5.1 Digestion Flashcards
What is the difference between digestion and absorption?
Digestion involves the mechanical and chemical breakdown of food, extraction of nutrients and breakdown of macronutrients.
Absorption is the transfer of nutrients from the lumen of the small intestine to blood or lymphatic capillaries surrounding the digestive tract.
what process of digestion happens in the mouth?
Salivary glands secrete saliva (starch digesting enzymes) and chewing (mastication) breaks down food
What is the epiglottis?
It is a flap in the throat that prevents food from entering the windpipe
What happens to food after swallowing?
The food (bolus) heads into the oesophagus where the oseophageal sphincter controls passage from oesophagus to the stomach
What is the role of the stomach in the GI tract?
The stomach adds juices and grinds the bolus into chyme (semi liquid)
What is the role of the pyloric sphinter?
It regulates the flow of chyme into the small intestine
Where does small intestine receive digestive juices from?
Gall bladder and pancreas
What are the three segments of the small intestine?
duodenum
jejunum
ileum
Where does food continue from the large intestine?
The large intestine (colon) begins at the ileocaecal valve and undigested residues continue through to the rectum (forming stool) and excreted through the anus
What are five aspects of muscular (mechanical) digestion)?
- Chewing (mastication)
- Peristalsis
- Stomach action
- Segmentation
- Sphincter contractions
What structures contribute to mastication?
- The human jaw is one of the most powerful muscles in the body
- Tooth enamel is the hardest substance produced by the body
- The tongue is a conglomeration of eight different muscles, which makes it the body’s most flexible muscle
- Several glands (including sublingual, submandibular and parotid) secrete saliva to help dissolve food and provide particles in solution to react with taste buds
What does peristalsis mean?
It is the way food is moved down the intestine and the oesophagus, through GI tract
Squeezing and pushing food through mechanism
How does muscles allow for peristalsis?
How does stomach action assist in digestion?
What is segmentation?
What are the four sphincters in the GI tract?
- Oesophageal sphincter
- Pyloric sphincter
- Ilocaecal valve
- two sphincters of the anus
How does the oesophagus muscles and diaphragm work together to act as a sphincter muscle?
What is ghrelin?
A hormone secreted by stomach cells which tells the brain when its hungry or full
What stimulates ghrelin release?
Empty stomach stimulates ghrelin release
Where are ghrelin receptors found?
hypothalamus
What stops ghrelin release?
A full stomach
What are the other roles of ghrelin?
- Glucose and energy homeostasis
- Cardio protection
- Muscle atrophy