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Current time:0:00Total duration:11:06

Pathophysiology - Type I diabetes

Video transcript

now diabetes mellitus is a group of disorders that's caused by improper function of insulin which is a hormone responsible for regulating blood sugar or blood glucose and this results in hyperglycemia but since diabetes is a group of disorders there's many different underlying pathophysiological mechanisms that can cause the disease and depending on which mechanism is occurring in someone the presentation of the disease can actually be very different so before we get started I want to briefly talk about the pancreas now you can see here we have the esophagus coming down and it dives behind the liver here and then it goes into the stomach and then the stomach goes back behind the liver and comes out as the small intestine and in yellow here nestled in next to the small intestine and behind the stomach is the pancreas now the pancreas is frequently referred to as being comma shaped and you can kind of get that all if you kind of turned it on its side it might look like a comma but the way I like to remember how the pancreas looks is by thinking about my favorite professional football team which is the Minnesota Vikings and I kind of think the pancreas may be it looks like the horns on the side of the Minnesota Vikings helmet so whatever helps you remember what the pancreas looks like but regardless the pancreas has two main functions and the first function is exocrine what this means is that the pancreas secretes enzymes into the digestive tract which then chemically digest food and help your body absorb the nutrients we eat so it helps with digestion but the pancreas also has some endocrine function and what this means is that it produces hormones and specifically for the pancreas these hormones help the body with metabolism but what does all this have to do with diabetes well I mentioned earlier the diabetes mellitus is caused by dysfunction of insulin which is one of these hormones that the pancreas produces and in type 1 diabetes certain areas of the endocrine portion of the pancreas are destroyed so that the pancreas cannot produce insulin and type 1 diabetes is actually a relatively uncommon disease it affects about 3 out of every 1000 people in the United States now let's dive a little bit closer into the pancreas to get a better understanding of what's going on so the cells that are responsible for the endocrine function of the pancreas are located in regions of the pancreas that are known as the islets of langerhans so let's just draw those in here so in these islets of langerhans there are two main cell types that are responsible for producing hormones so in blue here we have the alpha cells and the alpha cells are responsible for secreting glucagon then in green we have the beta cells and they're responsible for secreting insulin and as I mentioned before these two hormones are responsible for regulating much of the body's metabolism and one specific component of this is our blood glucose or a blood sugar level so what happens is if someone to say pretend you just had a meal and your body starts absorbing the sugar from that meal what's going to happen is your blood sugar levels or your blood glucose levels are going to increase and this increase in blood sugar is sensed by the beta cells in the pancreas and they'll secrete insulin into the blood and what it does is that insulin is then going to lower the blood glucose level by causing the cells all over the body to take up and absorb the glucose so that they can then use it for energy or it could be stored in the liver and either way the glucose comes out of the blood so the blood sugar level lowers now if insulin were to act on its own the blood sugar level or blood glucose level would get too low it would start to decrease from its normal level and luckily the pancreas senses this too in the Alpha cells or the blue cells here and secretes glucagon and what happens then is glucagon causes the blood glucose level to raise going back to normal and it does this by causing the liver to release the glucose that's stored there so what does this all have to do with diabetes or specifically type one diabetes well in type one diabetes there is destruction of these beta cells in the pancreas so the body can't produce the insulin and if the body can't produce insulin it's not able to lower its blood glucose level and you have an unbalanced glucagon response which results in this raising of the blood sugar and this is known as hyperglycemia hyper for high glycaemia for blood sugar but what is the underlying cause of this destruction of the beta cells I'm going to just slide this over so you can get a little more room to work on it well type one diabetes is an autoimmune disease and as you can imagine by the name it has something to do with the immune system and what happens is that someone who develops type 1 diabetes was born with a genetic predisposition to the disease now this doesn't necessarily mean that he or she had the disease at birth but they just we had something in their genes caused them to be more likely to develop type 1 diabetes then over time there was some sort of environmental trigger and this part of the disease process isn't quite as well understood it could be something potentially like a virus or some sort of toxin or something else but regardless there's some sort of trigger that causes someone with a genetic predisposition to have this autoimmune response or production of antibodies and T cells that then attack the beta cells and this is what causes the destruction of the beta cells and the absence of the production of insulin which is the underlying cause of type 1 diabetes and it's this autoimmune attack of the beta cells here that causes the pancreas to not be able to produce any insulin and when it can't produce any insulin what happens is that the individual individual will develop type 1 diabetes let me just move over again so we can get a little more space to go through why symptoms develop in type 1 diabetes alright so imagine a blood vessel here and this blood vessel is transporting glucose and in a normal individual without diabetes this glucose is going to go to lots of different organs in the body such as the brain and the muscles and maybe give them a little Popeye tattoo for good measure as well as the liver where that glucose can be stored but unfortunately in type 1 diabetes the insulin isn't present to take the glucose out of the blood and help it get to these organs it gets blocked almost like the body is starving despite having all of this glucose and so what happens is that the liver acts like it is starving and it releases its stored glucose back into the blood and then just like the glucose can't get out of the blood to some of these organs it also can't get out and be stored in the fat or the adipose tissue which I'll draw here and so the fat does is to also kind of try and help the body create more energy is it breaks down into something known as free fatty acids which I'll just abbreviate f f/a which the body can then also use for energy it's this process here that results in the symptoms of type 1 diabetes and the first one is what I'll call starvation in the face of plenty and by this I mean the body almost acts like it's starving even though it has all of this glucose pleasant present in the blood and this results in symptoms like lethargy and Geeg because it's trying to maintain the little glucose it thinks it has for the brain and the other organs that are vital and really needed so someone with diabetes will be lethargic and fatigued and then the next thing that happens is occurs in the kidneys now normally the kidneys reabsorb all of the glucose that's in the blood and put it back in the blood when it's when they're filtering the blood but when this glucose level gets so high from diabetes it overwhelms the kidneys and that glucose spills out in the urine and this is known as glucose area or glucose in the urine and glucose is an osmotic lea active solute but what does that means well what it means is that it tends to draw water with it so as the body pees out all of this glucose a lot of water comes with it and this is known as polyuria or poly for kind of lots or many and urea for urine and this results in dehydration because you're losing all the water and thirst so someone with type 1 diabetes is frequently going to present with being tired and fatigued going to the bathroom a lot and dehydrated and unfortunately for some individuals if they get sick when they have type 1 diabetes before it's been diagnosed the body can't compensate for this stress and you can get a life-threatening disease that's called diabetic ketoacidosis or DKA which is a life-threatening form of dehydration and acidosis when it comes to diagnosis about 70% of individuals with type 1 diabetes will be diagnosed in this stage before it gets too bad but unfortunately about 30% of individuals who are diagnosed with type 1 diabetes actually have diabetic ketoacidosis or DKA as they're presenting symptom so this is just a brief overview of type 1 diabetes which is an autoimmune disease meaning that there's antibodies and t-cells that destroy the beta cells of the pancreas so that the pancreas can't produce insulin resulting in hyperglycemia or high blood sugar and it's this high blood sugar that results in all of symptoms of type 1 diabetes