Form and Function: Cellular transport mechanisms
I am a Licensed Practical Nurse with five years' experience in this profession. I believe it is essential to go back to the basics in all things in order to really understand them. I am fascinated by how our bodies work and I hope I can get my readers to share my fascination. I hope we all learn new things and marvel again at the things we already know. This feature -- which includes a closing section on how disease affects the topic in question -- will run on The Cancer Blog on Wednesdays, and The Cardio Blog and The Diabetes Blog on Thursdays. [The contents in this post are for informational purposes only and should not be construed as medical advice or substitute for professional medical care.]We start with the cell, because so much of what happens to us when we get sick, and how we get healthy again, can be explained by what happens on a cellular level. The cell is extremely complex and I will only touch on the basics in these posts, but at least we can have a rudimentary understanding.
We have discussed cell membranes (May 24), as well as cell organelles (May 31). Before we look at the nucleus of the cell, I would like to do a short post on some of the mechanisms for molecular movement across the cell membrane. Transport across the cell membrane is important to understand, because a lot of the newer research seems to focus on this aspect.Living cells constantly interact with the external environment, like tissue or blood. In order to do that, materials must move through the plasma membrane, taking in some substances and secreting or excreting others. There are several methods by which movements can occur: diffusion, osmosis, facilitated diffusion, active transport, filtration, endocytosis and exocytosis. We will look at each of these briefly.
Diffusion: Movement of molecules from an area of greater concentration to an area of lesser concentration. An example would be the diffusion of oxygen from the lungs into capillaries.
Osmosis: The diffusion of water. The kidney tubules use osmosis to reabsorb water.
Facilitated diffusion: Diffusion assisted by a carrier protein. The carrier protein moves molecules across cell membranes. The intake of glucose by most cells happens by facilitated diffusion.
Active transport: Movement of molecules from an area of low concentration to an area of high concentration assisted by a carrier protein. Active transport requires ATP (Adenosine triphosphate- a specialized nucleotide that traps and releases biologically useful energy). An example of a process that uses active transport would be the absorption of amino acids and glucose from food by the cells of the small intestine.
Filtration: Movement of water and dissolved substances from an area of higher pressure to an area of lower pressure. This would be used in the first step in the formation of urine.
Endocytosis: The membrane engulfs something and draws it into the cell in membrane bound vesicles. An example of this would be white blood cells engulfing bacteria.
Exotysosis: Membrane bound vesicle fuses with the cell membrane, releasing it's contents outside the cell. An example of this would be the release of neurotransmitters by nerve cells or the cells of kidney tubules reabsorbing.
How does this affect you?
When insulin is released it proceeds by exocytosis to the plasma membrane. Studies are being done to determine if the transport mechanism plays a role in type 2 diabetes especially.Permalink | Email this | Linking Blogs | Comments
Form and Function: Cell organelles
I am a Licensed Practical Nurse with five years' experience in this profession. I believe it is essential to go back to the basics in all things in order to really understand them. I am fascinated by how our bodies work and I hope I can get my readers to share my fascination. I hope we all learn new things and marvel again at the things we already know. This feature -- which includes a closing section on how disease affects the topic in question -- will run on The Cancer Blog on Wednesdays, and The Cardio Blog and The Diabetes Blog on Thursdays. [The contents in this post are for informational purposes only and should not be construed as medical advice or substitute for professional medical care.]We start with the cell, because so much of what happens to us when we get sick, and how we get healthy again, can be explained by what happens on a cellular level. The cell is extremely complex and I will only touch on the basics in these posts, but at least we can have a rudimentary understanding.
Structure of cells
A cell has three basic parts:
1) Plasma membrane: A membrane lies at the border of cells and consists of lipids and proteins. See my post of 23 May on the cell membrane
2) Cytoplasm: All the cellular contents between the plasma membrane and the nucleus and can be further divided into the Cytosol and Organelles. We will discuss the organelles in today's post.
3) Nucleus: Technically an organelle, but usually considered separately because of its numerous and diverse functions.
Organelles
Organelles are specialized structures that evolved to perform specific functions. We could probably discuss each organelle in a separate post, because each one has it's own characteristic shape and function. i decided to keep this very basic and just list the different organelles, what they look like and what their basic function is. We will also just look at the "famous" organelles. There are other organelles, but the ones we discuss will give us a good understanding of what goes on inside the cell.
