Comparative endocrinologists investigate the evolution of endocrine systems and the role of these systems in animals' adaptation to their environments and their production of offspring. Studies of nonmammalian animalshave provided information that has furthered research in mammalian endocrinology, including that of humans. For example, the actions of a pituitary hormone, prolactin, on the control of body water and salt content were first discovered in fishes and later led to the demonstration of similar mechanisms in mammals. The mediating role of local ovarian secretions (paracrine function) in the maturation of oocytes (eggs) was discovered in starfishes and only later extended to vertebrates. The important role of thyroid hormones during embryonic development was first studied thoroughly in tadpoles during the early 1900s. In addition, the isolation and purification of many mammalian hormones was made possible in large part by using other vertebrates as bioassay systems; that is, primitive animals have served as relatively simple, sensitive indicators of the amount of hormone activity in extracts prepared from mammalian endocrine glands. Finally, some vertebrate and invertebrate animals have provided “model systems” for research that have yielded valuable information on the nature of hormone receptors and the mechanisms of hormone action. For example, one of the most intensively studied systems for understanding hormone actions on target tissues has been the receptors for progesterone and estrogens (hormones secreted by the gonads) from the oviducts of chickens.

An understanding of how the endocrine system is regulated in nonmammals also provides essential information for regulating natural populations or captive animals. Artificial control of salmon reproduction has had important implications for the salmon industry as a whole. Some successful attempts at reducing pest insect species have been based on the knowledge of pheromones. Understanding the endocrinology of a rare species may permit it to be bred successfully in captivity and thus prevent it from becoming extinct. Future research may even lead to the reintroduction of some endangered species into natural habitats.

Evolution of endocrine systems

The most primitive endocrine systems seem to be those of the neurosecretory type, in which the nervous system either secretes neurohormones (hormones that act on, or are secreted by, nervous tissue) directly into the circulation or stores them in neurohemal organs (neurons whose endings directly contact blood vessels, allowing neurohormones to be secreted into the circulation), from which they are released in large amounts as needed. True endocrine glands probably evolved later in the evolutionary history of the animal kingdom as separate, hormone-secreting structures. Some of the cells of these endocrine glands are derived from nerve cells that migrated during the process of evolution from the nervous system to various locations in the body. These independent endocrine glands have been described only in arthropods (where neurohormones are still the dominant type of endocrine messenger) and in vertebrates (where they are best developed).

It has become obvious that many of the hormones previously ascribed only to vertebrates are secreted by invertebrates as well (for example, the pancreatic hormone insulin). Likewise, many invertebrate hormones have been discovered in the tissues of vertebrates, including those of humans. Some of these molecules are even synthesized and employed as chemical regulators, similar to hormones in higher animals, by unicellular animals and plants. Thus, the history of endocrinologic regulators has ancient beginnings, and the major changes that took place during evolution would seem to centre around the uses to which these molecules were put.

Question/ Problem: The Effect of Various Antibiotics on Bacterial Growth.

Title: “Antibacterial Properties of Selected Hand Sanitizers”.

Hypothesis- If 5 recommended brands of hand sanitizers and Protex Antibacterial soap are added to cultivated bacteria, then Protex will work best in killing the bacteria.

Variables:

IV- Selected Hand sanitizers and Protex Antibacterial Soap.

DP- The number of the bacteria left over.

Constants- Amount of hand sanitizer, the size of the bacteria culture, environment, atmosphere, temperature, Petri dishes, placement, and the spaces between the Petri dishes.

Controlled Group- Protex Antibacterial Soap and water applied to bacteria.

Experimental Group- Bacteria exposed to selected brands of hand sanitizers.

Procedure:

1. Label the back of 6 agar plates correspondingly to what will be used on that slide. (Ex: AO 1, PR 1 etc.)
2. Cultivate bacteria cultures on the agar plates for all 6 plates.
3. After the bacteria have fully grown, smear the hand sanitizers and soap evenly on their corresponding plates.
4. Keep the agar plates in the same environment for an hour and observe the changes.
5. See how many bacteria have been eliminated and how many survived.
6. Repeat the same procedure 3 times in order to have accurate observations.
7. Based on your findings and observations, make an acceptable conclusion as to which hand sanitizer will work best in killing/declining the bacteria.

Materials-

1.                  Agar plates

2.                  Bacteria culture

3.                  Hand sanitizers (Avant, Original Germ-X, Purell, Wet Ones, EO),

4.                  Soup (Protex antibacterial soap)

5.                  Distilled water

6.                  Basic gloves

Introduction (Thesis):

The endocrine system is an integrated system of small organs which involve the release of extracellular signaling molecules known as hormones.

Hormones:

                     I.      Hormones are extracellular signaling molecules and participate in the transfer information and instructions form on set of cells to another.

1.  
   1. Among the hormones that this integrated system produce are prolactin, growth hormones, thyrotropin, and corticotropin.

1.  
   1. Factors such as stress, infection, and changes in the balance of fluid and minerals in blood can influence hormone levels.

1.  
   1. These hormones are active in the regulation of

·        metabolism

·        growth and development

·        tissue function

·        mood

1.  
   1. Among the hormones that this integrated system produce are prolactin, growth hormones, thyrotropin, and corticotropin.

1.  
   1. Each hormone affects only the cells that are programmed genetically to receive and respond to its message.

1.  
   1. Once the hormone locks into its receptor, it transmits a message that causes the target site to take a specific action.

g.  Among the hormones it produces are:

·        growth hormone: which stimulates the growth of bone and other body tissues and plays a role in the body's handling of nutrients and minerals

·        prolactin: which activates milk production in women who are breastfeeding

·        thyrotropin: which stimulates the thyroid gland to produce thyroid hormones

·        corticotrophin: which stimulates the adrenal gland to produce certain hormones

Functions:

                   II.      Glands located in many regions of the body release into the bloodstream specific chemical messengers called hormones, which regulate the many and varied functions of an organism.

a.      The endocrine system uses blood vessels as information channels.

b.      The endocrine system is an information signal system much like the nervous system. However, the nervous system uses nerves to conduct information, whereas the endocrine system uses blood vessels as information channels.

Role in Disease:

                  III.      Diseases of the endocrine system are common, including diseases such as

·        diabetes mellitus

·        thyroid disease

·        obesity

a.       Hypofunction of endocrine glands can occur as result of loss of

·        reserve

·        hyposecretion

·        agenesis

·        atrophy or active destruction

b.      Hyperfunction can occur as result of

·        hypersecretion

·        loss of suppression

·        hyperplastic or neoplastic change

·        Hyperstimulation

c.      Cancer can occur in endocrine glands, such as the thyroid, and hormones have been implicated in signaling distant tissues to proliferate

Conclusion:

Basically, the glands of the endocrine system and the hormones they release influence almost every cell, organ, and function of our bodies.