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MD3002 Week 1 > 4. Physiology of Gastrointestinal Physiology > Flashcards

4. Physiology of Gastrointestinal Physiology Flashcards

1
Q

Function of the stomach and it’s exocrine secretions

A

Stomach: Store, mix, dissolve and continue digestion of food.

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2
Q

Function of the stomach and it’s exocrine secretions

A

Stomach: Store, mix, dissolve and continue digestion of foo. Regulates emptying of dissolved food into small intestine.

Exocrine secretions:
HCl: Solubilisation of food particles, kill microbes
Pepsin: Protein-digesting enzyme
Mucus: Lubricate and protect epithelial surface

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3
Q

Function of the liver and its exocrine secretions

A

Liver: Secretion of bile

Exocrine secretions:
Bile salts: Solubilise water-insoluble fats
Bicarbonate: Neutralize HCl entering small intestine from stomach
Organic water products and trace metals: Elimination in faeces

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4
Q

Gall bladder function:

A

Store and concentrate bile between meals

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5
Q

Function of small intestine and it’s exocrine secretions

A

SI: Digestion and absorption of most substances; mixing and propulsion of contents.

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6
Q

Function of small intestine and it’s exocrine secretions

A

SI: Digestion and absorption of most substances; mixing and propulsion of contents.

Exocrine secretions:
Enzymes- Food digestion
Salt and water- Maintain fluidity of luminal contents
Mucus- Lubrication

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7
Q

Function of large intestine and its exocrine secretions

A

LI: Storage and concentration of undigested matter, absorption of salt and water, mixing and propulsion of contents, defecation

Exocrine secretion: Mucus for lubrication

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8
Q

Function of large intestine and its exocrine secretions

A

LI: Storage and concentration of undigested matter, absorption of salt and water, mixing and propulsion of contents, defecation

Exocrine secretion: Mucus for lubrication

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9
Q

List the 5 major physiological processes of the GI system

A 
Motility
Secretion
Digestion
Absorption
Excretion
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10
Q

What are the 5 major physiological processes of the GI system

A

MOTILITY
Propulsion of ingested food from mouth to rectum, mixing and reducing in size to optimise time for absorption and digestion
SECRETION
Salivary glands, stomach, small intestine, pancreas and liver all add fluid, electrolytes, enzymes and mucus
DIGESTION
Ingested food is digested into absorbable molecules
ABSORPTION
Nutrients, electrolytes and water are absorbed from the intestinal lumen into the bloodstream
EXCRETION

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11
Q

What are the major immunological and non-immunological defence mechanisms of the GI?

A

Immunological mechanisms: Mucosal immune system (gut-associated lymphoid tissue, GALT).
These are aggregate of lymphoid tissue i.e. Peyer’s patches and diffuse populations of immune cells.
Provides: Protection against microbial pathogens, mediates immunological tolerance to dietary substance sea gut bacteria

Non-immunologic mechanisms: Gastric acid, mucin, peristalsis and the epithelial cell layer barrier

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12
Q

What are the layers of the GI wall?

A
  1. Muscular mucosal, epithelium, lamina propria
  2. Submucosa
  3. Submucosal nerve plexus
  4. Circular muscle (muscular externa)
  5. Myenteric plexus
  6. Longitudinal muscle
  7. Serosa
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13
Q

What is the lamina propria?

A

Underlying loose connective tissue with capillaries, enteric neurones and immune cells

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14
Q

What is the muscular mucosal?

A

Thin smooth muscle layer of the mucosa

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15
Q

What is contained within the submucosa?

A 
Loose connective tissue
Larger blood vessels
Lymphatics
Secretory glands
Enteric neurones in the submucosa
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16
Q

What is the muscular externa?

A

Inner layer of circular muscle
Outer layer of longitudinal muscle
Enteric neurones between the muscle layers- myenteric plexus

17
Q

What is the serosa?

A

Outer layer of connective tissue covered with squamous epithelial cells

18
Q

What is the intrinsic component of the innervation of the GI tract?
What are the two plexuses? Where are they found and what do they do?

A

ENTERIC NERVOUS SYSTEM

  1. The submucosal plexus (Meissner’s plexus). In the LI and SI. Primarily regulates glandular, endocrine and epithelial secretions
  2. The myenteric plexus (Auerbach’s plexus). Between the circular and longitudinal muscle layers throughout he GI tracts. Primarily consists of motor neurones.
19
Q

Describe where the extrinsic nervous system secretes neurotransmitters within the GI

A

PS from Vagus or pelvic nerve: Synapses of ACh in myenteric and submuscosal plexus. Released into circular and longitudinal muscle and mucosa.

Symp from sympathetic ganglia: NE synapse in myenteric and submucosal plexuses. Released into the circular muscle and mucosa

20
Q

Which GI reflexes are integrated within the enteric nervous system?

A

Reflexes controlled secretion, peristalsis, mixing, local inhibitory actions

21
Q

Which GI reflexes are from the GI tract to prevertebral sympathetic ganglia and then back to the GI tract?

A

Reflexes that transmit signals to other areas of the GI tract

  • Gastrocolic reflex (stomach – colon)
  • Enterogastric reflexes ( stomach and colon inhibiting gastric motility)
  • Colonoileal reflexes (inhibition of ileal emptying)
22
Q

Which GI reflexes from the GI tract to the brain stem or spinal cord and then back to the GI tract?

