The total force opposing LV con-. traction (i.e., the afterload) is the product of the LV. pressure and the internal surface area of the LV. cavity. In hypertensive subjects, of course, the arterial and. LV pressures are abnormally high during systole and, therefore, the LV afterload tends to be high.
Sincerely, Dick Montgomery A Most of the North American Hummingbirds migrate. The ones that go the farthest are the Rufous and the Ruby-throat. They may make trips to destinations which are as far as 2000 miles away.The hummingbird you have in northern Wisconsin is the Ruby-throated.n spring the birds probably follow the same route to come back north. A Ruby-throated Hummingbird flies at about 27 miles per hour if there is no tail wind or head wind. This would mean that long 500 mile flight across the Gulf of Mexico would take about 18 1/2 hours.
1 In the Ruby-throated Hummingbird, incubation--which is done only by the female--usually lasts 16-18 days, sometimes longer during cool weather. 2  She typically lays one egg, skips a day, and then lays a second; incubation does not start until both eggs are laid.he best way to find a hummer nest is to wait for the female to lead you to it. This may not work, however, since the nest can be up to 1.5km or more from a good feeding area. Among Ruby-throated Hummingbirds, nests may be in hardwoods or evergreens from about one to 20 meters (three to 60 feet) from the ground.