Physiology [GIT] Flashcards
Who secretes the secritin and its site?
Apud cells, in the mucosa of deudenum and upper part of small intestine
Whats the mechanism of secritin secretion?
Due to the decrease of ph of fluid bathing the upper part of small intestine below 4.5
-due to the propulsion of acid chyme from pylorus to the deudenum
Whats the action of secritin?
- stimulates the pancreatic juice secretion from the duck larg in volume and electrolytes Hco3
- inhibit gastric acid secretion
- augment CCk for secretion of pancreatic digestive enzymes from the acinus of pancreas
Why does the secritin stimulates the pancreatic juice secretion?
Increase ph To make the deudenum suitable for the work of pancreatic digestive enzymes
What inhibits the secritin and what does it cause due to?
- nocotin in tobacco
- lead to drop of ph then ulceration
What secrete the GIP (gastrin inhibitory peptide) and where?
Special Apud cells in the upper part of small intestine
Whats the mechanism of GIP secretion and its function?
- released due to presence of fat and glucose in the lumin of deudenum
- inhibit gastric acid secretion in the stomach
- stimulates insulin secretion
Side release of VIP(vasoactive intestinal peptide)? And mechanism of secretion?
- By apud cell in mucosa of small intestine
- presence of digestion products in the lumin of small intestine
Functions of (vip)vaso active intestinal peptide?
- increase intestinal secretion of water and electrolytes
- vasodilation of intestinal vessels
- relaxation of smooth muscle in GIT
- stimulates secretion of bicarbonate from pancreatic duct
- inhibit gastric secretion
Whats the site of release of motilin?by what? Mechanism of secretion?
- by apud cells inth mucosa of upper part of small intestine
- due to presence of digestion products in the lumin of small intestine
Whats the function of motilin?
- stimulates antral and duednal motility
- contraction of LES
What releases the somatostatin?mechanism?
By D cells in Git And D cells of pancreas
-stimulated by Hcl in the lumin
Whats the functions of somatostatin?
- inhibit acid secretion
- inhibits gastrin GIP VIP secritin motilin
Where is the chewing nuclei is located?
Controled by nuclei in the brainstem
Who’s responsible for the mastication(chewing)?
- Incisors for cutting and molars for grinding
- masticatory muscles(5th cranial nerve) close the mouth with force of 25kg on the incisors and 90kg on molars
How is the mastication process is done?
-through mastication reflex(stretch reflex) entering the bolus of food into the mouth leads to stretch of the mastication muscles then leads to stretch reflex with causes the muscles to contract again and close the mouth then relaxe after that till the bolus stretch the muscles again
The swallowing (deglutation) devided into?
- oral stage voluntary
- pharyngeal stage involuntary
- esophageal stage involuntary
How is the oral voluntary stage is happening?
-Voluntary squeeze the food with ur tongue against the hard palate into the pharynx
How is the pharyngeal stage of swallowing happens?
-entering the food to the pharynx stimulates the receptors around its opening which send impulses to brainstem then comes back with pharyngeal peristalsis starts from its superior part and becomes rapid peristalsis in the middle and lower part of the pharyngeal muscles
How to protect the airways during the pharyngeal stage of swallowing?
- the soft palate goes upward to close the posterior nares
- larynx vocal cord are approximated and the larynx pulled upward by nech muscles then the epiglottis swings back to close the opening of larynx so the food dont go to the trachea
- relaxation of upper esophageal sphincter (pharngeosophgeal) to pass the food from pharynx to the esophagus
Deglutation or swallowing center is in?
Lower bone, medulla
The pharyngeal stage of swallowing reflex initiated by?
Entering the food to the pharynx voluntary which elicit pharyngeal reflex
Where the respiratory center resides? And its inhibited by? For how long?
Inthe medulla,
- by swallowing (pharyngeal stage)
- for 1-2 seconds
The duration of pharyngeal stage of swallowing?
1-2 seconds
When does the pharyngeal stage of swallowing inhibit respiratory center?
At any time if there was a swallowing happening
What are the two waves in the esophagus?
- primary peristalsis wave which a continuation of pharyngeal peristalsis from the pharynx to the stomach
- secondary peristalsis wave
How much does it take for the primary wave of esophagus to reach from pharynx to the stomach?
8-10seconds
Whats the secondary peristalsis wave of esophagus?where it comes from?when it ends?
