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IMS > W8- Lecture 39- Digestive system > Flashcards

W8- Lecture 39- Digestive system Flashcards

1
Q

what are the components of the digestive system ?

A 
Mouth
Pharynx
Oesophagus
Stomach
Intestines
Anus
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2
Q

what are the accessory organs that are not in the digestive tract, but help in digestion?
+ function

A

Liver-Bile production; storage
Gall bladder-Stores & concentrates bile
Pancreas-Exocrine cells (fluid & enzymes), endocrine cells (hormones)
Salivary glands-Lubricating fluid & enzymes

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3
Q

describe the function related to structure of the mouth in the digestive system

A

Secretion of salivary amylase (breaks down carbohydrates)
Lingual lipase begins the breakdown of fat into smaller fat molecules.
Highly muscular tongue
Manipulates food for mastication (bolus)
Surface of tongue covered with lingual papillae:
Filiform (most numerous)
Fungiform
Circumvallate
Foliate

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4
Q

the surface of tongue covered with lingual papillae name the 4 types

A

Filiform (most numerous)
Fungiform
Circumvallate
Foliate

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5
Q

which three transport passages make up the digestive system

A

Pharynx
Oesophagus
Anal canal

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6
Q

what cells line the digestive transport passages ?

A

Lined with stratified squamous epithelium

Some mucous glands for lubrication

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7
Q

describe the structure of the oesophagus

A

Approximately 25cm long
Lined with mucosa
Stratified squamous epithelium Columnar epithelium
Well defined lamina propria + muscularised mucosae.
Peristalsis propels food and water into stomach

Tough stratified epithelium without keratin
Squamous mucosa
Submucuosal glands secrete fluid into the difestive tract where they serve a variety of protective functions.
Circular layer and muscularis externa provides peristaltic contractions
Longitudinal layer plays a role in the physiology of motor function

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8
Q

what are the 4 layers of the alimentary tract

A

mucosa
submucosa
muscularis externa
serosa/adventitia (most lateral)

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9
Q

describe the mucosa layer of the alimentary tract

A

contains both epithelia and lamina propria
Epithelium
Mainly columnar epithelial cells
Glandular secretions moisten surface

Lamina propria
Composed of loose connective tissue
Contains small blood vessels, lymphatics, nerve fibres
Other specialist cells (macrophages and lymphocytes)

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10
Q

describe the submuscosa layer of the alimentary tract

A

Separates mucosa from underlying muscle layers

Regulates contractions + glandular secretions

Submucosal plexus (meissnr’s plexus)

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11
Q

describe the MUSCUALRIS EXTERNA layer of the alimentary tract

A 
Smooth muscle (two layers
Inner: circular layer
Outer: longitudinal

Layers allow peristaltic contractions

Second nerve plexus located between muscular layers – myenteric (Auerbach’s) plexus

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12
Q

describe the outermost layer: ADVENTITIA layer of the alimentary tract

A

Made of fibrous connective tissue

layers structure determined by the surrounding tissues

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13
Q

describe the structure of the stomach

+ 4 anatomical regions

A

Digestive organ + reservoir.
Inner folds (rugae) increase surface area)
Food is mixed with gastric juices, hydrochloric acid and enzymes (pepsin)

Mucosa
Muscularis mucosae – circular and longitudinal muscle fibres

Muscularis externa
Three layers (oblique, circular, longitudinal)
Four anatomical regions:
Cardia
Fundus
Corpus (body)
Pylorus
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14
Q

if pepsin breaks down proteins and the stomach is made out of protein why is it not broken down?

A

Mucus secreted by stomach cells (foveolar cells) protects the stomach lining.

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15
Q

label the stomach

A 
did you find
1- Cardia
2- Cardiac notch
3- Fundus
4- Body
5- Pylorus
6- 1st part of duodenum
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16
Q

what are the three subdivisions of the small intestine

A

Duodenum
Jejunum
Ileum

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17
Q

describe the mucosa in the small intestine

A

Plicae and villi
Increase surface area approximately 3x
Permanent structures (don’t change with distension
Absent from start of duodenum

Intestinal villi – entire intestinal mucosa
Increase surface area approx. 10x
Main cell type: enterocytes (have absorptive function

Microvilli on enterocytes
Increase surface area approx. 20x

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18
Q

what is absorbed in the large intestine ?

+ three main sections

A

Reabsorption of water and inorganic salts

Three main sections
Caecum (inc appendix)
Colon (ascending, transverse, descending, sigmoid)
Rectum (inc anal canal)

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19
Q

describe the mucosa layer of the large intestine ?

