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Flashcards in Digestive System 1 Deck (85):
1

What is the digestive tract also called?

Alimentary tract
Gastrointestinal tract

2

Where does the digestive tract extend to and from?

Extends from the mouth to the anus.

3

What is the digestive tract composed of (when simplified to one component)

A muscular tube.

4

What can be said about the muscular tube of the digestive tract?

It is composed of internal and apical surfaces. The apical surfaces are exposed to the external environment.

5

The function of the digestive system involves supplying the body with what main three components?

Nutrients
Electrolytes
Water

6

What is the supply of nutrients in the digestive system dependent on?

The food ingested.

7

What does the gastrointestinal tract optimise conditions for?

Digestion and Absorption.

8

In the digestive system, what is ingested food broken down into?

Substrates available for cells.

9

What are the six main functions of the digestive system?

Ingestion
Mechanical Processing
Digestion
Secretion
Absorption
Excretion

10

Describe ingestion in the digestive system.

Material enters digestive tract via mouth

11

Describe mechanical processing in the digestive system.

Makes ingested material easier to propel along tract
Increases surface area to allow easier breakdown

12

Describe digestion in the digestive system.

Chemical breakdown of food for absorption
Large molecules (e.g. starch) broken into down small molecules (e.g. absorbable sugars)

13

Describe secretion in the digestive system.

Release of water, acids, enzymes, buffers, salts

14

Describe absorption in the digestive system.

Movement of substrates, electrolytes, vitamins and water across epithelium into interstitial fluid.

15

Describe excretion in the digestive system.

Removal of waste products from body

16

What is the end result of the functions of the digestive system?

The body is supplied with nutrients, electrolytes and water; and waste is removed

17

What are digestive organs?

Components that make up the digestive tract.

18

Name 6 digestive organs.

Oral Cavity (Mouth)
Pharynx
Oesophagus
Stomach
Small intestine
Large intestine

19

What are the major functions of the oral cavity/mouth?

Ingestion, mechanical processing with accessory organs (teeth and tongue), moistening, mixing with salivary secretions.

20

What are the major functions of the pharynx?

Muscular propulsion of materials into the oesophagus.

21

What are the major functions of the oesophagus?

Transport of materials to the stomach.

22

What are the major functions of the stomach?

Chemical breakdown of materials by acid and enzymes; mechanical processing through muscular contractions.

23

What are the major functions of the small intestine?

Enzymatic digestion and absorption of water, organic substrates, vitamins, and ions.

24

What are the major functions of the large intestine?

Dehydration and compaction of indigestible materials in preparation for elimination.

25

What is the function of accessory organs?

To contribute to the function of the digestive tract.

26

Name 7 accessory organs.

Teeth
Tongue
Salivary glands
Liver
Gallbladder
Pancreas
Serous Membrane

27

What are the major functions of the teeth?

Mechanical processing by chewing (mastication)

28

What are the major functions of the tongue?

Assists mechanical processing with teeth
Sensory analysis

29

What are the major functions of the salivary glands?

Secretion of lubricating fluid containing enzymes that break down carbohydrates.

30

What are the major functions of the liver?

Secretion of bile, storage of nutrients, many other vital functions.

31

What are the major functions of the gall bladder?

Storage and concentration of bile.

32

What are the major functions of the pancreas?

Exocrine cells secrete buffers and digestive enzymes; endocrine cells secrete hormones.

33

What is bile important for?

Lipid Digestion.

34

What is Serous membrane composed of?

Two sheets

35

What is between the sheets of serous membrane?

Areolar tissue:
Blood supply
Nerves
Lymphatics

36

What is the function of serous membrane?

Stabilisation and attachment of digestive organs to the peritoneal cavity
Stops digestive organs from entangling

37

Is histological organisation the same for all organs?

Yes.

38

Describe the histological organisation of organs.

4 Layers: Mucosa, submucosa, muscularis externa, serosa.

39

Describe the mucosa layer.

Contains mucous membrane
Participates in secretion and absorption.

40

Describe the submucosa layer

Binds to the muscularis externa
Dense irregular connective tissue
Surrounds muscularis mucosae
Large blood and lymphatic vessels
May contain exocrine glands
Secrete buffers and enzymes into digestive tract

41

Describe the muscularis externa layer

Smooth muscle - contraction.

42

Describe the serosa layer

Is a membrane that allows attachment
A lining of serous membrane covering muscularis externa
Attaches to the mesentery

43

What is the inner lining of the mucosa layer composed of?

Mucous Membrane.

44

What is the mucous membrane of the mucosa layer made of?

