GI tract Flashcards
What is GI tract.
From mouth to anus
Adventitia
Outermost layer surrounding the tract
Types of Smooth muscle in tract
Longitudinal muscle layer (under adventitia)
Circular muscle layer (under longitudinal muscle layer)
(Under involuntary control)
Plexus
Web of nerves
Myenteric plexus (underneath circular Muscle layer)
Submucosal plexus (underneath myenteric plexus)
Submucosa
Underneath the submucosal plexus
Contains nerves,blood vessels and collagen
Epithelium
Under submucosa
Secretes mucus to reduce friction between food and wall
Function of Lumen
Constantly contracting to push food through
Types of contractions
Peristalsis- moves forwards
Segmentation- back and forth to break up food
Mass movement- rapid movements forwards
Peritoneum
Serous membrane sac encasing the abdominal organs to prevent movement and provide structure and prevents organs coming into contact with each other so reduces inflammation due to serous fluid
Goblet cell
In the epithelial cells
Secretes mucus for lubrication
Mouth
Physical breakdown of food by chewing (mastication)
Anterior roof is hard palate made from bone
Posterior roof is soft due to muscle
Amylase released here by salivary glands
Pharynx
Throat
Food goes from mouth to oesophagus via pharynx
Oesophogus
Long tube which transport bolus to stomach
Sphincter
Thickened rings of circular muscles keeping the tract a one way stystem
Tounge
Voluntary muscle
Needed for swallowing (deglutition)
Anchored to mouth by frenulum
Papillae contains taste buds
How many parts is the Salivary glands
Three parts
Role of saliva
Releases amylase to break down carbs
Lubricates bolus
Contains anti microbial antibodies preventing tooth decay
Stomach
Produces chyme (bolus and gastric juice)
Physical and chemical breakdown of food
Contains three muscle layers to churn food
Rugae (folds) enable stomach to stretch
Gastric juice
Unravels proteins
Activates pepsinogens to pepsin
Disinfects stomach contents
Duodenum
Start of small intestine
Chyme neutralised here
Water enters through gut walls
More digestive enzymes
Liver
Composed of hepatocytes
Bile produced
Stores glycogen
Gallbladder
Connected to liver and duodenum
Stores bile
Bile
Bile salts emulsify fats
Forms micelles
Contains bilirubin
Bilirubin
In RBC
livers breaks down RBC and processes them
bilirubin gives poop it’s colour and needs to be excreted from body
If not, jaundice
Pancreas
Produces insulin and glucagon
Contains enzymes for digestion
Jejunum
Middle section of SI
Ileum
Last part of SI
Jejunum and ileum function
Neutralises acidic contents by alkali juice
Final digestion and water and nutrient absorption
SI structure
Mucous membrane have circular folds (plicae)
Has villa
Villi covered by enterocytes
Enterocytes have microvilli
Parts of Large intestine
Caecum
Ascending colon
Transverse colon
Descending colon
Sigmoid colon
Rectum
Anal canal
Function of LI
Final water absorption
Temporary storage
Defecation
Gut microbiome
Refers to the bacteria/fungi living in our gut
Prevents other bacteria causing diseases
Plays a big role in health and gut disease
Infants gain these bacteria as they pass through mothers vagina, near her rectum
What is in the Anus
Two sphincters
Internal is involuntary
External is voluntary (u can clench)
Changes in the mouth during pregnancy:
-altered smell and taste due to inflammation of the nasal mucosa
- appetite may increase as progesterone is an appetite stimulant
-excess salivation which may taste bitter,causing nausea and vomiting
-oestrogen can cause gums to bleed and become spongey
Why do pregnant women experience heartburn?
Progesterone relaxes the cardiac sphincter, allowing for acid to reflux
What happens to the stomach during pregnancy?
-Progesterone reduces muscle tone and mobility
-gastric emptying is delayed
Why are women told not to eat before their C-section?
- delay in stomach emptying
-risk of acid aspiration
During pregnancy, what happens to the absorption of iron and calcium?
Increases
Why can pregnant women get constipation more easily?
-Progesterone relaxes smooth muscle
-peristalsis is slowed
Why can pregnant women get haemorrhoids easily?
- gravid uterus puts pressure of the rectum and veins causing them to bulge
-prolonged second stage and instrumental delivery
