W1 L1 - Intro To Gut Physiology And Function Flashcards
(56 cards)
1
Q
What’s pharmacokinetics (PK)
A
what the body does to the drug
2
Q
what’s pharmacodynamics (PD)
A
what the drug does to the body
3
Q
what does ADME stand for
A
Absorption
Distribution
Metabolised
Excretion
4
Q
System involved in Absorption
A
GI tract
5
Q
System involved in Distribution
A
Circulatory
6
Q
Organ involved in Metabolism
A
Liver
7
Q
Organ involved in Excretion
A
Kidneys
8
Q
which route of administration is the most convenient and cost-effective
A
oral
9
Q
Functions of the GI system (3)
A
- Digestion of food (Mechanical + chemical breakdown of food into small molecules to be absorbed into the circulatory system for distribution throughout body)
- Absorption of nutrients and drugs
- Elimination
10
Q
4 Regions of the GI tract
A
- mouth
- oesophagus
- stomach
- small intestine
11
Q
4 Accessory organs (help with the process of digestion but are not part of the digestive tract itself)
A
- salivary glands
- liver
- gall bladder
- pancreas (Produces digestive enzymes and bicarbonate to neutralize stomach acid, and releases them into the small intestine)
12
Q
3 Regions of the digestive system
A
- mouth
- oesophagus
- stomach
13
Q
function of mouth
A
saliva breaks up food particles
14
Q
function of oesophagus (1)
A
- transport of food to stomach
- entry to stomach via sphincter
15
Q
function of stomach (3)
A
- secretion of gastric juices for chemical digestion
- mechanical break up the food
- mixing of food + gastric juices
16
Q
2 types of transmucosal tablets (type of medication designed to be absorbed through the mucous membranes rather than swallowed and digested in the stomach)
A
- sublingual
- buccal
17
Q
By which 2 mechanisms are drug molecules released from mucosal membrane to blood vessel and describe them
A
- transcellular - through cell
- paracellular - between cells
18
Q
What’s peristalsis
A
INVOLUNTARY contraction and relaxation of (longitudinal and circular) muscles throughout the digestive tract
19
Q
how does the stomach allow for food and drug absorption and what’s digested there(2)
A
- gastric juices - HCl (controlled by vagus nerve + hormone gastrin) and digestive enzymes
- initiates the digestion of proteins (pepsin)
20
Q
Example of chemical digestion
A
HCl + pepsin
21
Q
Example of mechanical digestion
A
• Chewing in the mouth
• Churning in the stomach
• Segmentation in the intestine
22
Q
Types of cells in gastric gland (5)
A
- surface mucous cell
- mucous neck cell
- parietal cell
- chief cell
- enteroendocrine cell
23
Q
what do surface mucous cells and mucous neck cells secrete
A
- bicarbonate
- gastric mucus
24
Q
functions of gastric mucus (2)
A
- lubricates stomach lining
- protects stomach wall from pH
25
what do parietal cells produce
- HCl
- castle intrinsic factor
26
function of HCl in stomach (2)
- lowers pH to around 2
- pepsinogen splits into pepsin which then hydrolyses protein peptides into smaller peptides
27
function of intrinsic factor
- helps absorb B-12
28
What do chief cells release (2)
- pepsinogen (inactive precursor that’s activated to pepsin by stomach acid)
- gastric lipase
29
function of gastric lipase
Gastric lipase breaks down short + medium chain fats
30
What lubricates the stomach and what is made there?
- mucus coating - lubricates and protects epithelial surface against pepsin
- formation of chyme
31
what's chyme
thick semi fluid mass of partially digested food formed in stomach/ small intestine
32
what's gastric emptying
movement of food to small intestine
33
what delays gastric emptying and affects rate of absorption
presence of food in stomach
34
other factors that affect gastric emptying (7)
- volume of meal
- Kcal contents
- Fat content
- Protein content
- Liquid/solid state
- Sex
- Particular disease states
35
Parts of small intestine (3)
- Duodenum
- Jejunum
- Ileum
36
role of small intestine (5)
- completes digestion of nutrients in chyme
- major site of absorption of different nutrients
- major site of absorption of orally administered drugs
- site of first-pass metabolism of drugs (the process where a drug is metabolized (broken down) in the liver (and sometimes the gut wall) before it reaches the rest of the body through the bloodstream)
- movement of food residues to the large intestine
37
small intestine is a major site of absorption due to...
- large SA and high perfusion (the passage of fluid through the circulatory system or lymphatic system to an organ or a tissue)
- exposure to enzymes and solubilisers
- receives bile from liver and digestive enzymes from pancreas (amylase, lipase…)
38
what makes SA of small intestine large
- highly convoluted, circular folds
- villi
- micro villi
39
Why is large surface area so important for drug absorption after oral administration?
large SA for
- passive diffusion
- paracellular and transport facilitated
40
what are enterocytes
- simple epithelial cells which line the inner surface of the small and large intestines
- contain metabolic enzymes
- site of intestinal first pass
41
where does blood perfusing the intestine go
liver via hepatic portal vein
42
where does drug go after passing through liver
- drug goes into systemic circulation
43
what's coeliac disease (3)
- chronic autoimmune disorder of small intestine
- inflammation process triggered by consumption of gluten-containing food
- causes atrophy of villi in the small intestinal epithelium
44
Role of liver secretions
- xenobiotics metabolised
- secrets bile, enters duodenum via hepatic duct
- stored in gall bladder between meals
- important for digestion of lipids
45
role of pancreas secretions
- proteolytic enzymes (trypsin and chymotrypsin for protein digestion)
- lipase for lipid digestion
- HCO3- neutralises stomach acid
46
what does bile do
- Its main role is to break down (emulsify) fats in the small intestine, making them easier to digest
47
amylase role
starch to disaccharide (maltose, lactose)
48
role of enzymes in digestion of starch in small intestine epithelial cells
disaccharide to monosaccharide (glucose, galactose)
49
role of pepsin
peptide to peptide fragments
50
role of trypsin and chymotripsin
peptide fragment to a a (actively transported to epithelial cells)
51
what are lipids digested to
fatty acids
52
how are lipids digested
- Emulsification (bile salts) – formation of small lipid droplets
- Pancreatic lipase breaks down triglyceride to monoglycerides and fatty acids
- micelle formation for transportation of lipids
- lipid digestion completed in small intestine
53
role of large of intestine
- water + salts absorbed from chyme
- little absorption of drug minerals
- mixing and propulsion of contents
- indigestible residue and liquid eliminated as faecal waste
54
role of bacteria in distal intestine
- ferment carbs and proteins escaping into absorbable energy
- ability to metabolise drugs and xenobiotics
55
what's the gut-brain axis
- the network of nerves that connect your brain and gut and send signals back and forth
- brain influences GI physiology, motility, mucin production
- GI influences brain, behaviour and mood
56
What are xenobiotics
- Xenobiotics are foreign substances to the body — meaning they are not naturally produced or expected to be present in it.
Examples include
• Drugs/medications
• Pollutants (like pesticides or industrial chemicals)
• Food additives
• Toxins from bacteria or the environment