Digestive epithelium
Lamina propria

45

Describe the digestive epithelium of the mucosa layer.

Simple columnar or stratified squamous enteroendocrine cells
Secretes hormones
Moistened by glandular secretions
Longitudinal folds, circular folds and villi to increase surface area.

46

Describe the lamina propria of the mucosa layer.

Areolar tissue containing:
-Blood and Lymphatic vessels
-Sensory nerve endings
-Lymphoid tissue
Made of smooth muscle cells (muscularis mucosae)

47

What type of cells are found in digestive epithelium?

Stratified squamous
Simple columnar

48

Where are stratified squamous cells found in digestive epithelium?

Oral cavity
Pharynx
Oesophagus

49

Where are simple columnar cells found in digestive epithelium?

Stomach
Small Intestine
Large Intestine

50

In what type of digestive cells are goblet (mucous) cells found in?

Simple Columnar.

51

What does digestive epithelium protect against?

Digestive acids and enzymes
Mechanical stresses, such as abrasion
Bacteria

52

Name 4 specialised epithelial cells found in digestive epithelium.

Stem Cells
Enteroendocrine cells
Goblet Cells
Paneth's Cells

53

Describe the stem cells of digestive epithelium.

Constant cell renewal – digestive epithelial cells are renewed every 3 days on average.

54

Describe the enteroendocrine cells of digestive epithelium.

Secrete hormones

55

Describe the goblet cells of digestive epithelium.

Secrete mucus

56

Describe the Paneth's cells of digestive epithelium.

Secrete antimicrobial peptides
Aid in protecting microbes

57

What is the submucosal plexus also called?

Meissner's Plexus

58

Describe the submucosal plexus.

Enzymes that help to "switch the system on or off"
Innervates the mucosa and submucosa
Sensory neurons, ganglionic neurons & postganglionic neurons

59

What is the muscularis externa made of?

Smooth muscle cells
Arranged in an inner circular layer and outer longitudinal layer.

60

What is the muscularis externa involved in?

Mechanical processing and the movement of materials along the digestive tract.

61

What are the movements of the muscularis externa coordinated by?

The enteric nervous system.

62

What are the movements of the muscularis externa primarily innervated by?

The parasympathetic division of the autonomic nervous system.

63

What does digestive movement involve?

The contraction and relaxation of smooth muscle.

64

Describe pacesetter cells

Undergo spontaneous depolarisation
Trigger waves of contraction (depolarisation) that spread throughout the entire muscular sheet
Located in the muscularis mucosae and muscularis externa

65

What is vital for movement of materials along the digestive tract?

Coordinated contractions.

66

What is the role of the peristalsis?

To move food/material along the digestive tract.

67

How does the peristalsis move food/material along the digestive tract?

Waves of muscular contraction:
-Circular muscles – push forward
-Longitudinal muscles – shorten
This propels bolus forward

68

What is segmentation also called?

Mixing/churning

69

What is segmentation?

Cycles of contraction
-Churn and fragment bolus
-Mix with intestinal secretions (e.g. duodenum)
Not directional

70

Why does the digestive tract need to be regulated?

The rate of secretion/absorption must be regulated so the process is effective

71

What receptors are involved in the digestive system?

Chemoreceptors, Osmoreceptors, Stretch receptors, External (Sight, Smell)

72

What are the two main components involved with the regulation of the digestive tract?

Processing/control centres
Effectors

73

Describe processing/control centres.

Local factors
Nerves of the:
-Enteric nervous system( part of Peripheral Nervous System, housed within the digestive tract, local regulation)
-Autonomic Nervous System (sympathetic and parasympathetic)
Hormones (endocrine system) such as Gastrin, GIP, CCK, secretin, VIP

74

What is the role of the large intestine?

To absorb the final nutrients and secrete the final waste products.

75

Why is it important to have a balanced diet?

To ensure we have the correct amino acids to make our cells regulate properly

76

What are carbohydrates broken down into?

Monosaccharides.

77

What do acids help to do in the digestive system?

Break down proteins.

78

What is the key process in the digestive system and why?

Absorption, because all in all, the important thing is what is going into our body.

79

What part of the body is the site of the first major chemical digestion?

The stomach.

80

What protects the lining of our organs from acid in the digestive system?

Mucous.

81

What is the mysentery?

A serous membrane that holds all of our organs together in one place.

82

What is the innermost layer of histological organs?

Mucosa.

83

What do the stratified squamous epithelium of the digestive system protect against?

Mechanical stresses.

84

What do goblet cells do?

Secrete mucous onto the surface of epithelium to lubricate it.

85

In what direction does food flow?

Always from the mouth to the anus.