A

Smooth surface
Neither plicae nor villi
Goblet cells-More numerous than in small intestine

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20
Q

what are the two types of waste excreted by the digestive system

A

Two types of waste:
Solid waste – from the digestive system in the form of faeces.
Metabolic wastes – produced by chemical reactions like respiration, hydrolysis, synthesis and neutralization:

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21
Q

what is a Hiatal hernia?

A

Protrusion of stomach into the mediastinum through the oesophageal hiatus of the diaphragm.
Caused by weakened muscle tissue or excessive pressure
Can cause heartburn
Chest pain
Shortness of breath

22
Q

what are Gastric ulcers?

+main cause

A

Lesions in stomach lining

Caused mainly by the bacterium helicobacter pylori

23
Q

name the 5 types of salivary glands

A 
Lingual
Labial
Buccal
Molar
Palatine
24
Q

where are salivary glands situated ?

A

Situated in submucosa of oral cavity + tongue

25
Q

name three of the large salivary glands

+Location

A

Sublingual
Beneath tongue
Many ducts

Submandibular
Floor of mouth
Along inner surface of mandible
Ducts behind teeth

Parotid
Largest, empties into mouth at the second molar

26
Q

what are the functions of The liver?

A

Filter the blood coming from the digestive tract before passing it to the rest of the body.

Detoxifies chemicals and metabolizes drugs.
The liver makes bile and removes toxin.

27
Q

describe the surface anatomy of the

lover

A

The liver is the largest internal organ (1.2-1.5kg) and is situated in the right hypochondrium.

The liver lies mainly in the right upper quadrant of the abdomen.

It is protected by the thoracic ribs (7-11) and the diaphragm.

28
Q

describe the divisions of the liver

A

A functional division into the larger right lobe (containing caudate and quadrate lobes) and the left lobe is made by the middle hepatic vein.
The liver is further divided into 8 segments, by divisions of the right, middle, and left hepatic veins.
Each segment has its own portal pedicle, permitting individual segment resection at surgery.
functional lobules separated to each other by a septum.

29
Q

describe the flow of bile in the liver

A

Bile canaliculi collects the bile produced by hepatocytes and drains it into the bile duct.

Bile passes from the liver via the biliary ducts – right and left – that join to form the common hepatic duct which unites with the cystic duct to form the common bile duct.

Bile aids in the digestion of lipids.

30
Q

describe movement of blood in the liver

A

The hepatic blood supply constitutes 25% of resting cardiac output and is delivered via two main vessels, entering via the liver hilum (porta hepatis):
The hepatic artery, a branch of the coeliac axis.
The portal vein, drains most of the GI tract and spleen.

31
Q

explain the actions of each of these functions of the liver
1digestion
2metabolic & synthesis
3detoxification

A

1Synthesis of bile salts
Conjugation and excretion of bile pigment (bilirubin)
Glucose metabolism (regulation of blood sugar)
Conversion of blood glucose to glycogen and fat
Production of glucose from glycogen and other molecules by gluconeogenesis
Secretion of glucose into blood

2Fat metabolism
Synthesis of triglycerides and cholesterol, excretion of cholesterol in bile, and production of ketone bodies from fatty acids.

3Protein metabolism
Production of albumin, plasma transport proteins, clotting factors.
Phagocytosis by Kupffer cells
Chemical alteration of biologically active molecules (hormones and drugs)
Production of urea, uric acid and other compounds that are less toxic than the parent compound.

32
Q

what is the composition of bile?
produced by ?
+ exporting

A

Bile composition
Organic: bilirubin
Inorganic: bile salts

Produced by hepatocytes

Passes into bile canaliculi

Canaliculi carry bile to bile duct
Over production may result in Jaundice.

33
Q

what is jaundice ?

causes?

A

Skin, eyes and mucous membranes turn yellow due to high level of bilirubin, a yellow-orange bile pigment.
Many causes:
Hepatitis, liver disease, pancreatitis, gallstones and tumors, sickle cell disease.

34
Q

how is bile secreted ?

A

Terminal bile ducts
Lined with cuboidal epithelium

Intrahepatic bile ducts
Coalesce into left + right hepatic ducts
Unite to form common hepatic duct
Columnar epithelium

Cystic duct (to/from gallbladder)
Common bile duct (to duodenum)
35
Q

describe the function of the gall bladder

A

Concentrates and stores bile
H2O and ions absorbed by mucosa
Receives watery bile from hepatic duct
Contraction of muscularis layer empties thick, concentrated bile into common bile duct and into small intestine.

When small intestine is empty, sphincter of Oddi closes.

36
Q

what are gall stones ?

