GI

Question 1

Label the regions of the body and their associated GI tract organs

Answer 1

Question 2

List the functions of each organ of the GI tract

Oral Cavity

Pharynx

Oesophagus

Stomach and Small Intestine

Large Intestine and Anus

Answer 2

Oral Cavity:

• 1. Sensing (NOT tasting)
• 2. Salivaton
• 3. Chewing
• 4. Swallowing

Pharynx

• 1. Swallowing
• 2. Airway protection when swallowing (soft palate and uvula)
• 3. Immunity (tonsils): Defence against infection

Oesophagus

• 1. Transit only: from pharynx to stomach

Stomach and Small Intestine

• 1. Digestion
• 2. Immunity (acid): defence against infection
• 3. Absorpton
• 4. Transit

Large Intestine and Anus

• 1. Reabsorption (water and electrolytes)
• 2. Stool Formation
• 3. Excretion
• 4. Transit

Question 3

What are the names for the upper jaw and lower jaw?

Answer 3

Upper jaw: Maxilla

Lower jaw: Mandible

Question 4

Label the parts of the Oral Cavity

Answer 4

Question 5

What is the function of the soft palate? What is it’s midline extension?

Answer 5

Soft palate rises to prevent fluid going into nasal cavity/lowers to allow breathing

The uvula is the midline extension of the soft palate

Question 6

Where do the palatine tonsils lie?

How many do we have?

What is its function?

Answer 6

• Extending laterally from the uvula we have arches of the soft palate.
• We have a posterior arch and an anterior arch,
• Sandwiched between the arches we have the palatine tonsils
• We have 4 pairs of tonsils – cannot call palatine tonsil just tonsil

The tonsils serve an immunity function: defence against infection

Question 7

What is the function of mastication? Which organs are involved in it?

Answer 7

Mastication facilitates taste and digestion by mixing food with saliva

Conducted by movement of the jaw, tongue and buccinator muscle to breakdown food

Tongue manipulates, pushes and aligns bolus of food in between teeth

Buccinator muscle pushes food in to align it in between teeth

Question 8

What is the joint involved in mastication?

Answer 8

• Movement of opening and closing the jaw occur at the TMJ (Temporomandibular Joint)

Question 9

How many muscles are there at each TMJ? Which muscle of mastication opens the jaw? Why do we have more muscles to close the jaw than to open it?

Answer 9

1. Temporalis (close)
2. Masseter (close)
3. Medial Pterygoid (close)
4. Lateral Pterygoid (open)

We have 3 muscles to close and 1 to open because of the force of gravity – so we can keep our jaw closed

Question 10

Label the Muscles of Mastication

Answer 10

Masseter and Medial Pterygoid act together like a sling - M & M

Top muscle = temporalis

Question 11

Which muscle of mastication acts like a sling with the masseter?

Answer 11

Medial Pterygoid: lies internally to the masseter and works with it to close the jaw

Question 12

What are the names of the dental arches?

How many teeth in adult dentition? By what age do they erupt?

Answer 12

• Upper (Maxillary) Dental Arch
• Lower (Mandibular) Dental Arch
• 32 teeth in adult dentition (16 per arch; 8 per quadrant)
• All erupted by age 18

Question 13

What are the numbers and names of adult dentition?

Answer 13

• 1, 2 = incisors
• 3 = canine
• 4,5 = premolars
• 6,7,8 = molars (8 = wisdom tooth)

Question 14

Label the diagram

Answer 14

Question 15

Why is the tongue split into two parts? What is the border between the two?

Answer 15

In development they develop separately and the innervation is separate

The border between the anterior/posterior tongue lies just behind the vallate papilla

Question 16

What are papillae? List their functions

Answer 16

The papillae are not taste buds, they are finger like projections – there are taste buds on the papillae

On the tip of our tongue we have filiform papillae with touch, temperature and pain sensors bc it is the first bit of our tongue to come into contact with anything so protects the rest of the interior. All the other papillae have taste buds

Question 17

Name the types of muscles associated with the tongue. How many of each type are there? What are their functions?

