Gastrointestinal Flashcards
Which gastrointestinal layer is characterised by having tough, fibrous connective tissue?
Serosa
The _____ nervous system division mornally stimulates and promotes digestion
Parasympathetic
What type of cell (in the stomach) secretes HCl?
parietal
Parasympathetic =
Sympathetic =
rest and digest
fight or flight
What is the role of HCl in the stomach
keeps the stomach acidic (relatively a pH of 2)
What do these cells secrete? Parietal cells: Chief cells: Globlet cells: Delta cells:
Parietal cells: HCl and instrinic fac
Chief cells: Pepsinogen
Globlet cells: Mucus
Delta cells: Somatostatin
What is Gastrointestinal system generally about?
digestion and converting food into energy and basc nutrients
What is GI made up of?
oral cavity, pharynx, oesophagus, stomach, smallintestine, large intestine.
How is digestion achieved?
by a combination of nerves, hormones, enzymes and bacteria
DIgestion is important for_____ and ____
growth and cell repair
What is the peritoneum?
A thin, serous membrane lining of the abdominal and pelvic cavities
How many peritoneums are there?
Split into parietal and visceral peritoneum with a potential space in between
Parietal peritoneum =
lines the walls of the abdominal and pelvic cavities
Visceral oeritoneum =
lines the organs/vicera
Intraperitoneal =
when an organ is completely covered in visceral oeritoneum Eg stomach jejunum and ileum
Retroperitoneal =
when an organ lies behind the peritoneum/ is only partly covered by it
eg pancreas, ascending and decending colon
What are the phases on digestion called?
Cephalic
Gastric
Intestinal
What is te Cephalic phase
Smell, sight, thought or intial taste of food that activates nerual centres in the brain and prepares the mouth and stomach for food to be eaten.
What is the Gastric phase?
Neural and hormonal mechanisms promote gastric secretion and motility
What is Intestinal phase?
When food enters the small intestine and slows exit of chyme from stomach, it stimulates flow of bile and pancreatic juices for digestion from being in the stomach
.
.
What lines the tongue?
papillae
What type of papillae are on the outer/ tips of the tongue?
Fungiform Papillae
- Round and large
- Along margins of tongue
What type of papillae are on the centre of the tongue?
Filiform Papillae
- Small, cone shaped (increase SA of the tongue)
- Mucosal projections
- NO TASTE BUDS
What type of papillae are on the back of the tongue?
Vallate Papillae
- normally 8-12 in V shape
- blunt ended, cylindrical
- largest
- anterior to terminal sulcus
What are foliate papillae?
linear folds od mucosa that lines the sides of the tongue
What are the muscular layers of the stomach?
Longitudinal
Circular
Oblique
What is the fundus in the stomach?
Gas filled area that you can see on a CT
Cardia is the…….
opening of the stomach
What is the largest part in the stomach?
the body
Before going into the duodenum from the body , what does the food need to go through?
pyloric orfice/sphincter
What are rugae?
Circular folds in the stomach which allows the stomach to expand on the digestion of a large meal
Where is the gall bladder located in the liver?
Tucked behind the liver (middle)
Which area is the only area that is retroperitoneal in the liver?
The bare area ( top of the right lobe)
What divides the left and right lobes?
Falciform ligament
What is the importance of the hepatic portal vein?
important in the venous drainage
Name all the lobes in the liver?
Right
Left
Caudate
Quadrate
What is in the porta hepatis?
hepatic portal vein
Proper hepatic artery
Common hepatic duct
The right and ledt hepatic ducts leave the liver and fuse to form_____
the common hepatic duct
The common hepatic duct binds with the systic duct from the gall bladder to go down into the_____
the common bile duct
Features of the large intestine
Appendix (bottom of ascending colon) Ascending colon Right hepatic flexure (corner) Transverse colon Left hepatic flexure Decending colon Rectum
Intervation of the GI tract is______
autonomic
GI tract has innervation coming from its own nervous system called____
Enteric Nervous system
The autonomic NS acts on the
Enteric Nervous system
What is the role of the parasympathetic NS
rest and digest so increases activity of the enteric NS
What is the role of Sympathetic NS
inhibit the activity of the GI tract
Sympathetic NS comes from
T5-L2
The sympathetic NS consits of 3 nerves which are called
Greater splanchnic nerve
Lesser splanchnic nerve
Lumbar splanchnic nerve
Greater splanchnic nerve supplies_____
The foregut
Lesser splanchnic nerve supplies______
The midgut
Lumbar splanchnic nerves supplies______
The Hindgut
The parasympathetic NS consits of
the cranial nerve = vagus nerve
the sacral nerve = pelvic splanchnic nerves
Vagus nerve supplies _____
the foregut and midgut
Pelvic Splanchnic nerves supplies___
hindgut
We refer to sympatheic in GI as
thoracolumbar
We refer to parasympathetic in GI as
Craniosacral
What are the names of the two plexus in the enteric nervous system?
Myenteric Plexus (Auerbach's) Submucosal Plexus (Meissner's)
Myenteric Plexus
⚡Parasympathetic and Sympathetic input
⚡ Innervates the muscular layers of the walls of the GI tract
⚡ Involved in control of gut motility
Submucosal Plexus
⚡ Parasympathetic input only
⚡ Provides secretomotor innervation to the mucosa (near the lumen of the gut)
What is the blood supply to the forgut?
Supplied by the coeliac trunk
What is the blood supply to the midgut?
supplied by the superior mesenteric artery
What is the blood supply to the hindgut?
supplied by the inferior mesenteric artery
The coeliac trunk, superior mesenteric artery and theinferior mesenteric artery are branches of the________
Abdominal aorta
How is the portal vein creating?
by the joining of the superior mesenteric vein and the splenic vein.
