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Gut, metabolism and hormones > Organisation of GI Tract, Salivary glands+swallowing reflex 1 > Flashcards

Organisation of GI Tract, Salivary glands+swallowing reflex 1 Flashcards

1
Q

LEARNING OBJECTIVES:

*Gut functions
*Gut wall
*Control of Digestive Activity
-Central role of neural and endocrine
pathways
*Salivary glands and secretion
*Swallowing reflex

A
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2
Q

*proximal distal
1. Salivary secretion,
swallowing reflex
2. Stomach
3. Small intestine
4. Liver and pancreas
5. Large intestine

A
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3
Q

Gut general functions: 5

A

Motility - movement down through tube
Some shunting back and forth, especially in small intestine
Secretion - derived from circulation system plasma
Digestion - product of carbohydrates, proteins and fats to absorption units
Absorption - movement from material from tube into tissue
Immunological - GALT gives protective

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4
Q

Small intestine - primary role?

A

Absorption

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5
Q

Where does most absorption occur in small intestine?
What is absorbed?
Does it have abundant reserve absorptive cavity?

A

Duodenum and jejunum
Carbohydrates, proteins and fats
Electrolytes vitamins and water from them^
Yes - caveat: terminal ileum

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6
Q

Energy rich nutrients are derived from food so that these absorption units can be taken up by the circulatory system:
The role of the digestive system is to convert 1,2,3 into absorption foods what are they converted into:
1.Carbohydrates?
2. Proteins?
3. Fats?

A
  1. Monosaccharides - sugar chains
  2. Amino acids
  3. Fatty acids and glycerol - more complex in management
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7
Q

Digestive tract wall - what tissue types? 5

A

Epithelium, Lymphoid tissues Connective tissue, Nerve plexuses and Smooth muscle

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8
Q

Parts of digestive tract wall
1. Inner - mucosa what parts does it contain and what kind of tissue layer do they have?
2. Submucosa?
3. Muscularis externa?
4. Myenteric plexus?
5. Enteric NS?
6. 2 others?

A
  1. Membrane membrane: epithelium lining
    Lamina propria: connective tissue layer
    Muscularis mucosa: smooth muscle layer
  2. Connective tissue layer that gives distension and flex
    NB collection of nerves here: plexisim network associated called the submucosal plexus
  3. 2 muscle layers orginated in 2 different places Outer longitudinal layer: fibres original length ways along tube which shortens at contraction.
    Inner circular muscle: contracts and re diameter
  4. Associated with muscularis externa
  5. Myenteric plexus and submuocsal plexus
  6. Serosa and mesentery

SLIDE 7 DIAGRAM SEE

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9
Q

Central role of neural and endocrine pathways?
4 Important factors?

A

Control of motility and secretion
1. Autonomous smooth muscle function
2. Intrinsic nerves
3. Extrinsic nerves
4. Gastrointestinal hormones

DIAGRAM SLIDE 8

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10
Q
  1. What does receptor activation alter?
  2. Receptors in digestive tract?
  3. Intrinsic nerve plexuses what kind of reflex?
  4. Extrinsic autonomic nerves what kind of reflex?
  5. Intrinsic nerve plexus, extrinsic autonomic nerves, Gastrointestinal hormones what effects do these have?
A
  1. Digestive Activity via neural and hormonal pathways
  2. Chemoreceptors, mechanoreceptors, osmoreceptors
  3. Short reflex
  4. Long reflex
  5. Smooth muscle: contraction for motility
    Exocrine gland cells: secretion of digestive juices
    Endocrine gland cells: Secretion of GI and pancreatic hormones
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11
Q

Is smooth muscle self excitable?

A

Yes

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12
Q

CNS?
PNS?

A

CNS - brain and spinal cord
PNS - nerve fibres carry information between CNS and body

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13
Q

PNS
1. Afferent?
2. Efferent?
3. Efferent is broken into?
4. Somatic nervous system?
5. Autonomic nervous system?
6. Autonomic nervous system is split up into?

