Plant Hormones and Human Endocrine System Functions
Plant Growth Regulators and Synthesis
Plant Hormones: Auxin, cytokinin, ethylene, abscisic acid, and gibberellins.
Sites of Synthesis: Apical shoots, roots, fruits, stems, and young leaves in all types of tissues.
Main Functions:
- Regulate stem and root growth.
- Encourage the growth of lateral branches.
- Ethylene release promotes maturation.
- Controls the opening and closing of stomata.
- Regulates seed germination.
Factors Influencing Activity:
- Light activates the mechanism of action.
- Activated by red light and high temperature.
- Activated by auxin.
- Drought increases concentration.
- Action activated by long photoperiod.
The Hypothalamus and Pituitary Gland
Hypothalamus Function
The Hypothalamus receives information about the body's condition and regulates metabolic processes through the endocrine system. It is formed by nerve tissue, whose neurons receive information from the cerebral cortex regarding external or internal stimuli. The hypothalamus synthesizes neurohormones sent to the pituitary gland. These can be:
- Neurohormones with stimulatory or inhibitory function on the anterior pituitary.
- Neurohormones that pass to the posterior pituitary, where they are stored before reaching target organs (e.g., oxytocin and antidiuretic hormone).
Pituitary Gland Structure
The Pituitary Gland is distinguished as the anterior pituitary and the posterior pituitary.
Anterior Pituitary Secretions
The anterior pituitary secretes six different hormones grouped as follows:
- Hormones that act directly on the target organ (growth hormone and prolactin).
- Hormones that stimulate endocrine glands (adrenocorticotropic hormone, thyroid-stimulating hormone, luteinizing hormone, follicle-stimulating hormone).
Tissue Hormones
Gastrin and histamine are two of the best known:
- Gastrin: Secreted by the stomach mucosa in the pylorus area.
- Histamine: Found in mast cells, which are a type of white blood cell.
Hormonal Mechanisms of Action
According to their composition, hormones can be classified as:
- Lipid Hormones: Fat-soluble hormones that can easily traverse the plasma membrane.
- Peptide Hormones: A group of hormones made by a chain of amino acids of varying length.