Air goes in your nose and flows over the smell sensors.
Your nose and sinus cavities act as a resonating chamber for your voice. That's why you sound funny when you hold your nose or when your nose is stopped up from a cold or allergies. This is important in talking and singing.
What makes something smell?
Volatile molecules evaporate at normal temperatures and pressures, so actually molecules of the thing are in the air and available to go in your nose. Don't think about this too hard....
The smelling sensors are on the roof of the nasal cavity --> olfactory receptors (olfactory is the fancy word for smelling). The molecules fit into the receptors like a key in a key hole. Our brain likes to categorize things, and so certain compounds have similar structures and get lumped together ("smells like eggs" but you know it's not real eggs).
The olfactory receptors send the signals to the olfactory bulb (which is the area in the brain that translates all the smells and allows you to identify a smell). It's not a very long trip....
The olfactory bulb is a part of the limbic system (the emotion center). this is why smell is more strongly connected to emotions and memory - even stronger than sight and sound.
If you go to the perfume counter at a department stores, you'll find that they all start smelling the same. The perfume department will have coffee beans because it helps clean out the receptors.
Coffee-scented, caffeinated perfume <-- free idea!!
Inflammation and mucus congestion blocked off the receptors.
No concrete evidence of why pregnant women get a "super smeller" during pregnancy.
One rogue molecule won't make you smell something.
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Episode 94 - Nose Anatomy
Your nose is responsible for breathing and smelling. These things work better when you're nose isn't stopped up.
The part of your nose that you can see and touch is cartilage covered in skin. There is bone above your nose, beside your nose, below your nose, and right in the middle of your nose (inside your head). Part of the cartilage is stiff and hold shape, other parts of cartilage are soft for flexibility.
The nasal root (the bone that extends between your eyes) connected to the bridge of your nose (which is made of cartilage). The tip of your nose is also called the lobe. The wings are on each side of your nose that you can flare. The nostrils is actually the hole that leads into your nose.
There are 4 main sinus cavities.
- Frontal sinuses = in your forehead, between your eyebrows
- Maxillary sinuses = run under your eyes, behind your cheeks
- Ethmoid sinus = right between your eyes, in the middle of your head, connected to your tear ducts
-Sphenoid sinus = under your sphenoid bone (in the middle of your head)
The sinus cavities are lined with mucous membranes that keep them moist and have lots of blood flow to them. Their job is to warm and moisten the air you breathe in your nose before it goes into the lungs. Your lungs don't like cold air.
Mouth breathing is not very efficient. This is true in athletics as well as sleep. But breathing out through your mouth can be useful because you can get a large amount of air out rather quickly and the lungs empty better.
You have a fast-flow and a slow-flow nostril - this has to help you perceive smell. Sometimes almost as good as dogs.
The cartilage of your ears and nose never stop growing through your life.
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PSA: Please don't stick things in your ear any larger than your elbow...and that includes your finger.
Outer ear = the part that you can touch
Middle ear = the area being the ear drum
Inner ear = the cochlea and area responsible for your balance
3 common ear issues
- Ear infections (otitis media)
- Vertigo (and motion sickness)
- Tinnitus (ringing in your ear)
*Ear wax? <-- Go here
The area behind your ear drum has air in it and that pressure is equalized through the eustachian tube. If that area gets fluid in it, that fluid can grow bacteria and that leads to infection. The natural motion of opening and closing your jaw helps massage the eustachian tubes and moves air in and out (like when you fly or drive in the mountains and you chew gum or yawn).
Cold and allergies can be the source of the fluid build up that leads to ear infection. You may have decreased hearing, pain, decreased balance - infection can require antibiotics.
Vertigo = the sensation of spinning, dizziness, being off balance
The semi-circular canals are responsible for your balance. If it get sloshed too much, or doesn't level out exactly right, then the signals sent to the brain may translate to being off balance even though your body is upright. The signal confusion is what can lead to nausea (it's not actually happening in your stomach - at least not until you vomit!)
