Digestive System I Flashcards
3 things that contribute to ‘you are what you eat’
You are what you:
Digest
Absorb
Don’t Excrete
3 Accessory organs in the digestive tract
Salivary glands
Liver
Pancreas
Gall bladder
Explain ingestion process
Oral intake of substances
Explain secretion process
Digestive juices - water, acid, emulsifiers, buffers and enzymes added
Explain mixing and propulsion
Contraction and relaxation in walls to help mix and propel food
Explain absorption
Substances pass through the walls of the alimentary canal into blood and lymph.
explain digestion
Mechanical and chemical processes
break down ingested food and liquids
into absorbable substances
Explain elimination
Excretion of water and indigestible materials
4 layers of the gastrointestinal tract
- Mucosa
- Submucosa
- Muscularis
- Serosa (peritoneum)
Describe the role of microvilli
Increase the surface area for absorption
Describe the role of goblet cells
secretion mucus to
lubricate food and protect against
digestive juice erosion
What is meant by MALT
mucosa associated lymphoid tissue
What percentage of the immune system is in the gut
70%
Describe the role of GALT
GALT part of the
first line of defence
against ingested
pathogens.
25% of the intestine
mucosal mass.
Locations of MALT in the body
tonsils,
oesophagus,
small intestine,
appendix and
large intestine.
2 functions of involuntary smooth muscle contractions in the digestive tract
Mixing of food with digestive juices.
Propelling food (chyme / bolus) along the digestive tract
(peristalsis)
Role of the peritoneum
is supplied with many blood
and lymph vessels.
It provides a physical
barrier to local spread of infection.
Mucosa Epithelium what is it and key elements
Inner layer
Stomach and intestines have
- Microvilli (small intestines)
- Goblet cells
- Enteroendocrine cells
Describe the mucosa’s second layer, lamina propria
connective tissue with GALT
Mucosa’s muscularis mucosa
Thin layer of smooth muscle
Creates the villi
Describe the submucosa layer
connective tissue layer that lies between the
mucosa and muscularis.
Contains the submucosal plexus - ‘brain of the gut’
How is the submucosal plexus described?
Brain of the gut
Describe the Muscularis Externa
- The mouth, pharynx, upper oesophagus and
anal sphincter contain skeletal muscle to
allow voluntary swallowing and defecation.
The GIT is mostly smooth muscle
Myenteric plexus and nervous system
sympathetic and
parasympathetic nerve fibres
Controls strength and frequency
of muscle contraction: gut motility.
Submucosal plexus and nervous system
controls digestive secretions
and detects sensory information.
2 ways sensory neurons receive info about environmental changes
Motor neurons (outgoing / action
signal)
control peristalsis & secretions.
Sensory neurons (incoming
signal) receive information
about the mucosal environment:
chemoreceptors and stretch
receptors.
2 veins that drain the digestive system
The portal vein drains the lower oesophagus,
stomach, pancreas, small and large intestine,
upper rectum and spleen.
The iliac veins drain the lower part of the
rectum and anal canal.
What is meant by peristalsis
Wave like contractions that propel food (chyme / bolus) along the digestive tract
4 functions of the oral cavity
Mastication
Speech
Taste
Swallowing
2 glands that produce saliva
Sublingual gland
Submandibular gland
How is saliva production affected by parasympathetic nervous system?
Decreased