Answer 17

• Extrinsic Muscles:
  
  • 4 pairs = 8 muscles
  • Attach to bony skeleton
  • Move tongue around during
    
    • mastication
    • speech
    • swallowing
• Intrinsic Muscles
  
  • Upper layer of tongue
  • Changes shape of tongue
    
    • Aids speech

Question 18

What are 6 consituents of saliva?

What are their functions?

Answer 18

1. 99% water
2. Solute: allows tasting to occur
3. Mucin: lubricant to keep mucosa moist and aid swallowing and speech
4. Amylase: enzyme to begin carbohydrate digestion
5. Buffer for plaque acids
6. Antimicrobial elements: that is why salivation stimulated in painful conditions

Question 19

What are the types of salivary glands? List each one.

When are they activated?

Answer 19

• Major salivary glands: 3 bilateral pairs (6 total)
  
  • Parotid gland: near ear
  • Submandibular gland: under mandible
  • Sublingual gland: under tongue
• Minor salivary glands
  
  • 1000s in orac mucosa: Everywhere

The major glands activate when stimulated. What stimulates for salivation?

• Thought, sight, smell of food/presence of food in mouth
• Painful oral conditions e.g. teething or fractured mandible

The minor glands are involved in basal section - which is background and continuous - to keep the mouth moist

Question 20

Label the diagram

How and where do the salivary glands release saliva?

Answer 20

Arrows top to bottom:

• Parotid gland: sits on the outside of the face (can swell up and cause all sorts of jaw pain: duct clogging/blockage can cause swelling, due to back up of secretions)
• Submandibular gland
• Sublingual gland
• Sublingual caruncle
• The dashed red lines are ducts: parotid duct, submandibular duct, sublingual duct

The glands secrete saliva into ducts

• Parotid duct crosses face secretes into mouth by upper 2nd molar
• Submandibular duct enters floor of mouth and secretes via lingual caruncle
• Sublingual gland lays in floor of mouth and secretes via several ducts superiorly

Question 21

Name 2 muscles of facial expression (and the groups they belong to). Describe where they lie and list their functions.

In general:

Where do muscles of facial expression lie? What is their general function

Answer 21

• Sphincter muscles e.g. orbicularis oris
• Pulley muscles e.g. buccinator

Orbicularis Oris

• Circular muscle
• Lies within the lips and surrounds the mouth
• Functions:
  
  • Prevents dribbling during chewing and swallowing
  • Tone of muscle keeps the teeth aligned

Buccinator

• Thin quadrilateral muscle occupying the interval between the maxilla and the mandible at the side of the face
• Functions:
  
  • Tenses the cheek
  • Aligns food between teeth

Muscles of facial expression lie between superficial fascia and facial skeleton: attach bone to skin (not bone to bone)

• Their contraction cause skin of the face to be pulled in to expressions

Question 22

Label the diagram

What are the borders of the different parts of the pharynx?

What is the pharynx made of?

Answer 22

The pharynx is skeletal muscle (voluntary) – we can control swallowing

Question 23

What is pulmonary aspiration? What mechanisms are there to prevent it?

Answer 23

The oropharynx and laryngopharynx used in both Respiratory Tract Pathway and the GI Tract Pathway

Pulmonary aspiration is the entry of material into the larynx (voice box) and lower respiratory tract (the portions of the respiratory system from the trachea to the lungs)

• The epiglottis moves posteriorly aiding closure of laryngeal inlet
• Larynx very well innervated with sensory receptors. So if food touches it, it stimulates cough reflex - raising of the larynx towards oesophagus reduces the chance of aspiration

Question 24

What is the oesophagus made of? Where does it lie?

Answer 24

The oesophagus is a muscular tube with gradual transition of skeletal muscle proximally to smooth muscle distally - i.e. we cannot control swallowing process through oesophagus

Travels inferiorly through the THORACIC CAVITY (behind the trachea)

Then joining the stomach, within the ABDOMINAL CAVITY

Question 25

What protects (forms) the abdominal cavity?

