201 L14 & L15

Question 1

Where is the oesophagus located?

Answer 1

Dorsal to the trachea

Question 2

What is between the trachea and adventitia?

Why is it structured like that?

Answer 2

Loose connective tissue allowing flexibility when the bolus of food is travelling through the oesophagus allowing it to expand

Question 3

When does the oesophagus expand?

Answer 3

When the food is moving down it

Question 4

What is the function of the oesophagus?

Answer 4

Rapid transport (peristalsis) of food bolus to the stomach.

Question 5

What do all the blood vessels in the digestive system drain into?

Answer 5

The liver

Question 6

All the blood vessels in the digestive system drain to the —– first.

If there is congestion in the —— then the blood is going to want to —– flow through the ——— vein and back into the organs of the —-.

This means that the blood would backflow into the ———- which is not a very strong structure. There is a ——- width in the ——— barrier so it is easy for the —— —— to burst and cause the person to bleed to death (esophageal varices)

Answer 6

All the blood vessels in the digestive system drain to the liver first.

If there is congestion in the liver then the blood is going to want to back flow through the portal vein and back into the organs of the gut.

This means that the blood would backflow into the esophagus which is not a very strong structure. There is a decreased width in the epithelium barrier so it is easy for the blood vessel to burst and cause the person to bleed to death (esophageal varices)

Question 7

What does the presence of skeletal muscle tell you about the part of the oesophagus that you are looking at?

Answer 7

This is the upper part of the oesophagus because of conscious voluntary swallowing

Question 8

How can you differentiate between skeletal and smooth muscle?

Answer 8

Skeletal muscle has striations and the nuclei are peripheral.

Question 9

What indicates that you are looking at the lower esophagus histology?

Answer 9

There is only smooth muscle present.

Question 10

The ——– ——– epithelium of the esophagus transitions to the ——— ——- epithelium in the stomach.

There are some glands in the ——— zone as well as in the ——– but they are not within the ———-, but rather in the ———– tissue.

Answer 10

The stratified squamous epithelium of the esophagus transitions to the glandular gastric epithelium in the stomach

There are some glands in the transitional zone as well as in the esophagus but they are not within the epithelium, but rather in the connective tissue

Question 11

The ——– ——– epithelium of the esophagus transitions to the ——— ——- epithelium in the stomach.

There are some glands in the ——— zone as well as in the ——– but they are not within the ———-, but rather in the ———– tissue.

Answer 11

The stratified squamous epithelium of the esophagus transitions to the glandular gastric epithelium in the stomach

There are some glands in the transitional zone as well as in the esophagus but they are not within the epithelium, but rather in the connective tissue

Question 12

In the oesophagus is the epithelium keratinised?

Answer 12

No

Question 13

The muscularis mucosae is —– near the upper esophagus but developed near the ——–.

Answer 13

The muscularis mucosae is rare or absent near the upper esophagus but developed near the stomach.

Question 14

The pharyngeal end of the esophagus has a muscularis externa that is ——– muscle, while the gastric end is mostly —— muscle.

Answer 14

The pharyngeal end of the esophagus has a muscularis externa that is skeletal muscle, while the gastric end is mostly smooth muscle.

Question 15

Is the esophagus lined with adventitia or serosa?

Answer 15

Adventitia

Question 16

What is peristalsis and what does it require?

Answer 16

Peristalsis is the process of squeezing food from one segment to another requires the cooperation and coordination of the inner circular and outer longitudinal layers of muscle

Question 17

What is segmentation and what happens?

Answer 17

Segmentation is when only one of the muscle layers is doing the work.

The food is being broken down but it is not being moved anywhere.

Question 18

Does the esophagus have sphincters?

If so what are they called?

Answer 18

Upper esophageal sphincter

Lower esophageal sphincter

Question 19

What sphincter of the oesophagus if damaged leads to stomach reflux?

Answer 19

Lower esophageal sphincter

Question 20

What is tonal contraction?

Answer 20

This is a baseline level of contraction that keeps both esophageal sphincters in check

Question 21

What can stomach reflux potentially lead to?

Answer 21

Chronic oesophagitis

Question 22

Chronic oesophagitis

If the ——- esophageal sphincter was leaky this would cause —— ——.

Contents from the ——– would easily escape the sphincter and regurgitate into the ———–

When this happens it can cause irritation and ——– of the esophagus

If the reflux is ——- you can end up with chronic oesophagitis and you can see regions of ——–.

There is damaged ——–, specifically the ———- lining is gone, which has resulted in the ——- and —— —— being in direct contact.