Endoplasmic reticulim (ER): A network of membranous tubules that extend from the nuclear membrane to the cell membrane. The ER can further be subdivided into a rough and smooth. The rough ER is continuous with the nuclear membrane and has an outer surface studded with ribosomes. The ER function is to be a passageway for the transport of materials within the cell. It also synthesizes lipids and proteins.
Ribosomes: These are either floating bodies for the internal needs of the cell or attached to the ER for transport out of the cell. Ribosomes are the sites for protein synthesis.
Golgi apparatus: Besides having a cool name (named after the scientist that discovered it), it refines and moderates proteins produced in the ER prior to transport and packages materials for secretion from the cell. It is a series of membranous sacs, described as looking like a stack of pita bread.
Mitochondria: These organelles are roughly bean-shaped with inner membranes. They are (literally) the powerhouses of the cell. They break down sugar molecules into energy. Tissues that need a lot of energy, like muscles, have more of these organelles in their cells .
Lysosomes: They are single membrane structures and have a membrane. The lysosome breaks down larger molecules into smaller molecules and it also digests old cell parts. It is the waste manager of the cell. It has powerful digestive enzymes to break down the waste.
Chromatin: Fibers composed of protein and DNA molecules. It contains the genetic information for protein synthesis. It is the heredity material in cells
Sentriole: A pair of rod shaped structures perpendicular to each other. It plays an important part in cell division. It organizes the spindle fibers during cell division.
These are some of the most common organelles. It is easy to understand that what goes on in the cell can have a huge impact on tissues and systems and therefore on the disease process.
How does it affect you?
There are studies about the various organelles and their impact on diabetes. One study links type 2 diabetes and dementia through the mitochondria, for example. It is clear that research into the form and function of organelles will yield a lot of answers in the years to come.
Permalink | Email this | Linking Blogs | Comments
Form and Function:Cellular transport mechanisms
Filed under: Women Heart Health, Men Heart Health
I am a Licensed Practical Nurse with five years' experience in this profession. I believe it is essential to go back to the basics in all things in order to really understand them. I am fascinated by how our bodies work and I hope I can get my readers to share my fascination. I hope we all learn new things and marvel again at the things we already know. This feature -- which includes a closing section on how disease affects the topic in question -- will run on The Cancer Blog on Wednesdays, and The Cardio Blog and The Diabetes Blog on Thursdays. [The contents in this post are for informational purposes only and should not be construed as medical advice or substitute for professional medical care.]We start with the cell, because so much of what happens to us when we get sick, and how we get healthy again, can be explained by what happens on a cellular level. The cell is extremely complex and I will only touch on the basics in these posts, but at least we can have a rudimentary understanding.
We have discussed cell membranes (May 24), as well as cell organelles (May 31). Before we look at the nucleus of the cell, I would like to do a short post on some of the mechanisms for molecular movement across the cell membrane. Transport across the cell membrane is important to understand, because a lot of the newer research seems to focus on this aspect.Living cells constantly interact with the external environment, like tissue or blood. In order to do that, materials must move through the plasma membrane, taking in some substances and secreting or excreting others. There are several methods by which movements can occur: diffusion, osmosis, facilitated diffusion, active transport, filtration, endocytosis and exocytosis. We will look at each of these briefly.
Diffusion: Movement of molecules from an area of greater concentration to an area of lesser concentration. An example would be the diffusion of oxygen from the lungs into capillaries.
Osmosis: The diffusion of water. The kidney tubules use osmosis to reabsorb water.
Facilitated diffusion: Diffusion assisted by a carrier protein. The carrier protein moves molecules across cell membranes. The intake of glucose by most cells happens by facilitated diffusion.
Active transport: Movement of molecules from an area of low concentration to an area of high concentration assisted by a carrier protein. Active transport requires ATP (Adenosine triphosphate- a specialized nucleotide that traps and releases biologically useful energy). An example of a process that uses active transport would be the absorption of amino acids and glucose from food by the cells of the small intestine.
Filtration: Movement of water and dissolved substances from an area of higher pressure to an area of lower pressure. This would be used in the first step in the formation of urine.
Endocytosis: The membrane engulfs something and draws it into the cell in membrane bound vesicles. An example of this would be white blood cells engulfing bacteria.
