Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Physiology for Anaesthetists > GIT - Saliva, oesophagus and swallowing > Flashcards

GIT - Saliva, oesophagus and swallowing Flashcards

1
Q

What volume of saliva is excreted by which glands daily. what is it excreted in response to

A

500 - 1000mls
Parotid, submandibular, sublingual

thought, smells, taste and presence of food in the mouth or stomach

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is saliva made up of

A 
98% water
2% other
- electrolytes: hypotonic lower Na but higher K vs plasma. Resting pH is 7.0 --> 8.0 when HCO3 is secreted
- proteins and enzymes 
- Bacerticidal substances
- HCO3 -
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Name the proteins, enzymes and bactericidal substances found in saliva

A

Mucin
Haptocorrin
alpha - amylase
Lingual lipase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the function of haptocorrin

A

Protection of the acid sensitive vitamin B12

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the 4 functions of saliva

A

LUBRICATION –> protects pharyngeal and oesophageal mucosa from damage during swallowing.

DIGESTION
- alpha - amylase: identical to pancreatic amylase –> catalyses CHO polymers at pH of 7.0. Cleaves up to 75% of starch before becomming denatured in the stomach. Mixing into food well –> prolonged action –> center food bolus protected from acids in stomach

  • lingual lipase: commences digestion of triglycerides. (NB in neonates with immature pancreatic lipase)
  • Haptocorrin: binds and protect B12 from lo pH environment of stomach

NEUTRALIZATION of acid

  • when stomach acid enters oesophagus (reflux)/oral cavity (vomiting).
  • protects enamel against acid erosion

ANTIBACTERIAL
Little evidence for significant bactericidal action in humans despite present of bactericidal substances

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

In which patients is lingual lipase important and why

A
  • lingual lipase: commences digestion of triglycerides. (NB in neonates with immature pancreatic lipase)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How is saliva produced

A

In salivary glands, acinar cells, surrounded by contracile myoepithelial cells produce saliva in 2 phases

  1. Acinar cells –> active transport of Na, Cl, HCO3- + passive movement of H2O (resemble plasma
  2. Ductal cells –> Secondary secretion of K+ and HCO3- and reabsorption of Na, Cl. Reabsorption > secretion. therefore saliva becomes more hypertonic as it progresses through the duct.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How does the rate of saliva production effect its composition

A

High rate –> Higher Na + HCO3-

Low rate –> Higher K + Cl

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What effect does aldosterone have on salivary composition

A

Aldosterone increase Na reabsorption a K secretion similar to its affects in the kidney

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the effects of the autonomic nervous system on the secretion of saliva

A

Secretory unit = acinus
Acini of parotid / submandibular and sublingual glands have:

PSNS
- vasodilation + myoepithelial contraction –> secretion of serous electrolyte rich saliva

SNS
- vasoconstriction + myoepithelial cell contraction –> brief increase in secretion of mucous saliva rich in amylase followed a period of reduced saliva production

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Which glands produce mucous vs serous saliva

A

Serous saliva: parotids / submandibular

Mucous saliva: sublingual

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the anatomical innervation of the salivary glands

A

Parotid - Glossopharyngeal = CN9. PReganglionic fibres synapse at the OTIC ganglion

Submandibular and sublingual = Facial CN7. Preganglionic fibres synapse at submandibular region
Postganglionic fibres travel in the lingual nerve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is swallowing

A

Complex process involving co-ordinated voluntary and involuntary muscle movement

Food bolus from oral cavity, via pharync into oesophagus with closure of larnyx to prevent pulmonary aspiration.

Control: swallowing center in medulla oblongata

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe the phases of swallowing?

A

3 PHASES
ORAL
- Voluntary
- bolus pushed into hard palate by tongue
- sensory information from hard palate to medulla
- glossopharyngeal nerve sensory
- triggers involuntary phases of swallowing

PHARYNGEAL
- Involuntary
- Closure naspharynx (soft palate)
- Protection of laryngeal inlet
–> 1. Adduction vocal cords
–> 2. Adduction aryepiglottic folds
both 1 and 2 above - recurrent laryngeal nerve supply
–> 3. Elevation of hyoid (larynx moves superiorly and anteriorly.
–> 4, Epiglottis moves downward
- propulsion of food bolus by superior and middle pharyngeal constrictor muscles
Cricopharyngeus (upper oesophageal sphincter) relaxes to allow food bolus to pass into the oesophagus
- Medulla co-ordinates 1 - 2 seconds of apnoea during pharyngeal phase of swallowing.

