Gut motility

what happens when the longitude muscle contracts?

It opens the lumen making it wider

What happens when the circular muscle contracts?

Constriction of the lumen pushing the food foward

What is the function of the myenteric plexuses?

This is nerve ending which controls contraction allowing for gut motility

What is the functions of the submucosal pelxuses?

contain chemoreceptor, which stimulates glands to produce secretion and dilate blood vessel in response to changes in chemical competition of the chyme

What does the parasympathetic system do to gut motility?

Stimulates it

What does the sympathetic nervous system do to gut motility?

Inhibits it

Describe how food is swallowed?

Tongue pushes the bollus down, the upper osephageal sphincter relaxes, and epiglottis closes to allow the movement of food down by peristalsis and gravity.

What part of the GI is under voluntary control

The upper third of oesophageal muscle is skeletal, and under voluntary control, as well as the external anal sphincter

What happens to the stomach during the cephalic phase?

The internal rughae flatten which allows the fundas part of the stomach to relax to allow gastric accomodation for food

What does receptive relaxation describe?

The reflex action of the stomach wall relaxing to allows the accommodation of food

How much can the stomach increase its capacity in ml?

Goes from 50ml to 1.5L

What is the function of gastric motility?

To allow mixing of the blous and churn the food to form chyme

Describe the gastric contractions that characterise gastric motility

Pacemaker of the stomach located in the body sets of action potentials. These action potenattais increase in intensity and force going from the fundus region to the pyloric region. At the pyloric region the contraction are so powerful that the lumem becomes very narrowed and only allows the small molecules to pass through the narrow sphincter and into the duodenum.

What happens to the large molecules in the stomach when they approach the pyloric sphincter?

As they are too large to pass through the narrow lumen, they are regurgitated back into the body of the stomach to allows more mixing/churning

What types of motility is preset in the small intestine?

Segmentation

What is the different between segmentation and peristalsis?

Peristalsis is a forward movement, by coordinated contraction which forces the bolus down the GI tract e.g. in the oesophagus, where as segmentation is Sluggish short lived contraction which pushes the bolus in a alternating foward and backwards contraction, where the aim is to mix the chyme with secretion and enhance absorption, it is also very slow.

What allows the movement of food from the ileum to the colon?

The ileocaecal vale relaxes due to distension or upstream pressue, this alongside the contraction of the smooth muscles of the ileum allows the movement of waste into the colon.

What are two main types of motility present in the large intestine?

Haustration and mass movement

Describe haustartion movement in the large intestines?

These are a type of segmentation(small short lived movement) to allow close contact with the walls for water absroption, that take place in the haustra of the colons

Describe mass movement and where it takes place in the large intestines?

This a for bulk Movement and consist of contractions of larger segment to move the waste out into the rectum. It occur mainly in the descending part of the colon.

What part of defecation is under involuntary control(pararsympthatiec)

The rectal circular muscle and internal rectal sphincter

What part of defection is under voluntary control?

External rectal sphincter

Describe the process of defecation?

Distension of the walls of rectum cause the relaxation of the internal anal. Sphincter and the contraction of the lavatory ani muscles, when a person is ready to defecate, voluntary control of the external rectal sphincter allows defecation

What happens to motility during the fasted state?

Motilin hormone is release which propagates a contractile wave from the stomach to the ileum, which allows the removal of any undigested foods, dead cells,bacteria

What are some problems cause by abnormal gut motility?

Acid reflux,malabsorption of food, bacterial overgrowth, diarrhoea and constipation.

What hormone stimulates gut motility?

Gastrin

What hormones inhibit gastric motility?

Cck, secretin and GIP and GL1-p

describe how the lower esophageal sphincter is kept shut? 3 marks

tonic contraction of the smooth muscle as well as the angle at which the esophagus enters the stomach ensures that the increase in intragastrical pressure closes off the sphincter

how does the diaphragm help to keep the lower esophageal sphincter shut?

when the diaphragm contracts it increases the intrabdominal pressure which restrict the diameter of the sphincter closing it .