GI System Physiology 1 Flashcards
What are the 2 types of tissue that forms the spleen?
Red pulp
White pulp
What are the 2 motor activities of the mouth?
Mastication
Deglutition (swallowing)
What is the motor activity of the esophagus?
How is this accomplished?
Propulsion by peristalsis
What are the 3 motor activities of the stomach?
Mixing
Storage
Emptying
What 2 things regulate stomach emptying?
Gastrin
Stomach distention
How do long chain fatty acids affect stomach emptying?
They decrease it by causing release of cck which inhibits gastrin
How does duodenal distention and irritation affect stomach emptying time?
The decrease emptying time
What is the purpose of rhythmic segmentation in the S.I.?
To mix up the chyme to expose it to enzymes and absorptive surface
What structure prevents backflow from colon and separates S. I. bugs from L.I. bugs?
Ileocecal valve/sphincter
What causes the sphincter to relax?
Gastric distention via gastroileal reflex
Gastrin
Where does most of the water absorption take place?
In cecum and transverse colon
What does rectal dissension cause?
A desire to defecate
What are the 2 types of electrical activity in the G.I.?
Slow waves (Basic Electrical Rhythm ber)
Spike potentials
Which of the 2 types of electrical activity leads to smooth muscle contraction?
Spike potentials
Which of the 2 electrical activities keeps G.I. in a state of readiness by helping set up gut tone?
Slow waves
What helps set up frequency and rhythm of action potential and smooth muscle contraction?
Slow waves
Which branch of the ans has most affect on the G.I.?
Parasympathetics
What are the 2 areas of intrinsic nervous control on the gut?
Myenteric (Auerbach’s) plexus
Submucosal (Meissner’s) plexus
Which of the 2 plexuses control motility and contraction?
Myenteric plexus
Which of the 2 plexuses controls secretions?
Submucosal plexus
Which of the 2 extrinsic nervous system controls will decrease blood flow leading to decreased secretions?
Sympathetics
Which of the 2 extrinsic nervous system controls will increase motility and secretions?
Parasympathetics
What are the antibacterial substances found in saliva?
Lactoferrin - binds iron to prevent bacterial cell growth
IgA
Muramidase (Breaks down bacterial cell walls)
What enzymes are found in saliva?
Lingual lipase
Amylase
What affect does increased parasympathetics have on saliva secretion?
It will increase rate of secretion
What are some of the functions of hcl?
(1) Activation of pepsinogen into pepsin
(2) Provides the adequate pH for pepsin activity, micronutrient absorption
(3) Storage and mixing up of chyme
(4) Denatures proteins
(5) Antibacterial
What is secreted from parietal cells?
hcl
Intrinsic factor
What is secreted from chief cells?
Pepsinogen
What is secreted from goblet cells?
Mucous
What breaks down the aromatic amino acid bonds of proteins?
Pepsin
What are 3 stimulants for hcl secretion?
(1) Parasympathetics
(2) Gastrin release stimulated by stomach distention and secretagogues
(3) Histamine
What enzyme is present in infants but not adults?
Rennin, which breaks down milk protein. Don’t confuse this with renin.
What neutralizes the acidic chyme as it moves into the duodenum?
Bicarbonate
What causes release of bicarbonate?
Secretin
Where are zymogen granules produced and released from? (organ and cells)
From acinar cells in pancreas
Which pancreatic cells secrete both insulin and glucagon?
Islet of Langerhans or Pancreatic islets
Which cells produce bicarbonate?
Ductal cells
What activates trypsinogen into trypsin?
Enterokinase. Kinase enzymes transfer phosphates from ATP to another molecule.
What activates the remaining zymogens?
Trypsin
What 2 enzymes cleave proteins into smaller peptides?
Trypsin and chymotrypsin
Which enzymes cleave off individual amino acids off of peptides?
Carboxypeptidase, aminopeptidase, and dipeptidase
What is the difference between carboxypeptidase and aminopeptidase?
Carboxypeptidase cleaves amino acids off of the carboxyl end
Aminopeptidase cleaves them off the amine end
What is major stimulus for zymogen release?
cck
What stimulates release of cck?
Fat in S.I.
Partially digested proteins
What hormone enhances activity of cck?
Insulin
What 2 hormones inhibit pancreatic juice production and activity?
Somatostatin
Glucagon
Where is secretin produced?
In the duodenum of the S.I.
What effects does secretin have on its target organs?
Pancreas: Stimulates duct cells to release bicarb
Liver: stimulates bile and bicarb release
What action does acetylcholine have on pancreatic secretions?
It will increase secretion due to parasympathetic action
What does gelatinase breakdown?
Proteoglycans that are present in connective tissue of flesh products
Facilitated diffusion of sugars across gut epithelium is dependent on Co-transport of what?
Sodium
How are D verus L amino acids transported across the gut lumen?
D-amino acids are diffuses
L-amino acids are actively transported across the mucosa
What nutrients are stored within the liver?
Vitamin A, D, E, K, and B12 and iron and copper
What does the P450 system do to xenobiotics?
Makes them more hydrophilic with addition of -OH group
Which components of bile are responsible for solubilizing fat?
Bile salts and lecithin
What are the active phagocytes of the liver?
Kupffer cells
Which plasma protein makes up 50% of the liver’s total protein production?
Albumin