Exotysosis: Membrane bound vesicle fuses with the cell membrane, releasing it's contents outside the cell. An example of this would be the release of neurotransmitters by nerve cells or the cells of kidney tubules reabsorbing.
How does this affect you?
In 1985 Michael Brown and Joseph Goldstein won the Nobel prize in medicine for receptor-mediated endocytosis. They were investigating the internalization of cholesterol by cells in the bloodstream. For more information on their findings, read the discussion of endocytosis on the biology reference website.
Form and Function: Cell organelles
Filed under: Research, Women Heart Health, Men Heart Health
I am a Licensed Practical Nurse with five years' experience in this profession. I believe it is essential to go back to the basics in all things in order to really understand them. I am fascinated by how our bodies work and I hope I can get my readers to share my fascination. I hope we all learn new things and marvel again at the things we already know. This feature -- which includes a closing section on how disease affects the topic in question -- will run on The Cancer Blog on Wednesdays, and The Cardio Blog and The Diabetes Blog on Thursdays. [The contents in this post are for informational purposes only and should not be construed as medical advice or substitute for professional medical care.]We start with the cell, because so much of what happens to us when we get sick, and how we get healthy again, can be explained by what happens on a cellular level. The cell is extremely complex and I will only touch on the basics in these posts, but at least we can have a rudimentary understanding.
Structure of cells
A cell has three basic parts:
1) Plasma membrane: A membrane lies at the border of cells and consists of lipids and proteins. See my post of 23 May on the cell membrane
2) Cytoplasm: All the cellular contents between the plasma membrane and the nucleus and can be further divided into the Cytosol and Organelles. We will discuss the organelles in today's post.
3) Nucleus: Technically an organelle, but usually considered separately because of its numerous and diverse functions.
Organelles
Organelles are specialized structures that evolved to perform specific functions. We could probably discuss each organelle in a separate post, because each one has it's own characteristic shape and function. i decided to keep this very basic and just list the different organelles, what they look like and what their basic function is. We will also just look at the "famous" organelles. There are other organelles, but the ones we discuss will give us a good understanding of what goes on inside the cell.
Endoplasmic reticulim (ER): A network of membranous tubules that extend from the nuclear membrane to the cell membrane. The ER can further be subdivided into a rough and smooth. The rough ER is continuous with the nuclear membrane and has an outer surface studded with ribosomes. The ER function is to be a passageway for the transport of materials within the cell. It also synthesizes lipids and proteins.
Ribosomes: These are either floating bodies for the internal needs of the cell or attached to the ER for transport out of the cell. Ribosomes are the sites for protein synthesis.
Golgi apparatus: Besides having a cool name (named after the scientist that discovered it), it refines and moderates proteins produced in the ER prior to transport and packages materials for secretion from the cell. It is a series of membranous sacs, described as looking like a stack of pita bread.
Mitochondria: These organelles are roughly bean-shaped with inner membranes. They are (literally) the powerhouses of the cell. They break down sugar molecules into energy. Tissues that need a lot of energy, like muscles, have more of these organelles in their cells .
Lysosomes: They are single membrane structures and have a membrane. The lysosome breaks down larger molecules into smaller molecules and it also digests old cell parts. It is the waste manager of the cell. It has powerful digestive enzymes to break down the waste.
Chromatin: Fibers composed of protein and DNA molecules. It contains the genetic information for protein synthesis. It is the heredity material in cells
Sentriole: A pair of rod shaped structures perpendicular to each other. It plays an important part in cell division. It organizes the spindle fibers during cell division.
These are some of the most common organelles. It is easy to understand that what goes on in the cell can have a huge impact on tissues and systems and therefore on the disease process.
How does it affect you?
Features of mitochondrial diseases have been shown to mimic the symptoms of heart disease. Researchers are looking at the possible connections and are trying to find out if restoring the mitochondrial "dysfunction" can prevent or cure heart disease.Permalink | Email this | Linking Blogs | Comments
The specials tonight are fulminant and non- fulminant
Filed under: Type 1, Childhood, Research, Allie Beatty, Support, Complications, Personalities, Form and Function
A type 1 diabetic mystery is why do some Type 1s get complications and others seem to never get them? A massive Japanese study of Type 1 diabetics found that those with fulminant diabetes developed complications much faster and more severely than those with non-fulminant diabetes.
