Week 1 Flashcards
what does serotonin do?
it activates sensory afferent neurons of the myenteric plexus but 2) it also inhibits its own production from the epithelium. Otherwise we will have continuous peristaltic movements even without food.
Excitatory motor neurons
release Acetylcholine (Ach) & Substance P (P)
Inhibitory motor neurons
release Nitric Oxide (NO) & Vasoactive Intestinal peptide (VIP).
what happens in the propulsive segment
interneurons activate the excitatory neurons for the circular muscles (contraction) but inhibit the excitatory neurons for the longitudinal muscles. Interneurons also activate the inhibitory neurons for the longitudinal muscles (relaxation
what happens in the recieving segment
interneurons inhibits the excitatory neurons for the circular muscle and activate the inhibitory neurons (relaxation). Interneurons activate the excitatory neurons for the longitudinal muscles and inhibits the inhibitory neurons (contraction).
what are the differences in the stomach
mucosa does not have an epithelium organized in villi, but is made of gastric pits or gastric glands where specialized cells can be found.
what are the main organs
Mouth
Esophagus
Stomach
Small intestine: Duodenum (stomach exit); Jejunum; Ileum
Large intestine: Cecum; Ascending Colon; Transverse Colon; Descending Colon; Rectum; Anus
what is the anatomy of the esophaegus
The esophageal Muscularis propria has 2 types of muscles: striated and smooth (unlike the rest of the GI tract).
where is lactase located and what does it do
small intestine
used to digest lactose
what are the types of transporters involved in carbohydrate absorption
GLuT - 1 to 12
what does food intolerances cause
gas, bloating, cramping and diarrhoea
Immune Mediated examples
oral allergy and acute uriticaria
coeliac disease
contact dermatitis
Non-Medicated
lactose intolerance
caffieine
sulphites
explain how lactose intolerance works
Lactose transits undigested into the large intestine
Gut bacteria metabolise lactose and the resulting fermentation produces gas (carbon dioxide, hydrogen and methane) which may result in flatulence, bloating and distension pain.
The unabsorbed lactose and the fermentation products (e.g., short fatty acids) raise the osmotic pressure in the colon.
This increases the flow of water into the lumen of the colon, causing “osmotic diarrhoea” associated with lactose intolerance.
Congenital alactasia
automosal recessive mutation in the LCT gene causing the complete lack of lactase from birth. Infants with this mutation cannot be breastfed or given milk, and have to be fed with soybean-derived formulas.
difference between primary and secondary
primary is genetically inherited caused by lack of persistent allele and secondary is caused by the damage to the lining of the intestine where lactase is produced.
hypolactasia
occurs in adulthood
types of test
Hydrogen breath test
Lactose tolerance
Type I hypersensitivity
immunoglobulin E (IgE) antibody against soluble antigen, triggering mast cell degranulation.
Type II hypersensitivity
IgG and IgM antibodies directed against cellular antigens, leading to cell damage mediated by other immune system effectors.
Type III hypersensitivity
interactions of IgG, IgM, and, occasionally, IgA antibodies with antigen to form immune complexes. Accumulation of immune complexes in tissue leads to tissue damage mediated by other immune system effectors.
Type IV hypersensitivity
T-cell–mediated reactions that can involve tissue damage mediated by activated macrophages and cytotoxic T cells.
Imunoglobin is an antibody what happens there
The Fragment crystallizable (Fc) region of the antibody is formed by the two heavy chains coming together, usually linked by disulfide bonds. The Fc portion is important as many immune cells have Fc receptors. These receptors can then bind to antibody-coated pathogens.
At the other end of the Ig are two identical antigen-binding sites.
difference between IgE and IgG
IgE is typically the least abundant isotype whilst IgG is the most abundant isotype.
IgE is associated with type I allergic reactions and binds to Fc receptors on mast cells and basophils.
what does histamine do
Histamine stimulates mucus secretion in nasal passages and tear formation from lacrimal glands, promoting the runny nose and watery eyes of allergies.
food allergy and intolerance difference
allergy is in the GI tract and the immune system and the symptoms will appear on the skin
intolerances are more internal so like stools gas wheezing
when activated what are ig e cells made up of
b cells
ige cells are created in what
type 1 allergic reaction
primary exposure for example peanuts
the food is incorrectly ingested the allergen is taken in proccesed by antigen presenting cells presents the antigen to TH2 lymphocytes TH2 releases cytokines IL4 and IL3 which activates the B cells B cells undergo clonial expression IgE specific is produced Fragment crystalizable regions of IGE bind s to the receptors presented on mast cells
secondary exposure how does it work
allergen binds to the igE molecules binds to many mast cells which cross linking the IgE molecules
Mast cells activates and triggers degranulation where histamine seratonin which are tumour necrosis factors are released, can cause anaphylaxis
cross activity
those allergic to radweed may be sensitive and could possibly react to honeydew peach and apples
what does fodmap stand for and what are they
Fermentable, Oligo-, Di-, Mono-saccharides and Polyols (FODMAPs) are short chain carbohydrates that are poorly absorbed in the small intestine.
