Tweety Flashcards
What is the role of the GI system
Bring nutrients/water into internal environment to be used by the body
Function of the the GI system
• Motility: transport food into & through the body,
mixing luminal contents, and transport waste out
• Secretion: synthesise and release enzymes,
mucus & serous fluid into the lumen (lumen still part of external environment - internal means blood system and shit)
• Digestion: break nutrients into smaller pieces (mechanically and chemically)
• Absorption: bring nutrients/water from the lumen to
internal environment
How does structure allow function
yes
What is GI system - simple
- long tube with outgrowths
What do sphincters do?
close off ends, and separate sections (environments) of tube
Within different organs, to allow function to occur there are different____
Environments
What is GI system lined by
Epithelium
Sphincters what are they
Smooth muscle that can dilate or constrict
Unicellular gland
Goblet
Features of goblet cells
- columnar
- goblet shape
- apical mucous granules
- basal nucleaus
Function of intestine goblet cells
- lubrication
- protective barrier
Multicellular glands
Simple and compound
Epithelium can invaginate to form
Glands
Simple glands:
Gland with single function (e.g stomach and small intestine)
Compound glands
gland with 2 or more ducts (e.g. salivary glands)
Increased SA for increased secretion
Epithelium in mouth
- need protective epithelium
- statified squamous
Where is stratified squamous epithelium found in the GI system and why
- mouth/oral cavity
- esophagus
- protection from abrasion
Location and function of simple columnar epithelia in GI
- stomach
- small intestine
- large intestine
- section and absorbtion
Where and why is stratified squamous found and why
- anus
- protection from abrasion
4 layers of the gut
- Mucus
- Submucosa
- Musciularis (externa/proper)
- Adventitia
What does the mucosa (GI) consist of?
- epithelium
- basement membrane
- lamina propina (FCT)
- muscularis mucosa
- sometimes multicellular glands
What does the submucosa consist of
- FCT
- glands
- blood vessels
- (submucisal nerve plexus)
What is secretion regulated by?
Secretion is regulated by the submucosal nerve plexus, part of the enteric nervous system (ENS)
What kind of muscle does the muscularis (externa/proper) consist of?
- the muscularis (externa/proper) consists of smooth muscle
How many and names of rhe layers of the muscularis ?
- liner circular
- outer longitudinal
Where is the myenteric plexus
- located between muscle layers
What is the myenteric plexus part of
ENS
Two gut layers with components in the enteric nervous system.. what are the components?
- myenteric plexus
- submucosal nerve plexus
What does the myenteric plexus do?
Regulates motility
Histology of smooth muscle of the muscularis
Features of the Adventitia
- outermost layer
- consists of FCT
- supports organ and anchors to surrounding structures
When organs are in the peritoneal cavity there is an additional,…
Outer covering
what is the additional outercovering of the Adventitia called
Serosa
What is the serosa
Additional outer covering when organs are in the peritoneal cavity
What is the function of having two layers of smooth muscle with different orientations
- motility patterns - different orientations of muscle will cause different movements of the gut tube
Why are there glands in both the mucosa and submucosa in some regions?
- more surface area
- if more secretion are needed you need more cells - for extra protection
Epithelium in the mouth and oral cavity and why
- stratified squamous
- protection
Where does digestion begin
Mouth and oral cavity
How does such digestion start in the mouth - what kind of statergy and what else is needed fir this
- mechanical digestion
- chemical digestion - requires enzymes
- lubrication is needed
How does lubrication occur on mouth and oral cavity
- through salivary glands
- secrete mucos and serous fluid
Where is food travelling… what kind of epithelium is found here?
Though faucets into oropharynx and laryngopharynx then into esophagus
What are the salivary glans connected to the oral cavity by?
Ducts
How many pairs of salivary glands are connected to the oral cavity via ducts
3
The 3 pairs of salivary glands connected to the oral cavity via ducts
Parotid: (Watery) serous fluid with amylase (breakdown carbs)
Sublingual: mucus only ( lubrication)
Submadibular: mixed
Salivary glands are ____ glands
Compound
Acinus
- cells in clusters
What do acinar cells do?
Secrete:
- serous fluid and enzymes ( amylase)
- mucus
Duct cells in salivary glands secrete:
- bicarbonate (buffering)
Histological diagram of a submandilbular gland
What is the esophagus and how long
Long basic tube modified to pass food
About 25cm
Where is the esophagus located and where does it extend and end
- located posterior to the trachea
- extends from pharynx to stomachs
What does the epiglottis ensure?
That food enters the esophagus and not the trachea
What moves the food bolus
Muscularis externa
Muscle make up of the muscularis externa of the esophagus down its length
- first 1/3: skeletal muscle
- middle 1/3: a mixture
- last 1/3: smooth muscle
Basic modifications of the esophagus to m=pass food
Muscularis externa: Move food bolus
• First 1/3: skeletal muscle
• Middle 1/3: a mixture
• Last 1/3: smooth muscle
Highly folded submucosa and mucosa
• Capacity to expand for passage of bolus
What kind of epithelium is the esophangous
Squamous epithelium
Lubrication in the esophangous
- need mucus for lubrication and protection
- no goblet cells, instead have glads with ducts to surface
- in the mucosa
- plus in mucosa close to stomach
Different structure =
Different function
What is the role of epithelium in the GI tract
To protect against abrasion (oral cavity/esophagus & anus), to secrete and absorb (stomach and intestines) and to form glands throughout.
What are the key features/function of the
oral cavity, salivary glands and esophagus?
Oral cavity: receive food, begin digestion Salivary glands: secretions for digestion and lubrication Esophagus: deliver food to stomach
