Upper GIT Structure and Function Flashcards
What makes up the upper GIT?
Mouth
Oesophagus
Pharynx
Stomach
Why do we chew?
-To make us happy :) it’s due to prolonging taste exposure and enjoying the taste more!
-Prevents against respiratory failure
Is chewing voluntary or involuntary?
Voluntary
How many salivary glands are in the mouth?
6- 3 pairs
Name the three pairs of glands
Sublingual glands
Submandibular glands
Parotid glands
Why does food need saliva before we swallow?
To moisten it and prevent it from causing irritation to the mouth and oesophagus
What are the components of saliva?
Water
Mucins
Amylase
Electrolytes
Lysosomes
If you have water and mucins, what does it produce?
Mucus
What does amylase do?
Catalyses the breakdown of polysaccharides into disaccharide and glucose.
Where is amylase secreted from?
Salivary glands and pancreas
What is the pH of saliva?
Approx 7.4
Why is i important to keep the mouth at a neutral, or nearly neutral, pH?
Because if it’s too acidic, it makes the teeth weaker and more easily damaged
If it’s too alkaline, it deposits a thing called matter on the teeth
What are lysosomes?
Bacterial chemicals which can cause cleaving of polysaccharides and kill bacteria
Is saliva controlled by parasympathetic or sympathetic NS?
Both
Is the parasympathetic control inhibitory or stimulatory?
Stimulatory for all parts of the GIT
Is the sympathetic control inhibitory or stimulatory?
Inhibitory for all but the saliva glands
Which nerves provide the parasympathetic innervation to all the GIT?
Vagus nerves (nerve 10)
Which nerves provide the parasympathetic innervation to salivary glands?
Facial nerves (nerve 7)
Glossopharyngeal (nerve 9)
Describe the saliva produced by stimulation from the sympathetic NS.
Small volume, more viscous
Describe the saliva produced by stimulation from the parasympathetic NS.
Larger volume, watery
Why is saliva produced by stimulation from the sympathetic NS a lot thicker and less volume?
Due to the activation of Alpha 1 adrenoreceptors
What happens if there is activation of the beta 2 adrenoreceptors?
Mainly amylase would be released
So basically, what happens-
1. When the alpha 1 adrenoreceptor is activated
2. When the beta 2 adrenoreceptor is activated
- More mucous produced
- More amylase produced
Hmm check this. Doesn’t seem right.
Where does the oesophagus go between?
Mouth and stomach
How long is the oesophagus?
25cm
What are the four layers of the oesophagus?
Mucosa
Submucosa
Muscularis externa
Adventitia
Which type of cells lines the oesophagus?
Stratified squamous epithelium
Why is there keratin is the oesophagus?
It needs to be flexible and keratin provides strength
What is the main function for the submucosal mucous glands?
Produce mucous for lubrication
Describe the muscle in the muscularis exertna
Upper third is composed of skeletal muscle, lower two thirds are composed of smooth muscle
What is the role of the upper and lower oesophageal sphincters?
Regulates movement of material in and out of the oesophagus
Name the three phases of swallowing.
- Oral phase
- Pharyngeal phase
- Oesophageal phase
Which part of the brain controls swallowing?
Swalloqing centre in the medulla
When the upper sphincter opens, when needs to happen at the same time?
The epiglottis needs to close over the trachea
Describe the difference between vomiting and regurgitation.
Vomiting is a forceful expulsion of gastric content, regurgitation is non-forceful
How long does it take the bolus (chewed food) to reach the stomach?
10 seconds
How much volume does an empty stomach have?
50ml
What volume can the stomach expand to fit?
1.5L
Is there a change in pressure in the stomach depending on how full it is?
No
What are the functions of the stomach?
-Temporarily stores ingested material
-Dissolves food particles and initiates digestive process
-Controls delivery of material to small intestine
-Sterilises ingested material
-Produces intrinsic factor (helps w Vitamin B12 absorbtion)
Where will digestion start for foods like glucose and carbs?
Mouth
Where will digestion start for proteins?
Stomach
What type of acid is stomach acid?
Hydrochloric acid
What are the two layers of the muscularis externa?
Circular muscle
Longitudal muscle
What does the circular muscle do to the lumen?
Narrows it
What does the longitudal muscle do to the lumen?
Shortens it
What is the function for the oblique muscle in the stomach?
It allows the stomach to twist and helps mix and break the food
List the three layers of muscle of the stomach from outer to inner.
Longitudal, circular, oblqiue
Which enzymes degrades protein?
Pepsin
