Lecture 7 - Anatomy of GI

Question 1

3 saliva glands

Answer 1

parotoid, submandibular and sublingual

Question 2

Where is water, amylase filled saliva secreted from?

Answer 2

parotoid and submandibular saliva glands

Question 3

Where is thick saliva and mucus secreted from in mouth?

Answer 3

Sublingual saliva gland

Question 4

How food travels down GI tract

Answer 4

mouth, then to pharynx and down oesophagus into stomach, then from stomach into s. intestine. Food travels on to large intestine and then rectum and excreted.

Question 5

Accessory Organs

Answer 5

Liver, gallbladder and pancreas

Question 6

What’s the gut?

Answer 6

GI tract as a whole

Question 7

Well fed/absorptive state

Answer 7

glucose levels increase, resulting in storage of fuels and protein synthesis and glycogen synthesis. INSULIN secreted from pancreas to enhance glucose uptake and metabolism in cells, reducing blood glucose

Question 8

Glucose levels in Post-absorptive state

Answer 8

decrease in glucose causes an increase in glucagon (glycogen is broken down) and gluconeogenesis (production of glucose from e.g amino acids). Body tries to save glucose using fats (lipolysis) and ketones are produces as a source of energy during prolonged fasting

Question 9

Hunger

Answer 9

decrease in glucose, fat, protein and an INCREASE in GHRELIN affects appetite centre in LATERAL Hypothalamus and makes us feel hungry

Question 10

Satiety Signals

Answer 10

increase in glucose, fat, protein and leptin targets satiety centre in MEDIAL hypothalamus telling us to stop eating.

Question 11

What effects gastric emptying?

Answer 11

meal size (more food=larger digestive phase), calories control gastric emptying. FAT DELAYS GASTRIC EMPTYING. It also lowers intragastric pressure. Feel fuller for longer after high fat meal. It prolongs elevation of pH in stomach.

Question 12

Structure of GI (inside out)

Answer 12

lumen, mucosa (villi if small intestine and always epithelium) , submucosa (contains glands and SUBMUCOUS PLEXUS), circular muscle, MYENTERIC PLEXUS, longitudinal muscle.

Question 13

Other name for myenteric plexus

Answer 13

Auerbach’s plexus

Question 14

Other name for Meissner’s plexus

Answer 14

Submucosal plexus

Question 15

Parts of CNS

Answer 15

brain and spinal cord

Question 16

What does PNS do?

Answer 16

connect CNS to limbs and organs, ANS is a division of PNS

Question 17

What does the autonomic nervous system do?

Answer 17

influences the function of organs

Question 18

What is the enteric nervous system?

Answer 18

Myenteric plexus and submucosal plexus, the intrinsic nervous system of GI Tract

Question 19

how are CNS and ENS connected

Answer 19

via vagus nerve, 10th cranial nerve that runs from brain stem down to abdomen.

Question 20

Vagus nerve

Answer 20

primary route gut bacteria use to transmit info to brain

Question 21

Afferent neurons

Answer 21

otherwise known as sensory receptor neurons, carry nerve impulses away from receptors or sense organs towards the central nervous system

Question 22

Efferent nerves

Answer 22

otherwise known as motor or effector neurons, carry nerve impulses away from the central nervous system to effectors such as muscles or glands

Question 23

Myenteric Plexus

Answer 23

largely motor in function, influencing muscle activity.

Question 24

Submucosal plexus

Answer 24

largely sensory, receiving signals from epithelium and stretch receptors influencing secretory activity

Question 25

How are myenteric and submucosal plexuses regulated?

Answer 25

via ANS (sympathetic and parasympathetic) since fibres from both can synapse with neurons in ENS. Allows CNS to influence GI activity.

Question 26

Segmentation

Answer 26

facilitates mixing of food, circular muscle

Question 27

Peristalsis

Answer 27

propulsion of food along tract, longitudinal muscle

Question 28

Gut transit time

Answer 28

12 to 24hrs

Question 29

Drugs that can cause constipation

Answer 29

Antacids, anticholinergics (reduce muscle spasms) and Antihypertensives (reduce blood pressure)

Question 30

loperamide

Answer 30

targets opioid receptors (suppress motility through action on myenteric plexus - decreased peristalsis, increased tone of anal sphincter (Ca2+ channel blocker

Question 31

Tegaserod

Answer 31

target serotonin receptors in ENS, motility stimulants

Question 32

Antibiotics

Answer 32

can have negative effects on gut microbiome and can result in antibiotic-resistant organisms, which can lead to antibiotic-associated bacteria

Question 33

inhibits gastric secretions

Answer 33

-fat in duodenum, secretin, decreased para. input and somatostatin