Week 17 Flashcards
What are the three distinct muscle regions in the oesophagus
Superior third- voluntary striated muscle
Middle third- voluntary striated and smooth muscle
Inferior third- smooth muscle
What is Barrett’s oesophagus?
Refers to the metaplasia (reversible change from one differentiated cell type to another) of lower oesophageal squamous epithelium to gastric columnar epithelium. Usually caused by chronic acid exposure as a result of a malfunctioning lower oesophageal sphincter. Acid irritates the oesophageal epithelium, leads to potential metaplastic change.
What is the main composition of the oesophagus?
External longitudinal muscle
Internal circular layers
Mucosal lining (large obvious smooth layer- changes to ridges at the stomach junction
Where does the oesophagus pass through the diaphragm?
Oesophageal hiatus
Where does the oesophagus enter the stomach?
Cardial orifice
What are the 4 parts of the stomach?
Cardia- closest to the oesophagus
Fundus- upper part of stomach next to the cardia
Body- main part of the stomach
Pylorus- stomach end at the duodenum
How many curvatures does the stomach have and what are they called?
Lesser curvature (medial surface)
Greater curvature (lateral surface)
What are the longitudinal gastric folds called and what do they allow for?
Rugae- stomach expansion.
What is the pyloric sphincter?
It is circular smooth muscle that controls the discharge of stomach contents into the duodenum.
What are the gastric pits?
Gastric pits are indentations in the stomach which denote entrances to 3-5 tubular shaped gastric glands. THESE ARE NOT RUGAE.
Where are the gastric glands?
They are just next to the gastric pits and empty into these pits.
What are the 4 types of secretory cells in the gastric glands?
Chief
Parietal
Mucous
G cells
N.B wont be able to distinguish these without special staining.
What do the 4 secretory cells produce?
Chief- pepsinogen and gastric lipase
Parietal- HCl, and intrinsic factor for B12 absorption
Mucous- mucous
G cells- secrete gastrin into the blood (to then act on chief and parietal cells.
How can the pyloric sphincter appear within histology?
A large lump of muscle.
How to identify the villi change from the stomach- duodenum?
The stomach has villi but in the duodenum it is much longer
What is the name for the mucous gland only found in the duodenum?
Brunner’s glands (can be a large lump of gland tissue)
What is the chief function of the small intestine?
Absorption of nutrients (90% of this happens in small intestine) Large bowel mainly for water absorption.
What is the general histology of the small intestine wall?
Thick mucosa specialised for providing massive surface area
Extensive folding known as “crypts of Lieberkuhn”
Microvilli on apical surface of cells lining the crypts further increase surface area.
What are the absorptive cells that line the crypts and what do they secrete?
Goblet cells- secrete mucous
Paneth cells- secrete lysozyme
What main structures secrete into the duodenum?
Pancreas
Liver
Gall bladder
Where do these structures secrete into the duodenum?
At major duodenal papilla
How are fats absorbed in the small intestine?
Through simple diffusion into lacteals. (the lymphatic vessels of the small intestine)
What is the difference between the Jejunum and the Ileum?
Jejunum joins the duodenum and the ileum.
Jejunum is in the upper left part of the peritoneal cavity whereas the ileum is lower left.
Ileum is a lot larger that the jejunum.
Where is the circular smooth muscle vs the longitudinal smooth muscle?
Circular is inner and longitudinal is outer.
How does the villi compare in the duodenum vs the ileum?
Longer in the duodenum.
How can coeliac disease show in histology?
A flattening of the villi (from an immune response).
Where is the villi and where is the crypts typically?
Villi are long structure protruding out. Crypts are an between villi (kind of burrowing inward.)
What is in a crypt of lieberkuhn?
Goblet cells (white circles)
Paneth cells (small red dots (smaller than goblet)
Endocrine cells in the very bottom of the crypt.
What are the clinical signs and symptoms of dehydration? (11)
Thirst
Weight loss
Dry mucous membranes
Sunken-appearing eyes
Decreased skin turgor
Increased capillary refill time
Hypotension and postural hypotension
Tachycardia
Weak and thready peripheral pulses
Flat neck veins when the patient is in the supine position
Oliguria- low output of urine between 80 ml-400ml/day. Anuria (<80)
How is hydration be maintained in a patient who has vomiting and/or diarrhoea?
Enteral routes preferred (oral rehydration solution) but if that is not possible
NG tube or
IV fluids (with sodium, glucose and potassium chloride)
What fluids should a dehydrated patient get?
Some fluids which have glucose, sodium and potassium to ensure best possible absorption of the fluids in the GIT. Of main importance is the sodium glucose symport.
What is Oral rehydration solutions (ORSs)?
Specifically designed fluids that contain an appropriate amount of sodium, glucose and other electrolytes and are of the appropriate osmolality, to maximise water absorption from the gut. They use the principle of glucose facilitated sodium transport whereby glucose enhances sodium and secondarily water transport across the mucosa of the upper intestine.
Challenges in maintaining a child/infant with gastroenteritis?
Low blood volume increased risk of dehydration
Cannot communicate pain properly
Greater chance of vomit aspiration
Baby would have a lot less exposures like this in general (low immunity)
What are some signs to look out for in a deteriorating infant (infant red flags)
Being floppy
Not eating
Stopped interacting
Etc
Infant with gastro/dehydration bad symptoms to look out for?
Amount of wet nappies
Increases irritability/crying
Floppy limbs
What are the benefits of the hydrolyte ice blocks?
More appealing
Slow introduction of fluid into the system (as ice needs to melt) means less chance of induced vomiting.
What is the clinical features of Staphylococcal food poisoning?
Sudden onset of symptoms (1-6 hours).
