Gastrointestinal System (GI) Flashcards
What is the GI system a collective name for?
The alimentary canal, accessory organs and digestive processes
Where does the alimentary canal begin, pass through, and end at?
It begins at the mouth, passes through thorax, abdomen and pelvis, before ending at anus
What do digestive processes do?
Break down foods until they can be absorbed in the form of amino acids, mineral salts, fat and vitamins
What does the absorption of amino acids, mineral salts, fat and vitamins from food help create?
Cells Hormones Enzymes Energy Waste disposal
What organs are in the alimentary canal/GI Tract?
Mouth Pharynx Oesophagus Stomach Small intestine Large intestine Rectum Anal canal
What are the accessory muscles used in the digestive system?
Salivary glands Pancras Liver Biliary ducts Gall bladder
What is the abdomen split into? (4)
Right upper quadrant
Left upper quadrant
Right lower quadrant
Left lower quadrant
What organs are located in the right hypochondriac region?
Liver
Gallbladder
Right kidney
What organs are located in the epigastric region?
Stomach
Liver
Pancreas
Right and left kidney
What organs are located in the left hypochondriac region?
Stomach
Liver (tip)
Left kidney
Spleen
What organs are located in the right lumbar region?
Liver (tip)
Small intestines
Ascending colon
Right kidney
What organs are located in the umbilical region?
Stomach
Pancreas
Small intestines
Transverse colon
What organs are located in the left lumbar region?
Small intestines
Descending colon
Left kidney
What organs are located in the right iliac region?
Small intestines
Appendix
Cecum
Ascending colon
What organs are located in the hypogastric/suprapubic region?
Small intestines
Sigmoid colon
Bladder
What organs are located in the left iliac region?
Small intestines
Descending colon
Sigmoid colon
What are the digestive processes? (5)
Ingestion - eating and drinking
Propulsion - mixing and moving
Digestion - mechanical breakdown (eg. mastication which is the chewing of food) and chemical digestion (enzymes)
Absorption - some digested food passes through some of the digestive tract organ walls in to circulation.
Elimination - some food cannot be digested and absorbed
What is the peritoneum?
A closed sac containing small amount of serous fluid within abdominal cavity
What is the purpose of the peritoneum?
Provides barrier to stop spread of infection
What are the two layers of the peritoneum?
Parietal layer - lines abdo wall
Visceral layer - covers organs within abdo and pelvic cavity
What is the mouth also known as?
Oral cavity
What is the oral cavity lined with?
Mucous membrane
Stratified squamous epithelium containing mucus secreting glands
What is between the gums and cheek?
Vestibule
What is the mucous membrane on the cheeks and lips continuous with?
The skin of the face
What is the palate in the oral cavity split into?
Hard and soft palate
What is the hard palette formed by?
Maxilla and palatine bones
What is the uvula?
Curved fold muscle hanging from soft palate
What is the tongue?
A voluntary muscle
Where is the base of the tongue attached?
To the hyoid bone and a fold of mucous membrane called frenulum
What region of the tongue contains taste receptors?
It superiorly has papillae (projections) containing these
What is the four functions of the tongue?
Chewing (mastication)
Swallowing (deglutition)
Speech
Taste
What are the three main salivary glands?
Parotid
Submandibular
Subligual
What is saliva?
A combination of secretions from salivary glands and mucus secreting glands of oral mucosa
How many litres a day of saliva is produced?
1.5 litres
What does saliva consist of?
Water
Salts
Salivary amylase (enzyme to break down sugar)
Mucus
Lysozyme (protects against bacteria)
Immunoglobulins (protect against infection)
Blood clotting factors
What are five functions of saliva?
Aid digestion of polysaccharides (complex sugars)
Lubricate food
Cleaning and lubrications mouth - preventing damage to mucous membrane
Non-specific defence to infection
Taste - taste buds only stimulate when chemical substance is in solution. If no saliva, try food would not taste of anything
What 3 sections is the pharynx spilt into?
Oropharynx
Nasopharynx
Laryngopharynx
What two pharynxes are passages for both the respiratory and digestive systems?
Oropharynx and laryngopharynx
How long is the oesophagus?
25cm long
What is the diameter of the oesophagus?
2cm wife
Where does the oesophagus lie?
In the median plane of the thorax, anterior to vertebral column
What is the oesophagus continuous with?
Pharynx
What is the purpose of the oesophagus?
Joins the stomach just below diaphragm allowing food to pass through
Where does the oesophagus join to the stomach?
Around the level of the 10th thoracic vertebrae
What is the cavity above the diaphragm?
Thoracic cavity
Where are the sphincters on the oesophagus?
At the superior and inferior ends
What shape is the oesophagus before entering the stomach and why?
Sharp curve upwards to reduce regurgitation
What is the function of the mouth, pharynx and oesophagus in the digestive system?
Form a volume
Mastication by teeth
Moved around mouth by tongue and cheek muscles
Mixed with saliva
Formed into soft bolus
Amount of time this takes depends on food
What happens in stage 1 of deglutition (swallowing)?