Oligo-saccharides: e.g. fructans (found in wheat, rye and some vegetables) and galacto-oligosaccharides (found in pulses and legumes)
Di-saccharides: e.g. lactose (found in mammalian milk)
Mono-saccharides: e.g. free fructose (found in honey, some fruit and fruit juices)
Polyols: e.g. sorbitol and mannitol (found in some fruits and vegetables)
stages of fodmap
3
stage 1 of fodmap
an individual reduces their FODMAP intake by avoiding foods that are high in FODMAPs for 4 to 8 weeks as this period is considered long enough to identify if symptoms will respond to a low FODMAP diet.
stage 2 of fodmap
If the individual’s symptoms have improved following FODMAP restriction, it is important to reintroduce some high FODMAP foods. This will enable them to identify which FODMAPs they are most sensitive to, as well as how much of a high FODMAP food triggers their symptoms.
stage 3 of fodmap
Stage 3 Personalisation : The long term aim of a low FODMAP diet is to personalise their diet so they only avoid foods that trigger their symptoms and enable them return to as normal a diet as possible.
irritable bowl syndrome what can help it
low fodmap
food intolerance tests
IgG tested
bile salts are what
both hydrophilic and hydrophobic
where is bile made
in the gall bladder and is released into the duodenum
what is emulsification
fat globules broken down into little droplets to make digestion easier
what is micelles
small droplets of fat surrounding the bile
what doesn’t need to be enzymatically digested
cholesterol and fat-soluble vitamins
types of lipase
lingual lipase
gastrial lipase made in the stomach
lingual lipase made as food is chewed and swallowed.
what happens in the digestion phase
pancreatic lipase is a water soluble molecule
synthesised by pancreatic acinar cells
intestinal lumen breaks down the bonds between the 1- 3 triglycerides
leaving 2 monoglyceride and two free fatty acids
the emulsification of lipids by the bile anions create a large surface
for lipids to act on
fatty acids 2 monoglycerides with phospoholipids and cholestrol make micelles
bile salts emulsify to make more micelles
SCFA’s what are they and what do they produce
used by the liver and colonial cells
and acetate, propionate, and butyrate are produced
what is butyrate
it is the main source of energy for human colonocytes
intestinal production of glucose
what is butyrate essential for
its essential for epithelial cells to get oxidation through b oxidation which is when fatty acids can get to atp
which allows more atp production
prevents gut microbiota dysbiosis.
what does propionate do
regulates gluconeogenesis and satiety signalling through interaction with the gut fatty acid receptors.
what does acetate do
reaches the peripheral tissues where it is used in cholesterol metabolism and lipogenesis, and may play a role in central appetite regulation.
how is glucose absorbed
Glucose is co-transported with Na+ ions
into the cells on a co-transporter SGLUT1.
Once in the cell, glucose exits to the interstitial fluid down its concentration gradient via GLUT2 one of the family of glucose transporters.
GLUT2 transports glucose out of the cell into the portal circulation, going to the liver.
The Na+ that entered with the glucose is actively pumped out of the cell into the interstitial fluid by Na+/K+ATPase, thus maintaining the Na+ gradient (which is necessary for Na+ to enter the enterocyte in the first place).
how is fructose and galactose absorbed
Galactose is transported into the enterocytes via SGLT1
Fructose is transported into the enterocytes by facilitated diffusion via GLUT5, another member of the glucose transporters.
Both Galactose and Fructose exit the enterocytes via GLUT2.
what do gut microbials do
Gut microbial enzymes leads to contribute to bile acid metabolism, generating unconjugated and secondary bile acids that act as signalling molecules and metabolic regulators to influence important host pathways.
what is a chylomicron
large lipoprotein that enters the lymphatic system before being released into the bloodstream which transport them to various destinations including the liver
what is an VLDL
Very low-density lipoproteins are made in the liver from remnants of chylomicrons and transport triglycerides from the liver to various tissues in the body.
how is cholesterol absorbed
poorly absorbed when compared to phospholipids and triglycerides. Cholesterol absorption is aided by an increase in dietary fat components and is hindered by high fiber content. This is the reason that a high intake of fiber is recommended to decrease blood cholesterol. Foods high in fiber such as fresh fruits, vegetables, and oats can bind bile salts and cholesterol, preventing their absorption and carrying them out of the colon
how is protein absorbed
Gastric and pancreatic enzymes hydrolyze protein to short-chain peptides (up to 6 residues long), which are further hydrolyzed at the brush border to free amino acids or to di-or tri-peptides.
The different amino acids resulting from protein digestion are absorbed by different types of carriers coupled to the active transport of Na+.
Dipeptides or tripeptides are also actively absorbed and then digested to their amino acids within the epithelial cells.
Amino acids leave the cell across the basolateral membrane either by simple diffusion or by carrier-mediated processes.
functions of the urinary tract
excrete wastes
regulating water absorbpion
regualting sodium consumption
vitamin synthesis
what does the kidney do
they get rid of waste products
they keep the electrolytes
they secrete hormones
examples of hormones in the kidney
renin which keep blood pressure
what is the anatomy of kidneys
The structure of the kidney is divided into two principle regions: the peripheral rim of cortex and the central
medulla
The two kidneys receive about 20 percent of cardiac output.
The renal arteries arise directly from the aorta, and the renal veins drain directly into the inferior vena cava.
Kidney function is derived from the actions of about 1 million nephrons per kidney; these are the “functional units.”
A capillary bed called the glomerulus, filters blood and the filtrate is captured by Bowman’s capsule.
A portal system is formed when the blood flows through a second capillary bed surrounding the proximal and
distal convoluted tubules and the loop of Henle. Most water and solutes are recovered by this second capillary bed.
This filtrate is processed and finally gathered by collecting ducts that drain into the minor calyces, which merge to
form major calyces; the filtrate then proceeds to the renal pelvis and finally the ureters.
what are LDLs , how are they produced and what do they do
aka bad cholesterol
low density lipoproteins
carry cholesterol and other lipids from the liver to tissue throughout the body.
what are LDLs , how are they produced and what do they do
aka bad cholesterol
low density lipoproteins
carry cholesterol and other lipids from the liver to tissue throughout the body.
what is steaorrheoa
when lipids arent absorbed