A

Gallstones are cholesterol that have crystallised within the gall bladder.

37
Q

what is the impact of Cholecystokinin(CCK) on bile

A

CCK from the duodenum triggers dilation of the hepatopancreatic sphincter and contraction of the gallbladder
bile is ejected into the duodenum through the duodenal ampulla

38
Q

describe the endo and exocrine functions of the pancreas

A

Exocrine:
Acini cells are clusters surrounding ducts responsible for secreting digestive enzymes.

Endocrine:
Islets of Langerhans
There are 3 major types of cells in an islet:
Alpha cells makeglucagon, which raises the level ofglucose(sugar) in the blood
Beta cells make insulin
delta cells make somatostatin which inhibits the release of numerous other hormones in the body

39
Q

what is gastritis?
main cause
what else gastritis can lead to

A

Gastritis indicates inflammation associated with mucosal injury of the stomach

Helicobacter pylori (H. Pylori) infection is the most common cause of gastritis.

Chronic inflammation can lad to gastric intestinal metaplasia, a precursor to gastric cancer.

40
Q

how does H. Pylori infection lead to cancer ?

A

H. Pylori infection causes chronic gastritis, which eventually leads to atrophic gastritis and pre-malignant intestinal metaplasia

41
Q

what are the two major types of gastric cancer ?

A

Intestinal (type 1) – Intestinal metaplasia is seen in the surrounding mucosa, often with H. pylori. This type is more likely to involve the distal stomach and occur in patients with atrophic gastritis.

Diffuse (type 2) – It may involve any part of the stomach, especially the cardia, and has a worse prognosis than intestinal type. Loss of expression of the cell adhesion molecule, E-cadherin, is the key event in the carcinogenesis of diffuse gastric cancers.

42
Q

what are the two major types of Inflammatory bowel disease

A 
Two major forms of IBD are recognised:
Crohn’s disease (CD) which can affect any part of the gastrointestinal tract.
Ulcerative colitis (UC) which affects only the colon.

There is a degree of overlap between these two conditions and in 10% of cases of IBD it is termed colitis of undetermined type.

43
Q

what are the clinical feastures of crohn’s disease

A

Major symptoms are diarrhoea, abdominal pain and weight loss.
Approximately 50% of patients will require an intestinal resection within 5 years of diagnosis.
CD can also present as an emergency with acute right iliac fossa pain mimicking appendicitis.

44
Q

how can you investigate crohn’s disease ?

A

Stool test: including Clostridium difficile (c. dofficile) toxin assay should be performed.
Blood tests:
Anaemia
Raised ESR and CRP
Hypoalbuminaemia: present in severe disease as part of an acute phase response to inflammation associated with raise CRP.

45
Q

how can you manage crohn’s disease ?

A

Oral prednisolone used to induce remission of CD.
Antibiotics are used for treating secondary complications of CD (abscess and perianal disease).
Anti-TNF agents are used for maintenance of remission.

46
Q

what are the clinical features of Ulcerative colitis (UC)?

A

The major symptom in UC is diarrhoea with blood and mucus, accompanied by lower abdominal discomfort.
General features are malaise, lethargy and anorexia.
Toxic megacolon is a serious complication associated with acute severe colitis.
The X-ray shows a dilated, thin walled colon with a diameter of >6cm.

47
Q

how can you investigate Ulcerative colitis (UC)?

A

Colonoscopy
Blood tests:
White cell and platelet counts are raised in moderate to severe attacks.
ESR and CRP are often raised.
pANCA* may be positive (this is in contrast to CD where pANCA is usually negative.

48
Q

how can you manage Ulcerative colitis (UC)?

A

Main treatment is aminosalicylate.

Aminosalicylate delivers 5-ASA (aminosalicyclic acid), which is absorbed in the small intestine.

49
Q

what is Gastroesophageal reflux disease

A

GERD happens when the oesophagus does not close properly.
Thus allows stomach contents to reflux into the oesophagus.
GERD is a chronic condition of mucosal damage caused by stomach acid coming up from the stomach into the oesophagus

50
Q

what are the causes for Gastroesophageal reflux disease?

A

Caused by changes in the abnormal relaxation of the lower oesophageal sphincter due to oesophagitis, oesophageal spasm or a hiatal hernia.

51
Q

what is Splenomegaly?

A 
enlargement of the spleen
Granulocytic leukaemia (high leukocyte and white blood cell count) may enlarge spleen 10x.

Spleen (which is not normally palpable) can be palpated below the left costal margin when it is enlarged >3x.

Splenectomy (removal of spleen) may be lifesaving.

IMS (74 decks)

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