A

(1) Reflexes from stomach and duodenum to brain stem and back to stomach to control gastric motor and secretory activity
(2) Pain reflexes causing general inhibition of entire GI tract
(3) Defecation reflexes from the colon and rectum that travel via the spinal cord back to produce powerful colonic, rectal and abdominal contractions

23
Q

What is the

(1) Source
(2) Target
(3) Action

of the following GI hormone: Gastrin

A

(1) Source
G cells in the atrium of stomach

(2) Target
Parietal cells in body of stomach

(3) Action
Increases H+ secretion
Stimulates growth of gastric mucosa

24
Q

What is the

(1) Source
(2) Target
(3) Action

of the following GI hormone:
Cholecystokinin (CKK)

A

(1) Source
I cells in duodenum and jejunum; neurones in ileum and colon

(2) Target
Pancreas and gall bladder

(3) Action
Increases enzyme secretion
Increases contraction

25
Q

What is the

(1) Source
(2) Target
(3) Action

of the following GI hormone:
Secretin

A

(1) Source
S cells in SI

(2) Target
Pancreas and stomach

(3) Action
Increases HCO-3 and fluid secretion by pancreatic ducts
Decreases gastric acid secretion

26
Q

What is the

(1) Source
(2) Target
(3) Action

of the following GI hormone:
Gastric inhibitory peptide

A

(1) Source
K cells in duodenum and jejunum

(2) Target
Pancreas and stomach

(3) Action
Exocrine: Decreases fluid absorption
Endocrine: Increases insulin release
Decreases gastrin release

27
Q

What is the

(1) Source
(2) Target
(3) Action

of the following GI hormone:
Motillin

A

(1) Source
Endocrine cells in upper GI tract

(2) Target
Oesophageal sphincter
Stomach
Duodenum

(3) Action
Increases smooth muscle contraction

28
Q

What is the

(1) Source
(2) Target
(3) Action

of the following GI hormone:
Glucagon

A

(1) Source
Alpha cells of pancreatic islets of Langerhans

(2) Target
Liver

(3) Action
Increases glycogenolysis and gluconeogenesis

29
Q

What is the

(1) Source
(2) Target
(3) Action

of the following GI hormone:
Guanylin

A

(1) Source
Ileum and colon

(2) Target
Intestine

(3) Action
Increases fluid absorption

30
Q

What is the

(1) Source
(2) Target
(3) Action

of the following GI hormone:
Neurotension

A

(1) Source
N cells of the ileum

(2) Target
Smooth muscle and vagus

(3) Action
Relaxes smooth muscle
Decreases gastric acid secretion

31
Q

What is the

(1) Source
(2) Target
(3) Action

of the following GI paracrine:
Somatotrophin

A

(1) Source
D cells of stomach and duodenum
B cells of pancreatic islets

(2) Target
Stomach
Intestine
Pancreas
Liver

(3) Action
Decrease gastric release
Increases fluid absorption, decrease fluid secretion
Decrease endocrine and exocrine secretions
Decrease bile flow

32
Q

What is the

(1) Source
(2) Target
(3) Action

of the following GI paracrine:
Histamine

A

(1) Source
Endocrine cells of the gastric mucosa (esp H+ secreting region of the stomach)

(2) Target
Stomach

(3) Action
Stimulates H+ secretion from parietal cells in the stomach

33
Q

What is the

(1) Source
(2) Target
(3) Action

of the following GI neurocrine:
ACh

A

(1) Source
Cholinergic neurons

(2) Target
Smooth muscle
Salivary glands
Stomach
Pancreas

(3) Action
Contraction of GI wall, relaxation of sphincters
Increases secretion of salivary glands, stomach and pancreas

34
Q

What is the

(1) Source
(2) Target
(3) Action

of the following GI neurocrine: NA (NE)

A

(1) Source
Adrenergic neurons

(2) Target
Smooth muscle and salivary glands

(3) Action
Relaxation of GI wall and increases saliva secretion

35
Q

What is the

(1) Source
(2) Target
(3) Action

of the following GI neurocrine:
Vasoactive intestine peptide

A

(1) Source
Enteric nervous system

(2) Target
Smooth muscle
Pancreas and intestine

(3) Action
Smooth muscle relaxation
Increase intestine and pancreas secretion

36
Q

What is the

(1) Source
(2) Target
(3) Action

of the following GI neurocrine:
Gastrin released peptide (GRP)

A

(1) Source
Neurons of the gastric mucosa
Vagal nerve endings

(2) Target
G cells in the Antrum of the stomach

(3) Action
Increases gastrin secretion

37
Q

What is the

(1) Source
(2) Target
(3) Action

of the following GI neurocrine:
Enkephalins (opiates)

A

(1) Source
Neurons of the mucosa and smooth muscle

(2) Target and action
Smooth muscle - relaxation
Intestinal secretion - decreases

38
Q

What is the

(1) Source
(2) Target
(3) Action

of the following GI neurocrine:
Neuropeptide Y

A

(1) Source
Neurons of the mucosa and smooth muscle

(2) Target and action
Smooth muscle - relaxation
Intestinal secretion - decreases

39
Q

What is the

(1) Source
(2) Target
(3) Action

of the following GI neurocrine:
Substance P

A

(1) Source
Co-secreted with ACh

(2) Target and action
Smooth muscle - contraction
Salivary glands - Increases secretion

MD3002 Week 1 (10 decks)

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