The wave that takes the remaining food in the esophagus and push it to the stomach
- from distenationof esophagus due to the remaining food
- untill all of the food is pushed to the stomach
The secondary peristalsis wave of esophagus initiated by?
Partially by enteric NS of esophagus and partially by reflexes transmitted through affernt vegus that goes to the medulla then comes back with effernt vegus
What forms the LES
- smooth muscle of esophagus at the junction with stomach (intrinsic sphincter)
- fiber crural of diaphragm
- skeletal muscle (extrinsic sphincter)
Whats the function of LES?
- allow the orderly flow of food to the stomach
- prevent the backflow of gastric content to the esophagus
What prevents the gastric fluid from regrugating even during the increase of intragastric pressure?
Flap valve that close to esophgastric junction
Whats the difference between LES and upper , middle portion of the esophagus?
- Les is tonically contracted
- upper, lower relaxed completely
When the LES is not tonically contracted?
-in the reciptice relaxtion , when the peristalsis wave reache it to empty into the stomach
TONES OF LES under the neural control?
- AC released by the vagus to contract the LES
- NO,VIP released by interneurons that innervated by other vegus nerves to relax the LES
LES between meals?
Tonically contracted to prevent the reflex from the stomach
Abnormalities of the LES?
- Decrease innormal tone will allow gastric regurgitation and ulcer and strictures of the esophagus, eosphagitis
- Achalasia the LES is not completely relaxed
The Achalasia leads to? Caused by?treated by?
- accumulation of food till the esophagus is dilated
- defect in myenteric plexus of the esophagus
- defect inNO,VIP
- treated by Esophageal muscle incision or inject botolinium toxin in the LES to inhibit the acitylecholine
Whats the function of gallbladder?
- storage of bile
- concentration of bile
- prevent increase in intrabiliary pressure
- acidification of bile
Whats the function of gallbladder?
- storage of bile
- concentration of bile
- prevent increase in intrabiliary pressure
- acidification of bile
How the gallbladder concentrate the bile?
What happens to the rest of the gallbladder content?
By absorption of Na by active transport in gallbladder mucosa followed passively Cl,bicarbonate,water
—————————————-
Increase in licithin,cholesterol,bilirubin,bile salts
How the intrabilliary pressure effects bile flow?
Increase in this pressure stops the secretion of bile
How is the acidification of bile in gallbladder happen?
And why?
By absorption of Hco3 of hepatic liver
—————-
To keep a solution of bilirubin,cholesterol,bile salts,lacithin not precipitated
Whats the Hco3 content in hepatic bile and gallbladder?
In hepatic bile:23
In gallbladder:10
The maximum volume of gallbladder?
And it can store?
20-60ml
———-
500ml(24h secretion)
Whats the contraction of the gallbladder called?
Who’s responsible for it?
Cholagugues
- cck the major one for the contraction of gallbladder and relaxation of oddi sphincter
- vegal stimulation is less strong contraction of gallbladder and relaxation of oddi sphincter
Whats the cholelithsias?
Presence of gallstones
What are the types of gallstones?
- cholesterol stones(radiolucent)
- calcium stones(radiopaque)
What are the types of gallstones?
- cholesterol stones(radiolucent)
- calcium stones(radiopaque)
How the cholesterol stones is formed?
Cholesterol is insoluble in water it needs bile salts and licithin to keep it in bile solution so it form the micelle if the colestrol level exceeded or ultered than the micelle components it starts to crystallize
(Rafiolucent)
Whats the effect of cholecystectomy?
Removal of gallbladder
—————————-
It starts emptying slow but continuously direct to
the intestine for sufficient nutrition-avoid fat meals
Secretion of the intestine are?
- mucos
- alkaline fluid
- enzymes
Whats the component for the intestinal mucus?
Its fumction?
Mucin ——————— -protect the wall of intestine -lubricant to the chyme -bind to bacteria and immunoglobulins
Who secret mucus in the intestine?
- surface epithelium cells
- goblet cells
- brunners glands in the deudenum
The brunner glands secrete mucus in the intestine in response to?
- chemical and physical irritation of mucosa
- cholingergic stimulation (vagus)
- Git hormones(secritin)
What inhibit mucus secretion in intestine?
What does it cause?
Sympathetic
-no protection to the walls og intestine so it leads to ulcer in 50% of cases
Who secret the alkaline fluid in the intestine? Its daily formation rate?
Composition of the fluid? Its ph? Who takes it?