Mouth closed
Voluntary muscles tongue and cheeks push bolus towards pharynx
What happens in stage 2 of deglutition (swallowing)?
muscles of pharynx stimulated reflex action
Involuntary contraction of these muscles push bolus in to oesophagus
All other routes closed
Soft palate rises to close Nasopharynx
Tongue and pharyngeal folds block entry in to oral cavity
Larynx lifts up and forward so is opening is occluded by epiglottis
What happens in stage 3 of deglutition (swallowing)?
Presence of bolus
Stimulates wave of peristalsis through oesophagus
Cardiac sphincter relaxes
What shape is the stomach?
J shaped
Where is the stomach located in the regions of the stomach? (Hypochondriac etc)
Epigastric region
Umbilical region
Left hypochondriac region
What is the stomach continuous with?
Oesophagus at cardiac sphincter and duodenum at pyloric sphincter
What are the 3 regions of the stomach?
Fundus
Body
Pyloric
How many layers does the stomach have?
3
What are the three layers of the stomach?
Outer layer longitudinal fibres
Middle layer circular fibres
Inner layer oblique fibres
What do the different arrangement of the layers of the stomach allow?
Churning motion
Peristaltic movement
What is gastric mucosa?
Mucous membrane layer of the stomach contains glands and gastric pits
What do the specialised cells that secrete gastric juice secrete?
Gastric juice
Where is the mucosa gastric gland positioned?
Sits inferior to the surface of the stomach within the mucous membrane
How much food can the stomach of an adult hold?
1.5L
What do gastric muscles do?
Churn food to break it down in to a bolus and mix it with gastric juice
What pushes the bolus toward the pylorus?
Peristaltic waves
What closed when the stomach is active?
Pyloric sphincter
What is the purpose do strong peristaltic contact of the pylorus?
Forces chyme through pyloric sphincter in to duodenum in small bits
What is chyme in the stomach?
Partly digested food that is expelled by the stomach, through the pyloric valve, into the duodenum at the beginning of the small intestine
What are some of the functions of the stomach?
Temporary storage to allow enzymes to act
Chemical digestion
Mechanical breakdown
Limited absorption water, medication
Non specific defence against microbes
Prep for absorption of iron
Secretion of intrinsic factor needed for vitamin B12 absorption
Regulation of passage of gastric contents in to duodenum
Secretion of gastric (hormone)
How many litres of gastric juice is secreted approximately everyday?
2L
When is secretion of the gastric juice max?
1 hour after meal
When does secretion return to fasting level for gastric juice?
4 hours after
What does gastric juice consist of?
Water Mineral salts Mucus Hydrochloric acid Intrinsic factor Inactive enzyme precursors
What are some of the functions of gastric juice? (5)
Water - further liquifies
Hydrochloric acid - acidified food and stops action of salivary amylase.
Kills ingested microbes.
Provides acid environment for effective digestion
Pepsinogens - activates to pepsins by HCL. They are enzymes that break down proteins.
Intrinsic factor - a protein needed for absorption of vitamin B12
Mucus - prevents injury to stomach wall by keeping it lubricated
What is the small intestine continuous with?
Pyloric sphincter
How long is the small intestine?
Less than 5m
What does the small intestine lead to?
Large intestine at ileocaecal valve
What happens in the small intestine?
Chemical digestion completed
Absorption nutrients
What are the three parts of the small intestine?
Duodenum
Jejunum
Ileum
How long is the duodenum do the small intestine?
25cm
How long is the jejunum of the small intestine?
2m
How long is the ileum of the small intestine?
3m
What are some of the functions of the small intestine?
Movement of peristalsis
Secretion of intestinal juice (1.5L a day)
Completion chemical digestion
Protect against infection due to presence of lymph follicles
Secretion of digestive hormones
Absorption nutrients
What does chyme mix with?
Pancreatic juice, bile and intestinal juice
What is the pancreatic juice secreted from?
Pancreas
What does pancreatic juice consist of?
Water
Mineral salts
Enzymes (amylase, lipase, nucleases)
Inactive enzyme precursors (trypsinogen and chymotrypsinogen)
What is bile secreted by?
Liver
Where is bile stored?
Gall bladder
What pH is bile?
8
What pH is intestinal juice?
7.8-8.0
How much bile is secreted daily?
500ml-1L
What does bile consist of?
Water
Mineral salts
Mucus
Bile salts
Bile pigment (mainly bilirubin)
Cholesterol
What are some functions of bile?
Bile salt - emulsifies fats
Bile pigment (bilirubin) - waste product of breakdown of erythrocytes, excreted in bile
Deodorise faeces
Where are Most digestive enzymes located?
In small intestine within erythrocytes of wall of the microvilli
What are the enzymes in intestinal juice?
Peptidases Lipase Sucrase Maltase Lactase
How long is the large intestine?
1.5m
What is the diameter of the large intestine?
6.5cm
Where does the large intestine begin?
Caecum in the right iliac fossa
Where does the large intestine end?
Ends at rectum and anal canal
What sections is the large intestine divided into?
Caecum, colon, sigmoid colon, rectum, anal canal
What is the function of the large intestine? (4)
Water absorption through osmosis until right consistency of faeces, some meds, salts and vitamins
Microbial activity - lots of bacteria which is harmless unless transferred to wrong area. Gases produced by bacteria fermentation.
Mass movement - peristaltic movements only about twice an hour
Defaecation - contraction of abdo muscles and lowering of diaphragm assists