Increased amount of ———– are seen in the lamina propria - Sign of inflammation

Answer 22

If the lower esophageal sphincter was leaky this would cause stomach reflux.

Contents from the stomach would easily escape the sphincter and regurgitate into the esophagus.

When this happens it can cause irritation and inflammation of the esophagus

If the reflux is chronic you can end up with chronic oesophagitis and you can see regions of ulcerations.

There is damaged mucosa, specifically the epithelial lining is gone, which has resulted in the lumen and lamina propria being in direct contact.

Increased amount of lymphocytes are seen in the lamina propria - Sign of inflammation

Question 23

What happens if oesophagitis persists?

Answer 23

It can develop into Barrett’s oesophagus

Question 24

Barrett’s oesophagus

This is when the epithelium undergoes ———–.

It goes from a ——- —— epithelium (good for withstanding shear force) into this ——— epithelium (good for withstanding acidic insults)

Therefore the epithelium has ——- itself to better cope with the changing ——— (increased amount of acidic insults)

Barrett’s oesophagus is a precursor to ——— ———.

Answer 24

This is when the epithelium undergoes metaplasia.

It goes from a stratified squamous epithelium (good for withstanding shear force) into this glandular epithelium (good for withstanding acidic insults)

Therefore the epithelium has modified itself to better cope with the changing environment (increased amount of acidic insults)

Barrett’s oesophagus is a precursor to esophageal cancer.

Question 25

What is the main function of the stomach?

Answer 25

Store food temporarily

Question 26

——– are transient (not there all the time) folds of the ——-
.
When the ——– is empty they are very visible but when the ———- is full they disappear.

When they get stretched they flatten out to increase the —— —–.

Answer 26

Rugae are transient (not there all the time) folds of the mucosa
.
When the stomach is empty they are very visible but when the stomach is full they disappear.

When they get stretched they flatten out to increase the surface area.

Question 27

The —– —— is a thickening of the —— ——- muscle layer in the stomach. It controls the rate and volume of —– release into the —– —–.

It is made up of —– —–.

Answer 27

The pyloric sphincter is a thickening of the inner circular muscle layer in the stomach. It controls the rate and volume of chyme release into the small intestine.

It is made up of smooth muscle.

Question 28

Name 3 main parts of the stomach.

Answer 28

Cardia - entrance
Body
Pylorus - exit

Question 29

What area of the stomach is described below;

Over here the mucosa is made up of mostly mucus glands so the secretion is mostly mucus

Answer 29

Cardia

Question 30

What area of the stomach is described below;

Mostly mucus with some enzymes and hormones, but NO ACID

Answer 30

Pylorus

Question 31

What does the mucus in the Cardia and Pylorus of the stomach do?

Answer 31

Act as buffers,

If there is any reflux and the acidic contents move through the cardia the mucus dilutes the acid a little bit.

When chyme is leaving the pylorus it will mix with mucus which will dilute the acidic contents a little bit.

Question 32

Where are the acid and enzyme secreting cells mostly found in the stomach?

Answer 32

Fundus and body

Question 33

What is the order of the muscle layers in the muscularis externa?

Answer 33

Innermost oblique
Inner circular
Outer longitudinal

Question 34

Name the cells present in the stomach?

Answer 34

Simple columnar mucous cells

Mucous neck cells

Parietal cell

Chief cells

Enteroendocrine cells

Question 35

What cell of the stomach is described below?

The ——- ——— form a mucus coat to create a ——–.

The ———– secreted by the ——- cells are transported and released to make the mucus coat ———, adding to the ——- protection function

There is a ———– enrichment within the apical membrane

These cells undergo rapid replacement by the ———- stem cells

All these properties help to protect the stomach/ gastric mucosa from —- ——–.

Prostoglandin E2 (inflammatory mediator PE2) helps to stimulate the production of ——- and the ——— enrichment

Non-steroidal anti inflammatory drugs (NSAID) - e.g. aspirin - it interferes with the inflammatory cascade that produces —– and blocks its production.

Answer 35

Simple columnar mucous cells

The mucous granules form a mucus coat to create a barrier.

The bicarbonate secreted by the parietal cells are transported and released to make the mucus coat alkaline, adding to the barrier protection function

There is a phospholipid enrichment within the apical membrane

These cells undergo rapid replacement by the undifferentiated stem cells

All these properties help to protect the stomach/ gastric mucosa from auto digestion.

Prostoglandin E2 (inflammatory mediator PE2) helps to stimulate the production of mucus and the phospholipid enrichment

Non-steroidal anti inflammatory drugs (NSAID) - e.g. aspirin - it interferes with the inflammatory cascade that produces PE2 and blocks its production.

