Purpose Of The Gut

Question 1

Alimentary canal

Answer 1

Mouth 
Oesophagus
Stomach 
Pancreas 
Duodenum 
Jejunum 
Ileum 
Cecum 
Ascending colon 
Transverse colon 
Descending colon 
Sigmoid colon 
Rectum 
Anus

Question 2

Sphincters of oesophagus

Answer 2

Start - upper oesophageal sphincter - prevents air entering GI tract

Bottom - lower oesophageal sphincter - helps prevent reflux into oesophagus from stomach

Question 3

Stomach function

Answer 3

Storage, physical/ chemical breakdown.

Infection control through HCL

Secretes intrinsic factor to absorb Vit B12 (folate) (without-> pernicious anaemia)

Produces chyme - fluid consist of gastric secretions and partially digested food

Question 4

Function duodenum

Answer 4

Neutralisation (HCO3) and osmotic stabilisation of chyme (makes less hypertonic)

Bile and pancreatic secretions are delivered into second part through a common entrance for the liver and pancreas

Question 5

Jejunum and Ileum functions

Answer 5

Final digestion

Nutrient absorption (mainly j)

Water/ electrolyte absorption (mainly I), bile recirculation, B12 absorption (terminal i ) (ileum)

Question 6

Large bowel function

Answer 6

Final water and electrolyte absorption (Some bile salts and production of some Short chain FAs)

Temporary storage

Question 7

Autonomic nervous system neurones of sympathetic and parasympathetic

Answer 7

Sympathetic:
CNS -> SHORT preganglionic neurone release Ach -> autonomic ganglia outside CNS -> LONG postganglionic N release mostly noradrenaline -> peripheral effector organs

Parasympathetic:
CNS-> LONG preganglionic neurone releases ACh-> autonomic ganglia-> SHORT postganglionic N release Ach mostly/ neuropeptides (gastric releasing peptide and Vaso-inhibitory peptide) / norepinephrine -> peripheral effector organs (walls of viscera, smooth muscle, endocrine and secretory cells)

Question 8

Parasympathetic nerves names and supply

Answer 8

Responsible for rest and digest

Originates brain and sacral spine (craniosacral)

Cranial nerves:
3, 7, 9 -> eye, lacrimal gland, sublingual g, submandibular g, mucous membrane of nose and palate, parotid g

10 (vagus Nerve) -> heart (atria muscle fibres, SA/AV nodes, larynx, trachea, bronchi, lungs, liver, gallbladder, bile ducts, stomach, pancreas, colon

Pelvic splanchnic nerves (S2-4) pelvic nerve -> transverse colon- anal canal

Preganglionic and then postganglionic in walls -> myenteric and submucosal plexuses (enteric Ns)

Question 9

Sympathetic function

Answer 9

Restrict blood flow to viscera and direct it to muscles T1-L2 -> eye, lacrimal g, BVs, salivary, heart, lung, liver, gallbladder, stomach, spleen, AG, kidney, intestines, rectum, genitalia, bladder

T5-L2 innervation to gut
Pass through sympathetic trunk

Splanchnic nerves: synapse on preveterbral ganglia Coeliac, renal, superior mesenteric, inferior mesenteric

Postganglionic go to myenteric and submucosal plexuses (enteric NS)