What is the role of the portal venous system ?
All the venous blood from the GI tract and accessory organs passes through the liver via the portal venous system before returning to the inferior vena cava
Inferior mesenteric venin drains to
the splenic vein
Splenic vein joins with
superior mesenteric vein
DIgestion starts in the
mouth
What is in the mouth that aids the digestion porcess?
Accessory organs
How many teeth are found in the later and anterior edges of the mouth?
32
What is mastication?
It is the mechanical breakdown of food by chewing anf chopping of the teeth
Function of rough papillae?
for gripping food as it is moved by the tongue muscles
What detects the taste molecules in food?
the taste buds
Absorption of small molecules can happen in the motuh. Examples of small molecules are?
glucose and water
What are the three glands called that produce saliva?
Parotid,
submandibular,
sublingual
Properties of parotid gland?
- Large, irregular shape and secretes 25% of saliva
- Produces a watery secretion rich in protein
- Immunoglobulins are secreted to fight microorganisms
- a-amylase to start carbohydrate breakdown
Properties of submandibular gland?
- Secretes 70% of saliva
- Duct opens near frenulum of the tongue
- Produce a think secretion, rich in mucin (lubricant) and less protein
Properties of subligual glands?
- Secretes 5% of saliva (Smallest salivary gland)
- Very sticky secretions due to large amounts of mucin (buffers and lubrication)
The oseophagus is_____
a muscular tube connection the pharynx to the stomach
What is peristalysis?
muscular contraction by the inner curcular and outer longitudinal muscles of the oseophagus
Function of oseophagus
Carries swallowed masses of chewed food along its length
Where is the lower oseophageal sphincter located?
between the oesophagus and stomach
Function of the oseiophageal sphincter?
it closes to trap food inthe stomach and prevents backflow into the oesophagus
What is the stomach?
Muscular sac on the left side of the abdominal cavity, just inferior to the diaphram
Properties of the stomach?
- Approx the size of two fists placed next to each other
- Acts as a storage for food so body has time to digest larger meals
- Containd HCl to maintian a low acidic pH
- Has digestive enzymes secreted from gastric pits
- has rugae (increase SA)
Goblets cells secrete______
mucus (protects stomach lining)
Parietal cells secrete______
gastric acid (eg HCl)
Chief cells secrete______
Pepsinogen (protein presursor)
D cells secrete______
Somatostaitin (inhibits acids secretion)
G cells secrete_______
Gastrin (stimulates acid secretion)
What is the liver?
triangular accessory organ of the digestive system located on the right og the stomach, just inferior to the diaphram
Function of the liver?
- Production of bile and metabolism of nutrients
- Detoxification of several metabolities (inc breakdown of bilirubin and oestrogen)
What is the gallbladder?
Small, pear shaped organ just inderior to the liver
Function of gallbladder
- stores and concentrates bile before releasing it during digetsion
- recycles excess bile from the small intestine so it can be reused in subsequent meal digestion
Bile =
thick fluid that emulsifies lipids in the intestines
Where is bile released from?
gall bladder
When is bile released?
When it recieves the signal that the duodenum has food present,
What is the pancreas?
Large gland located just inferoposterior to the stomach. Made up of a head, neck, tail and uncinate process.
Function of pancreas?
- secretes digestive enzymes into the small intestine to aid with chemical digestion of the food
- secretion of fluid in carbihydrates and inactive enzymes (carbohyrases, lipases, nucleases)
- secreted in an inactive form to prevent digestion of the pancreas itself
Names 3 pancreatic enzymes that have protein as its substrate?
trypsin
chymotrypsin
carboxy peptidase
Name a pancreatic enzyme that has a carbohydrate as a substrate
Pancreatic amylase
Name 3 pancreatic enzymes that have fats as a substate
pancreatic lipase
chloesterol esterase
phospholipase
What is the small intestine?
composed of the duodenum, jejunum and ileum
Function of duodenum
mixing function combing digestive secretions (from the pancreas and liver) with the contents that are expelled from the stomach
Function of Jejunum
Responsible for the majority of digestion and absorption
Function of Ileum
Longest segment and emoties into the caecum at the ileocaecal junction
What happens in the pancreas
Food constituents (fats, carbs, proteins) are broken down and absorbed into the blood stream (via villi)
What is the large intestine?
Long, thich tube located just inderior to the stomach
What is the large intestine made up of?
appendix, caecum , Asc colon, Transverse colon, Desc colon, Sigmoid colon, Rectum
What are the walls of the colons made uo of?
Haustra (pouches) that are held under tension by thick bands of muscle (taenia coli)
Function of large intestine
- absorps water, suhar, salts and vitamins into the body
- contains many symbiotic bacteria
- rectum expands to hold faeces
What does CCK stand for?
Chloecystokinin
What does CCK do?
- it is a peptide hormone stimulating the digestion of fat and protein
- regulator of small intestine digestion
- intergrator of brain and gut function
CCK stimulates____
-Pancreatic enzyme secretion
-gall bladder contraction (thereby promoting small
intestine digestion)
CCK inhibits_____
Food intake and gastric emptying, via vagal afferent neurons (thereby delaying nutrient delivery to the small intestine)
Which salivary gland produces th emost saliva
Submandibular
There is a balance between which two hormones?
somatastain and gastrin
What is a huge difference between the large intestine and small intestine? (hint: the answer is not one is small and one is large)
no villi in large intestine
