*Anatomy - GI Flashcards
What is the GI tract lined by?
Mucosa
What is the purpose of the pharynx (3)?
Defence against infection (tonsils)
Swallowing
Airway protection
What is the dividing point between the upper and lower GI tracts
Small intestines = upper
Caecum = lower
Parts of the large intestine?
Appendix Caecum Colon (ascending, transverse, descending, sigmoid) Rectum Anal canal
What is there to protect us against sharp or excessively hot/cold substances
General sensory receptors
What prevents things becoming obstructed in the upper GI tract? (4)
Chewing
Lubrication
Swallowing
Peristalsis
What bones is the hard palate composed of?
The maxilla and palatine bones
At what joint does jaw opening and closing occur?
What are these joints between?
The temperomandibular joints
synovial joints between the mandibular fossa and articular tubercle of the temporal bone and the condylar process of the mandible
4 muscles of mastication
Masseter
temporalis
medial pterygoid
lateral pterygoid
What muscle produces an anterior oral seal preventing dribbling
Orbiculrais oris
In the oral cavity, what is the mucosa lined with?
What in the mouth has surface keratin?
Stratified squamous epithelium (for its protection)
Gingivae and hard palate (for protection during chewing)
General sensations of the oral cavity (4) and special sensation?
Pain
Temperature
touch
proprioception
Taste
How many different types of papilla does the dorsum of the tongue carry?
4 (some just give surface texture to help manipulate food whereas others are concerned with taste)
Names of the 4 different types of tongue papilla and their function?
Foliate papillae
Vallate papillate
Fungiform paillae (all above = taste)
Filliform papillae (touch, temperature, etc.)
What 2 types of tongue muscles do you get and what does each type do in general
Extrinsic = move tongue around in oral cavity during mastication, swallowing and speech Intrinsic = modify shape of tongue during function
What is the muscle of the cheek and what does it do?
Buccinator
Helps the tongue to position the food bolus between the occlusal surfaces of the teeth for mastication
How many teeth should an adult have?
32 (3 molars (1 is wisdom tooth), 2 premolars, 1 canine and 2 incisors per quadrant)
How is the dentition split in terms of areas
Quadrants e.g. upper right, lower left, etc.
What should any patient with a suspected fracture of the mandible or maxilla be asked?
How does your bite feel?
Displaced fracture may affect occlusion and patients are very sensitive to changes in occlusion
What does saliva contain which aids in swallowing and speech and for keeping the mucosa moist
Mucin which is a lubricant
What does saliva buffer
Plaque acids
What are some of the things saliva contains
Mucin (lubricant)
Antimicrobial elemetns
Amylase
What are the major salivary glands?
Parotid glands (near ear)
Submandibular glands (under mandible)
Sublingual glands (under tongue)
These produce 90% of our saliva (500-750ml/day)
Also have 1000s of minor secretions in our oral mucosa which keep the mouth moist by creating background and continuous secretion
What stimulates salivation (4)
Sight, smell or presence of food in mouth
Painful oral conditions
What type of mucosa is the pharynx lined with
Non-keratinised stratified squamous mucosa
Are the muscle controlling the pharynx voluntary or involuntary?
Voluntary
Where does the nasopharynx run to?
What does the laryngopharynx run between
The soft palate
The epiglottis and oesophagus (posterior to the larynx)
What is the name for the group of tonsils in the oral cavity?
Waldeyer’s ring
What 2 structures guide the food bolus away from the midline laryngeal inlet?
The uvula of the soft palate
The epiglottis
What are the 2 layers of muscle of the oropharynx
Inner vertically arranged layer of longitudinal muscles of the pharynx
Outer circularly arranged layer of constrictor muscles of the pharynx
Purpose of the inner vertically arranged layers of longitudinal muscles of the pharynx?
To contract during swallowing to shorten the pharynx (reducing bolus transit time)
Raises the larynx towards the epiglottis closing the laryngeal inlet
Purpose of the outer circularly arranged layer of constrictor muscles of the pharynx
Sequentially contract (superior then middle and then inferior constrictors) to push food bolus inferiorly into the oesophagus
What is the inferior continuation of the laryngopharynx?
The oesophagus
What type of muscle is the oesophagus?
Transitions from skeletal muscle proximally to smooth muscle distally
What type of mucosa is the oesophagus lined with?
Non-keratinised stratified squamous mucosa
How long is the jejunum approx.?
How long is the ileum approx.?
3m
4m
What type of mucosa does the oral cavity+oesophagus+anus, stomach, small intestine and large intestine have out of absorptive, secretory, protective?
Oral, etc. = protective
Stomach = secretory
Small intestine = absorptive
Large intestine = absorptive
What are the structures of the soma from superficial to deep?
Skin Fascia Skeletal muscle Skeleton Internal lining layer of body cavities e.g. parietal pleura
What is the retroperitoneum
The space within the abdominal cavity posterior to the peritoneum
What is an intraperiotenal organ?
Almost completely covered with visceral peritoneum e.g. liver
Minimally mobile
What is a retroperitoneal organ
Organ located in the retroperitoneum (visceral peritoneum only on its anterior surface e.g. pancreas and kidneys
What is an organ with a messentery
Covered in visceral peritoneum and suspended from the posterior abdominal wall by a mesentery (organ’s double layer of visceral peritoneum) e.g. intestines
Highly mobile
What does blood, pus or bowel contents within the peritoneal cavity cause?
Severe, painful inflammation of the peritoneum (peritonitis) - life threatening emergency
Organs of the foregut?
Oesophagus to mid-duodenum, liver, gallbladder, spleen, 1/2 of pancreas
Organs of the midgut?
Mid-duodenum to proximal 2/3rds of transverse colon + 1/2 of pancreas
Organs of the hindgut?
Distal 1/3rd of the transverse colon to proximal 1/2 of the anal canal
What part of the abdomen does the inferior vena cava and aorta pass through
The retroperitoneum
What are the 3 midline branches of the abdominal aorta?
Coeliac trunk (to the foregut organs)
Superior mesenteric artery (to the midgut organs)
inferior mesenteric artery (to the handgun organs)
Where are branches of the superior mesenteric artery found?
In the mesentery of the small intestine
Where are the branches of the inferior mesenteric artery found?
In the mesentery of the sigmoid colon
What does the hepatic portal vein do?
Drains the blood from the foregut, midgut and handgun structures to the liver for first pass metabolism
What does the splenic vein do?
Drains blood from the foregut structures to the hepatic portal vein
What does the inferior mesenteric vein do?
Drains blood from the handgun structures to the splenic vein
What does the superior mesenteric vein do?
Drains blood from the midgut structures to the hepatic portal vein
What are the 2 venous systems?
Portal venous system - drains blood from absorptive parts of the GI tract and the associated organs to the liver via the hepatic portal vein
Systemic venous system (IVC+SVC) - drains deoxygenated blood from the rest of the body to the right atrium of the heart (this includes the venous blood draining from the liver via the hepatic veins)
Where do the foregut structures drain their lymph?
Via nodes located along the splenic artery towards the coeliac nodes
Where do the midgut structures drain their lymph?
Via nodes located along the superior mesenteric artery towards the superior mesenteric nodes
Where do the handgun structures drain their lymph?
Via nodes located along the inferior mesenteric artery towards the inferior mesenteric nodes
