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Cell And Tissue Biology > Extra Mural Digestive System > Flashcards

Extra Mural Digestive System Flashcards

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1
Q

What do the associated glands of the extra mural system consist of? ( 4 glands)

A

Salivary glands
Pancreas
Liver
Gallbladder

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2
Q

Provide a description of salivary glands. What do they produce, wha the the three major pairs of glands?

A

These are a type of exocrine gland. Salivary glands produce saliva, a digestive and lubricating/protective function.

Three major pairs:
-parotid
-submandibular (submaxillary)
Sublingual

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3
Q

With regards to salivary glands, what are septas?

A

Septa is a type of CT that divides the parenchyma into lobules. CT surrounds each gland.

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4
Q

With regards to salivary glands, what is acini?

A

Acini are the arraignment of parenchyma within each gland, these are secretory units

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5
Q

With regards to salivary glands, what are acinus’?

A

These are a blind sac (spherical unit) composed of secretory cells

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6
Q

What are the three types of acini? (Don’t describe)

A

Serous Acini

Mucous acini

Mixed acini

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7
Q

Provide a description of Serous Acini

A

These contain only serous cells (secrete protein)

The cells are pyramidal in shape, round nasal nucleus

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8
Q

Describe mucous acini

A

This contains only mucous cells
The cells are in pyramidal shape, somewhat columnar in shape

These are also have apical granules which contain mucins (lubricating properties)

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9
Q

Describe mixed acini

A

This contains both serous and mucous cells

These have caps of serous cells called serous demilunes

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10
Q

What are the three sequential enlargement segments of ducts systems within glands?

A

Intercalated ducts

  • leads from the acinus
  • lined by low cuboidal epithelium

Striated ducts (intralobular)

  • lined by simple columnar epithelium
  • modifies electrolytes components of saliva

Excretory ducts

  • large ducts that empty into oral cavity
  • epithelium begins as simple columnar but. transitions to stratified cuboidal or columnar
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11
Q

What are myoepithelial cells?

A

These are small flattened contractile cells that lie between the basal plasma membrane of the epithelium cells of the acini and the basal lamina

These extend contractile processes around the acini and duct

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12
Q

What are parotid glands? Where are they located and what do they contain and produce?

A

Location:
- below and in front of ear

Contents:
- only serous acini

Production:
- abundant Alpha amylase

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13
Q

What is alpha amylase?

A

This initiates hydrolysis of CHO, and proline rich proteins with antimicrobial and other protective properties

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14
Q

What are submandibular glands? Where are they located and what do they contain and produce?

A

Location:
- under either side of the floor of mouth close to the mandible

Contents:
- this has a mixed gland, serous acid intermixed with many mucous acini with serious caps (CALLED SEROUS DEMILUNES)

Production:
- produces lysozyme

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15
Q

What is lysozyme?

A

This is secreted visa submandibular glands and helps with the hydrolysis of bacterial walls

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16
Q

What are sublingual glands? Where are they located and what do they contain and produce?

A

Location:
-floor of the mouth anterior to submandibular gland

Contents:
- mixed glands, mostly mucous acini, the main product is mucus

Production:
- produces mucus, adds both alpha amylase and lysozyme

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17
Q

What is the pancreas? What are the components of it, what are its two functions?

A

The pancreas is an elongated glad grossly divided into three components/regions:

Head—> expanded portion lies in C shaped curve of duodenum
Body—> narrow portion in centre
Tail—> extends to the left towards hilum of spleen

Functions as:
Exocrine
Endocrine

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18
Q

Describe exocrine function of the pancreas

A

This is when the pancreas synthesizes and secretes digestive enzymes into duodenum, it takes up most of the parenchymal tissue space

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19
Q

Describe the endocrine function of the pancreas

A

This is when the pancreas synthesizes and secrete insulin and glucagon into blood.

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20
Q

What is a distinct cell cluster that the pancreas secretes via endocrine?

