Digestive System BETTER Flashcards
Oral Cavity
- Cheeks, tongue and palate frame the mouth
Describe the palate briefly
- Forms roof of mouth
- Arched shape allows digestion and respiration to occur simultaneously
Cheeks
- Sidewalls
- outer covering = skin
- inner = mucous membrane (non-keratinised, stratified squamous epithelium
Hard palate
- Anterior 2/3 of palate
- Structure: bone tissue and external mucous membrane covering
- Function: divides oral and nasal cavity. And a shelf which tongue can push food on
Soft palate
- Posterior part
- Structure: Skeletal muscle and external mucous membrane covering
- Function: moves with uvula to help keep foods from entering nasal cavity
Uvula
- Median inferior tissue extension of soft palate
Tongue
- Location: floor of oral cavity
- Function: facilitates ingestion, mechanical digestion, chemical digestion, sensation, swallowing, vocalisation
Name the tonsils
- Nasopharyngeal
- Palatine
- Lingual
- Clusters of lymphoid tissue that protect pharynx
What are baby teeth
- Deciduous teeth
- appear 6 months of age
- 20 teeth
Baby teeth development
PERMANENT DENTITION
- added: 4 molars (wisdom) + 8 premolars
- 32 teeth
Types of teeth
- 8 incisors: sharp front teeth bite into food
- 4 canines: pointed to tear food
- 8 premolars: flat surface for mashing food
- 12 molars: crush food ready for swallowing
Types of salivary glands
- Parotid gland: paired, located subcutaneously, anteroinferior to ear
- Submandibular gland: paired, floor of the mouth
Lips and Cheeks action and outcome
Action: Confine food between teeth
Outcome: Food is chewed evenly during mastication
Salivary Glands action and outcome
Action: Secrete saliva
Outcome:
- Moisten and lubricate lining of mouth and pharynx; moisten, soften and dissolve food
- Clean mouth and teeth
- Salivary amylase breaks down starch
Teeth action and outcome
Action: Shred and crush food
Outcome: Breakdown solid food into smaller particles for deglutition
Pharynx Function
- Digestive and respiratory functions
- receives food and air from mouth, and air from nasal cavity
Parts of pharynx (digestive functions)
Oropharynx and laryngopharynx (continuous w/ oesophagus)
Oesophagus
- Muscular tube, connects pharynx and stomach
- Penetrates thoracic diaphragm through esophageal hiatus
Function: transmits bolus of food and liquids to stomach
Histology of oesophagus
Non-keratinised stratified squamous epithelium (mucosa)
Protects against erosion
Peritoneum
Broad, serous membranous sac
Squamous epithelial tissue
Parietal peritoneum
Lines walls of a abdominopelvic cavity
Visceral peritoneum
Envelopes abdominal organs
Intraperitoneal Organs
Abdominopelvic organs surrounded by visceral peritoneum
E.g: liver, stomach, spleen, SI (not duodenum), transverse and sigmoid colons
Retroperitoneal organs
Organs that are located along posterior abdominal wall
E.g: kidneys, adrenal glands, pancreas, ascending and descending colons, aorta, inferior vena cava
Extraperitoneal organs
Structures that lie deep to parietal peritoneum
Falciform ligament
Anchors liver to anterior abdominal wall and inferior border of thoracic diaphragm
Fold of peritoneum
Forms boundary between R and L lobes of liver
Mesentery of small intestine
Only jejunum and ileum. Anchors to posterior abdominal wall
Structure: 2 layers of peritoneum
Carries all BVs, LVs and nerves to and from jejunum and ileum
Mesocolon
Attaches 2 portions of LI (transverse and sigmoid colon) to posterior abdominal wall
Describe the stomach
Location: inferior to thoracic diaphragm in upper left region of abdomen
Links oesophagus and duodenum.
3 main regions of stomach
Fundus: Superior pouch of the stomach. Dome shaped.
Body: main region of the stomach
Pylorus: funnel-shaped, connects stomach to duodenum.
Pyloric sphincter
Smooth muscle, located distally in stomach
Function: controls entry of chyme into SI
Rugae
Temporary mucosal folds (present when stomach is empty)
Diminish as stomach expands
Regions of small intestine
- Duodenum (shortest): Retroperitoneal. 20-25cm. Forms C-shaped loop to the right of pancreas
- Jejunum: Intraperitoneal. Duodenum ascends anteriorly, back to peritoneal cavity to join jejunum
- Ileum: Intraperitoneal
Hepatopancreatic ampulla
Location: duodenal wall
Common bile duct and main pancreatic duct unite
Opens into duodenum
Ileocaecal sphincter
Where ileum joins caecum
Plicae circulares
Permanent mucosal folds in SI. Decrease in number and size in distal parts of SI
Shape causes chyme to spiral, increasing time for nutrient absorption
Caecum and vermiform appendix
1st part of LI. Intraperitoneal.
Sac like structure, suspended inferior to ileocaecal valve
Function: receives contents of ileum, continues abs of water and salts.
Vermiform appendix: winding tube that attaches to caecum. Many lymph nodules
Parts of colon
Ascending: retroperitoneally located in right side of abdominal cavity.
Transverse: Intraperitoneal, horizontal, in L side it angles inferior to spleen
Descending: Retroperitoneal in L side.
Sigmoid: S-shaped, Intraperitoneal, extend medially to midline
Rectum
Food residue leaves sigmoid colon and enters rectum in pelvis. Extends anterior to sacrum and coccyx
Anal canal
Outside of abdominopelvic cavity.
Internal anal sphincter: smooth muscle (involuntary)
External anal sphincter: skeletal muscle (voluntary
