Goodbye winter (and notes on duck feet)

Days are longer, the sun is brighter and the snow is slowly melting away. But I can't help remembering how a few weeks ago, on a bleak, frigid February afternoon, I watched a group of ducks paddling along the icy river through town.

The ducks were surrounded by snowy banks and sections of thick ice. And as my own breath came out in crystalline puffs, I wondered how they stayed warm. I wasn't worried about their bodies - yes, the air was frigid, but they have down coats for that. I was more curious about their thinly webbed feet that were submerged in the icy water. 

After a bit of research, here's what I learned.

Ducks have a counter-current heat exchange system: the warm oxygenated blood flowing to their feet passes close by the cold, waste-carrying blood returning to the heart. It's a finely webbed system of arteries and veins that allows the birds to efficiently recapture heat. Since the blood in their feet is already cooler, they don't lose as much heat to cold water. All to say they're not wasting too much energy keeping their feet warm.

But their feet are still chilly: the blood that circulates through is just warm enough to prevent frostbite. And that's surprisingly okay with these birds. Their legs and feet are mostly free of soft tissue. Even the muscles that operate the foot are higher up in the leg, connected to the foot bones by long tendons. So their feet don't need much warm blood. And if they get too chilled, the ducks can pulse extra blood to the foot through valves in leg arteries, providing the needed warmth and preventing frostbite.

Believe it or not, this whole system is also helpful in warm weather. Birds can forage in water hotter than their body temperature as the counter-current exchange keeps their feet cool. This also explains why the Great Flamingo, which has very complicated branching in its arteries and veins, stands on one foot: it's limiting its exposure to heat through its feet. This same system is found in the flippers of whales and sea turtles, as well as some reptiles. 

So the next time you stand at an icy pond and watch ducks paddling along, there's no need to cringe and shiver and worry why those little feet don't turn into icicles. Instead, you can tuck your hands in your pockets, watch your breath cloud in front of you, and marvel once again at intricacy of nature.

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photos from Creative Commons/Pixabay

The Eye

Look at this word.  Then this one.  And think for a moment how it is that you

See.

How your gumball-sized sense organs studded by ears and straddling nose differentiate among 10 million colors, detecting the brightest noontime sun down to a single photon of light.

How an image passes through the clear cornea. Along the colorful iris. Through the gatekeeping pupil, M&M-sized black hole to your soul that it is.

Through the damp aqueous humor and the jelly-esque vitreous body that reminds scientists of egg whites

and lands on the retina.

Where cone cells, 6 million strong in the center of your eye film, detect bright light and colors quickly. And rod cells, 90 million or so along the edges of your field of view, detect low light slowly.

Both important, yet the rod cells are your friends for the deep, dark nights. Slower but more sensitive. Allowing you to see starglow and to pilot submarines.

When light hits, pigments shift, ion channels snap and brain words release,

travelling along the optic nerve

all in a blink of an – well, you know.

Lest you think the optic nerve is too fancy, sending its pitter-patter of information to the brain so three-dimensional images form,

you should know it is also responsible for your blind spot. The blank area in all of your images that your brain somehow fills back in.

To find your blind spot, close one eye and focus – really focus – on one of two dots.  Move your face closer or further and suddenly, the second dot disappears.

Ah-ha. You’ve found it.

Maybe now you can truly see.

Blind spot test. Close your right eye and look at the cross with your left eye. Move closer or further from the screen until the dot disappears. Switch eyes, look at the dot with your right eye, repeat. www.exploratorium.edu/snacks/blind-spot

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Creative Commons/Pixabay | neh.gov | ncbi.nlm.nih.gov

The Virus

Life, but not it’s own,

borrowed from another.

A shady spot – chemical or life form or just entirely

different.

Tiny, tiny thing

(millions on a pinhead, for scale).

Mere genes in a protein coat

coming in an array of beautiful shapes and flavors,

all so the virus can pop onto a cell and then enter

without knocking.

Once inside, it commandeers and reprograms the cell’s own hard-earned organelles

making them, eager slaves that they are, do its dirty work:

Copy down the viral recipe. Then use it to make more of the one thing the host cell does not want:

viruses.