A
  1. Information from periphery to CNS via sensory neurons
  2. Information from CNS to periphery
  3. Somatic and autonomic nervous system
  4. Skeletal muscle: voluntary
  5. Smooth muscle: - gut, blood vessels bladder: involuntary
  6. Parasympathetic and sympathetic nervous system
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14
Q

Parotid gland - what kind of gland is it?
Where is it located?
Parotid duct?
What does duct produce?
Dissect parotid by slicing through and staining with?
What is shown?
Dysfunction in parotid can effect which nerves?

A

It is a Salivary gland
Near ear, it extends across masseter, once past it goes through buccinator
Penetrates buccinator opposite crown of 2nd upper molar tooth
Serous secretion
H+E stain
Purple staining cells: serous secreting gland which contains amylase to break down carbohydrates
Facial nerves

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15
Q

What kind of gland is a submandibular gland?
What does it look like?
Where is it?
Where does the submandibular duct merge from?
What kind of secretion does it make?
Flap of tissue under the tongue is called?
What nerve does it come across?
How does this mixed gland stain?
What is the mucous secretion for?

A

Salivary gland
Hook shaped with superficial and deep arms
Inside mandible looking at back - at floor of mouth
Merges from deep part to open on sublingual papilla: runs medial to sublingual gland and comes up into oral cavity
Produces a mixed mucous/serous secretion
Lingual Ferenum
Lingual nerve
Stains lighter
Lube and protection

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16
Q

What kind of gland is sublingual gland?
What does it look like?
Is there one on the left/right or both?
What does the sublingual duct drain into?
What kind of secretion does it make?
Predominant what type of secretion is that even though it is still classed as a mixed gland?
Where does it come into the oral cavity?

A

Salivary gland
Almond shaped lying lateral to submandibular duct
One left+right =both
Drains into oral cavity via several minor ducts
Produces a mixed secretion
Predominant mucous secreting
Comes in at sublingual folds

17
Q

3 Major salivary glands?

A

Sublingual, Parotid and Submandibular Glands

18
Q

What does tonic low-level parasympathetic stimulation induce?
What does it innervate?
What does it ensure?
How much saliva is made per day?
How can this salivary secretion be enhanced?

A

Production of basal salivary secretion
It innervates the above glands
Ensures saliva is constantly produced
1-2L of saliva made per day
Can be enhanced by 2 salivary reflexes

19
Q

How may salivary secretion be increased?
Explain this

A

2 types of salivary reflexes: conditioned and simple

Positive feedback

Input to cerebral cortex which goes to salivary centre in medulla and then:
1. Pressure receptors and chemoreceptors in mouth
2. Autonomic nerves - salivary glands - increased salivary secretion

20
Q

In terms of digestion what is the steps of preprocessing of the bolus in the mouth?

A
  1. Sensory analysis of material before swallowing
  2. Mechanical processing (teeth, tongue, palate)
  3. Lubrication (mucus, and salivary gland secretions)
  4. Sterilisation (lysozyme, lactoferrin)
  5. Neutralisation (bicarbonate)
  6. Beginning of digestion (amylase)
21
Q

2 Major divisions include the organs of digestive system and glands, what are these?

A

Organs of digestive system and glands
Organs - Oral cavity, pharynx, stomach, small intestine: duodenum, jejium, illium and large intestine
Glands - Salivary glands, liver, gall blader, etc

22
Q

Digestive system is what kind of tube and what length when dissected and when in vivo?

A

Simple hollow tube
Dissected: 30ft
In vivo: 15ft

23
Q

What does the small intestine do in terms of calcium and iron?

A

It will adjust Iron are calcium absorption, depending on physical requirements

24
Q

Small intestine is a very efficient system, when are most materials absorbed?
SI structure function is relative what does this mean?

