Understanding Obesity: Evolutionary Roots and Health Solutions
Cosmological Models and Theories
Geocentric Model (Ptolemaic System)
In the Geocentric Model, the Earth is believed to be motionless at the center of the universe, with the Sun, Moon, planets, and stars revolving around it. This model could explain:
- The apparent movement of the Sun and Moon.
- The phenomenon of day and night.
- The apparent rotation of the stars.
- Planetary motion using complex epicycles and deferents.
However, it could not accurately explain the phases of Venus as observed, nor why planets
Read MorePathological Processes and Neoplasm Characteristics
Edema
Edema is the abnormal accumulation of fluid in the interstitium or body cavities due to an imbalance in fluid homeostasis.
Types of Edema
Types include pitting edema, caused by protein deficiency, increased hydrostatic pressure, increased capillary permeability, or fluid retention; and non-pitting edema, caused by lymphatic obstruction or hypothyroidism (myxedema).
Edema Pathogenesis
Pathogenesis involves decreased plasma oncotic pressure, increased capillary hydrostatic pressure, lymphatic obstruction,
Read MoreKey Eukaryotic Organelles: Structure and Roles
Centrosome: Structure and Functions
The centrosome is a dense material, often referred to as the centrosphere, with few radial microtubules. Each centriole consists of nine groups of microtubule triplets arranged as a cylinder, held together by proteins. These triplets remain united by proteins.
Functions:
- Microtubule organizing centers.
- Involved in the formation of cilia and flagella.
- Forms the mitotic spindle during cell division.
- Contributes to the structure of the cytoskeleton.
Ribosomes: Essential
Read MoreHuman Reproductive System: Gamete Production & Hormonal Control
Gonads: Primary Reproductive Organs
Female Gonads: Ovaries
Male Gonads: Testes
Primary Functions of Gonads
- Gametogenesis: Production of gametes (reproductive cells) from germ cells.
- Gametes: Reproductive cells
- Ova: Female gametes
- Spermatozoa: Male gametes
- Sex Hormone Secretion: Gonadal steroids including androgens, estrogens, and progesterone.
Accessory Reproductive Organs
- Ducts for Gamete Transport:
- Males: Epididymis, vas deferens, ejaculatory ducts
- Females: Ovarian tubes (fallopian tubes)
- Glands Secreting
Cell Division, Genetics, and Inheritance Fundamentals
Mitosis: Nuclear Division Process
Mitosis is a fundamental process of cell division where the nucleus divides, resulting in two genetically identical daughter cells. It is crucial for growth, repair, and asexual reproduction. This nuclear division is followed by cytokinesis, the division of the cytoplasm, which differs in animal and plant cells:
- In animal cells, cytokinesis occurs via a constriction furrow.
- In plant cells, a phragmoplast forms, leading to a new cell wall.
DNA duplication occurs during
Read MoreBiological Organization, Cell Biology, and Human Tissues
Biological Organization: From Subatomic to Biosphere
Universal Levels of Organization
- Subatomic Level: Protons, neutrons, and electrons.
- Atomic Level: Formed by atoms.
- Molecular Level: Formed by molecules.
- Cellular Organelles: Structures performing complex biological functions within cells.
- Cellular Level: Formed by cells.
- Multicellular Level: Includes tissues, organs, and systems.
- Population Level: Includes groups of living things of the same species.
- Community Level: Interacting populations within a shared