Question 36

If someone takes too much aspirin what impact would that have on the protective mechanisms of the simple columnar mucus cells?

Answer 36

Aspirin inhibits the actions of prostaglandin E 2 so you would lose the encouragement of PE2 on mucus production and phospholipid enrichment

Question 37

What is the biggest cause of gastric ulcers?

How does it occur?

Answer 37

Helicobacter pylori bacteria

The urease (enzyme) converts urea into ammonia which attacks the mucus coat

The toxins it releases directly damages the mucus secreting cells.

Question 38

What cell of the stomach is described below?

Produce a mucus secretion during meal times

Located around the neck region

Answer 38

Mucous neck cells

Question 39

What cell of the stomach is described below?

—– is secreted by these cells which sterilise food that is digested by attacking ——- in the ingested food.

So if you don’t have enough —- it will result in decreased ——— killed which leads to gastroenteritis

The ——- also helps to —– the environment for the activation of ——- to ———.

So when there is a decreased ——– environment there is reduced activation of ———- to ——— resulting in decreased ——– digestion

Secrete ——– factor which is important for ——— —- absorption.

——– — is important for RBC haematopoiesis (making RBC).

So if there is not enough ——- factor you will get pernicious anaemia (don’t make enough RBCs)

Answer 39

Parietal cells

HCl is secreted by these cells which sterilise food that is digested by attacking bacteria in the ingested food.

So if you don’t have enough HCl it will result in decreased bacteria killed which leads to gastroenteritis

The HCl also helps to acidify the environment for the activation of pepsinogin to pepsin.

So when there is a decreased acidic environment there is reduced activation of pepsinogin to pepsin resulting in decreased protein digestion

Secrete intrinsic factor which is important for Vitamin B12 absorption.

Vitamin B12 absorption is important for RBC haematopoiesis (making RBC).

So if there is not enough intrinsic factor you will get pernicious anaemia (don’t make enough RBCs)

Question 40

What cell of the stomach is described below?

Are located underneath the parietal cells

They have ——– granules in their cytoplasm which contain a precurso enzyme called ————.

The ———— is released and travels towards the ——-.

As they encounter the ——- environment it becomes activated into ——- which is involved in ——- digestion.

Answer 40

Chef cells

Are located underneath the parietal cells

They have zymogen granules in their cytoplasm which contain a precurso enzyme called pepsinogin.

The pepsinogen is released and travels towards the lumen.

As they encounter the acidic environment it becomes activated into pepsin which is involved in protein digestion.

Question 41

What cell of the stomach is described below?

Migrate both up and down to the replace the cells in the gastric glands

Answer 41

Undifferentiated stem cells

Question 42

What cell of the stomach is described below?

Cells that secrete gut ———

G cells make gastrin which is a hormone that stimulates the ——- ——- functions, stimulates the —— cells to start producing histamine and stimulates the —– cells to produce somatostatin

ECL cells produce histamine which stimulates the ——- cells.

D cells produce somatostatin which stops the —– cells from making too much histamine and stops the – cells from making too much gastrin (negative feed back)

Prostoglandin E2 inhibits —– cells and —- cells.

Answer 42

Enteroendocrine cells

Cells that secrete gut hormones

G cells make gastrin which is a hormone that stimulates the gastric mucosal functions, stimulates the ECL cells to start producing histamine and stimulates the D cells to produce somatostatin

ECL cells produce histamine which stimulates the parietal cells.

D cells produce somatostatin which stops the ECL cells from making too much histamine and stops the G cells from making too much gastrin (negative feed back)

Prostoglandin E2 inhibits G cells and ECL cells.

Question 43

If someone takes too much aspirin what impact would that have on the mechanisms of the enteroendocrine cells?

Answer 43

PE2 is normally inhibiting G cells

The NSAID is inhibiting the inhibitor so the inhibition of gastrin production is removed so there will be an overproduction of gastrin which will increase gastric activity. This means the person will be exposed to more acid production and is more likely to get gastric ulcers.

Question 44

What is the most obvious feature of the small intestine?

Answer 44

plyci circularus

Question 45

In the small intestine the evagination is the —– and the depression is the intestinal gland or crypt of liberkuhn

Answer 45

In the small intestine the evagination is the vilus and the depression is the intestinal gland or crypt of liberkuhn

Question 46

Movement of blood and bile in the small intestine

Venus blood is where the ——— and the ——— are carried away after they have been absorbed from the —— through the enterocytes. This is carried away through the hepatic portal vein to the ——.

