GI day 2 (motility and liver function) Flashcards
What is peristalsis and what controls it
Smooth muscle contraction that occurs in waves
Control: Reflexive response to stretch of GI tract wall
Which parts of the GI tract have Peristalsis
From Esophagus to anus
What is segmentation
Function is to slow the transit time
Occurs via circular muscle
blocks a portion of the GI tract to slow time
Deglutition
Swallowing
Tonic contractions and where they occur
Prolonged contractions ( occur in sphincters)
What allows peristalsis to be rythymic
we have automatic depolarizing cells (cells of cajal) that set the rythym of the GI tract
What are the spontaneous depolarizing cells of the GI tract
Cells of cajal
Smooth muscle cells membrane potential
-65 to -45 (spontaneously fluctuate between these two)
What ion is responsible for rhythmic depolarization/ repolarization in peristalsis
Depolarization: Ca influx
Repolarization: K efflux
((CA(CA)lifornia is so IN and I will K(K for potassium)nock you OUT if you don’t think so))
What leads to contractions but only during BER depolarization periods
spike potentials
What are the spontaneous flucutations in membrane potential of smooth muscle cells between -65 to -45 called
Basic electrical rythym
Function of BER
Sets rythym of peristaltic contractions
Effect of Ach on peristalsis
Parasympathetic NS- decreases time between depolarization (more depolarization, want more contractions b/c resting and digesting)
Effect of epinephrine on peristalsis
Increase time between depolarization, want less digestion in stressful times
Describe the phases 1, 2, and 3 of Migrating motor complexes (MMCs)
Phase 1: Quiescent period (no activation)
Phase 2: Small, irregular contractions
Phase 3: 5 minutes of irregular contractions
How many minutes after a meal do the MMCs begin
90-120 minutes
What stimulates migrating motor complexes
Motilin
What types of secretions do MMC contractions lead to
secretions of biliary, gastric, and pancreatic juices
What inhibits MMCs
Eating inhibits (MMCs begin 90-120 mins after)
What causes gurgling when hungry
MMCs
Part of pharynx behind nose
nasopharynx
Part of pharynx behind mouth
oropharynx
Part of pharynx behind epiglottis
laryngopharynx
What is the function of the soft palate during chewing
soft palate tips upwards to prevent food from entering nasal passage
What tips downwards to prevent food from entering the respiratory tract during chewing
The epiglottis tips downwards and covers the trachea
What does the esophagus connect
the laryngopharynx to stomach
Where is the gastroesophageal/cardiac/lower esophageal sphincter
Between esophagus and stomach
3 components of the lower esophageal sphincter
- intrensic (smooth muscle controlled via vagus nerve)
- Extrensic (crural portion of diaphram, controlled via phrenic nerve)
- Flap valve (oblique fibers in stomach)
Extrensic control of the Lower esophageal sphincter is coordinated with what
respiration (same innervation–phrenic nerve– as diaphragm)
What does a hiatal hernia lead to
GERD (the diaphragm was helping the sphincter, but now the sphincter is above the diaphragm
What are the 4 reflexive actions in deglutition
peristalsis, opening of sphincter, block nasopharynx, block larynx
Which phase of deglution is food formed into a bolus
voluntary phase
In the pharyngeal phase, what occurs with the soft palate?
The soft palate blocks the nasopharynx by moving upwards
What occurs with the trachea and pharyngeal muscle during the pharyngeal phase
The larymx lifts up and blocks the trachea, the eppiglottis tips down to close the glottis.
The pharyngeal muscle contraction moves the bolus into the esophagus
What occurs in the esophageal phase of deglutition
Upper esophageal sphincter opens
peristaltic contractions move bolus down to stomach
Gastroesophageal (lower esophageal( sphincter opens, bolus enters stomach)
Contractions in the stomach are stimulated by
stretch due to food
Gastric motility has 2 actions to digest food in the stomach. What are they?
- Relax fundus ( relaxation to recieve the food from the esophagus)
- Peristaltic contractions of antrum (antral systole–>pyloric region–>duodenum)
Why are contractions of the pyloric regions of the stomach slightly before the antral region
Stops larger food from getting to the pyloric sphincter
What is absorbed in the stomach
Alcohol
Some drugs (i.e. asprin)
which factors regulate contraction of the stomach
peptide YY and CCK inhibit gastric emptying ( PYY in jejunum and CCK in upper small intestine are released to inhibit more gastric emptying)
What neurotransmitter released by EC cells trigger vomitting
Serotonin released by enterocromaffin cells trigger vomitting
- Serotonin antagonists like zofran work to decrease
Which receptors and where trigger vomitting
Dopamine receptors in medulla
- Dopamine antagonists (haladol, antipsychotic) are able to have an inverse effect
What is the ileocecal valve opening based on
pressure- opens when pressure in lieum exceeds pressure in colon.
