The Digestive System Flashcards
digestion
the breakdown of large insoluble molecules into small soluble molecules by chemical and physical means
an/o
anus
append/o
appendix
appendic/o
appendix
cholecyst/o
gall bladder
col/o
colon
colon/o
colon
or/o
mouth
stomat/o
mouth
enter/o
intestines (normally small)
duoden/o
duodenum
esophag/o
oesophagus
gastr/o
stomach
hepat/o
liver
ile/o
ileum
jejun/o
jejunum
pancreat/o
pancreas
proct/o
anus and rectum
rect/o
rectum
sigmoid/o
sigmoid colon
processes of digestion - ingestion
mouth - mechanical (mastication) and chemical (enzymes) breakdown
processes of digestion - propulsion
oesophagus - movement of bolus/peristalsis
processes of digestion - digestion
stomach, duodenum - chemical (gastric juice) and mechanical (churning) breakdown
processes of digestion - absorption
jejunum, ileum - absorption of nutrients into cardiovascular system
processes of digestion - assimilation
small intestine - digested food products are converted into fluid and solid parts of a cell/tissue
processes of digestion - elimination
large intestine, rectum, anus - undigested food residues are egested from the body as semi-solid faeces
mouth
function = point of entry, commence ingestion for the digestive system
includes mechanical (teeth/tongue for chewing) and chemical (salivary glands/saliva) breakdown
teeth
tearing/grinding/cutting/breaking down food into small enough portions to swallow
maintain good oral health by having regular dental check-ups, daily tooth brushing and flossing, fluoride in water helps to strengthen enamel
tongue
chewing/mastication of food (moves food to between teeth), swallowing, speech and taste
salivary glands
includes parotid, submandibular, sublingual
function = produce saliva, lubricate food, chemical digestion, taste, cleaning of the mouth
oesophagus
long tube approx. 25cm long and 2cm wide, posterior to trachea
function = carry food from the pharynx to the stomach via peristalsis
stomach - structure
muscular bag - 3 layers - longitudinal (outer), circular (middle), oblique (innermost)
sphincter - ring like muscles surrounding and able to contract/close a passage or opening
- oesophageal
- pyloric (between stomach and duodenum)
stomach - function
mechanical - contraction = churn food, secrete mucous = lubrication
chemical - create and secrete pepsin (break down protein)
protective - HCl = kill invading pathogens and stops action of salivary amylase
small intestine - adaptations
single wall of columnar epithelial cells = short diffusion pathway
villi and microvilli = increase surface area of intestines for absorption
small intestine - duodenum
- first part of small intestine to leave stomach
- final stage of digestion
- gall bladder and pancreatic secretions merge at this point of the structure
small intestine - jejunum
- roughly 2m long, middle section of small intestines
- absorb nutrients
- villi + microvilli line walls
absorb: proteins carbs vitamins minerals lipids
small intestine - ileum
- end section, walls lined by villi and microvilli
- ileocecal valve = conjunction of small and large intestines to stop back flow of contents up alimentary tract
- absorb nutrients
absorb: water bile salts vitamin B12 lipids
pancreas
-abdominal organ, posterior to stomach, connected to duodenum by pancreatic duct
function:
pancreatic juice containing amylase (starch), trypsin (protein), lipase (lipids), nucleases (nucleic acids) and sodium hydrogencarbonate (neutralize acidic chyme)
regulate BGL - insulin respond to high, glucagon respond to low
liver
largest gland in body
function = metabolism of carbs/fats/proteins, production and secretion of bile
bile
composed of water/mucous/mineral salts/bile pigments (bilirubin - left over RBC)/bile salts/cholesterol
function = digest insoluble fatty acids - break down into smaller droplets
stored and concentrated by the gall bladder
absorption
the movement of digested food molecules and nutrients across the intestine wall into the blood or lymph
application - coeliac disease
autoimmune disease triggered by gluten = damage to small intestine
villous atrophy = inflammation and flattening of the villi therefore decreased absorption of nutrients
large intestines
consist of:
caecum
ascending/transverse/descending colon
sigmoid colon, rectum
receives indigestible food (fibre)
absorbs remaining water and electrolytes
faeces
composed of 60-70% water, fibre, dead/live microbes, epithelial cells from gut lining, fatty acids, mucous
formation:
1) undigested food (chyme) enters colon from ileum
2) water, salts, vitamins are reabsorbed
3) dehydration and compaction
4) semi-solid faeces/stool
rectum and anus
rectum: starts at sigmoid colon, terminates in the anal canal
anus: leads from rectum to the exterior of the body via an external sphincter (skeletal muscle - voluntary)
maintaining a healthy digestive system
healthy diet - fibre and water intake is adequate
regular exercise - aerobic exercise speeds up breathing and heart rate, stimulating the natural squeezing of muscles in the intestines
hygiene - prevent pathogens from remaining or reentering e.g. washing hands after using toilets