A

Islets of langerhan. These are randomly dispersed among the exocrine pancreas tissue

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21
Q

With regards to the exocrine portion of the pancreas, what are their secretory units?

A

The units are serous acini formed by simple epithelium of pyramidal shaped cells

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22
Q

With regards to the exocrine portion of the pancreas, what are zymogen granules?

A

These are the round nucleated secretory base of the cell

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23
Q

With regards to the exocrine portion of the pancreas, how does the initial intercalated ducts begin?

A

These begin within the acinus as well as centroacinar cells

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24
Q

With regards to the exocrine portion of the pancreas, what is the purpose of intercalated ducks and centroaciner cells?

A

These secrete bicarbonate to neutralize acidic chyme entering the duodenum from the stomach. Optimizing the pH for enzyme activity

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25
Q

What are the three types of pancreatic digestive enzymes that are found in zymogen granules of acinus cells?

A

Proteases: trypsinogen, chymotrypsinogen (these are digestive proteins)

Amylase (alpha amylase): these digest carbohydrates

Lipase: these digest lipids

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26
Q

How is pancreatic exocrine secretion regulated?

A

This is regulated via hormonal control. Mainly by two hormones (secretin and cholecystokinin) secreted by enteroendocrine cells of the small intestines

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27
Q

What is the purpose of of secretin within the pancreatic exocrine glads?

A

This promotes water and bicarbonate, the secretion buy the pancreatic ducts epithelial cells

28
Q

What is the purpose of cholecystokinin (CKK) within the pancreatic exocrine glands?

A

These stimulate enzyme secrete by the pancreatic acinar cells

29
Q

What is the overall purpose of the endocrine pancreas?

A

Regulate blood glucose

30
Q

What are the five components of the endocrine pancreas?

A 
Islets of langerhans 
A cells 
B cells 
D cells 
PP cells
31
Q

With regards to the endocrine pancreas, what are islets of langerhan?

A

These are scattered throughout the pancreas and secrete hormones that regulate blood glucose levels and have a rich network of fenstrated capillaries

32
Q

With regards to the endocrine pancreas, what are A cells?

A

These secrete glucagon, they stimulate the release of glucose into the blood (15020% of islets)

33
Q

With regards to the endocrine pancreas, what are B cells?

A

These secrete insulin, they stimulate the uptake of glucose from the blood ( 70% located centrally)

34
Q

With regards to the endocrine pancreas, what are D cells?

A

These secrete somatostatin, they inhibit insulin and glucagon secrete (5-10% of islet cells)

35
Q

With regards to the endocrine pancreas, what are PP cells?

A

These secrete pancreatic polypeptides that stimulate gastric chief cells and inhibit boiler and exocrine pancreatic secretion

36
Q

What is the overall structure of the liver? What is it covered in?

A

This is the largest internal organ, covered by a connective tissue capsule and extends septa (trabeculae) of CT that divides parachyma into lobules

37
Q

Explain the capsule and hilum of the liver. What entres and what exits? Where does this occur?

A

The ports hepatis is located on the inferior side of the liver.

The liver contains a duel blood supply:

Hepatic portal veins, hepatic artery ENTRE

Hepatic veins, lymphatics, and common bile duct EXIT

38
Q

Where is the major blood supply located within the liver? How mach?

A

Major supply from the hepatic portal vein (75%) the hepatic artery is 25%

39
Q

What is the main parenchymal cell within the liver? What type of cell is it?

A

The hepatocyte! This is an epithelial cells with apical microvilli

40
Q

How is liver parenchyma organized?

A

Thousands of hepatic lobes in which hepatocytes form hundreds of plates surrounding a central vein

41
Q

The classic hepatic lobule contains a portal triad. Name the three components of this triad.

A
  1. Branch of bile duct
  2. Branch of hepatic portal vein
  3. branch of hepatic artery
42
Q

With regards to the portal triad of the liver, describe the branch of the bile duct, what does it contain?