What is aerophagia
swollowed air (some absorbed, some belched, some in colon)
What produces gas in the colon
Bacteria byproducts (methane, CO2, sulfides)
What is rumbling noise known as in the gi tract
borborygmi
Extra carbs in colon leads to what
more gasses (i.e. lactose intolerance)
- usually only starch makes it that far, but in lactose intolerance, so does sugar b/c not broken down
Is the external or internal anal sphincter voluntary
External is voluntary skeletal muscle
How much pressure does it take to activate internal anal sphincter
18mm Hg
How much pressure does it take to activate external anal sphincter involuntarily
55mg Hg
What happens to the puborectalis muscle when bearing down
Typically it is contracted, but when we are bearing down, it relaxes, so we can poop
Describe the gastrocolic reflex
Food enters the stomach, cause contraction of rectum, amplified by gastrin release
Which artery delivers o2 rich blood to liver
hepatic artery
Which artery delivers nutrients for processing from the small intestine to the liver
hepatic portal vein
What kind of cells are in direct contact with blood in the liver
hepatocytes
Where does blood from the hepatic artery and hepatic portal vein go
to the central vein–> hepatic vein
Which 3 things are in the portal triad
Bile duct, portal venule, hepatic arteriole
What are the macrophages in the liver called
kupffer cells (immune function, help break down RBCs)
Kpuffer cells function
Immune function, help break down RBCs
Symptoms of gallstones
deep pain in abdomen and right arm or between sholder blades
What are gall stones made of
cholesterol or bilirubin
What proteins does the liver make
albumin, clotting factors, hormone binding proteins
Which organelle does blood detoxification occur in the liver
in the smooth ER (one of the most developed in the body)
Which nutrient metabolism occurs in the liver
Glycogen, vitamin A, iron, fats, proteins, cholestorol, lipoproteins
What is the primary contributer to oncotic pressire (osmolality of blood)
alblumin
What are acute phase proteins
made in the liver, secreted into the blood on exposure to stressful stimuli
What does IL-6 do in the liver
an acute phase protein- secreted by kupffer cells when exposed to inflammatory stimuli–> stimulate hepatocytes to release APPs
If you are in a time of intense stress, which protein is likely to be found in your blood?
C reactive protein (sign of active inflammation)
Example of Acute phase protein
Made in liver, emptied to blood in stressful times
Which cells are the only cells in the body that can complete the whole urea cycle
hepatocytes (turn NH3 into urea)
Hepatitis A transmission, infection, and symptoms
Transmitted by feces, food
Infected–>28 day incubation
Symptoms: weight loss, sore under ribs, sore muscles, jaundice
Hepatitis B transmission, infection, and symptoms
40% of cases
Transmission by blood, sexual contact
Does Hep A or b last longer
B (increases risk of liver cancer, too, goes away on its own)
Hepatitis c transmission, infection, and symptoms
NO vaccine
Lasts for years, might never go away
transmissed by sexual contact
symptoms: dark urine, itchy skin
What is the primary hepatitis
hep b
What causes you to bleed and bruise easily in cirrhosis
clotting factors in the body are decreased (Liver produces clotting factors, but is damaged and can’t keep up)
What causes you to swell in abdomen or legs in regards to cirrhosis
increase portal vein blood pressure, decrease in osmotic pressure)
- Inverse of what we want- we wnat lower portal vein pressure and higher osmotic pressure to push out fluid
Why are we extra sensitive to medicines in liver failure
detoxification is impaired
Why is blood sugar uncontrolled with liver failure
send too much glucose into the blood because cant filter
What is the new name for NAFLD
Metabolic dysfunction associated steototic liver disease
Where does NAFLD and MDASLD occur
in type 2 diabetes and obesity
Cause of NAFLD
visceral adipose tissue
What is type of heptatitis that increases the risk of liver cancer
hep b
which type of hepatitis can last for years and might never go away, but also sometimes has no symptoms?
hep c
