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Physiology 214 > The digestive system- 2 > Flashcards

The digestive system- 2 Flashcards

1
Q

What are the accessory digestive organs?

A

-Salivary glands
-Exocrine pancreas
-Biliary system
>liver
>Gall bladder

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2
Q

How many layers does the digestive tract have?

A

4

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3
Q

What are the 4 major layers of the digestive tract?

A
  • Mucosa
  • Submucosa
  • Muscularis externa
  • Serosa (outer layer)
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4
Q

Innermost layer

A

Mucosa

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5
Q

2 functions/ characteristics of mucosa

A

Highly folded- greatly increases the absorptive area

Lines luminal surface of the digestive tract

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6
Q

what lines the luminal surface?

A

Mucosa

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7
Q

3 layers of the mucosa

A
  1. Mucous membrane
  2. Lamina propria
  3. Muscularis mucosa
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8
Q

Serves as protective surface

Modified for secretion and absorption

A

Mucous membrane

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9
Q

What 3 cells does the mucous membrane contain?

A
  1. Exocrine gland cells
  2. Endocrine gland cells
  3. Epithelial cells
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10
Q

secrete digestive juices

A

Exocrine gland cells

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11
Q

secrete blood-borne gastrointestinal hormones

A

Endocrine gland cells

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12
Q

specialised for absorbing digestive nutrients

A

epithelial cells

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13
Q
  • Houses gut-associated lymphoid tissue (GALT)

- Important in defense against disease-causing intestinal bacteria

A

Lamina propria

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14
Q

Sparse layer of smooth muscle

A

Muscularis mucosa

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15
Q

what is under the mucosa?

A

Submucosa

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16
Q

Nerve network found in the submucosa

A

submucosal plexus

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17
Q

Functions and characteristics of the submucosa

A
  • Thick layer of connective tissue
  • Provides digestive tract with distensibility and elasticity
  • Contains larger blood and lymph vessels
  • Contains a nerve network known as the submucosal plexus
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18
Q

Provides digestive tract with distensibility and elasticity

A

Submucosa

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19
Q

Major smooth muscle coat of digestive tube

A

Muscularis Externa

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20
Q

The two layers of the muscularis externa

A
  • Circular layer (inner layer)

- Longitudinal layer (outer layer)

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21
Q

Contraction decreases diameter of lumen

A

Circular layer (inner layer) of the muscularis externa

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22
Q

Contraction decreases diameter of lumen

A

Circular layer (inner layer) of the muscularis externa

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23
Q

Contraction shortens the tube

A

Longitudinal layer (outer layer) of the muscularis externa

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24
Q

Contractile activity of what produces propulsive and mixing movements

A

Muscularis Externa

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25
Q

Myenteric plexus

A

Nerve network of the muscularis externa

-Lies between the two muscle layers

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26
Q

help regulate gut activity

A

Submucosal plexus + Myenteric plexus + hormones

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27
Q

outer connective tissue layer

A

Serosa

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28
Q

Function and characteristics of serous fluid (secreted from serosa)

A
  • Fluid is watery and slippery

- Lubricates and prevents friction between digestive organs and surrounding viscera

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29
Q

Continuous with mesentery throughout much of the tract

-What is the function of this?

A
  • ->Serosa
  • Attachment provides relative fixation
  • Supports digestive organs in proper place while allowing them freedom for mixing and propulsive movements
30
Q

Regulation of digestive function is complex and synergistic; why is digestive motility and secretion regulated?

A

to maximise digestion and absorption

31
Q

4 factors involved in regulation of digestive system function:

A
  • Autonomous smooth muscle function
  • Intrinsic nerve plexuses
  • Extrinsic nerves
  • GI hormones
32
Q

3 sensory receptors

A 
Chemoreceptors
Mechanoreceptors (pressure receptors) Osmoreceptors
33
Q

sensitive to osmolarity

A

Osmoreceptors

34
Q

sensitive to stretch or tension

A

Mechanoreceptors (pressure receptors)

35
Q

sensitive to chemical components within GIT

A

Chemoreceptors

36
Q

endocrine system

A

Hormonal regulation

37
Q

nervous system

A

neural regulation

38
Q

Mechanoreceptors and chemoreceptors

A

Mechanical and chemical regulation

39
Q

activate and inhibit accessory glands

A

Mechanoreceptors and chemoreceptors

40
Q

Neural regulation

A

Short (intinsic) controls
-Mediated by enteric nervous system
>entire reflex arc is located within GI tract wall

Long (extrinsic) control
-involves CNS and autonomic nervous system

41
Q

Hormonal regulation

A

Hormones produced by enteroendocrine cells

42
Q

Name the:
4 layers of the GI tract
4 factors of the GI tract
3 sensory receptors of the GI tract and what they stimulate

A

4 layers

  • Mucosa (innermost layer)
  • Submucosa
  • Muscularis externa
  • Serosa (outer layer)

4 factors

  • Autonomous smooth muscle function
  • Intrinsic nerve plexuses
  • Extrinsic nerves
  • GI hormones

