Subject: Re: insect analog

From: "DANNY A. BRASS" <[email-masked]>
Date: Thu, 11 May 1995 15:13:01 -0700

>
>What is the insect analog of the vertebrate arteriole?  The only
>candidates I have come up with so far are the dorsal vessel 'aorta' or
>perhaps the pulsatile organs at the base of the wing and antennae.  I
>picked these based on structure.  The arteriole contains smooth muscle
>and noradrenergic nerve fibers. I suppose one might find an insect analog
>based on function, ie the arterioles carry oxygenated blood to the tissues.
>

>Thank you,
>Carl Wigren

I am hardly an expert on insect circulation, so take this response
as such.

Is there are insect analog (or homolog) to the vertebrate arteriole?
Perhaps not.  Considering a typical mammalian circulatory system,
with the peripheral vasculature arbitraily classified into
elastic arteries, muscular (distributing) arteries, and arterioles--
I wonder what structure could be considered analogous--structurally,
functionally, or developmentally (homologous) to the arteriole?

Almost all of the major vessels in the body receive a sympathetic
innervation.  Arterioles are extensively innervated.  So, I don't
see that the presence of such an innervation has any significance.

Virtually the entire vascular system is lined with smooth
muscle, so this has no significance.

Functionally, arterioles do more than "carry oxygenated blood to
the tissues."  This is one of the functions of the arterial
system as a whole.  Arterioles play a vital role in
autoregulation of blood flow and pressure at the tissue level.

Can an analogous system be considered to operate in an animal
with an open ciruclatory system and a blood-filled hemocoel?
I don't see how.

Perhaps the insect's vasculature is best described (if one wanted
to make comparisons to vertebrates) as one large arteriovenous
anastomosis (AV shunt), or even better--as an arteriomyocardial
shunt?

Danny A. Brass