Gastrointestinal System Flashcards
What is the composition of saliva? (5)
- Mostly water in a hypotonic solution
- Potassium and bicarbonate ions
- Mucins
- Digestive enzymes e.g. amylase, lingual lipase
- Immune proteins e.g. lysozyme, lactoferrin
List 4 functions of saliva (4)
- Lubrication and moistening of food to form a bolus
- Solvent for taste molecules
- Initiation of digestion of food
- Oral hygiene (neutralises acidity on teeth)
Describe the appearance of the mouth of a patient with xerostomia (3)
- Tongue appears red, swollen and sore
- Mouth and lips appear dry
- Poor oral hygiene
Where does the duct to the parotid salivary gland enter the oral cavity?
Opposite crown to the 2nd upper molar tooth
Describe the locations of the sublingual and submandibular salivary glands in relation to the floor of the mouth
- Sublingual gland sits above the floor of the mouth
- Submandibular gland sits below the floor of the mouth
Which nerve innervates the parotid gland?
Glossopharyngeal nerve (cranial nerve IX)
Which nerve innervates the sublingual gland?
Facial nerve (cranial nerve VII)
Which nerve innervates the submandibular gland?
Facial nerve (cranial nerve VII)
Which gland can be affected by the mumps virus?
Parotid gland
What is a sialography and what is it used for?
- Radiological investigation of salivary glands by means of injecting a contrast medium followed by X-ray
- Used to investigate blockages by stones, presence of tumours etc.
Describe the events that occur in the oral preparatory phase of swallowing (2)
- Voluntary manipulation of food into a bolus by the tongue (secretion of saliva helps to lubricate and moisten food)
- Tongue pushes bolus towards the pharynx and pharyngeal phase begins
Describe the precautions taken in the pharyngeal phase of swallowing to ensure the bolus is sent down the correct passage (5)
- Soft palate moves up to close off nasopharynx
- Tongue moves up to block entrance to oral cavity
- Pharyngeal sphincters constrict to push bolus down
- Larynx moves up and epiglottis moves down to close of the glottis and entrance to the airways
- Vocal chords close to close off airways
Describe the oesophageal phase of swallowing (2)
- Opening of the upper oesophageal sphincter to allow bolus to enter oesophagus
- Closure of sphincter and peristaltic waves allow bolus to be pushed down the oesophagus through contraction of the circular and longitudinal layers of the muscularis externa in the wall
Why can babies swallow and breathe at the same time?
Epiglottis extends up towards nasopharynx in babies allowing them to swallow and breathe whilst still protecting airways
Which 2 cranial nerves are involved in swallowing and the gag reflex? (2)
- Glossopharyngeal nerve (IX)
- Vagus nerve (X)
What is dysphagia?
A condition in which the patient has difficultly swallowing
Give 3 possible causes of dysphagia (3)
- Oesophageal tumour
- Stroke
- Bulbar palsy
Describe 3 ways in which gastro-oesophageal reflux is avoided (3)
- Functional sphincter formed from the smooth muscle of the distal oesophagus to prevent acid reflux from stomach
- Acute angle of entry of oesophagus into stomach makes reflux difficult and unlikely
- Resting tone of diaphragm keeps oesophagus closed
Describe the structure of the oesophagus (5)
- Upper oesophageal sphincter
- 1/3 skeletal muscle
- 1/3 skeletal and smooth muscle
- 1/3 smooth muscle
- Lower oesophageal sphincter
Describe the arterial blood supply to the stomach
- Lesser curvature - left gastric (celiac trunk) and right gastric (common hepatic)
- Greater curvature - left gastroepiploic (splenic) and right gastroepiploic (gastroduodenal)
Where is the arcuate line (Line of Douglas) positioned and what is its significance? (2)
- 1/3 of the way down between umbilicus and symphysis pubis
- Site of Caesarian section
Describe the composition of the abdominal wall from external to internal
Skin/subcutaneous tissue; superficial and deep fascia; external oblique; internal oblique; transversalis abdominus; transversalis fascia; peritoneumw
Describe the sheathing of the rectus abdominus muscle
- Above umbilicus: sheathed anteriorly and posteriorly
- Below umbilicus: sheathed anteriorly only
Describe the direction of the muscle fibres in the external oblique, internal oblique and transversalis abdominus muscles (3)
- External oblique: fibres run inferiomedially
- Internal oblique: fibres run superiomedially
- Transversalis abdominus: fibres run anterioposteriorly