A

This is lined with cubodial epithelium, it is part of the bile conducting system

43
Q

With regards to the portal triad of the liver, describe the branch of hepatic arteries

A

This supplies less blood but the most O2

44
Q

With regards to the portal triad of the liver, describe the branch of the hepatic portal vein

A

This is rich in nutrients, low in O2

45
Q

With regards to the portal triad of the liver, what is the space of Mall?

A

This is a periportal space around the portal triad where lymph originates in the liver

46
Q

With regards to the portal triad of the liver, what are sinusoids?

A

These are discontinuous and fenestrated capillaries where arterial and venous blood mix

47
Q

Where does blood exit within the hepatic lobule?

A

It will exit or leave at the central vein

48
Q

How are physiological functions of the liver performed?

A

Via hepatocytes

49
Q

What are some physiological functions of the liver?

A
  • produce bile (exocrine release into bile caniculi)
  • produce plasma proteins
  • releases coagualtion proteins and transferrin (endocrine releases into sinusoids)
  • stores glucose
  • stores vitamin A D and K
  • modifies thyroxine (T4)
50
Q

What is the Billary Tree (in simple terms, its location)

A

Bile canaliculli—>canals of hering—> bile ductles

51
Q

What do hepatocytes produce?

A

These produce bile, a fluid for excretion of bilirubin

52
Q

What is bilirubin?

A

This is a byproduct of hemoglobin (RBC) breakdown

53
Q

What is an important role in bile with regards to absorption?

A

Bile is involved in the absorption of fats in the gut

54
Q

What do apical hepatocytes form?

A

Bile canaliculi, exocrine secretion of bile from the hepatocytes initially enter these structures

55
Q

What do bile canaliculi empty into?

A

These empty into the canals of hering, these are composed of epithelial cells called cholangiocytes

56
Q

What do canals of hering merge into?

A

These merge into the bile ductules

57
Q

The sinusoids of the hepatocytes have 3 structures/cells associated with them. Name them

A

Space of disse
Kupffer cells
Hepatic stellate cells (Ito cells)

58
Q

With regards to the sinusoids, what are the space of disse?

A

These are spaces that lie between surface of hepatocytes. These are the site of exchange of material between the blood and liver cells

59
Q

With regards to the sinusoids, what are Kupffer cells?

A

These are macrophages found within the sinusoidal lining. The APCs remove bacteria and debris

60
Q

With regards to the sinusoids, what are the hepatic stellate cells?

A

These store vitamin A and other fat soluble vitamins can synthesize ECM

61
Q

What are the three structures of the hepatic lobule?

A
  1. Classic hepatic lobule
  2. Portal lobule
  3. Hepatic acinus
62
Q

With regards to the structure of the hepatic lobule, explain what the classic hepatic lobule is

A

This is when blood flows past hepatocytes from portal areas to central veins. There is an emphasis on endocrine function

63
Q

With regards to the structure of the hepatic lobule, explain what the portal lobule is

A

This emphasizes the biliary tree with bile flow moving opposite of blood flow

64
Q

With regards to the structure of the hepatic lobule, explain what the hepatic acinus is and its three zones

A

This emphasizes blood flow and oxygen gradients from hepatic artery to central veins

Zone 1—> hepatocyte closest to hepatic artery (most O2 and nutrients)
Zone 2 —> intermediate
Zone 3—> hepatocyte closest to central vein (least O2 and nutrients, most prone to ischemic injury)

65
Q

What is the overall structure and function of the gallbladder? Wha are some important aspects to it?

A

Structure:

  • hollow pear shaped sac
  • mucosa lined with simple columnar and apical microvilli (increasing SA)
  • no true submucosal layer

Function:
-concentrates and stores pile
Has rokitantsky aschoff sinuses (RA sinus) which are deep diverticula of mucosa

66
Q

What happens in the gallbladder when the muscularis externa contracts?

A

The contraction itself is induced by cholecystokinin (CCK) which sends bile to the duodenum where it emulsifies fat

Cell And Tissue Biology (4 decks)

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