Lacteal - where the fats get transported, more leakier, join the circulatory system

Answer 46

Venus blood is where the carbohydrates and the proteins are carried away after they have been absorbed from the lumen through the enterocytes. This is carried away through the hepatic portal vein to the liver.

Lacteal - where the fats get transported, more leakier, join the circulatory system

Question 47

Muscularis mucosa of small intestine

There are extension of ——– muscles cells into the — —– from the muscularis mucosa.

They help to squeeze the ——— to help propel the contents along and cause localised ——– movement during the contraction of the muscularis mucosa layer.

Answer 47

There are extension of smooth muscles cells into the lamina propria from the muscularis mucosa.

They help to squeeze the lacteal to help propel the contents along and cause localised villus movement during the contraction of the muscularis mucosa layer.

Question 48

Name the cells present in the stomach?

Answer 48

Enterocytes (columnar absorptive cells)

goblet cells

Enteroendocrine cells

Paneth cells

Question 49

What cell of the small intestine is described below?

Lined with a ——— which increases its surface area for ——–

The ———- are not motile but are connected to the ——– of the cell so when the ——– —— moves and the smooth muscle in the ——– ——- move, the cells will move and so the ——- will have a degree of movement.

The ————- membrane is studded with digestive ——— (from the pancreas) such as ———– (activate other enzymes) and ———- (breakdown carbohydrates)

So the ——– also enhance the ———- ability of the small intestine.

On top of the ——– is a ———- layer called——– which helps to selectively bind desirable molecules that you want to absorbs and becomes a barrier to unwanted materials.

Answer 49

Enterocytes of the small intestine

Lined with a microvilli brush border which increases its surface area for absorption

The microvilli are not motile but are connected to the cytoskeleton of the cell so when the muscularis mucosa moves and the smooth muscle in the lamina propria move the cells will move and so the microvilli will have a degree of movement.

The microvillus membrane is studded with digestive enzymes (from the pancreas) such as enterokinase (activate other enzymes) and glycosidases (breakdown carbohydrates)

So the microvilli also enhance the digestive ability of the small intestine.

On top of the microvilli is a glycoprotein layer called glycocalyx which helps to selectively bind desirable molecules that you want to absorbs and becomes a barrier to unwanted materials.

Question 50

What cell of the small intestine is described below?

Lined with a ——— which increases its surface area for ——–

The ———- are not motile but are connected to the ——– of the cell so when the ——– —— moves and the smooth muscle in the ——– ——- move, the cells will move and so the ——- will have a degree of movement.

The ————- membrane is studded with digestive ——— (from the pancreas) such as ———– (activate other enzymes) and ———- (breakdown carbohydrates)

So the ——– also enhance the ———- ability of the small intestine.

On top of the ——– is a ———- layer called——– which helps to selectively bind desirable molecules that you want to absorbs and becomes a barrier to unwanted materials.

Answer 50

Enterocytes of the small intestine

Lined with a microvilli brush border which increases its surface area for absorption

The microvilli are not motile but are connected to the cytoskeleton of the cell so when the muscularis mucosa moves and the smooth muscle in the lamina propria move the cells will move and so the microvilli will have a degree of movement.

The microvillus membrane is studded with digestive enzymes (from the pancreas) such as enterokinase (activate other enzymes) and glycosidases (breakdown carbohydrates)

So the microvilli also enhance the digestive ability of the small intestine.

On top of the microvilli is a glycoprotein layer called glycocalyx which helps to selectively bind desirable molecules that you want to absorbs and becomes a barrier to unwanted materials.

Question 51

What cell of the small intestine is described below?

Located at the base of the glands

Secrete a diverse range of antibacterial defense molecules such as TNF alpha, lysozymes and defensins that have protective functions.

Answer 51

Paneth cells

Question 52

Duodenum

Duodenum is the ——- part of the small intestine

The stomach feeds — — with —- —- fragments and —- —- into the duodenum through the control of the ——- —–.

The arrival of these stimulates the ———- cells.

Stimulated ——— cells produce hormones (——-and ——-) which stimulate the ——– and the ——– to release it’s —–, digestive ——- and ——.

At the start of the duodenum the pH is about -

The ——– glands in the ——— of the duodenum is prominent in the ——– but decreases towards the —–.

The ——– glands secrete —— rich mucus which increases the pH up to -.

A neutral pH is important for the optimal operation of ——- enzymes (activated by the enterokinase) for digestions

Answer 52

Duodenum

Duodenum is the shortest part of the small intestine

The stomach feeds acidic chyme with amino acid fragments and fatty acids into the duodenum through the control of the pyloric sphincter.

The arrival of these stimulates the enteroendocrine cells.

