Gastrointestinal Tract - Structures + Layers Flashcards

1
Q

What is another word for the GI tract?

A

The alimentary canal

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2
Q

List the six structures of the alimentary canal.

A
Mouth
Pharynx
Oesophagus
Stomach
Small intestine
Large intestine
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3
Q

List the five accessory organs of the alimentary canal.

A

Teeth

Tongue

Salivary glands

Liver

Pancreas

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4
Q

List the five functions of the digestive system.

A
Mechanical breakdown
Digestion
Secretion
Absorption
Excretion
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5
Q

What is digestion?

A

The chemical breakdown of food

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6
Q

What is secreted in the alimentary canal?

4

A

H2O

Enzymes

Buffers

Acid

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7
Q

What is absorbed in the alimentary canal?

5

A

Substrates

Ions

Vitamins

Water

Minerals

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8
Q

What is excreted in the alimentary canal?

A

Waste

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9
Q

How many phases of digestion are there?

A

Three

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10
Q

What are the three stages of digestion?

A

Cephalic-phase

Gastric-phase

Intestinal-phase

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11
Q

What is the cephalic-phase of digestion?

A

• Control of gastrointestinal function by stimuli arising in the head (long reflexes)

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12
Q

What are long reflexes?

A

Stimuli arising in the head e.g. sight or sound

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13
Q

What is the gastric-phase of digestion?

A

Control by stimuli arising in the stomach (short reflexes)

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14
Q

What is the intestinal phase of digestion?

A

Control by stimuli arising in the small intestine (short reflexes)

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15
Q

What is the peritoneum?

A

A serous membrane encapsulated with peritoneal fluid

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16
Q

What is a serous membrane?

A

A membrane that lines the cavities in the bodies

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17
Q

How many parts are there to the peritoneum?

A

Two parts

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18
Q

What are the two parts of the peritoneum?

A

Outer parietal membrane

Inner visceral membrane

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19
Q

What is the outer parietal membrane?

A

It lines the inner surface of the body wall

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20
Q

What is the inner visceral membrane?

A

It covers the organs of the peritoneal cavity (also called the serosa of the GIT)

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21
Q

What is often known as the serosa of the GIT?

A

The inner visceral membrane covering the organs of the peritoneal cavity

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22
Q

Name a condition of the peritoneum.

A

Peritonitis

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23
Q

What is peritonitis?

A

Abnormal accumulation of peritoneal fluid

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24
Q

What conditions is peritonitis associated with?

4

A

Liver disease/cirrhosis

Renal disease

Heart failure

Infection

25
Q

What is the characteristic feature of peritonitis?

A

Abdominal swelling

26
Q

What are two clinical signs of peritonitis?

A

Heartburn/indigestion

Back pain

27
Q

What is a mesentery?

A

A doubled sheet of sandwiched peritoneum

28
Q

What is the function of mesenteries?

A

They form access routes for blood/lymph vessels and nerves

29
Q

Where are organs of the GIT suspended?

A

They are suspended within the peritoneal cavity

30
Q

What is the greater omentum?

A

Adipose tissue secreting a number of “hormone-like” substances called adipocytokines

31
Q

What are adipocytokines?

A

substances that are ‘hormone-like’ secreted by adipose tissue

32
Q

How many layers are there to the tissues of the GIT?

A

Four

33
Q

Name the four tissues of the GIT.

A

Mucosa
Submucosa
Muscularis Externa
Adventitia / Serosa

34
Q

What is another name for adventitia?

A

Serosa

35
Q

What is the mucosa?

3

A

The inner lining of the GIT

It includes the epithelium and lamina propria

There are regional differences in the mucosa - e.g. microvilli

36
Q

What types of tissue are found in the mucosa?

2

A

Epithelia

Lamina propria

37
Q

What are enterocytes?

A

Cells of the intestines

38
Q

Describe the epithelia of the mucosa.

A

Simple or stratified depending on region

39
Q

Describe the lamina propria of the mucosa.

4

A

Loose irregular connective tissue

Blood/lymph vessels

Nerves

Muscularis mucosa

40
Q

Where is the muscularis mucosa found?

A

Just underneath the epithelia

41
Q

Describe the submucosa.

6

A

Dense irregular connective tissue

Exocrine glands

Larger blood/lymph vessels

Enterogasterones

Chemoreceptors, stretch receptors, osmoreceptors

Submucosal/intrinsic nerve plexus

42
Q

What type of connective tissue is found in the submucosa?

A

Dense irregular connective tissue

43
Q

What do the exocrine glands in the submucosa secrete?

A

Buffers and mucus

44
Q

What are enterogastrones?

A

Any hormone secreted by the mucosa/submucosa of the duodenum in the lower gastrointestinal tract

45
Q

What are chemoreceptors?

A

A sensory cell or organ responsive to chemical stimuli

46
Q

What are stretch receptors?

A

A sensory receptor that responds to the stretching of surrounding muscle tissue and so contributes to the coordination of muscle activity

47
Q

What are osmoreceptors?

2

A

Cells which are sensitized to osmotic pressure.

Osmotic pressure changes with the concentration of solutes in the body.

48
Q

What is the submucosal/intrinsic nerve plexus?

2

A

Chain of interconnected neurons

The main control for GI secretion and local blood flow

49
Q

Describe the muscularis externa.

4

A

Transverse (circular) & longitudinal layers of SM

Regional differences

Peristalsis (motility) & segmentation

Myenteric intrinsic nerve plexus

50
Q

What type of muscle is found in the muscularis externa?

A

Transverse (circular) and longitudinal layers of smooth muscle

51
Q

What is the muscularis externa responsible for?

A

Peristalsis and segmentation

52
Q

What is segmentation?

A

Localized contractions of circular muscle of the muscularis layer of the alimentary canal

53
Q

What is the serosa/adventitia?

5

A

The outermost layer

Visceral peritoneum

Loose irregular CT covered by simple squamous epithelia

Double layered mesentery, houses vascular and nervous supplies to the GIT

Adventitia at oesophagus

54
Q

What type of the peritoneum is found in the serosa?

A

Visceral peritoneum

55
Q

What type of connective tissue is found in the serosa?

A

Loose irregular CT

56
Q

What type of epithelia are found in the serosa?

A

Simple squamous epithelia

57
Q

What houses the nervous and vascular supplies for the GIT?

A

The double layered mesentery of the serosa

58
Q

In which part of the body is the serosa called the adventitia?

A

In the oesophagus