Even the ingredients called for belong to the cell:

nucleotides, enzymes, ribosomes, tRNAs, amino acids, DNA mixers, energy.

The virus comes empty handed

and requires everything.

Suddenly, spontaneously, viral bits begin to self-assemble inside the host cell

poor, poor host that it is

And then, hundreds or thousands of the new viruses leave,

exit

usually destroying their host in the process.

The damage is not yet finished

for the new viruses move on to the host cell’s neighbors,

friends and family,

and take them over, too.

Our defenses are strong,

but so are viruses.

That one flu – remember – killed 40 million of us in the span of

two years.

But sometimes we can use viruses,

harness their power

to kill off bacterial infections.

Use the enemy to fight another enemy,

and hope it doesn’t then come for us.

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Creative Commons/Pixabay

On hiccups

Oh diaphragm,

you – hic – dome-shaped mass of muscle just below my lungs

that pulls down to pull in air, relaxes to push it out.

You work – hic – perfectly, most of the time.

Except for now.

Hic.

Did I swallow air or eat too fast or drink too much or – hic – is this merely some result of an amphibian ancestor's gil control? Whatever it – hic – is, it’s annoying. Really.

Caused by your contraction, just half of you (odds say the left) that starts to – hic – suck in air, until that’s cut short when the glottis, which – hic – resides in the small space between my vocal cords, snaps shut.

Wham. Three-hundredths of a second after the air intake starts

it’s – hic – ended so suddenly I make this sound.

Wait for it.

Hic.

Maybe the phrenic nerve, you know, that controls you, diaphragm, and talks with the brain about what’s going on in my neck and body is – hic – irritated. Or the vagus nerve, connected to the larynx, may be upset.

Dare I say the resulting outburst is – hic – childish?

I can – hic – sometimes make you go away. Overload the phrenic and vagus nerve systems or interrupt my breathing.

Bite a lemon, pour a spoon of sugar on the back of my tongue, get scared, hold my – hic – breath.

Often nothing works. Except for a spoon of my friend, peanut – hic – butter.

Cognitive behavioral therapy, one doctor calls it: I control my breathing and think about moving the smooth, nutty food through my mouth and down my throat. And just like that

they’re gone.

Until next time.

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pixabay.com

Hello, my blood

I nicked my finger on a knife

That day before dinner

and while the toddler howled and the dog whined

and peas boiled over and pizza burned,

I watched it:

thin red liquid line.

A few drops of blood.

Millions of erythrocytes – red blood cells.

A staggering loss

except that, at the same moment, 25 trillion red blood cells (minus these few million)

were speeding through my body.

Small disks without a brain or a powerhouse

because there simply isn’t room.

Not when you have a single job: pack yourself with oxygen.

One small red blood cell has 250 million molecules of hemoglobin clasping 1 billion molecules of oxygen.

They hold tight through arteries and blood vessels, until the capillaries, where oxygen – the unsocial, dissociative molecule it is – checks out, goes its own way, to where it’s actually needed.

Red blood cells are designed to not even use the oxygen they carry on their journey.

The body does not like to waste.

These millions of escapee cells, loosed by the slip of my knife will be quickly replaced.

Perhaps death to open air is preferred to being eaten by a phagocytic cell, which would’ve happened anyway after three or four months of constant service – clock in when you’re born and out at your death.

But it wasn’t just red blood cells lost in my carelessness:

there was water

and salts and proteins and hormones and wastes.

And there were the fighters,

those white blood cells always on patrol for enemies, ready to destroy.

Fingers crossed and prayers said they will only ever identify the

real enemies

otherwise, they might just take my whole ship down.

The dog howled again

and I picked up the toddler and

stuck my finger in my mouth

quelling the bleeding (knowing that platelets and fibrin were already doing their sticky work to plug the slender cut)

tasting that metallic, iron flavor

that is the cornerstone

of my life.

I turned off the peas, finger still in mouth,

then dumped the pizza into the trash

and called

for takeout.

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commonfund.nih.gov

nsf.gov, quantitative light imaging gallery