3 sensory receptors
-Chemoreceptors-sensitive to chemical components within GIT
-Mechanoreceptors (pressure receptorssensitive to stretch or tension
-Osmoreceptors-sensitive to osmolarity
STIMULATE: Effector cells
-Smooth muscle
> contraction for motility
-Exocrine gland cells
>Secretion of digestive juices
-Endocrine gland cells
>Secretion of gastrointestinal and
pancreatic hormones (GI hormones)

43
Q

Receptor activation results in…

A

two neural reflexes (short and long)

44
Q

Short neural reflexes

A

intrinsic nerve reflexes influence motility or secretion in response to local stimulation (within GIT)

45
Q

Long neural reflexes

A

extrinsic autonomic nerve activity to modify smooth muscle or glandular responses

> Correlate activity between different regions of digestive system
Modify digestive system activity in response to external stimuli

46
Q

Components of the oral cavity (mouth)

A
  • Lips
  • Palate
  • Tongue
  • Teeth
  • Saliva (salivary proteins)
  • Taste buds
47
Q

Lips

A
  • Forms opening
  • Help procure, guide and contain food in mouth
  • Important in speech
  • Well-developed tactile sensation
48
Q

Palate

A
  • Forms roof of oral cavity (separates mouth from nasal passages)
  • Uvula (seals off nasal passages during swallowing)
49
Q

Tongue

A
  • Forms floor of oral cavity
  • Composed of skeletal muscle
  • Movements aid in chewing and swallowing
  • Play NB role in speech
  • Taste buds
50
Q

Mechanically breakdown food

A

Teeth

51
Q

What happens in the mouth?

A
  1. Teeth mechanically breakdown food
    >Grind and breakdown food into smaller pieces to make
    swallowing easier and increase food surface area on which
    salivary enzymes can act.
    2.Food mixes with saliva
  2. Taste buds are stimulated
52
Q

What happens when taste buds are stimulated?

A
  • Increases salivary, gastric, pancreatic and bile secretions.
  • Although chewing can be voluntary, it’s a rhythmic reflex controlled by skeletal muscles of the jaw, lips, cheeks, and tongue
53
Q

Saliva

A
  • secretion associated with the mouth

- Produced by 3 major pairs of salivary glands

54
Q

Name the 3 major pairs of salivary glands

A

Parotid
Submandibular
Sublingual

55
Q

Describe saliva’s negative feedback mechanism:

A

Receptors:

  • Pressure receptors and chemoreceptors in the mouth
  • Cerebral cortex ( Thinking, seeing, and smelling food)
56
Q

Describe saliva’s negative feedback mechanism:

A

Receptors:
-Pressure receptors and chemoreceptors in the mouth
[Simple reflex]
-Cerebral cortex ( Thinking, seeing, and smelling food)
[Conditioned reflex]

They stimulate the salivary center in the medulla which sends nerve impulses to the salivary glands via the autonomic nerves.

Saliva is secreted

57
Q

Saliva composition

A
  • 99.5% H2O
  • 0.5% electrolytes
  • Proteins
58
Q

What is responsible for the perception of salty tastes?

A

Saliva is salty-contains NaCl

59
Q

Perception of sweet tastes

A

Absence of glucose

60
Q

Salivary proteins

A
  • Amylase
  • Mucus
  • Lysozyme
61
Q

Begins the digestion of carbohydrates

A

Amylase

62
Q

Facilitates swallowing by moistening food

A

Mucus-provides lubrication

63
Q

Antibacterial action

A

Lysozyme destroys bacteria

-Saliva rinses away material that could serve as food source for bacteria

64
Q

4 other functions of salivary proteins:

A

-Solvent for molecules that stimulate taste buds
-Aids speech by facilitating movements of lips and tongue
-Helps keep mouth and teeth clean
-Rich in bicarbonate buffers
>Neutralises acid in food or acid produced by bacteria in
mouth

65
Q

Chamber at the back of the throat

A

The pharynx

66
Q

Function of pharynx

A

Serves as a passageway for digestive system:
-Links mouth and oesophagus for food (oropharynx)

Serves as a passageway for respiratory system:
-Provides access between nasal cavity and trachea for air
(nasopharynx)

67
Q

Motility associated with pharynx and oesophagus

A

swallowing

68
Q

Explain the initiation of swallowing:

A
  1. Initiated when a bolus is formed
    > voluntarily forced by tongue to back of throat
    into pharynx
  2. Bolus in pharynx stimulates pressure receptors (pharyngeal pressure receptors)
  • Most complex reflex in body involving multiple coordinated responses
  • Although initiated voluntarily, cannot be stopped once started - ALL-or-NONE response
69
Q

pharynx’s pressure receptors

A

pharyngeal pressure receptors

70
Q

2 stages of swallowing

A
  1. Oropharyngeal

2. Oesophageal

71
Q

Peristalsis in the Esophagus

A

Ringlike peristaltic contraction sweeping down oesophagus

71
Q

Peristalsis in the Esophagus

A

Ringlike peristaltic contraction sweeping down oesophagus

Physiology 214 (26 decks)

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