Pituitary Gland: Functions, Hormones, and Pathophysiology
Pituitary Gland: Functions and Hormones
The pituitary gland, also known as the hypophysis, is a gland located at the base of the brain. It plays a crucial role in regulating other glands. The pituitary gland is divided into two main parts:
Anterior Lobe (Adenohypophysis)
The anterior lobe produces several hormones that stimulate other glands to secrete their hormones. These include:
- TSH (Thyroid-Stimulating Hormone): Stimulates the thyroid gland to produce T3 and T4, which regulate metabolism.
- FSH (Follicle-
Understanding DNA, Genes, and Chromosomes
ITEM 5: DNA
Deoxyribonucleic acid (DNA) is a molecule that contains all the genetic information, dictating traits like body structure and eye color.
DNA Components
- Monosaccharides
- Phosphoric acid
- Nucleobases
Nucleotide Components: A nucleotide consists of a nucleobase, a monosaccharide, and phosphoric acid.
Nitrogenous Bases:
- Cytosine
- Guanine
- Thymine (DNA)
- Uracil (RNA)
- Adenine
Double Helix: The double helix is the shape created when two nucleotide chains face each other, forming a structure resembling a spiral
Read MoreGenetic Mutations: From DNA to Chromosomes
Genetic or Molecular Mutations
1. Mutations
These are mutations that affect one or more of the nucleotides of DNA. They are not visible microscopically and can be of two types:
- Base substitution mutations: They occur in a position to change one base pair for another. Depending on the base exchange, these mutations are classified as:
- Transitional mutations: A purine base is changed by another purine (A↔G), or a pyrimidine by another pyrimidine (T↔C).
- Transversional mutations: A purine base is changed
Oparin, Lamarck, and Darwin: Theories of Life’s Origins
Oparin’s Hypothesis on the Origin of Life
In 1922, the Russian biochemist Alexander Oparin published The Origin of Life, detailing his theory:
- The early Earth’s atmosphere was composed of hydrogen, methane, ammonia, and water vapor, without oxygen.
- Ultraviolet rays, electric shocks, and high temperatures caused these gases to react, resulting in many small organic molecules (prebiotic synthesis).
- As the Earth’s temperature lowered, these molecules fell and accumulated, forming a “primordial soup.”
- Molecules
Origins of Life: From Spontaneous Generation to Neo-Darwinism
The Theory of Spontaneous Generation
It was believed that living organisms could arise spontaneously from decaying matter, and even inorganic matter. Louis Pasteur demonstrated irrefutably in 1862 that spontaneous generation did not exist.
Panspermia Theory
This theory states that life has an extraterrestrial origin. Life came to Earth in the form of bacterial spores from outer space (defended by Arrhenius).
Difficulties of this theory:
- It does not explain how life arose in its place of origin.
- Any living
Human Anatomy: Key Organs and Their Functions
Key Human Organs and Their Functions
- Jejunum: The long, coiled mid-section of the small intestine, between the duodenum and the ileum.
- Epiglottis: The flap at the back of the tongue that keeps chewed food from going down the windpipe to the lungs.
- Pancreas: An enzyme-producing gland located below the stomach and above the intestines.
- Gall Bladder: A small, sac-like organ located by the duodenum. It stores bile.
- Bile: A digestive chemical that is produced in the liver, stored in the gall bladder, and