Crypts cells-bicarbonate and NaCl-ph(7.5-8)
Slightly alkaline-absorped by the villi(isoosmotic)
—————-
1800ml
Whats the purpose of alkaline secretion in the intestine?
To be absorbed by the villi and create a medium for digestion inside of it
Where the enzymes of the intestine reside?
and where are the secreted?
Brush border of epithelium covering the villi
—————-
Not into the intestine
Whats the enzymes of the intestine?
- peptidase: cut the peptides into A.A
- enzymes for disaccharide to monosaccharides: sucarose- maltas-isomaltas-lactase
- lipase for fat to glysrol and fatty acids
The regulation of intestinal secretion due to?
- Local nervous reflex: the major and it caused by destination of Intestine by chyme (the greater the destination the greater the secretion)
- hormonal: secritin and CCK increase intestinal secretion
- vip also released by nerve endings leads to increase water and electrolytes in the intestine
What are the normal and abnormal movements of the intestine?
Normal- Segmentation mixing movement Peristalsis movement Migrating motor complex MMC Abnormal- Dynamic (paralytic)ilues Peristalsis rush
Whats the rate of segregation movement of the intestine and its function?
Initiated by? Controled by? And effected by?
Caused by destination of intestine wall by the chyme
- separated into segments each one contract and relax
- function to mix the food
- at a rate of 12contraction/min in intestine and 8-9time in terminal illium
- controlled by BER
- effected by the activity of enteric NS so the atropin inhibit the enteric NS lead to slowen the movement
The maximum frequency of segregation movement is in ?
Deudenum and proximal jejunum
Function of peristalsis movement of the intestine?
Where it happens? And its velocity?
Propulsion of cyme to ileocecal valve
- in all the intestine fast in proximal intestine and slow at the terminal intestine
- moves the chyme in rate of 1cm/min
How much time the chyme required to reach from pylorus to the ileocecal valve?
3-5houres
When the MMC of the intestine happens? And its function? What is it formed of?
When its stop?how much it takes to reach its way?
- in between meals
- take the indigested substance and the remaining of small intestine and takes it to the colon so the bacteria not grow and multiply
- 2h to reach the colon
What inhibit and enhance the intestinal motility?
Enhance:CCk, gastrin, seritonin,insulin
Inhibit:secritin,glucagon
Whats the peristaltic rush? Its function?
What initiates it?
- very powerful and fast peristaltic waves
- fast for carrying of the irritation and excessive chyme into the colon to relieve the intestine
- initiated partially by extrinsic Ns in brainstem then comes back to the gut or enhanced direct by myentric plexus
Function of eleocecal valve?and what the thickned part of the ilum forms?
Prevent movement of fecal from colon back to the small intestine
—————
Eleocecal sphincter that mildly contricted for emptying from ilum to cecum
When the paralytic ileus occurs ?and why?
What does it cause
-Occure in abdominal operation , inhibit peristalsis and intestinal motility due to trauma to the intestine or irritation in peritonum leads to norepinephrine discharge by splanchic nerve
——————————-
No propulsion to colon or absorption leads to irregularities and destination of the the intestine due to gases and fluid
The bilirubin is end product of?
And where do we get it’s soure from?
Hemoglobin catabolism
-breaking the old RBCs
Whats the catabolism of hemoglobin?
Globin:amino acids
Heme: F+ , 4pyrol rings > biliverden > bilirubin
⬆️
Transferred on transferrin in the blood to synthesis
New hemoglobin
The F+ from hemoglobin metabolism is transferred in blood by? And whats its purpose?
- on trasferrin
- synthesis new hemoglobin
The bilirubin released in blood called?
Free bilirubin or unconjigated or indirect
Whats the bilirubin bind to in plasma and why? Where it takes it?
- to albumin
- so it doesn’t get excreted in urin
- to the liver for its disassociation
When the the bilirubin reaches the liver its first encounter with?
Cytoplasmic protien
Whats the bilirubin conjugated with ? And where?
The enzyme? End product?
- With glucuroneic acid
- in the liver
- glucournyle transferade
- bilirubin diglucorunide
Whats the property of the bilirubin before and after conjugation?
Before: lipid soluble
After:water soluble
Bilirubin after its conjugation its excreted to? By?
Bile canaliculi
Active transport
The total plasma bilirubin normally includes?
