Nutritional Disorders (& the eye) Flashcards
What is our food mainly composed of?
- Carbohydrates
- Proteins
- Fats
- Vitamins
- Minerals/trace elements
What are the major nutrients sources?
- Carbohydrates - these are long chain sugar molecules = polysaccharides. And we break these down into monosaccharides in the form of Glucose. Glucose is needed to provide energy/ATP, where they feed into the Kerbs cycle in order to do this. (Primarily used as a source of energy)
- Proteins - these are chains of amino acids. They are used for lots of things structurally such as collagen for structural support, use as enzymes e.g. in haemoglobin is a protein for carrying oxygen. And most hormones are proteins. (Not used to make energy in the same way as carbs)
- Fats - It insulates us, its an energy source, makes up membrane and helps us to absorb vitamins
Explain the role of vitamins in our bodies:
Vitamins are not a source of energy , we don’t used them for structural things, so its not like carbs, proteins or fats but we do still need them and without them the carbs, proteins and fats would be useless!
We can use then in metabolism, for that we need vitamins because they act as co-enzymes which means they help in metabolism of things like proteins, carbs and fat.
Some vitamins are insoluble on fats, others are soluble in water.
Apart from vitamins what else do we need?
Minerals/trace elements such as sodium, potassium and calcium. These are not used for energy but to serve other functions such as calcium = bones, iron = haemoglobin, calcium/sodium/potassium = nerve/muscle
What is meant by the term ‘Essential Nutrients’?
These are the things the body cant make and has to be received by an intake of food etc.
What are the 2 types of nutritional deficiencies?
- Primary: (Mostly) - Insufficient intake, so don’t eat enough stuff
- Secondary: These are deficiencies that are secondary to other things. So your taking in the right about of substances but for various reasons they’re not arriving where they should.
• For example, you might be eating enough vitamins but they are not being absorbed due to something like Crohn’s disease. Therefore, the nutrient deficiency is secondary to Crohn’s disease .
• Sometimes, we just need more stuff during pregnancy when were growing, when were breast feeding. We might need specific nutrients and although we’re taking enough for normal demand, we’re not taking for that particular situation
• Sometimes, you get antagonists, which can neutralise the substance so you’re taking enough in but there is something in the body that is preventing it from being effective
- Secondary: These are deficiencies that are secondary to other things. So your taking in the right about of substances but for various reasons they’re not arriving where they should.
What are the 2 types of caloric deficiency also collectively know as Protein-energy malnutrition (PEM)?
- Marasmus: This is when your not taking enough nutrients into the body but your compensating that by catabolising the bodies tissue such as the fats and proteins. So its characterised by this extreme body wasting but also by catabolising these tissues your actually able to maintain normal cellular metabolism.
So when children who have this condition can actually be fairly awake and alert and of they are fed they can recover quite quickly thus the prognosis is quite good.- Kwasiorkor: This is a more extreme version. Here the deficiency is so great that the body is unable to metabolise the tissue. So metabolism starts failing. That’s more serious because it is much harder to reverse! So giving these people food might not be good is their metabolism has failed. It is characterised by this swollen belly. In the blood plasma there is serum albumin, which keeps the liquid in the blood vessels and it creates osmotic pressure. In Kwasiokor that fails so can’t maintain albumin levels so you retain water within the body and it gives this swollen belly
Define Marasmus and Kwasiokor?
Marasmus = is when the body ‘eats’ itself to keel itself going, its destroying its proteins and muscle and using it to maintain normal metabolism.
Kwasiorkor = when the body cannot compensate by catabolising tissues, normal metabolism then fails. It is then difficult to feed patients
Outline the ocular effect of Vitamin A:
Vitamin A is visually important. There are may types of vitamin A one of the main ones being Retinol.
We can obtain vitamin A from diet or form pro-vitamin e.g. is a form of Carotene, which the body can convert into vitamin A. However, we mainly get it from diary products, carotene we get from leafy green vegetables.
Retinol is a visual pigment which is made up of protein opsin bound to the chromophore which is 11-cis retinal. And so retinal is derived from retinol. If you have a deficiency in retinol, you have a deficiency in visual pigments.
So the first visual sign for lack of retinol is you get Nyctalopia = night blindness.
What happens in the rods, you just don’t have enough rod visual pigment and your unable to see in low light levels (scotopic). If the deficiency of retinol is extreme then the cone visual pigments start to get affected as well and you get deficits in photopic vision too. But one of the main visual signs of lack of vitamin A is lack of visual pigments which is expressed in poor night vision called Nyctalopia.
A lack of vitamin A also affects ….
the epithelial. Specifically the epithelial becomes Keratinised. Within the ocular structures the main epithelium are in the cornea and conjunctiva. Both of the epeithelium in Vitamin A deficiency can become excessively keratinised which is known as = Xeropthalmia. This is one of the major causes of blindness in the world.
A) Conjunctiva - this becomes wrinkly and dry with white spots know as = Bitot’s Spots.
B) Cornea - Ulceration and scaring of the cornea known as Keratomalacia which can also lead to blindness. Again the cornea is quite dry and wrinkly.
How can Vitamin D be obtained?
- Absorbed by intestine from the diet along with fats
UV light from the sun transform steroid in the skin
What can cause Vitamin D deficiency?
- Insufficient dietary intake
2. Lack of sunlight
What is the function of Vitamin D and what can arise as a consequence with a lack of vitamin D?
The main function of vitamin D is aiding absorption of calcium thus a deficiency would cause no enough calcium would get absorbed onto the blood stream and consequently there will be an inadequate calcium getting to bones. In children, these bones are still developing and so a lack of vitamin D can lead Rickets. This is a stunted growth and you get this characteristic of bow-legged appearance, because the bones are bendy and the muscles are pulling on the bones and bowing them out. You can also het a characteristic pigeon-chest where the intercostal muscles are pulling on the robs and caving them in because the bones are not strong enough.
A vitamin D deficiency in adults can cause Osteomalacia, which is a physical deformity where the bones are just not right and painful.
How is vitamin K obtained?
In terms of vision its not that important, however, It is required for the synthesis of blood coagulation factors e.g. prothrombin - for blood clotting.
The main source is synthesis by intestinal bacteria and can also be derived form leafy green vegetables and dairy products.
What can vitamin K deficiency cause?
Deficiency of vitamin K is rare but can still occur for example after a prolonged antibiotic treatment or various drugs that then kills the intestinal bacteria. A lack of vitamin K can also result in excessive bleeding - an e.g. is Rat poison which is a vitamin K antagonist
