Histologie du tube digestif

Question 1

What is the function of teeth?

Answer 1

Mastication et broyage

Question 2

How many permanent teeth and how many baby teeth are there?

Answer 2

32 permanent and 20 baby teeth

Question 3

What are the different parts of teeth?

Answer 3

Question 4

What type of epithelial tissue is the tongue made of?

Answer 4

Épithélium stratifié non kératinisé which is covering:

• Tissu musculaire (all directions to allow movement) —> skeletal (voluntary)
• Fibroelastic conjunctive tissue

Question 5

What is found between the faisceaux musculaires of the tongue?

Answer 5

Lobules graisseux

Glandes salivaires:

What kinds? (3)

• Linguales antérieurs —> mixtes
• Von Ebner —> séreuses
• Linguales postérieures —> muqueuses

Question 6

Histological cut of the tongue:

Answer 6

Question 7

What are the two main types of papillae?

Answer 7

1. Papilles calciformes —> taste buds
2. Papilles fungiforme et filliforme —> touch and sensation

Question 8

What are the principal salivary glands?

Answer 8

1. Parotid
2. Submaxillary
3. Sublingual

Question 9

What kind of gland is the parotid gland?

Answer 9

séreuse —> secrete aqueous secretions rich in enzymes/proteins, generally central nucleus

Question 10

What kind of gland is the submaxillary gland?

Answer 10

séromuqueuse —> serous and mucous mixed

Question 11

What kind of gland is the sublingual gland?

Answer 11

muqueuse —> lipidic secretions that work as lubrification, basal nucleus

Question 12

What is the function of the salivary glands?

Answer 12

Exocrine glands that secrete saliva into the mouth

Question 13

What is saliva?

Answer 13

Aqueous substance synthesized by serous glands (enzymes, antibodies, organic ions) and mucous glands (lubrification to facilitate food sliding down esophagus)

Question 14

What are the three kinds of tonsils and what are their functions?

Answer 14

1. Pharyngiennes
2. Linguales
3. Vélo-palatines

Question 15

What is the function of the tonsils?

Answer 15

Lymphatic tissue with important role in defence of the respiratory and digestive tract

Very prominent in childhood and get smaller as you get older starting in adolescence

Question 16

What is the function of the uvula?

Answer 16

10-15 mm long, made of membranous and muscular tissue, important role in swallowing and breathing

Covered in a épithélium pavimenteux stratifié non kératinisé with a muqueuse with a lot of muqueuse and séreuse glands, some striated skeletal muscles are present as well

Question 17

What is the function of the epiglottis?

Answer 17

Cartilaginous growth of the larynx covered on its forward-facing surface with digestive tissue and on the lower surface with respiratory tissue

Blocks the trachea when swallowing

Question 18

What are the different zones of the digestive tract?

Answer 18

Cavité buccale, esophagus, stomach, small intestin, large intestine (colon, rectum, and anus)

Question 19

How big is each zone and how long does it take for food to pass through?

Answer 19

Esophagus: 25 cm and 5-20 seconds

Stomach: 2.5L and 2-7 hours

Small intestine: 7-8 m and 7-8 hours

Colon: 1.5 m and 10-15 hours

Question 20

Image overview of the GI tract:

Answer 20

Question 21

What is the esophagus?

Answer 21

Uppermost tube of the GI tract, connects pharynx to the cardia of the stomach

Allows for transport of liquid and solids to the stomach due to peristalsis

Question 22

What are the sphincters of the esophagus?

Answer 22

top: upper esophageal sphincter

bottom: no anatomical sphincter but a functional one

Question 23

What are the layers of the esophagus?

Answer 23

No real intense physiological activity

Muqueuse: epithelium (pav. strat), chorion (lâche conjonctif), musculaire muqueuse (musc. lisse)

Sous-muqueuse: contains mucosa-type exocrine glands (lubrification)

Musculeuse: internal circular and external longitudinal

Adventice: lâche avec bcp. de substance fondamentale

Question 24

Histological cut of the esophagus:

Answer 24

Question 25

What is the stomach?

Answer 25

Muscular and glandular sac that is responsible for chemical and physical churning to form chyme

Question 26

What are the layers of the stomach?