A

Before ileum
SI will adapt to suit role
Has mechanisms for transporting materials especially for the reabsorption of vile involved in fat absorption and absorption if vitamins

25
Q

Lamina propria contains what?
Explain this abbreviation:

A

Lamina propria contains GALT
The Gut-Associated Lymphoid Tissue (GALT)

26
Q

What are the intrinsic nerves of digestive tract wall made up of?
What do they respond to?
What is their function?
Is there control local or distal?

A

Submucosal and myenteric plexus, Enteric NS, Intrinsic nerves plexus
Respond locally to chemical mechanical, osmolarity changes in DT wall
Control motility and secretion in DT
Local control

27
Q

What is the extrinsic nerve of the digestive tract?
What doe sit respond to?
Role of ANS here?

A

Vagal nerve
Responds to external stimuli such as smell food or see food being made
ANS will input onto DS to control secretion and motility.

28
Q

Gi hormones are relative locally in digestive tract what do they modulate?

A

Motility and secretion

29
Q

What role does the ANS have in secretion and motility

A

Parasympathetic NS increases secretions and motility and sympathetic does the opposite so decreases

30
Q

What does the simple reflex cause?
What causes this, give an example?
Where does it send afferent input to?
Where is the NS salivary centre located?
What happens after the input to salivary centre?
Does mechanical distention cause this?

A

Increased saliva secretion
Pressure or chemical changes in oral cavity such as ingesting food
Salivary centre
Medulla in brain stem
Efferent output is sent to autonomic nerves to salivary glands to increase salivary secretion
Yes, it takes place when any mech distention occurs ie dentist, food etc. Distention in oral cavity is inducing simple reflex

31
Q

How is the conditioned reflex different to the simple reflex?
Give an example?
Where is it made?
Once input is sent to medulla what happens?

A

It is due to experience and acts as a learned response
For example you see food you salivate
At higher cortical levels which sends inputs down to the medulla
Promotes autonomic nervous input to salivary glans to release this secretion

32
Q

What is bolus?
There is sensory analysis of material when eating, what does this mean?

A

Ball of material in oral cavity
Push bolus around against cheeks with tongue for sensory analyis

33
Q

Explain the 11 steps of the swallowing reflex - the oropharyngeal stage?

A
  1. Swallowing is initiated voluntarily. At the start of the swallow, the tongue presses the bolus agains hard palate.
  2. The tongue propels bolus to the pharynx
  3. Swallowing centre inhibits respiratory centre in brain stem.
  4. Elevation of uvula prevents food from entering nasal passageways.
  5. Position of tongue prevents food from reentering mouth.
  6. Tight alignment of vocal cords prevents food from entering trachae.
  7. Epiglottis folds over closed glottis.
  8. Contraction of pharyngeal muscles pushes bolus through opened pharyngoesophageal sphincter into esophagus.
  9. Pharyngoesophageal sphincter closes, oropharyngeal structures return to resting position and breathing resumes.
  10. Peristalsis propels bolus down length of esophagus.
  11. Gastroesophageal sphincter relaxes as peristalsis pushes bolus into stomach. Swallow is complete. Sphincter again contracts
34
Q

During swallowing reflex where is the oesophagus?
What does it pass between?
What does it run from?
What is significant in its structure?

A

*Oesophagus is posterior to trachea in superior mediastinum
*Significant mobility in structure
*Passes between pharynx and stomach
*Runs from CVI to TXI

35
Q

Peristalsis is a wave of contraction - what does this mean?

A

*Basic electrical rhythm (BER) sets up a wave of contraction in the muscularis externa

36
Q

RECOMMENDED READING:
*Human Physiology: From Cells to Systems. Lauralee Sherwood
*Principles of Human Physiology. Cindy Stanfield
*Grays Anatomy for Students. Drake, Vogl and Mitchell.

A
37
Q

How many inches from pharynx to stomach?

A

10 inches

38
Q

Peristalsis waves - fast/slow?
Is there membrane depolarisation?
Action potential of peristalsis relative to?

A

Normally more slow waves but can fast
Yes membrane depolarisation in rhythmic contraction
AP relative to contraction of muscular layers

Gut, metabolism and hormones (22 decks)

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