Digestive System Flashcards
functions of the digestive system
- ingestion - taking food in
- digestion - breaking food down both phys and chem
- absorption - movement of nutrients into blood stream
- defecation - waste
organs of digestive system
alimenrary canal: (gi tract)
- mouth
- (salivary glands) - pharynx
- oesophagus
- (liver)
- (lower esophageal sphincter) - stomach
- (pyloric sphincter)
- (gall bladder)
- (pancreas) - small intestine (Jejunum, ileum)
- large intestine (appendix, cecum, ascending, transverse, descending, sigmiod, rectum, anus)
- (sphincters lie between each region)
mouth function
mastication (chewing)
mixing food and saliva
initiation of swallowing by tongue
allows sense of taste
salivary glands
3 pairs
help form food bolus
contains amylase (enzyme brakedown of starch)
dissolves chems so we can taste
oesophagus
around 25cm ling
pharynx-stomach
conducts food by peristalsis (slow rhythmic squeezing)
passage for food only
stomach
LEFT side of body (like heart)
food entres caradic sphincter (top)
- empties at pyloric sphincter/valave (bottom)
middle section is acidic (hydrochloric acid; HCL)
- empties in 4–6 hours
both mech and chem happen
delivers chyme (processed food) to SI
- kills microorganisms and acivates enzymes in hydrocholric acid
protein digesting enzymes
small intestine
- most chemical digestion occurs/absorption
- muscular tube extending from the pyloric sphincter to the ileocaecal valve and LI
- nearly all food absoprtion here/amino acids, simple sugars, minerals, water soluble vit (B/C).
- lined with projections that increase surface area:
villi/microvilli
3 major regions
1. duodenum
2. jejunum
3. ileum
- duodenum
most chem digestion occurs and some absorption takes place
receives chyme from stom, bile from liver/gall and pancreatic juice.
bile
made by liver
stored in gall bladder
emulsifies fat - brakedown of fat to smaller globules.
Bile is also released at the same time as pancreatic juice and acts
like a detergent to emulsify or mechanically break down large fat
globules and is also necessary for absorption of fat soluble vitamins.
pancreatic juice
contain enzymes which brake down all food groups
- Pancreatic juice is released into duodenum contains enzymes that Help complete digestion of starch (pancreatic amylase)
– Carry out about half of all protein digestion
– Digest fats using lipases from the pancreas
– Digest nucleic acids using nucleases
• Pancreatic juice is alkaline and helps return pH of chyme to a level to
activate intestinal and pancreatic enzymes and protects the intestine
- jejunum
bulk of absorption.
By the time chyme has passed through the jejunum, around 90% of
all available nutrients have been absorbed
into the body
- ileum
longest region of SI
any last nutrients that isnt absorbed are now done here before passing through to LI
large intestine
reabsorb fluids, process waste products from the body and prepare for its elimination.
4 parts: ascending, transverse, descending, sigmoid.
pancreas
- exocrine: Produces digestive enzymes (pancreatic juice) that breaks down proteins, fats and carbohydrates (chemical digestion)
• Pancreatic juice is secreted into duodenum
• Endocrine: hormones; Also produces insulin and glucagon which enter bloodstream and control blood glucose levels - Bicarbonate produce to neutralise stomach acid
liver
located on right side of body. - Produces bile/chloestrol (emulsifies fats by physically breaking large fat globules into smaller ones) • Makes important proteins and hormones. • Stores glucose (as glycogen) and releases it as needed. • Stores iron/processes of haemoglobin. • Breaks down harmful substances • Clearance of bilirubin – by product of red blood cell breakdown (if there is a build up of bilirubin, become jaundice) - regulate blood clotting
