PHYLUM PRIAPULIDA
saadiaPHYLUM PRIAPULIDA (priapos, phallus, Creek god of reproduction symbolized by the penis) 1. Habitat: The priapulids are a small group. It has only 16 species of marine worms found in…
PHYLUM LORICIFERA (Lorica, clothed in armor + ferro, to bear)
PHYLUM LORICIFERA (Lorica, clothed in armor + ferro, to bear) The phylum Loricifera is a recently described animal phylum. Zoologists have described !about 14 species of Loriciferans. Its first members…
Phylum Acanthocephala (akantha, spine + kephale, head)
PHYLUM ACANTHOCEPHALA (akantha, spine + kephale, head) 1.Habitat: Adult acanthocephalans are endoparasite in the intestinal tract of vertebrates (especially fishes). They complete their life cycle in two hosts. The juveniles…
PHYLUM NEMATOMORPHA
PHYLUM NEMATOMORPHA(nema, thread + morphe, form) Nematomorphs are a small group of about 250 species. They are elongated worms. They are commonly called horsehair worms or Gordian worms. Habitat: The…
Write a brief overview of the endocrine system of
rubab(a) cnidarians' (b) platyhelminths (c) nemerteans (d) nematodes and (e) annelids. (a) Cnidarians The nerve cells of Hydra contain a growth promoting hormone that stimulates budding, regeneration, and growth. For…
What kind of hormones stimulate protein synthesis In a cell?
Steroid hormones stimulate the protein synthesis, because steroid hormones pass easily through the plasma membrane, their receptors are inside the target cells. After being released from a carrier protein in…
Define the mechanism that hormones modify the biochemical activity of a target cell.
Hormones modify the biochemical activity of a target cell or tissue. Two basic mechanisms are involved. Fixed - Membrane - Receptor Mechanism The fixed - membrane - receptor mechanism, applies…
If a hormone Is the “first messenger” what is the “second messenger”? , Give a specific example.
At the cells of the target organ, the hormone acts as a "first or extracellular messenger", binding to a specific receptor site for that hormone on the plasma membrane. The…
What is the importance of feedback systems in the control of hormonal output? Offer an example of a hormonal feedback pattern.
The concentration of a hormone in the plasma depends on two factors: i) Its rate of secretion, and ii) the rate at which it is inactivated and removed from the…
Describe the biochemistry of hormones. How hormones help control biochemical reactions in the target cell?
In terms of their chemical structure, hormones can be grouped into two general classes: i) lipid, or steroid, hormones ii) hormones derived from amino acids. Steroid hormones, which include the…