Upper GI structure Flashcards
What is the purpose of chewing
Prolong taste experience
Defence against respiratory failure - prevent blockage of airways
How is chewing voluntarily controlled
Somatic nerves innervating the skeletal muscle of jaw/mouth
What is pathway of the reflex control of chewing
Contraction of jaw muscle, which creates a pressure of food against the gums/hard palate and tongue
This pressure stimulates mechanoreceptor, that inhibit jaw muscles,
This then reduce pressure causing jaw to contract again
What is the three salivary glands and where do they sit in reference to the oral cavity
Sublingual - Underneath the tongue
Submandibular - underneath the jaw
Partoid - Largest and sits above
What is the 5 components found in salvia
Water Muccins Alpha amylase Electrolytes Lysozyme
What is the purpose of water in saliva
Softens, moistens and dilute particles creating a solvent to ease digestion
What does Muccins combins with to form Mucus
What is the Purpose of Mucus
Water and Muccins creates Mucus
Mucus is a viscous solution with a lubricant function
What is the function of alpha amylase
Catalyses the brakdown of polysaccaharides / complex carbohydrates into glucose
What is the purpose of the electrolytes in the saliva
Control the tonicity and ph
What is the purpose of lysozyme in salvia
Baceriocidal, kills of unwanted components at first entry part of the body
(by breaking down polysaccharide component of bacterial cell wall)
What kind of gland is a salvia gland
Exocrine gland -releases its secretions external to the body
What stimulates watery salivary secretion
parasympathetic intervention via the cranial nerves facial + glossopharnygeal
What stimulates viscous salvia with high mucus content
Sympathetic intervention through alpha 1 adrenoreceptros
What stimulates viscous salvia with a high amylase content
Sympathetic intervention of beta 2 adrenoceptors
How does reflex control work in the secret of saliva
The presence of food in the mouth stimulates the chemceptors due to the pressure in the mouth, triggering the secretion of saliva
What is the cell arrangement of the mucosa layer in the oesophagus
Mucosa is a Non keratinised stratified squamous epithelium
Why isn’t keratin present in the oesophagus
Needs to remain flexible
What Layer of the oesophagus is is mucous glands and serous glands present and what is their function
Found in submucosa layer
Mucus glands produce mucus for lubrication
serous glands produces amylase
Why is the superior part of the oesophageal muscular extern layer skeletal and the inferior part is smooth muscle
Skeletal muscle present in the upper third for the swallowing reflex
What helps regulate material in and out of oesophagus
Upper and lower spinchters
What happens in oral phase of swallowing
You voluntarily chose to swallow and bolus is pushed back to the mouth by the tongue
What starts of the sequence of the pharyngel phase
The presence of the bolus (chewed food)
What co-ordiantes the relflex contractions of the pharyngeal muscles
The swallowing centre in the medulla
What is the first reflex of the pharyngeal phase
Soft palate reflected backward and upward (closes off nasopharynx)
What happens as the bolus approaches the oesophagus in the pharyngeal phase of swallowing
Upper oseophageal sphincter relaxes and epiglottis covers opening to larynx (prevents food entering trachea)
What is the affect of the epiglottis covering the opening of the larynx when you swallow
Breathing is inhibited
What happens once food has entered the oesophagus in the pharyngeal phase
Upper Oesophageal spinchter contracts
Epiglottis opens again
Prevents reflux of food
In the oesophageal phase how is the bolus propelled to the stomach and how long does this take
Through a peristaltic wave
Propelled in 10 seconds
What happens to the lower oesophageal spinchter as the bolus enters the stomach
Lower oesophageal spinchter relaxes
What is initiated following the relaxation of the lower oesophageal sphincter and the bolus entering the stomach
Receptive relaxation of the stomach
What occurs in receptive relaxation of the stomach
Relaxation of thin, elastic smooth muscles of the fundus and the body of the stomach which therefore increases the volume of the stomach
What coordinated the receptive relaxation of the stomach
Vagal reflexes
What is the overall functions of the stomach
Temporary store of ingested material
Dissolve food particles and initiate digestive process
Control delivery of contents to small intestine
Sterilise ingested material
Produce intrinsic factor (Vitamin B12 absorption)
What does the stomach overall control the rate of
Digestion
hat is the three different parts of the stomach
Top = Fundus Middle = Body Bottom = Antrum
What is the muscular changes in the stomach from top to bottom and why
Muscle at the Top/Fundus is thinner
Muscle moving down the stomach becomes thicker to help in the contractions of digestion and to squeeze products of digestion out into the duodenum
What is the two normal muscle layers of the stomach and the third additional muscle layer found at the bottom of the stomach
Longitudinal - outer
Circular - middle
Additional:
Oblique muscle layer - inner
Where is the cardiac region located on the stomach
In-between the lower oesophageal spinchter and the funds
Where is the pyloric spinchter located
In the pyloric region that sits above the duodenum
Why doesn’t stomach stretch when increasing in volume
As submucosa and mucosaa are arranged as folded (Rugae) when the stomach is empty
What is present on the lumenal surface of the stomach (in the mucosa)
Gastric pits (Surface mucus cells) Gastric glands (Mucus neck cells +parietal cells + chief cells + G cells + D cells )
