8 gastrointestinal system Flashcards
What are the main components of the gastrointestinal (GI) tract?
The GI tract consists of:
* Oral cavity 😋
* Oesophagus 🫣
* Stomach 🍽️
* Small intestine (Duodenum, Jejunum, Ileum) 🍴
* Large intestine (Caecum, Ascending colon, Transverse colon, Descending colon, Sigmoid colon, Rectum) 🚽
* Anal canal and anus 🍑
Associated organs:
* Liver 🏥
* Gall bladder 🐄
* Pancreas 🥄
What is the primary function of the oral cavity in the GI tract?
The oral cavity is the entry point for both food and pathogens 🦠. It is responsible for digestion (mechanical and chemical) and pathogen defence 🛡️.
👅What type of epithelium covers the mouth and tongue?
👅The mouth and tongue are covered by stratified squamous epithelium 🧠 with an underlying submucosa containing salivary glands 🧴.
What are the three main salivary glands and their secretions?
Parotid: Secretes serous saliva 💦
* Submandibular: Secretes both serous and mucous saliva 🥤
* Sublingual: Secretes mucous saliva 💧
What is the role of autonomic stimulation in saliva production?
Parasympathetic stimulation: Produces a large volume of watery saliva 💦
* Sympathetic stimulation: Produces a small amount of mucous saliva 💧
What are the muscles of mastication, and what do they do?
The muscles of mastication help break down food into smaller pieces for digestion 🍴. They include:
* Temporalis 🦷 (elevates and retracts the jaw)
* Masseter 🦷 (elevates and protrudes the jaw)
* Lateral pterygoid 🦷 (protrudes and helps with lateral movement)
* Medial pterygoid 🦷 (helps with lateral jaw movement)
What happens during the pharyngeal stage of swallowing?
The bolus triggers the swallow reflex 🧑⚕️:
* Soft palate rises to block nasopharynx 🛑
* Larynx elevates, and epiglottis covers the trachea 🚶♂️
* Pharyngeal constrictors contract to push food down into the oesophagus 🍲
How does the oesophagus function during swallowing?
The oesophagus is a muscular tube that moves food via involuntary smooth muscle contraction 🤖 towards the stomach 🍽️. It passes through the diaphragm at T10. The lower oesophageal sphincter prevents acid reflux ⚠️.
What is a hiatus hernia and how is it treated?
A hiatus hernia occurs when the stomach pushes through the diaphragm 🏥. It can cause reflux (gastro-oesophageal reflux) 🌶️. Treatment options include:
* Antacids 🧴
* Small meals 🍽️
* Lifestyle changes 🚶♀️
* Surgery in severe cases 🏥
What are the main functions of the stomach in the GI tract?
The stomach acts as a food blender and reservoir 💥, with gastric secretions aiding digestion and providing a barrier to pathogens 🦠. It has a J-shape and is located below the diaphragm 🫁.
What are the different regions of the stomach?
The stomach consists of:
* Fundus 🍴
* Body 🍖
* Greater curvature 🌍
* Lesser curvature 🔎
* Antrum 🍲
* Pylorus and pyloric sphincter 🔒
What is the role of gastric secretions in digestion?
The stomach secretes acidic fluids to aid digestion and protect against pathogens 🦠.
Secretions include:
* Acid from parietal cells 🔥
* Pepsinogen (precursor to pepsin) from peptic cells 🧪
* Gastrin, Histamine, Somatostatin from the antral region 🧬
What are the three parts of the small intestine?
The small intestine is divided into:
* Duodenum 🍽️
* Jejunum 🍴
* Ileum 🥄
What is the function of the duodenum?
The duodenum receives digestive secretions from the liver 🏥, gallbladder 🐄, and pancreas 🥄 to break down food. It loops around the vertebral column and connects to the jejunum 🍴.
What is the role of the jejunum and ileum?
The jejunum and ileum are the primary sites of nutrient absorption 🧬 and are anchored to the posterior body wall by the mesentery 🌍.
what are the parts of the duodenum
superior: travels superiorly and posteriorly at the side of the vertebral column (level L1)
descending: travels inferiorly oveer part of kidney to L3
horizontal: travels medially to the left, crossing aorta at L3
ascending: travels superiorly on the left of aorta to L2 where it becomes the jejunum
position of jejunum and ileum?
The jejunum begins at the duodenojejunal junction, to the left of the L2 vertebrae.
It is the middle part of the small intestine and becomes the ileum, the distal small intestine, at an anatomically indistinct junction.
The jejunum and ileum are anchored to the posterior body wall by the mesentery (see the peritoneum section) and are the primary site of nutrient absorption.
the majority of the small intestine (jejunum and ileum) are anchored to the posterior abdominal wall.
