Lecture 4 - Gastrointestinal System Flashcards
Overview
Components (8)
GastroIntestinal / Alimentary tract
Oral cavity to anus
Pharynx, Oesophagus, Stomach, Small, Large intestines, AND accessory digestive organs Liver, Gall bladder, Pancreas.
NOT the spleen (lies in the abdominal cavity)
Mechanical and chemical digestion
Why is it important? (3)
Without it, no adequate nutrition therefore the body cannot function.
GI tract breaks down food into smaller molecules so they can enter the cells of the body.
Different/specialised parts for chemical/mechanical digestion.
Oral cavity - contents (8)
Lips Inner lining of the lips Cheeks (buccal muscosa) Teeth Gum Hard palate (front of mouth- bony roof) Anterior 2/3rds of the tongue Floor of the mouth below the tongue
Oral cavity - Surface of the tongue (3)
Anterior 2/3rd. Fungiform and filiform papillae
Posterior 1.3rd Circumvallate papillae (V-shape)
Oral cavity - Epiglottis + Function (2)
Flap of cartilage behind the tongue, at the top of the larynx/voice box.
Marks division of ORO and LARYNGOpharynx.
Seals off the windpipe whilst eating/swallowing (deglutition) so that food is not accidentally inhaled.
Oral cavity - Glands (3) + (1)
Submandibular gland - lies under the body of the mandible.
Parotid gland - Space between the ramus of the mandible and the external ear.
Parotid duct runs anteriorly from the gland to pierce the muscle of the cheek (buccinator).
Sublingual salivary gland - inferior to the tongue
Tonsils (3)
Collection of lymphatic tissue.
Palatine
Pharyngeal
Lingual
Pharynx and Oesophagus (2,2,1)
A muscular tube open anteriorly, lying behind nose, mouth and layrnx.
Superior –> Inferior
NASOpharynx –> OROpharynx –> LARYNGOpharynx
Soft palate marks boundary between NASO and ORO.
Soft palate and uvula close of the NASO during swallowing.
Epiglottis marks division between ORO and LAYRNGO.
Pharynx and Oesophagus - Pharyngotympanic (Eustachian) tube (4)
Pharyngotympanic (Eustachian) tube
- found on the lateral wall of NASO.
- links NASO to middle ear.
- Pressure equalisation (usually closed) but may open to let air through to prevent damage and equalise pressure between middle ear and atmosphere.
- tubal tonsil is associated with the opening of this tube.
Pharynx and Oesophagus - Can you find a structure which closes off the nasopharynx during swallowing?
During deglutition (swallowing), the soft palate rises to close off the nasopharynx, the larynx elevates, and the epiglottis folds over the glottis. The oesophagus includes an upper oesophagal sphincter made of skeletal muscle, which regulates the movement of food from the pharynx to the oesophagus.
Layrnx (4)
• The larynx is continuous inferiorly with trachea, and the laryngopharynx is continuous inferiorly with the oesophagus.
• Trachea is anterior to oesophagus.
Check FC if confused
• Opening of oesophagus kept closed by cricopharyngeus muscle, which relaxes to allow swallowed food to pass through.
• The oesophageal hiatus is where the oesophagus penetrates the diaphragm, entering the stomach, at T10.
Layrnx - Cartilage (3)
Thyroid
Arytenoid
Circoid
Oesophageal hiatus
Where the oesophagus penetrates the diaphragm, entering the stomach, at T10.
9 sections
FC
4 sections
FC
