M4 GIT Flashcards

1
Q

What are the 6 major organs of the GIT?

A
  1. Oral cavity (mouth)
  2. Pharynx
  3. Esophagus
  4. Stomach
  5. Small intestine
  6. Large intestine (including rectum and anus)
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2
Q

What are the 6 accessory organs of the GIT?

A
  1. Teeth
  2. Tongue
  3. Salivary Glands
  4. Liver
  5. Gall Bladder
  6. Pancreas
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3
Q

What are the 6 key steps (or processes) of the GIT?

A
  1. Ingestion
  2. Motility (movement of contents ingested)
  3. Digestion (Mechanical and chemical)
  4. Secretion
  5. Absorption
  6. Defecation
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4
Q

What are the layers of the GI?

A

(Inner to Outer)
Lumen (inner cavity)
Mucosa
Submucosa
Muscularis Externa
Serosa
Body wall

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5
Q

What are the 2 layers of the Muscularis Externa and their functions?

A
  1. Inner circular smooth muscle - contracts inwards
  2. Outer longitudinal smooth muscle - contracts along GIT
    + Myenteric plexus (intrinsic nerve plexus)

Responsible for peristalsis and segmentation.

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6
Q

What are the 3 layers of the Mucosa and their functions?

A
  1. Epithelium
  2. Lamina propria - connective tissue
  3. Muscularis mucosa

Responsible for Protection, absorption and secretion

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7
Q

What does the Submucosa contain?

A

Submucosal plexuses
Capillaries and lymph

Responsible for transport and regulation

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8
Q

Which areas of the GI feature Stratified squamous epithelium for protective purposes?

A

Oral cavity, pharynx, esophagus and anal canal.

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9
Q

Which area of the GI features columnar epithelium upon villi to increase surface area for absorption?

A

Small Intestine.

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10
Q

Which area of the GI features both Columnar epithelium and tubular glands for further absorption and protection?

A

Large Intestine

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11
Q

Which area of the GI features gastric glands mainly focusing on secretion?

A

Stomach

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12
Q

What is bolus?

A

Small rounded mass of chewed food substance.

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13
Q

What are the 3 steps in peristalsis?

A
  1. Contraction of circular muscles behind food mass.
  2. Contraction of longitudinal muscles ahead of food mass.
  3. Contraction of circular muscles propels food forward.
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14
Q

Where does peristalsis occur?

A

Esophagus, stomach, small/large intestines.

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15
Q

What is peristalsis?

A

contraction and relaxation of adjacent sections to propel food forward.

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16
Q

What is segmentation?

A

Contraction and relaxation of non-adjacent sections to move food forward and backward as a form of mechanical digestion (food is churned and mixed)

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17
Q

What is the purpose of segmentation?

A

Mixes chyme with digestive secretion and increases exposure to epithelium for absorption.

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18
Q

Where does segmentation occur?

A

Small and large intestines

19
Q

Where can the submucosal plexus be found and what is its purpose?

A

Submucosal layer.

Control local blood flow, gastrointestinal secretion and absorption from GIT into blood/lymph vessels.

20
Q

Where can the Myenteric plexus be found and what is its purpose?

A

Between the circular and longitudinal muscles.

Regulates gastric motility and contractility.

21
Q

What is enteric plexus?

A

Nerve plexuses relating to the intestines.

Myenteric and submucosal plexuses.

22
Q

What nervous system controls the GIT?

A

Autonomic
- Parasympathetic nervous system via the vagus nerve. (CN X)
- Sympathetic nervous system via splanchic nerves.

23
Q

What happens to the GIT when PNS activates?

A

Acetylcholine released

Promoting vasodilation to GIT, increasing secretion, motility and relaxation of sphincters.

24
Q

What happens to the GIT when SNS activates?

A

Norepinephrine is released

Ceases digestive activities.

25
Q

How do internal and external stimuli affect digestive activities?

A

Stimuli is received by the CNS or first detected by chemo/osmo/mechanoreceptors (internal stimuli).

Signaled to intrinsic (local) nerve plexuses, effects smooth muscles/glands, causing a change in digestive or secretory activities.

26
Q

What are short reflexes?

A

Occur entirely within the gastrointestinal wall.

27
Q

What are long reflexes?

A

Involves the CNS.
- External stimuli

28
Q

What are the 4 functions of the oral cavity?

A

Ingestion - sensory analysis before swallowing
Mastication - teeth, tongue, palatal surfaces (chewing)
Lubrication - mixing with mucus and salivary secretions.
Partial digestion - break down of carbs (salivary amylase) and lipids (lingual lipase)

29
Q

What are the 4 functions of the tongue?

A
  1. Mechanical digestion
  2. Chemical digestion (lingual lipase) - carbs and lipids
  3. Lubrication
  4. Sensory analysis (taste, temp and texture)
30
Q

What are the 3 glands of the oral cavity?

A
  1. Parotid (Cheek)
  2. Submandibular (Jaw)
  3. Lingual (Below tongue)
31
Q

What does the Parotid gland produce?

A

Salivary amylase (Carb/starch)

32
Q

What does the Submandibular gland produce?

A

Buffers (pH 7)
Glycoprotein - Mucin
Salivary amylase

33
Q

What does the Lingual gland produce?

A

Lingual lipids - fats/lipids
Mucus

34
Q

What control is the salivary reflex?

A

Autonomic (Parasympathetic)

35
Q

Which 3 sensory nerves in the mouth signal to the medulla to drive salivary secretion?

A
  1. Trigeminal (CN V)
  2. Facial (CN VII)
  3. Glossopharyngeal (CN IX)
36
Q

Which 3 receptors receive information to drive salivary secretion?

A

Mechanoreceptor in tongue +palate
Chemoreceptor in taste buds.

37
Q

What sensory inputs can drive salivary secretion?

A

Smell
Sight
thought of food
Unpleasant stimuli

38
Q

What is deglutition

A

Swallowing

39
Q

What is Uvula

A

Gateway to nose

40
Q

Is Swallowing voluntary?

A

Yes

41
Q

What is the first phase of deglutition?

A

Buccal phase

Uvula open, esophageal sphincter shut.

Bolus pushed to the pharynx, activating mechanoreceptors.

Afferent nerves (trigeminal + glossopharyngeal) 5+9 stimulate the swallow centre in the medulla.

42
Q

What is the second phase of deglutition?

A

Pharyngeal phase

Uvula and glottis close, epiglottis folds down, seals trachea.

Sensory receptor in oropharynx stimulated. afferent signals via trigeminal, Glossopharyns and Vagus nerves. (V, IX, X)

43
Q

What is the third phase of deglutition?

A

Esophageal phase

Motor impulse from swallowing centre (medulla) carried to pharynx + esophagus via glossopharyngeal and vagus nerve (IX, X)

Peristaltic contraction propel bolus toward stomach.

Gastroesophageal sphincter opens allowing bolus to enter. (normally closed to prevent stomach acid rising)