Lasts 1-2 days
Sudden onset severe Nausea and vomiting. Cramps and diarrhoea may be present
What is the clinical features of Norovirus and rotavirus infection?
Onset 12-48 hours after exposure to virus.
Fever, nausea, vomiting (more in children), abdominal cramping, diarrhoea (more in adults), headache.
Lasts 12-60 hours.
What is the clinical feature of salmonella?
Onset 6-48 hours
Symptoms- diarrhoea, fever, abdominal cramps, vomiting.
Lasts 4-7days
What is the clinical features of toxin producing organisms like E.coli O147?
Onset 1-8 days after exposure.
Symptoms- severve bloody diarrhoea, abdominal pain and vomiting, usually no fever (illness more common in children under 4.
Lasts 5-10 days
What are the symptoms of a clostridium difficile infection?
Watery diarrhea 10 to 15 times a day
Abdominal cramping and pain, which may be severe
Tachycardia
Fever Blood or pus in the stool
Nausea
Dehydration
Anorexia (loss of appetite)
Weight loss
Distended abdomen
How should a stool sample be collected?
As cleaning as possible trying not to introduce any new bacteria types to the stool.
Not from hands, urine or toilet.
What tests to order on a stool test?
MCS- microscopy culture and sensitivity.
OCP- ova, cysts and parasites.
PCR- typing
List more information i.e. suspected gastroenteritis so the pathologist can add anything they also thing is required
What are some challenges of identifying pathogens by culture and microscopy?
Growth conditions may be poor
Might be a virus or other particle that is too small to see/wont culture.
What is the common method used for direct antigen detection?
Faecal multiplex PCR
How does faecal multiplex PCR work?
Primers for an array of common pathogens, can type the pathogen of interest.
How does the amount and outcome of cases of gastroenteritis compare globally?
Less cases in Australia, rarely results in death
Lots of cases in developing countries, many deaths result.
Underlying causes of increased mortality from gastroenteritis in some countries?
Lack of medical facilities
Poor food prep/storage
No clean drinking water
What is the latent period in disease transmission?
The time between an exposure to an infectious organism and the infection of the host by the pathogen. (after infectious host is often infectious to others)
What is the incubation period in disease transmission?
The time between exposure and the onset of clinical symptoms (different to latent period)
What is the transmissibility in disease transmission?
How it is able to be transferred/spread.
What is the infectious period in disease transmission?
The period of time in which the host may spread the pathogen to others.
What is the reproductive rate in disease transmission?
The rate in which a single case can generate other cases (how many people one case can infect).
What does Enteral mean?
Refers to intake of food via the gastrointestinal (GI) tract.
What can be the effect of taking medications that regulate stomach acidity (reduce)?
Can increase risk of bacterial infection as gastric juice not acidic enough to kill them.
What are the red flags for gastroenteritis symptoms?
Meningitis
Sepsis
What investigation should be done in the case of Maria?
Stool sample- MCS, O&P (ova and protozoan), PCR
Bloods- FBC, CRP, UEC (urine electrolytes count????)
What treatment for Maria?
Rehydration IV
Anti emetic (vomit prevention)
Anti-diarrhoeal probably not because of paralytic ileus.
What about a baby with gastro?
Might try anti emetics to allow for oral rehydration.
NG tube.
Could do IV but tricky
Should you give someone with diarrhoea gastro antimotility drug?
No because it may cause an ileus (paralytic), want to flush out the bug that is causing the issue.
Supportive care of rehydration should be enough.
What is the common lowered electrolytes by diarrhoea?
Potassium and bicarbonate
What is a bolus in terms of IV fluid?
It is a fast delivery mechanism for IV fluids.
Would you do a stool culture on every gastro case?
No because there is way too many, only on bad cases or in an outbreak situation.
Why do small amounts of liquid for rehydration in someone who is vomiting?
Large amount can trigger vomiting
Sources of fluid intake and average intake amount?
Oral (external)- intake of fluids and food (and/or IV fluids)
Fluid-1500ml, Food-700ml
Metabolic water production (internal) 300mL
What are some ways for fluid loss?
Faeces- (200ml)
Sweat- (100ml)
Urine- (1400ml)
Insensible loss- (800ml) (evaporative loss from the respiratory tract and skin (deemed insensible because we are not aware of it.
What is the approximate intake and output of water per day?
2500 in and 2500 out.
What are some general volumes for water internal fluxes?
Diffusion turnover in the capillaries 80,000L
Lymph flow = 2.5L
Glomerular filtration rate (Kidneys) = 180L
Fluid in the GIT = 8-9L
How much water is lost per day to insensible losses?
800mL
How much water is lost by faeces per day?
200mL
What are the net fluid movements during ingestion?
Food and fluid 1200mL
What are the net fluid movements during secretions?
Saliva 1400mL
Gastric juice 2500mL
Bile 600mL
Pancreatic juice 1500mL
Intestinal juice 1000mL
What are the net fluid movements during absorption?
7000mL from Small intestine
1000mL from large intestine (can increase up to 5000mL)
What is the net fluid movements during loss?
Faeces- 200mL
What is a simple way to summaries the fluid movement in the GIT?
Fluid in (ingestion + secretion) - fluid out (intestinal absorption) = fluid lost (faeces)
What is the function of saliva?
contains digestive enzymes, mucous, antibacterial compounds and electrolytes Lubricates and softens food, helps to form a bolus. Enzymes begin digestive process (i.e. salivary amylase breaks down starch to glucose)
How is water absorbed?
Nutrients and ions are absorbed with transporter proteins
The influx of these nutrients and ions such as glucose, sodium and potassium cause an osmotic gradient.
Water flows down this gradient through the enterocytes and through tight junctions, thus absorbed in the intestines