The difference between fulminant and non-fulminant is the speed and intensity at which the disease develops. Fulminant Type 1 diabetes typically develops suddenly with near total loss of beta cell function. This type of diabetes is confirmed with testing c-peptide levels. Non-fulminant type 1 diabetes has residual c-peptide levels that eventually taper to undetectable. Sometimes this is seen through many years of the Honeymoon Period.
This study may be the antithesis of conventional wisdom for preventing complications. Staking all hopes on blood sugar control is heavily optimistic. Yes controlling blood sugar does lessen the workload for existing beta cells, and thus extends the lifespan of each beta cell. Research suggests that c-peptide offers protection to beta cells, both from apoptosis (cell death) and encourages new cell growth. This new cell growth applies to beta cells and other cells of the body that endure long-term Type 1 diabetes complications.
Diabetics are instructed that maintaining normal blood sugars is the Holy Grail of preventing long-term complications. Yes and no. The truth is controlling your blood sugar will not allow complications of Type 1 diabetes to develop as quickly, presuming you still had some level of beta cell function upon diagnosis (i.e., c-peptide). That doesn't sound like a reward as much as it does a delayed punishment. I'd like c-peptide with my insulin, please. It's off the ?a carte menu? That's fine - serve it up! I want to thank Klausen for bringing this study to my attention.
Why don't insurance companies insure diabetic kids?
Filed under: Type 1, Childhood, Opinion, Products, Allie Beatty, Support, Personalities, Form and Function
Ed Hinerman, a life insurance specialist with the Hinerman Group, was posed an interesting challenge recently. For years he has successfully found affordable life insurance for many adults with type 1 diabetes, but he had never been asked about life insurance for children with Type 1 diabetes until now.
After speaking with underwriters in the top 40 or so companies, he found a discernible lack of interest due to lack of data. Companies would say that they couldn't consider someone with type 1 diabetes until they were either age 15 or age 20. A peer in the industry told Ed the knee jerk reaction was because insurance companies haven't done mortality studies on children. They simply don't have any data upon which to base the pricing for products. Uh oh!! That coupled with the fact that there really isn't any financial incentive for them to study and create products for a relatively small market that would produce relatively low premium, kind of sets the tone. Well, now the war has been defined and the battles are becoming clearer.
When Ed contacted the ADA for assistance in this matter - hold your breath (it's a shocker!) - they turned a cold shoulder on a diabetic's need. What if the diabetic's parents were doing what so many families do - and trying to buy a whole life policy to help pay for their kids college someday? It's really not fair! Here's where fair begins -- Ed asked me to gather some facts it will take to get the insurance companies attention. Does anybody have any idea of the mortality rate of children after being diagnosed with type 1 diabetes?
Bottom line. Life insurance companies make big money and for them to cut and run from children just because it might not make them more big bucks, or because they really haven't done their homework and aren't interested in doing it, isn't acceptable. Game on! I hope we can make a good showing, at the very least - hit one out of the park for the fans. Thanks for inviting me to play, Ed!
The true gifts in life come in the form of advice
Filed under: Type 1, Type 2, Childhood, Adult Onset, Opinion, Allie Beatty, Support, Personalities
My recent blog on interlopers offering advice about controlling diabetes upset a good friend of mine. He asked a question that gave me one of those What if...dream sequences. The reality check warrants a new blog.
He asked -- what if an interloper talked your doctor into reconsidering the use of natural animal insulins because they read the research and figured out that it was the better choice? Would you still think interlopers have no value in diabetes control?
Touch?- you sunk my battleship. I had to confer with a fellow diabetes OC blogger to get the he said / she said feedback. She made a very good point, too. In her words, there is a special group of non-diabetics who have an acute understanding of the disease, and who may have a somewhat intuitive understanding of how it works, but most of the time there is a silent acknowledgement that their opinion can at any given time be dismissed in favor of the diabetics'. Words of wisdom typed from the sorceress of Lemonade Life.
Today's lesson for Allie: listen without prejudice. Learn from all who are willing to share their experiences. Prosperity in life comes from the gifts we share with each other. My friends have shared valuable insight to teach me how to gain from every experience in life. I now see that the advice others have to share is the gift we have yet to receive. Denying the gift before we ever receive it is ungrateful. Graciously humbled - Allie B
[RESEARCH] Low dose aspirin and cognitive function in the women's health study cognitive cohort
Objective To determine whether low dose aspirin protects women aged 65 or more against cognitive decline.
Design Cohort study within both arms of the women's health study, a randomised, double blind, placebo controlled trial of low dose aspirin for the primary prevention of cardiovascular disease and cancer, 1992-5.
Setting Women's health study, 1998-2004.
Participants 6377 women aged 65 or more.
Interventions Low dose aspirin (100 mg on alternate days) or placebo for a mean of 9.6 years.
Main outcome measures Women had three cognitive assessments at two year intervals by telephone. The battery to assess cognition included five tests measuring general cognition, verbal memory, and category fluency. The primary prespecified outcome was a global score, averaging performance across all tests. The key secondary outcome was a verbal memory score, averaging performance on four measures of verbal memory.
Results At the initial assessment (mean 5.6 years after randomisation) cognitive performance in the aspirin group was similar to that of the placebo group (mean difference in global score -0.01, 95% confidence interval -0.04 to 0.02). Mean decline in the global score from the first to the final cognitive assessment was also similar in the aspirin compared with placebo groups (mean difference 0.01, -0.02 to 0.04). The risk of substantial decline (in the worst 10th centile of decline) was also comparable between the groups (relative risk 0.92, 0.77 to 1.10). Findings were similar for verbal memory; however, a 20% lower risk was observed for decline in category fluency with aspirin (relative risk 0.80, 0.67 to 0.97).
Conclusion Long term use of low dose aspirin does not provide overall benefits for cognition among generally healthy women aged 65 or more.
Victims of circumstance in hypoglycemic unawareness
Filed under: Type 1, Type 2, Childhood, Adult Onset, Lifestyle, Drugs, Research, Opinion, Support
Lately the news has seen a lot of devastating diabetic events due to hypoglycemic unawareness. Hypoglycemic unawareness is commonly defined as an inability to recognize the symptoms (sweating, tremor, hunger, anxiety, and palpitations) of decreased blood sugar or a failure of the warning signs to occur before development of neuroglycopenia, which means a shortage of glucose in the brain. Curiously, this term was not coined for diabetes until 10 years after the introduction of genetically modified human synthetic insulin and insulin analogues.
I hate to say it but diabetes is a crapshoot. You never know what you are going to get, but you can sure try your best to keep your eye on the ball. Removing the inherent dangers of hypoglycemic unawareness would make me a happier diabetic, and improve the lives of all those I care about (diabetics like myself). The answer might lie in the only type of treatment available nowadays, insulin analogues. Diabetics who do not take any form of drug to control blood sugar do NOT have hypoglycemic unawareness.
It's called human but it is nothing like natural human insulin. It may be faster acting or longer lasting but I'm sure He didn't intend for insulin to break sound barriers or last three moons. If Big Pharmaceutical companies were asked to compare insulin analogues with natural human insulin you'd hear crickets. I promise you NO Big Pharma will fund a study that would become the antithesis of their marketing campaigns, human insulin is better. It's not better, it's just different -- totally different! Natural insulin is fat-loving. Insulin analogues are water-loving. The global command center of the body (the brain) is one big blob of fatty material. This means as your blood sugar is dropping, your brain is last fed, if it eats at all. Here in the United States we are victims of circumstance in hypoglycemic unawareness. Sorry brain, no soup for you.
Take your tea the healthy way
I've said it enough times on this blog, just as so many other people have spoken highly about the health benefits of 
drinking tea. The stuff is good for you, bottom line. But, it turns out that adding milk to your tea can make it less healthy than if you were to drink it as is.
German scientists found that people who drank their tea without adding milk showed signs of improved blood-vessel function, a well-known cardiovascular benefit of drinking tea. However, people who added milk to their tea did not show any signs of improvement with regard to their blood-vessel function. The study's author suggests that the proteins in milk may bind to the heart-healthy compounds in tea known as catechins. From there, the binding may lessen the teas beneficial effects.
If tea without milk isn't your...um...cup of tea, then maybe you can try a flavored or spiced tea in place of the added flavor you're used to getting from the milk. A personal suggestion is the Celestial Seasonings' blueberry flavored Green Tea.