L10*-Digestion & Absorption of nutrients-FATS-part II Flashcards
(20 cards)
What is Sphingolipid ?
a Membrane lipid, has a serine backbone rather than glycerol, found in ceramide & skin.
Give some facts about fatty acids and their functions.
-cannot me made endogenously, linoleic and linolenic - cannot be made in the body, in the absence of linoleic also arachidonic acid
Functions - Cell membranes, Erythropoiesis, Eicosanoids, Blood pressure / viscosity
Name 3 types of Lipases
- Lingual lipase
-from the tongue😝
-starts the process
-optimum at low pH - Gastric lipase
-chief cells - Pancreatic lipase
-Acinar cells
Describe the digestion process of lipids
-Digestion begins in the mouth
-Continues in the stomach
-lingual & gastric lipase
- Triglycerides are broken down into Diglyceride.
- Then the long chains remain with triglyceride droplets which are insoluble at acidic pH.
- Shorter chains remain in the pH solution then cross gastric mucosa and then into portal blood.
Describe the digestion process for fatty acids.
-Fatty acids in duodenum stimulate enteroendocrine cells to release CCK and secretin into the duodenum.
-SAME with proteins.
What does CCK do after its release ?
- Stimulates contraction of gallbladder (Gallbladder contains bile).
- Stimulate contraction and dilation of ‘sphincter of Oddi’ > bile released into duodenum.
- Stimulate pancreas to release pancreatic juices > pancreatic lipase.
How does Bile help in digestion ?
-Neutralises gastric pH
- Needed to create an emulsifies lipids into droplets, which creates a Large surface area for lipase.
How does Colipase help in digestion ?
-released from the pancreas
* Facilitates attachment of lipase to the droplet
* Needed for efficient enzyme activity
* Prevents inhibitory effect of bile > sometimes bile surrounds the lipids to digest them, preventing the lipase to reach the lipids.
➢ 2-monoacylglycerol(monoglycerides) + FA
What is the importance of droplets ?
-surface triglycerides are hydrolysed.
-replaced by core lipids
-get smaller (lipase)
- vesicles bud off.
What is the use of vesicles in digestion of lipids ?
-Lamella (membrane / layer)
-Multi-lamellar > Uni-lamellar vesicle
-Get smaller (lipase)
-Vesicles > micelles
Absorption of lipids are divided into 3 steps. Name the first step and explain it.
Absorption I : Getting into the erythrocyte
i). short chain fatty acids are water soluble so they can simply diffuse through the unstirred water layer(a thin layer of water between the intestinal lumen and surface of enterocytes-intestinal cells) into the enterocyte and into the blood.
-Bile is reabsorbed in the terminal ileum and headed back to Enterohepatic recirculation
ii). Long chain fatty acids are put into a mixed micelle. Micelles diffuse through a Na+/H+ antiporter in the low pH brush border. Protonation of the lipid occurs.
-diffusion
-membrane incorporation
-carrier mediated transport
Absorption of lipids are divided into 3 steps. Name the second step and explain it.
Absorption II : In the enterocyte
- Converted back to triglycerides in the SER.
- Fat droplets form in Smooth ER (SER).
- Apoproteins made in Rough ER and
transferred to SER and associate with lipids. - ‘New’ chylomicrons(lipoprotein particles) & VLDL (Very low density lipoproteins) transferred to Golgi (cis side).
- Vesicles of chylomicrons & VLDL bud off
Golgi (trans side) > move to membrane. - Transport vesicles fuses with membrane
releasing chylomicrons & VLDL. - Enter the lymphatic system > blood (thoracic duct)
Absorption of lipids are divided into 3 steps. Name the last and final step and explain it.
Absorption III : In the blood
i). In the blood
-Lipoprotein lipase (endothelial surface)
-Chylomicrons > FA + glycerol
-Remnant chylomicrons /glycerol > Liver
ii). Fatty Acids
* Adipocytes store FA as triglycerides & muscles uses FA for energy during prolonged low-intensity activity.
* Fat storage
Name few reasons as to y lipids are so important and their special properties.
-main source of energy in the fasted state
-most concentrated source of energy
-estimated 43-70dyas supply of energy
-nonpolar : can be stored in an anhydrous state
- can adapt to be stored anywhere.
Where do we find lipids?
-stored all over the body
-most in sub-cutaneous tissue / adipose
-In obese people lipids are found as Visceral deposits around the organ.
Vitamin A,D,E,K are fat soluble. Give details about Vitamin A. and what may happen in its deficiency ?
Retinol (animal sources)
Beta carotene (plants)
Deficiency > Night blindness > Needed for Rhodopsin
Vitamin A,D,E,K are fat soluble. Give details about Vitamin D. and what may happen in its deficiency ?
-from sunlight -vitamin D3
-Humans > Adequate exposure no need from diet
-Cats / Dogs > Food only
Deficiency:
* Poor diet / lack of sun
* Bone softening
* Demineralisation
* Rickets (children) / Osteomalacia (adults)
Vitamin A,D,E,K are fat soluble. Give details about Vitamin E. and what may happen in its deficiency ?
-α-tocopherol
-Oily foods are the major source
- Antioxidant (protection against cardiovascular diseases/cancer)
Deficiency:-
* Rare
* Effects are related to not ‘mopping up’ oxidants
* Immune system > Creates ROI and RNI
* These must be inactivated
Vitamin A,D,E,K are fat soluble. Give details about Vitamin K. and what may happen in its deficiency ?
Vitamin K (Koagulation)
* α-tocopherol
* Green leafy veg are the major source
* Produced by intestinal microbiota
-Vitamin K is involved in the carboxylation of specific glutamate residues in proteins to form γ-carboxyglutamate residues. These proteins are important for regulating :
* Blood coagulation: risk of uncontrolled internal bleeding
* Bone metabolism: malformation of developing bone
* Vascular biology: prevent deposition of Ca salts in arterial vessel walls.
Fat malabsorption is when the body cant absorb the nutrients from food. Example of a case, symptoms, how to find out.
-Many of the vitamin deficiencies are due to poor nutrition or intestinal malabsorption.
-Fat malabsorption could be due to liver/gallbladder disease, pancreatic disease and/or intestinal disease.
Symptoms: steatorrhea (fat in faeces), essential fatty acid deficiency and/or vitamin deficiency
Faecal fat test is the required diagnostic test to
evaluate the amount of fat digested and absorbed.