Answer 25

Bone: * Ribs * Vertebrae * Pelvis Muscle: * Anterolateral abdominal wall (**3 layers of skeletal muscle** - on top of which we have skin, superfical fascia [fatty and membranous], deep fascia) * Posterior abdominal wall * Back * Diaphragm NB. Abdominal cavity is continuous with the pelvic cavity

Question 26

What is peritoneum? What is its function? What are its layers? What is the peritoneal cavity? Where does it lie?

Answer 26

The peritoneum is a serous membrane (a membrane that produces serous fluid) that lines the abdominal cavity and the viscera. * Visceral peritoneum invests an organ * Parietal peritoneum lines the internal abdominal wall * They are continuous The peritoneum secretes lubricating peritoneal fluid into the peritoneal cavity. The peritoneal cavity is the space between the visceral peritoneum and parietal peritoneum, within the abdominal cavity

Question 27

What is inflammation of the peritoneum called? How is it caused? What does it lead to?

Answer 27

Peritonitis Caused by infection from surgery or trauma It leads to "guarding". Can be life threatening since infection is freely movable within

Question 28

What regulates the passage of food from the stomach to the first part of the small intestine (name it)?

Answer 28

Pyloric sphincter: regulates passage of chime into the duodenum

Question 29

Name the parts of the small intestine proximally to distally. List distinguishing characteristics What is the double fold of peritoneum called that attaches the small intestine to the body wall?

Answer 29

* **Duodenum** * **Jejunum:** has lots of folds in it and very vascular (larger surface area for absorption) * **Ileum:** As we go through the GI tract it has less surface area Mesentery: double layer of peritoneum * Connects organs to body wall * Allows passage of nerves, arteries and veins

Question 30

What is the pancreas? Where does it sit? What are its functions

Answer 30

An accessory organ of the GI tract Sits in the curvature of the duodenum with its tail towards the spleen 2 Functions: * Endocrine: releases hormones into the bloodstream * Exocrine: releases digestive enzymes into the small intestine

Question 31

Name and label the duct from the pancreas What does it drain into?

Answer 31

**Main pancreatic duct** Joins the **common bile duct** (from liver and gallbladder) to drain into duodenum

Question 32

Label the biliary tree When do the names of the ducts change? What are the organs of the biliary system? What is the function of bile?

Answer 32

* Bile produced comes down from liver through the **common hepatic duct.** * After the **cystic duct** the name changes to **common bile duct** * **The CBD has a sphincter which is normally closed when bile not needed** * So bile **backflows** back up through cystic duct into gallbladder * Gallbladder concentrates bile while it stores it Biliary system involves: * Liver (largest abdominal organ) * Gallbladder * Biliary tree * Duodenum Function: * Production and Transportation of Bile * Bile important for digestion of lipids

Question 33

What is the function of the liver?

Answer 33

Every nutrient that is absorbed goes through the liver first – liver decides what to do * Metabolism of carbohydrates, lipids, proteins * Detoxifies blood * Bile production Liver largest organ in abdomen: takes up 5% of abdominal spacein adults and 10% in children

Question 34

Label the diagram List the different parts of the large intestine What is the characteristic feature of the large intestine? Describe the muscles of the rectum, anal canal and anus

Answer 34

* Caecum * Ascending colon * Transverse colon * Descending colon * Sigmoid colon * Rectum * Anus The pouches are the characteristic feature of the large intestine Sigmoid colon = the S shape at the bottom The rectum loses the pouches on the walls * Muscular wall of the rectum and anal canal is smooth muscle * The sphincter forming the anus is skeletal (voluntary) muscle.

Question 35

What are the 3 different parts of abdominal organs (the gut)? Where do they begin/end? How are they classified?

Answer 35

Question 36

Label the diagram and name the part of the gut supplied Where do the gut arteries branch out from?

Answer 36

Question 37

Label the diagram What does the hepatic portal vein constitute of? How many main hepatic veins drain into the IVC?

Answer 37

Once in the liver three main hepatic veins drain into IVC

Question 38

Name the two types of venous systems What are their functions and what kind of blood do they carry?

Answer 38