones are secreted from the small intestine?
- Enterokinase- converts trypsinogen to trypsin
- Somatostatin- inhibits acid secretion by stomach
- CCK- inhibits gastric glands, stimulates pancreas to release enzymes in pancreatic juice, tells gallbladder to release bile
- Secretin- stimulates pancreas to release bicarb ions in pancreatic juice
Match the following absorption mechanisms
A. Monosaccharide
B. Amino acids
C. Fatty acids and glycerol
D. Electrolytes
E. Water
- Active transport
- osmosis
- diffusion and active transport
- facilitated diffusion and active transport
- Facilitated diffusion of glycerol and diffusion of fatty acids
A with 4
B with 1
C with 5
D with 3
E with 2
General function of the liver is?
Metabolism (carbs, protein, lipids), Storage, synthesis (blood proteins/cholesterol), Detox
Digestive function of liver?
Bile—> emulsification, absorption of lipids, hydrophobic waste and excretion
What two ducts form the common hepatic duct?
Left and right hepatic duct
What two ducts form the common bile duct?
Common hepatic and Cystic ducts
Layers of the gallbladder are?
Mucosa
Muscularis
Serosa
describe the bile pathway?
Bile canaliculi—-> bile ducts—-> hepatic ducts (left and right) —> Common hepatic duct—-> bile duct enters at hepatopancreatic sphincter into small intestine
If not used bile will back up via bile duct into cystic duct
Function of gallbladder
Storage and concentration of bile
true or false: biles function is emulsification which increases surface area of fat?
True
What two types of tissue is the pancreas made of?
- 98% of tissue built of acini: exocrine secretion of amylase, lipase, protease, and nuclease
- 2% islet cells- endocrine secretion of insulin and glucagon
- Alpha cell- glucagon
- beta cell- insulin
Which of the following is the site of contact digestion
A. Gastric pits
B. Surface of the gastric mucosa
C. intestinal crypts
D. brush border of small intestine
E. Cytoplasm in the cells of the small intestine
D. brush border of the small intestine
Which of the following enzymes function at the lowest PH
A. Salivary amylase
B. Pancreatic amylase
C. Pepsin
D. Trypsin
E. Dipeptidase
C. Pepsin- pepsinogen is converted to pepsin by the presence of HCL, so ya that’d be a low PH
What three functions does the large intestine serve?
- Absorption- water & electrolytes, indirectly vitamin B’s and K
- Compaction
- Storage
True or false the large intestine has plicae and villi
False
What cells does the large intestine have?
Large # of goblet cells, intestinal glands and lymph nodules. Also teniae coli
What is haustral contraction
uncoordinated contraction every 25 minutes
Describe mass movement of the large intestine
3-4 waves/daily based on gastrocolic reflex and duodenal colic reflex
Which is smooth muscle and which is skeletal.
A. External anal sphincter
B. Internal anal sphincter
A is skeletal
B is smooth
The conscious decision to poop is controlled by what cortex?
cerebral
What two places are carbs digested?
Oral cavity and small intestine
True or false: the brush border of the small intestine takes disaccharides and converts them to monosaccharides?
True
What parts of the small intestine are involved in the absorption of carbs?
Jejunum & ileum via epithelial lining to blood capillaries in villi to hepatic portal system
Usage of Carbs?
- Energy storage
- ATP production
- Structural components
- Markers as oligosaccharides
What completes the breakdown of starch to individual glucose molecules and are responsible for the digestion of disaccharides?
brush border enzymes
What enzymes break down protein and where are they released from?
proteolytic and from the pancreas
What activates trypsinogen to trypsin and then what does trypsin activate?
Enteropeptidase activates trypsinogen to trypsin and trypsin activates other proteolytic enzymes
Proteolytic enzymes break proteins down into what 2 things?
AA and peptides
true or false: brush border peptidases break down proteins into single AA to be absorbed through columnar cells into blood
False: brush border peptidases breakdown peptides into single AA then to be absorbed through epithelia into blood
Describe the lipid digestion/absorption after lingual & gastric lipases
- Bile salts from liver and gallbladder emulsify lipid droplets forming micelles
- now pancreatic lipase action
- Monoglycerides and FFA’s enter epithelia while bile salts remain in the intestinal lumen to be reabsorbed and recycled
describe the steps for liver carb metabolism
- Monosaccharides are absorbed from the small intestine into the blood and then enter hepatocytes. Fructose and galactose are converted to glucose.
- Noncarbohydrates are converted to glucose by gluconeogenesis.
- Glucose molecules are bonded together to form glycogen by glycogenesis.
- Glucose molecules are released from glycogen by glycogenolysis.
Describe the protein metabolism done by the liver
- Deamination: amine group removed from amino acids -NH2 is converted to urea and urea enters blood (urea eliminated by kidney) - remaining components oxidized in cellular respiration to generate ATP from the liver
- Amino acids used to form proteins, including plasma proteins
- Transamination: amino acids converted from one form to another
Describe lipid metabolism within the liver
- Fatty acids joined with glycerol to form triglycerides (lipogenesis)
- Fatty acids released from triglycerides (lipolysis)
- Fatty acids broken down into acetyl CoA (beta oxidation)
- Acetyl CoA changed to ketones bodies (water soluble molecules) Ketone bodies released into blood, transported to other cells, where they can be oxidized in cell respiration pathways
- Acetyl CoA used in cholesterol synthesis; cholesterol released into blood within VLDL’s and some used to form bile salts and released as a component of bile
Chemical digestion breaks down______ into _______
A. Proteins; nucleotides
B. Amino acids; proteins
C. Polysaccharides; amino acids
D. Nucleic acids, nucleotides
E. Fatty acids; cholesterol
D. Nucleic acids; nucleotides- by nucleases from pancrease
What two things breakdown nucleotides to N-base, ribose & phosphate that can be absorbed into blood capillaries
Phosphatases and nucleosidases (brush border)
