S1) Purpose of the Gut Flashcards Preview

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Flashcards in S1) Purpose of the Gut Deck (26)
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1
Q

Label the following components of the digestive system:

A
2
Q

Identify the 8 functions of the gut

A
  • Port of entry for food into the body
  • Mechanically disrupt the food
  • Temporarily store the food
  • Chemically digest the food
  • Kill pathogens in the food
  • Move the food along the tract
  • Absorb nutrients from the resultant solution
  • Eliminate residual waste material
3
Q

Which areas of the GI tract mechanically disrupt food?

A
  • Mouth/teeth
  • Stomach (vigorous contractions cause the food to be liquefied – chyme)
4
Q

Describe how the upper and lower areas of the stomach mechanically disrupt food

A
  • Upper area creates basal tone (slow/sustained contractions)
  • Lower area has powerful peristaltic contractions that effectively grind food (thicker muscle layer distally)
5
Q

Why must the GI tract temporarily store food?

A

We eat faster than we digest

6
Q

How does the stomach act as a storage facility?

A
  • Distension – accommodates entry of food
  • Receptive relaxation – maintains intraluminal pressures
7
Q

Explain how the colon also acts as a temporary store

A

Contents are only evacuated several times a day from the colon (mass movements)

8
Q

In which areas does chemical digestion occur?

A
  • Oral cavity (saliva)
  • Stomach
  • Duodenum/jejunum
9
Q

Which substances are used for digestion by saliva?

A
  • Amylase (starch)
  • Lipase (fats)
10
Q

Which substances are used for digestion by the stomach?

A
  • Acid
  • Pepsin (protein)
11
Q

Which substances/structures are used for digestion by the duodenum/jejunum?

A
  • Bile
  • Exocrine pancreas secretions
12
Q

What are the challenges to the GI’s ability to kill pathogens?

A
  • Thin epithelia
  • Large surface area
13
Q

What are the defences of the GI tract to pathogens?

A
  • Saliva
  • HCl
  • Liver (kupffer cells)
  • Peyers patches (immune surveillance)

I. Lymphoid follicles

II. Submucosa/mucosa (terminal ileum)

14
Q

Different regions in the GI tract used different types of movement to move food along.

Identify them

A
  • Peristalsis
  • Segmentation
  • Haustral shuttling
  • Mass movements
15
Q

What type of muscle is found in the bowel?

A
  • Small amounts of skeletal muscle
  • Mainly smooth muscle
16
Q

What does the gut absorb?

A
  • Digested food + secretions
  • Fluids (fluid balance of the gut)
17
Q

Which structural features of the gut aid absorption?

A
  • Length of gut
  • Folds
  • Villi/microvilli
18
Q

Describe, briefly, how residual waste is eliminated from the colon by mass movement

A
  • Colon acts as temporary storage site, so the rectum is normally empty
  • Internal/external anal sphincter open and residual waste is egested via the gastrocolic reflex
19
Q

What is the broad function of the mouth?

A
  • Physical breakdown of food
  • Initial digestive enzymes released
  • Infection control
20
Q

Identify 3 functions of the oesophagus

A
  • Rapid transport of bolus to stomach through thorax

- Upper oesophageal sphincter prevents air from entering GI tract

- Lower oesophageal sphincter prevents reflux into oesophagus

21
Q

Identify 4 functions of the stomach

A
  • Storage facility
  • Produces chyme (physical and chemical digestion)
  • Infection control (HCl)
  • Secretes intrinsic factor (Vit B12)
22
Q

Identify 2 functions of the duodenum

A
  • Neutralisation/osmotic stabilisation of chyme (HCO3 rich secretions)
  • Concluding digestion: pancreatic secretions and bile
23
Q

Identify 2 functions of the jejunum

A
  • Final point of digestion
  • Nutrient absorption
24
Q

Identify 3 functions of the ileum

A
  • Water/electrolyte absorption
  • Bile recirculation
  • B12 absorption (terminal ileum)
25
Q

Identify 2 functions of the colon

A
  • Final water absorption
  • Final electrolyte absorption
26
Q

What is the main function of the rectum/anus?

A

Defaecation