Free bilirubin plus small amount of conjugated bilirubin
The small amount of conjugated bilirubin escapes to the blood how its excreted?
In urin
What happens to the bilirubin after it gets to intestine?
- Most of glucorunide transfers by bacteria into urobilinogen 50% that reabsorped by hepatogastic circulation
- the other 50% of urobilinogen turns into stercobilinogen that goes to stool
- 5% of urobilinogen excreted by the kindney in urin
What gives the urobilinogen its properties and whats its properties?why?
Highly soluble
By bacteria
To be reabsorped in the enterohepatic circulation
The urobilinogen in urin oxide ……. To give?
Outside the body
Urobilins
Where is the glucuronide is deconjugated? And why?
In the intestine
To be absorbed to the enterohepatic circulation
Whats jaundice (ictrus)? And it’s general cause?
Yellow tint to the skin sklera and mucous membrane
-increase in free and conjugated bilirubin
Whats the normal value for bilirubin?
At what level its called jaundice?
- 5mg to 2mg %
- Above 2
When jaundice due to theses process the free bilirubin rises?
- increase production of bilirubin (hemolytic anemia)
- disturb in hepatic uptake of free bilirubin
- disturb in cytoplasmic enzyme(intercellular binding protein) and conjugation
The glucuronyle transferase enzyme found in?
Smooth ER
How much bilirubin excreted in urin?
5%
When jaundice due to one of these processes it rises the conjugated bilirubin?
- intra and extra hepatic bile duct obstruction
- disturb in excretion of conjugated bilirubin into bile canaliculi
Jaundice classified into?
Hemolytic jaundice
Hepatocellular jaundice
Obstruction (cholestatic) jaundice
Hemolytic jaundice cause by? Its effect on plasma bilirubin concentration?
Increase in bilirubin production by excessive breaking of RBC so the hepatic cell cant secrete and conjugate rapidly
-rises the free bilirubin in the blood(indirect von den bergh)
Whats the effect of hemolytic jaundice on the intestine?
The bile conjugate a lot of bilirubin so it’s secreted to the intestine and increase it turning into urobilinogen then to stercobilinogen to the feces(dark stool)
Hemolysis of RBCs can be due to?
- hemolytic anemia: heridatory spherocytosis- sickle cell anemia-thalassemia- erythroblastosis fetalis
- blood transfusion- malaria-reaction to some drugs as an autoimmune
The liver excretion in the hemolytic jaundice is?
Normal
Hepatocelluar jaundice caused by?its effect on the plasma bilirubin concentration?
Inability of hepatocytes to excretion or conjugation all bile pigments
-increase both direct and indirect bilirubins(free and conjugated)
Whats the effect of hepatocellular jaundice on intestine?
Reduce the bilirubin diglocurnide excretion in the intestine lead to reduce of urobilinogen and stercobilinogen in feces, and urobilinogen in urin
Hepatocellular jaundice occures due to?
Viral hepatitis, chemicals chloroform carbon tetrachlorid, arsinic , mercury,
-drugs as tetracyciine, chloramphnicol
What causes the obstructing jaundice (cholistatic)? An its effect on the plasma bilirubin concentration?
The bilirubin is conjugated in the live but it cant pass to the intestine due to an obstruction
- the conjugate bilirubin goes back to the blood directly through live sinasoids or indirect through bile duct and lymphtics(direct bilirubin)
Whats the effect of obstruction jaundice on the intestine?
No conjugated bilirubin pass to the intestine so no urobilinogen and stercobilinogen (gives pale stole)
-dark urin due to the conjugated bilirubin in the blood(direct von den betgh reaction)
Whats the intrahepatic and extra hepatic causes of obstruction jaundice?
Intra: viral hepatitis, liver cirrhosis
Extra: gallstones,carcinoma, strictures
How the obstruction jaundice effect the bile salts?
The bile salts and pigments are in the same sac so releasing them must be together
-obstruction leads to no absorption of fat(statoreah) and leading to puritits and bradycardia
How the obstruction jaundice effect the cholesterol?
-Increase cholesterol levels(hypercholestrolemia)
- increase level of alkaline phospatase enzyme
These two substances are normally excreted by bile
The general parasympathetic supply of GiT is due to? And ends on?
Its effect onthe GIT in general?
Pregangelionic fibers of vagus, sacral nerves
- ends on the cholenerguc nerve cells of intrinsic Nerve system
- increase the activity of intrinsic nerve system