W3 A Digestion System Flashcards
What are the 6 main processes that happen throughout digestion?
- Ingestion
- Secretion
- Motility
- Digestion
- Absorption
- Defecation
Organs involved in digestive system.
(…) = Accessory Organs (aren’t directly involved in passing food)
- Mouth
- (Salivary Glands)
- Stomach
- (Pancreas)
- (Gall Bladder)
- (Liver)
- Small Intestine
- Large Intestine
Name the three phases to swallowing:
- Buccal phase - Voluntary, goes to back of throat
- Pharyngeal phase - Enters Oesophagus
- Oesophageal phase - Down Oesophagus
What does the Oesophagus do?
How many layers does the tube have? What are they called?
Name the thing that constricts and relaxes the two layers.
- It moves food from the mouth to the stomach (4-8s)
- Tube with double layer of muscle. First is Circular. Second is Longitudinal.
- Peristalsis, constrict circular layer & relax longitudinal layer
Name the four parts of the Stomach.
- Cardia (top)
- Fundus (above + left storage)
- Body (mixes)
- Pylorus
Name 3 Stomach Functions:
- Storage (6L)
- Mixing, creating chyme (soup like paste) which is a gastric juice
- Emptying chyme to duodenum
Name the different phases of gastric secretion:
- Cephalic phase - 30% of response to meal, prior to food arrival
- Gastric phase - 60% of response to meal, gastric juice released
- Intestinal phase - chyme entering duodenum decreases gastric secretion & motility
What does the Liver do?
- Portal vein comes from the digestive tract & pancreas to the liver
- Bile production (helps to digest fat)
- Metabolism
- Processes drugs & hormones (detoxifies)
What does the Gall Bladder do?
- Stores & concentrates bile!!!
- Stimulates release by secretion & CCK
- 90% bile salts reabsorbed & recycled
- You can survive if your gall bladder is removed but 40% less dietary lipids are absorbed
What are the 3 parts of the small intestine?
- Duodenum
- Jejunum
- Ileum
What’s does the small intestine do?
- It’s the main site for digestion & absorption of nutrients
- Mixing food up
- Moving it down throw the body
Why does the SI have a big surface area?
How long do cell live for in the SI?
- It has a large surface area because of Villi & Microvilli
- Cells of your small intestine are related every 2-5 days
What two processes does the SI use to create motility?
- Peristalsis (Outer longitudinal muscle inner circular)
- Segmentation (Lumen lined with mucosa)
After food leaves the SI (Ileum) what sphincter/valve does it have to go through to enter the LI?
- Food has left the SI and moved into the LI via the Ileocecal (goes from Ileum to cecum) sphincter/valve.
What does the LI do?
- Reabsorbs water
- Stores faeces
- Bacteria ferment (remaining CHO, release H, CO2 & methane)