Stimulated endocrine cells produce hormones (CCK and Secretin) which stimulate the gallbladder and the pancreas to release it’s bile, digestive enzymes and bicarbonate.

At the start of the duodenum the pH is about 1-2

The brunner’s glands in the submucosa of the duodenum is prominent in the beginning but decreases towards the ilium.

The brunner’s glands secrete bicarbonate rich mucus which increases the pH up to 7-8.

A neutral pH is important for the optimal operation of pancreatic enzymes (activated by the enterokinase) for digestions

Question 53

What is the main function of the large intestine?

Answer 53

Compact the lumenal wastes, dehydrate gut content and reabsorb water and vitamins.

Question 54

Muscularis externa of large intestine

The ——— muscle of the large intestine is not in a —— layer.

In 3 parts its concentrated onto these bands called —- —-.

There tonal contraction causes the colon to form these pockets called the —— which allow different regions of the colon to contract ——— and reabsorb water in a modular manner.

Answer 54

The external muscle of the large intestine is not in a uniform layer.

In 3 parts its concentrated onto these bands called taenia coli.

There tonal contraction causes the colon to form these pockets called the haustra which allow different regions of the colon to contract independently and reabsorb water in a modular manner.

Question 55

What is the ilocecal valve and its function?

Answer 55

Is the valve between the ilium and the caecum (first part of LI).

It regulates the passage of materials into the caecum

Question 56

List the main structures of the large intestine from the side closest to the small intestine to the end of the tract.

Answer 56

Caecum
Ascending colon
Transverse colon
Descending colon
sigmoid colon
Rectum

Question 57

Mucosa of the large intestine;

No plicae or villi

numerous —– of ———

——– —– cells and —– cells predominate

———- cells near the base of the glands

Answer 57

Mucosa of the large intestine;

No plicae or villi

numerous crypts of lieberkuhn

columnar absorptive cells (have microvilli) and goblet cells predominate

undifferentiated cells near the base of the glands

Question 58

Is there more goblet cells at the beginning or end of the large intestine?

Answer 58

At the end of the LI there are more goblet cells to increase lubrication for the movement of dehydrated contents

Question 59

Lamina propria of large intestine

Dense layer of ——- underneath the —–.

——– nodules extending down into the submucosa (GALT) - help provide —— responses to keep the —- in check.

Answer 59

Dense layer of collagen underneath the epithelium.

lymphatic nodules extending down into the submucosa (GALT) - help provide immune responses to keep the bacteria in check.

Question 60

Internal anal sphincters have —— muscle

external anal sphincters have —– muscle

Answer 60

Internal anal sphincters have smooth muscle

external anal sphincters have skeletal muscle

Question 61

The oesophagus, basal part of the epithelium surface cells take ——- to replace.

Answer 61

Days

Question 62

The stomach, near the neck of gastric glands, surface cells take ——- to replace while deeper cells take —/—.

Answer 62

Days

weeks/months

Question 63

The small intestine, lower 1/2 of glands, surface cells take ——- to replace, while deeper cells take —/—.

Answer 63

Days

weeks/months

Question 64

The Large intestine, lower 1/3 of glands, surface cells take ——- to replace

Answer 64

Days

Question 65

Where are the portal triads embedded in the liver?

Answer 65

In the CT septa

Question 66

Portal Vein

We know its a vein because it looks ——–, has bigger ——– compared to its —– thickness (low pressure).

Carries highly rich ——– blood from the —- to the —— and is ———

75% of the blood coming to the liver

Answer 66

Portal Vein
We know its a vein because it looks floppy, has bigger lumen compared to its wall thickness (low pressure).

Carries highly rich nutrient blood from the gut to the liver and is deoxygenated

75% of the blood coming to the liver

Question 67

Hepatic artery

Carries richly ———- blood from the ——-

Low nutrients

Has a much smaller ——- and a thicker —– (high pressure)

25% of blood coming into the liver

Answer 67

Hepatic artery

Carries richly oxygenated blood from the heart

Low nutrients

Has a much smaller lumen and a thicker wall (high pressure)

25% of blood coming into the liver

Question 68

Portal vein and hepatic artery feed blood into the ——-

So in the ——— there is mixed blood (——- and ——- rich)

The ———– blood is drained through the ——- vein and eventually ends up in the —— —- ——-.

Bile ——- feed bile into the bile —— in the opposite direction

Answer 68

Portal vein and hepatic artery feed blood into the sinusoids

So in the sinusoids there is mixed blood (nutrient and oxygen rich)

The sinusoidal blood is drained through the central vein and eventually ends up in the inferior vena cava

Bile canaliculi feed bile into the bile duct in the opposite direction