Answer 26

**Muqueuse**: simp. prismatique epithelium, conjonctive tissue with lots of WBCs, thin musculature (musculaire lisse) **Sous-muqueuse**: conjunctive tissue rich in fibroblasts that synthesize extracellular matrix, nervous cells and immune cells also present **Musculeuse**: THREE LAYERS 1. external longitudinal 2. medial circular 3. internal oblique **Séreuse**: pav. simple epithelium on a thin layer of conj. lâche

Question 27

What are the crypts in the stomach for?

Answer 27

Small so that food can't enter... contain 4 cell types with different endo and exocrine functions

Question 28

What are the 4 cell types found in the stomach?

Answer 28

**Calciformes**: goblet cells —\> secrete mucous to protect stomach from acid **Principales**: synthesis of gastric pepsin and lipase **Pariétales**: secrete HCl **Endocrines** (cellules G): secrete gastrin (stimulates HCl secretion) is inhibited by a low gastric pH

Question 29

What are the different parts of the stomach?

Answer 29

Question 30

What is the small intestine?

Answer 30

Has many villosities and isolated lymphatic nodules (mostly in Ilium) or ones found in bunches (plaque de Peyer)

Question 31

What are the layers of the small intestine? (brief overview)

Answer 31

**Muqueuse**: absorbing epithelium **Chorion**: full of exocrine glands **Sous-muqueuse**: contains glandes de Brunner (protection (alcaline))

Question 32

What are the four main cell types in the small intestine?

Answer 32

**Entérocytes**: absorbing cells that digest and absorb nutrients **Calciformes**: protect by secreting mucus **Cellules de Paneth**: secrete proteinaceous secretions (lysosome) **Cellules endocrines**: gastrine, serotonine

Question 33

What are the three different parts of the small intestine?

Answer 33

1. Duodenum 2. Jejunum 3. Ileum

Question 34

What is the duodenum?

Answer 34

Simple prismatic epithelia with bordure en brosse (entérocytes and calciforme) **Chorion**: tissue conj. lâche, with lots of WBCs and blood/lymphatic vessels, at its base **Sous muqueuse**: glandes de Brunner which increase pH of the chyme that leaves the stomach **Musculaire**: two layers of smooth muscle **External membrane is the péritoine**

Question 35

What is the jejunum?

Answer 35

Central part of the small intestine Contains large villosités made of pris. simple epithelium with a lot of enterocytes and cellules calciformes Sous-muqueuse: no glands In the internal third part of the crypts, there are cellules de Paneth that protect against potential infection

Question 36

What is the ileum?

Answer 36

Smaller villosités and bunches of lymphatic cells (plaques de Peyer) in the chorion and sous-muqueuse

Question 37

What is the colon/large intestine?

Answer 37

Segment of the large intestine between the caecum and the rectum 1.5 m long and 4 cm diameter (volume is around 1.8 L)

Question 38

What are the 4 parts of the colon?

Answer 38

1. Ascending (15cm) 2. Transverse (50cm) 3. Descending (25cm) 4. Sigmoid (40cm)

Question 39

What is the function of the colon?

Answer 39

Absorption of water and storage

Question 40

What are the 4 parts of the large intestine?

Answer 40

1. Caecum 2. Colon (4 segments) 3. Rectum 4. Anal canal and anus

Question 41

Histological cut of the large intestin:

Answer 41

Question 42

What is the appendix?

Answer 42

**Muqueuse**: colique with some exocrine glands and sparse number of cellules de Paneth **Musculaire muqueuse**: interrupted by lymphatic formations that protrude into the sous-muqueuse **Sous-muqueuse**: rich in lymphocytes, plasmocytes, polynucleaires, and macrophages **Musculeuse**: not very developed, 2 layers and some nervous system elements organized in plexuses

Question 43

Layers of the colon:

Answer 43

**Musculeuse**: two distinct layers of smooth muscle cells (circular internal and longitudinal external)... between these two layers, you'll find plexus mysentériques

Question 44

What is the "zone colorectale"?

Answer 44

Terminal portion of the colon that transforms when it reaches the rectum (opening to anal canal) **The rectum**: connects sigmoid colon to anal canal, has a muqueuse that forms "colonnes anales" **The anal canal:** mostly the muscle releveur de l'anus and the external sphincter, 3-4cm long, Lieberkhüm crypts disappear and epithelium becomes more and more keratinous pav. strat. **Anus**: terminal orifice of the GI tract