The fluid moving around in these canals are why kids can induce dizziness when they spin around in circles (think about the clothes in your washer during the spin cycle - they get pushed to the outside).
Medications for vertigo are the same as some medications for nausea - plus they have drowsy side effects, so maybe you just sleep it off.
There are many suspected causes, but nothing definite or proven.
Tinnitus = ringing, buzzing, roaring, whooshing sound when nothing is actually making that noise.
Causes: hearing loss (either due to aging or exposure to loud noises); high blood pressure (pulsating); medications
One theory: the hairs in the cochlea are damaged so those frequencies of sound (usually high pitched sounds) can't be picked up anymore; the brain fills in the gaps with "made up sound". This is NOT PROVEN!
High blood pressure can cause you to hear the blood pulsing through the blood vessels in your ears.
Medications that causing ringing in the ears
- Aspirin (acute over-use)
- Aminoglycosides (i.e. Gentamicin = antibiotic) - it has a small therapeutic window, too much can lead to ear damage, it stopped in time, permanent ear damage can be avoided
- Quinine = usually asked for to help leg cramps, also medically prescribed to prevent malaria. Can only be readily consumed by drinking tonic water.
Flavonoids are put in vitamins and advertised to help tinnitus. Flavonoids are phytonutrients (nutrients you get from plants). These nutrients can't grow the hairs back in the cochlea. Most of the vitamins and nutrients in the flavonoid vitamins have anti-oxidative properties, but I doubt that tinnitus is a major oxidation problem.
Can being slapped over time cause ringing in the ears?
- being bopped in the face and head can probably cause permanent damage to the structures on the inside and outside of your head. Being hit in the side of the head can cause pressure build-up in the ear where the air causes the ear drum to rupture.
- Slaps to the face (like "you jerk!" kind of slaps) don't affect the ears, but punches or slaps to the side of the head near or on the ears can possibly cause damage.
Be nice to your ears!
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The Auricle = the part of the ear you can see; made of cartilage (flexible tissue that doesn't have a large blood supply)
Everything else requires a tool for the doctor to see inside. And the doctor can only see to about the ear drum. The stuff behind the ear isn't visible because of the membrane that blocks it. The middle and inner ear are surrounded by your head bones.
Science of sound
Sound is created when the air around us is compressed and then expands. They move away from the source in circles (think radar or sonar or throwing a pebble in a pond.
The ear canal directs the sound waves towards the ear drum.
The ear drum (tympanic membrane) vibrates according to the intensity of the sound and trigger the Hammer-Anvil-Stirrup cascade.
- The ear drum vibrates the handle of the Hammer (Malus bone - yes, it's a real bone).
- The Hammer bangs on the Anvil (Incus bone). The Anvil has a tail that is connected to the Stirrup (Stapes bone).
- The Stirrup looks like the spurs on the back of boots. It it connected to a membrane on the Cochlea and works like a plunger.
- All of these bones are surrounded by air and the pressure is controlled by the Eustachian tube. This is the access point for ear infections or congestion due to allergies or a cold.
The Cochlea is a bone full of fluid and lined with hairs and shaped like a spiraled sea shell. The hairs pick up different frequencies of sound (sound wave frequency determines pitch). If certain levels of hairs get damaged, then you will not be able to hear pitches in that range anymore. If you unrolled the cochlea, it would be laid out low pitch to high pitch like a piano. And these hairs are connected to the auditory nerves and turn sound signals into electrical signal to send it to your brain.
Sound gets translated in 2 main ways
1. Identify the sound
2. Identify if the sound has meaning
Semicircular canals of the cochlea are little bone chambers full of fluid and they control balance. This works like a leveling bubble to help you stay upright. If it becomes dysfunctional, then it may trigger vertigo.
The middle ear (the area behind the ear drum) is where most of the trouble happens - whether allergies causing stopped up ears, or colds leading to ear infections.
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