digestive part 1 Flashcards
Functions of the digestive system
- Ingestion: taking in food
- Digestion: breakdown of food ( two categories )
- Mechanical: Chewing and churing tearin, physical
breakdown of food - Chemical: enzymes that breakdown food
- Mechanical: Chewing and churing tearin, physical
- Propulsion: movement
- Peristalsis: muscular contractions that coordinate
movement of food - Segmentation: muscular contraction that
coordinate the mixing of food
- Peristalsis: muscular contractions that coordinate
- Secretion: releasing fluids
-Mucin is needed because it provided lubrication
in movingof the food
- Acid: is going to break bonds in order to break
food up
-Bile: very useful for breakdown, its lipid emulsifier
-Enzymes break down food - Absorption: nutrients into blood and lymph
- Elimination of wastes: indigestible becomes feces
Peristalsis V Segmentation
Peristalsis think swallowing food down the esophagus
Segmentation occurs in both intestines but a lot of times in the small intestine
Oral cavity
considered the entrance of the GI tract
what are the borders of the oral cavity
Anterior: lips and teeth
- Posterior: oropharynx
- Superior: hard palate ant. 2/3 and post 1/3 soft
palate
- Floor: mylohyoidCavities within the oral cavity
Sub dividied into 2 diff chambers
Vestibule : waiting area, between lips and teeth
Oral cavity proper: central portion
Function of the oral cavity
mechanical and chemical digestion
Chemical portion: release of amaylase
What type of tissue is found in the oral cavity
non keratinized stratified squamous
Function of the Tongue
manipulate, and mix food to create a bolus which what is swallowed
What is an bolus
Bolus: globular mass of ingested materials
What is the structure of the tongue
Tongue: is skeletal muscle we have control over it
attaches to the floor via Lingual frenulum the web that connects the tongue
Function of salivary glands
produce and secrete saliva
Saliva functions
Moistens Cleanses Chemical digestion (enzymes) Antibacterial Dissolves materials for taste receptors
**Lysozyme: enzyme that kills bacteria cell walls. The saliva covers teeth when we eat , how it cleanses and kills bacteria
makes it antibacterial
What is the structure of salivary glands
Secretory cells
- Mucous cells: secrete mucin that turns into mucous (when hydrated)
- Serous cells: watery fluid with ions, lysozyme, amylase
What are the types of salivary glands
- Parotid gland: is the biggest think when sourfoods
make your mouth salivate - Submadibular: gland under the body of mandible
- Sublingual :under the tongue
Structure of the parotid glands
Largest
- Anterior to ear
- Parotid duct > 2nd upper molar
What does the parotid gland secrete
Serous secretions only, amylase
makes up to - 25-30% of saliva
Submandibular gland structure
Inferior to body of the mandible (deep to the mandible)
- Submandibular duct :: comes from floor, papilla on floor and later to lingual frenulum is wwhere the duct is located
what do the Submandibular glands secretes
Secretes serous and mucous, have more viscosity (make it thick)
Makes the majority of saliva (60-70%)
What is the innervation of the submandibular glands
parasympathetic because rest and digest
And Facial nerve CN VII
Structure of the Sublingual gland
Inferior to tongue
- Several sublingual ducts in inferior oral cavity
(Duct: several sublingual ducts found under the tongue)
What do the sublingual glands secrete
- Both Serous and mucous secretions
produce about 3-5% of saliva
What is the innervation of the sublngual gland
Parasympathetic, Facial nerve (CN VII)
how the pharynx is involved in the digestive system
Shared by respiratory and digestive systems
- Functions: participates in swallowing / swallowing
reflex
- Innervation: Vagus (CN X)
What is Peritoneum
Abdominopelvic serous membranes
there are 2 types
1. Parietal peritoneum : covers the wallks
2. Visceral Peritoneum: on organs
What does the Parietal and Visceral peritoneum create
forms the Peritoneal cavity
In between filled with serous fluid
Intraperitoneal organs
Completely surrounded by visceral peritoneum
- Ex. stomach, most of small intestines
- *Intra= inside peritoneal, organ is completely covered in serous membrane
Retroperitoneal Organs
- Only anteriolateral covered by visceral peritoneum
- Ex. pancreas, ascending and descending colon, rectum
**Retro: organs found against the back wall, only part of the organ is covered in serous membrane
What are messentaries ?
- Folds that support and stabilize intraperitoneal organs
- Contain: blood, lymphatic vessels, nerves
**Membranes on membranes (serous on serous)
Intra organ will have a mesentery associated with it
Types of Messentaries
- Greater omentum: apron sheet covering that covers the instestines, connects to the greater curvarure
- Lesser omentum: stomach is suspended from lesser curvature
- Mesentery proper : connective membrane that binds the small intestine together
- Mesocolon
Greater omentum
Apron covers most abdominal organs
- Connects: greater curvature of stomach
Lesser Omentum
Connects: lesser curvature of stomach and proximal duodenum to liver
(Proximal duodenum is the 1st part that comes off the stomach )
Messentary Proper
- Connects: small intestines to abdominal wall
Membrane that holds the small intestines together
Mesocolon
Connects: large intestine to posterior abdominal wall
Histology of GI tract
4 tunics (deep to superficial)
1. Mucosa
2. Submucosa
3. Muscularis
4. Adventitia or Serosa: depnds on if organ is
intra or retroMucosa
Components:
1. Superficial epithelium
- Non-ciliated simple columnar (for small
intestines)
-Microvilli: absorb , why in small intestine
because it absorbs
2. Lamina propria: areolar CT
- Capillaries
- Lacteals (for small intestines)
- Peyer patches
3. Muscularis mucosae: smooth muscleSubmucosa
- Tissue: areolar and dense irregular CT
- Contains:
- Lymphatic ducts
- Nerves
- Blood vessels
- Mucin secreting glands
- Contains:
Muscularis
- 2 layers of smooth muscles
1. Inner circular layer
- Constricts lumen (sphincter)
2. Outer longitudinal layer
- Shortens tube
What are the exceptions when it comes to muscularis
- Exceptions:
- Esophagus: has both smooth and skeletal
muscle - Stomach: 3 layers of smooth
- Esophagus: has both smooth and skeletal
Adventitia or Serosa
- Outer most layer
- Tissue: areolar CT
- Adventitia: retroperitoneal organs
- Serosa: intraperitoneal organs
- contains visceral peritoneum
Blood supply
Celiac trunk: under disphragm: supply blood for variety organs
Superior mesenteric artery: provide blood supply for most small some large
Inferior mesenteric artery: some of the large intestines
Nerves
- Both autonomic and sensory
- Plexus
- Celiac plexus
- Liver, spleen, and stomach
- Superior mesenteric plexus
- Small intestines, part of large
- Inferior mesenteric plexus
- Large intestines, rectum, anal canal
- Celiac plexus