OESOPHAGEAL

  • Food enters oesophagus –> closure of UOS and partial opening of LOS
  • peristalsis
  • -> Primary peristaltic wave: medulla. Entire oesophagus regardless of location of food
  • -> Secondary peristalsis –> local initiation induced by stretching of the oesophageal wall
  • by the time food reaches LOS –> completely relaxed.
  • then contraction of LOS to prevent acid reflux
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Differentiate the speed of food bolus movement in the oesophagus vs. pharynx during swallowing

A

Pharynx: 30 cm/s
Oesophagus: 3 cm/s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Name the muscles involved in the pharyngeal phase of swallowing and their functions

A

Closure of nasopharyncx (soft palate)

Protection of laryngeal inlet

  1. Adduction vocal cords
    - LATERAL CRICOARYTENOID
    - OBLIQUE and TRANSVERSE ARYTENOIDS
  2. Adduction aryepiglottal folds
    - ARYEPLIGLOTTIC muscles
  3. Elevation of hyoid
    - DIGASTRIC and STYLOHYOID muscles

Movement of food bolus through larynx

  1. SUPERIOR AND MIDDLE PHARYNGEAL CONSTRICTORS
  2. CRICOPHARYNGEUS = UOS
17
Q

Name three categories of causes that cause aspiration pneumonia

A
  1. Decreased level of consciousness
  2. Disorders of oesophagus
    - GORD
    - Stricture
    - Tracheoesophageal fistula
  3. Problems with swallowing
    - Myaesthenia Gravis
    - MND
    - GBS
    - Critical illness polyneuropathy
    - Stroke
    - Multiple sclerosis
18
Q

How do the muscles fibres differ in the different regions of the oesophagus

A

Upper 1/3 = skeletal (striated) muscle

Lower 2/3 = Smooth muscle

19
Q

What type of epithelium is present lining the oesophagus and when is this not the case?

A

Stratified squamous epithelium

Chronic GORD –> Barrett’s oesophagus –> normal mucosa replaced with columnar epithelium similar to that found in the gastric/duodenal mucosa (metaplasia)

20
Q

What factors prevent reflux of stomach content into the oesophagus

A

BARRIER PRESSURE = difference between the LOS pressure (20 - 30 mmHg) and intragastric pressure (5 - 10 mmHg)

  1. LOS: distal 2 - 4 cm of oesophagus = tonic contraction
  2. Diaphragmatic contraction as oesophagus transverses
  3. Acute angle of passage into stomach
21
Q

How does the resting pressure of the UOS and LOS differ

A 
UOS = 100 mmHg
LOS = 20 - 30 mmHg
22
Q

Which factors decrease barrier pressure

A
  1. Swallowing
  2. Pregnancy (progesterone + Gravid uterus –> RAIP)
  3. Hiatus hernia (Loss of alignment with diaphragm + loss of acute angle of passageway into stomach
  4. Drugs
    - Alcohol
    - Volatiles
    - Propofol and thiopentone
    - Opioids
    - Atropine and glycopyrrolate
23
Q

Which anaesthetic drugs increase/decrease/no change LOS tone

A

Decrease

  1. Alcohol
  2. Volatiles
  3. Propofol and thiopentone
  4. Opioids
  5. Atropine & glycopyrrolate

Incrase

  1. Succinylcholine
  2. Neostigmine / Edrophonium

No effect
1. Non-depolarising muscle relaxants

24
Q

Define Mendelson syndrome

A

Pneumonitis caused by pulmonary aspiration of gastric contents associated with general anaesthesia.

Aspiration > 25 ml of gastric fluid pH < 2.5 –> sufficient to cause severe pneumonitis

25
Q

How is mendelson syndrome prevented during anaesthesia

A
  1. Preoperative starvation
  2. Free drain NGT in SBO + aspirated before induction
  3. Neutralize
    - PPI / H2 block / non-particulate antacid (Na citrate)
  4. RSI with cricoid pressure
  5. Semi-recumbent induction

Physiology for Anaesthetists (61 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions