Fainting and Blood Pressure

A while ago, my friend asked me if blood pressure had anything to do with fainting. I said, “Yup”, and she said, “Explain it to me later”. So welcome to Later, everyone!

What is fainting?

For the people who don’t know, fainting is the loss of consciousness due to a lack of oxygen reaching the brain. Fainting also has a medical name, Syncope. It’s pronounced sing-co-pee (English is a strange language).

Why do people faint?

Biologically, people faint because they experience low blood pressure (though, there can be other cardiovascular problems). This isn’t necessarily of medical concern; you can have low blood pressure for several reasons. For example, if you are dehydrated, you have less fluid in your blood stream. This means that you have a lower blood volume in your blood vessels, which results in a lower blood pressure.

When you have low blood pressure, your blood vessels lose their tone and are unable to deliver blood cells to your brain as efficiently as it would if you had normal blood pressure. This results in your brain receiving less oxygen. The lack of oxygen is what makes you lose consciousness, since oxygen is required for the sustenance of your brain cells, not to mention your other cells!

So what can I do?

Stay hydrated folks! That’s one of the simplest ways to maintain a normal blood pressure 🙂

And that’s how blood pressure is related to fainting!

 

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Blood Pressure

High blood pressure, low blood pressure, what are you saying, doctors? What is blood pressure and why should we care?

What is blood pressure?

Blood pressure is the pressure that your blood exerts on the blood vessels. I know…. that’s a bit redundant.

Let me explain blood pressure a bit more, so you can visualize this. From what we’ve learned in school, the molecules in fluids interact closely with one another, meaning that they will not fill the entirety of a container unless you’ve placed enough of that fluid into the container to fill it completely. Each molecule exerts its own amount of force on each other and on the portion of the surface of the container that it interacts with.

Pressure is defined as a force exerted on a particular area. So the amount of force that the molecules exert on a particular portion of a container’s surface is equivalent to the pressure exerted by the molecule onto the container.

Now, if you replace the fluid with blood serum,the molecules with blood cells and the container with blood vessels, you’ll have the same situation; the blood cells each exert its own amount of force on portions of the blood vessel, which is the blood pressure.

Blood pressure naturally increases when your heart contracts to push blood into the blood vessels, and decreases when your heart relaxes.

Why is blood pressure important?

Blood pressure determines how hard your heart has to work to continuously feed your circulatory system with blood. The harder your heart works, the more strain there is in your circulatory system. This can lead to higher risk for health problems.

It’s also important to note that there are a variety of factors that affect blood pressure including how active you are, how much rest you get, your body temperature, diet, posture, medications and even your emotional state. So it’s important to try and stay healthy and active, for your heart and your health!

The Urinary System – Selective Reabsorption

Last week, we learned about the general filtration process that occurs in our kidneys. This week, we’ll learn just how our kidneys modify the filtrate to produce urine.

The filtrate that is in the renal tubule consists of water as well as other small molecules, like sugars and urea. Some of these molecules, like sugars, can return to the bloodstream in a ‘process’ known as selective reabsorption. It’s called ‘selective’ reabsorption because the bloodstream is picky as to what it absorbs from the tubule. The molecules that leave the tubule enter tiny blood vessels next to the tubule, which are called peritubular capillaries. The molecules can then be carried through the rest of the circulatory system, to provide our body cells with nutrients (if they’re sugars).

Parts of the Kidney

Selective reabsorption mainly occurs in the proximal tubule, which is the beginning of the tubule. The proximal tubule is just after the Bowman’s capsule. Whenever a molecule leaves, it is accompanies by water, which means a lot of water is reabsorbed by the bloodstream in this process.

By returning the molecules to the bloodstream, the remaining filtrate’s composition changes. As water leaves, the concentration of particles in the tubule increases.

Hormones can affect what is reabsorbed in the distal tubule. These hormones are the anitidiuretic hormone (ADH), which is also known as vasopressin, and aldosterone. They’ll be discussed next week when we talk about Concentration and Dilution!

Pins and Needles aka Parasthesia

Nowadays, it seems like my legs get a lot more sleep than I do. “#firstworldproblems, #universitywoes”. But, really, why do our limbs fall asleep and why do they tingle us so uncomfortably when they do?

Pins and Needles

The sleeping of our limbs, also termed ‘parasthesia’, is the result of our nerves acting abnormally due to an increased pressure on them for a prolonged period of time. Our nerves essentially act as little messengers between our limbs and our brain. So this prolonged pressure on the nerves results in the loss of communication between the limbs and our brain.

There is also a prolonged pressure placed on our blood vessels, which results in our nerves not receiving enough oxygen or nutrients.

So, in response to this pressure, nerves, much like how we respond to pressure, can react in to different ways: They can either become unresponsive and wait until the pressure has been removed, or they will essentially begin to spaz out and rapidly send signals in hopes of sending them in the right direction.

Now, the latter causes a problem because we have a lot of different nerves feeding our brains with a lot of different information: some inform us about temperature, some others about pressure on our skin and so forth. So when the nerves start spastically sending signals, the brain is unable to fully interpret what is happening and gets a mix of signals about warmth and numb sensations as well as conflicting signals about being cold and tingling sensations. This is why our sleeping limbs are described as having pins and needles. The mix of signals results in a mix of sensations, including an odd duality of numbness and tingling.

How to wake up your limbs

Many people try to hit their limbs that have fallen asleep. That doesn’t really do anything, unfortunately. The best we can do is to change our positions to remove the pressure and wait for the blood flow and nerve responses to return to normal.

And that’s all there is to know about pins and needles. Ironically, my foot has now fallen asleep so it’s time to practice what I preach.

 

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Nosebleeds aka Epistaxis

My roommate had a nosebleed a while ago, and I thought that it might be a good idea to go into why people get nosebleeds and how to properly take care of one.

What are the common causes for nosebleeds?

Picking your nose or Minor injuries

When you pick your nose, you might scratch against a blood vessel that lines the inside of your nose, which leads to blood escaping the vessel and your nose. Minor injuries like bashing your nose against a table or being punched in the nose can lead to the breaking of the blood vessels too.

Colds or Allergies or Dry, heated air or Blowing your nose

The inside of your nostrils are usually lined with mucous, which makes it a moist environment. On the other hand, these situations, excluding blowing your nose, cause your blood vessels to dry out and and become crusty, which can lead to the breaking of the vessels. Blowing your nose while having a cold or an allergic reaction can further irritate the vessel lining of your nose, which can eventually lead to a nosebleed too.

How to take care of a nosebleed

If your nose is bleeding because of a sustained injury, make sure to go see your doctor to ensure that everything is okay. If your nose starts bleeding on its own, likely due to the other reasons, then here are some things you should do:

• Do not lie down
• Damp washcloths usually work best to catch blood
• Do not tip your head back
• Pinch the part of your nose just below the bony part and breathe through your mouth for 10 minutes or so. If you do this for 20 minutes and your nose is still bleeding, talk to your doctor.
• If you have a room with dry air, getting a humidifier helps to prevent future nosebleeds.

Both of the italicized points are things you should not do. They both lead to the blood going down, into your throat, which can lead to you choking on your blood. So please remember to sit up or stand with your head leaned forward, not back!

See your doctor if: you feel like you might pass out, you look like you’re losing too much blood or you just started taking a new prescription.

So, all you nose-pickers, watch out because winter might be the worst time for you to do your thing; the dry air will make your nose lining less moist and picking your nose is basically like begging for a nosebleed.

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Bruises

Whenever you run into something or take a bad fall, you’ll find a bruise in the place that hurts (so long as your skin didn’t tear!). But what causes bruising and is there a way to treat it?

What is bruising?

Bruises, also known as contusions or ecchymosis, are the localized pooling of blood outside of blood vessels. So a bruise is simply when your blood escapes your blood vessels in a tissue yet remains in a certain area.

Why do we bruise?

When a part of your body is struck, the impact causes your blood vessels (more specifically capillaries, though sometimes it’s venules) in that area to rupture. This releases blood cells close to the skin’s surface, which spread out under the skin giving it a reddish colour.

The Colour changes of a Bruise

1. This reddish colour changes over the period of healing for a bruise. At the beginning, your bruise will be red because it will have an iron-oxygen complex.
2. After a couple days, however, your bruise will change to a deep purple or a blue colour; this is because the oxygen will have been used up by the surrounding tissues, resulting in the loss of an iron-oxygen complex (which gave the blood its red colour).
3. Then you bruise will slowly begin to heal; at around 5 days, your bruise may turn a green colour which is the result of hemoglobin, the protein found in our blood cells that contains iron to attract oxygen, breaking down in the blood cells that escaped.
4. The final colour stage is a yellow or brown colour, where the body is reabsorbing the lost blood and in its last stretch of healing itself. This usually occurs after 9 or 10 days.

How to help your bruise heal

When your bruise is healing, the blood that remains in the blood vessels needs to clot to prevent the further loss of blood. To help with the clotting process, it is recommended that you rest the affected area to ensure that there is no additional stress on the tissue.

Also, apply something to cool the area, perhaps a bag of ice or an ice pack. By cooling the area, you help influence the blood vessels to constrict. By constricting, the blood vessels reduce blood flow which means that there will be less blood that is lost through the rupture. Icing the area will also help calm down any swelling that occurs, but make sure to only apply ice intermittently for a maximum duration of 20 minutes. For the first day, it’s recommended that you ice the bruise for 20 minutes, take a break from the cooling for 20 minutes, and then repeat.

Both of these methods will help prevent the spread of blood underneath the skin but outside of the blood vessels; in other words, it helps contain the blood that escaped from the blood vessel in one area.

If you don’t rest the tissue after its blood vessel ruptures, it is likely that blood will spread to other areas in the vicinity of the impacted area. This is why you will sometimes find that there is a new bruise near the original one a day or two later.

Your blood vessels will heal themselves over the roughly 9 day period and your skin should go back to normal; just remember, rest and ice up! If you don’t, it can take a lot longer for the tissue to heal.

 

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