Phospholipids, Steroids, and Amino Acids: Building Blocks of Life
Phospholipids
Phospholipids, also known as phosphoglycerides, are the major lipid components of biological membranes. The simplest phospholipid is phosphatidic acid, composed of glycerol, two fatty acids, and phosphoric acid. Other phospholipids have a polar compound containing at least one amino or alcohol group linked to phosphatidic acid. Phospholipids are amphipathic, meaning they have both polar and nonpolar regions. The polar region includes the phosphoric acid and alcohol, while the nonpolar
Read MoreHormones & STDs: A Comprehensive Overview
Major Hormones: Origin and Function
Endocrine Glands and Hormones
| Hormone | Gland | Physiological Effects |
|---|---|---|
| Thyrotropin | Anterior Pituitary | Controls the thyroid and stimulates thyroxine production. |
| Adrenocorticotropin | Anterior Pituitary | Stimulates hormone production in the adrenal cortex. |
| Somatotropin | Anterior Pituitary | Stimulates growth. |
| Follicle-Stimulating Hormone (FSH) | Anterior Pituitary | Stimulates Graafian follicle formation in the ovary. |
| Luteinizing Hormone (LH) | Anterior Pituitary | Regulates testosterone and progesterone |
Bioelements and Biomolecules: Composition and Properties of Living Matter
Bioelements
Bioelements are the chemical elements that constitute living matter.
- Primary (95%): C, H, O, N
- Secondary (4.5%): P, S, Ca, Na, K, Mg, Cl
- Trace (0.5%): Mn, Cu, Zn, Fe
Biomolecules
- Inorganic: Water and mineral salts
- Organic: Carbohydrates, lipids, proteins, nucleic acids, biocatalysts (enzymes, vitamins, and hormones)
Water
Characteristics
Water is formed by two hydrogen atoms and one oxygen atom, linked by single covalent bonds. It is electrically neutral. Water molecules can interact with each
Read MoreCirculatory Systems in Animals: Open, Closed, and Double Circulation
Open and Closed Circulatory Systems
Open Circulatory System
In an open circulatory system, the heart pumps fluid (hemolymph) through open-ended vessels that lead to tissues and body cavities, directly bathing the cells. Molluscs (except cephalopods) exemplify this system. Cephalopods have a compartmentalized heart with one ventricle and one or two atria, enclosed within a pericardial cavity. Arthropods possess a tubular heart, a thickened dorsal vessel. Hemolymph is pumped from the heart into arteries,
Read MoreSensory Systems and Musculoskeletal Anatomy
Sensory Receptors
Sensory receptors are specialized nerve cells that capture stimuli and convert them into nerve impulses. Different types of receptors respond to various stimuli:
- Chemoreceptors: Sensitive to chemical changes.
- Mechanoreceptors: Sensitive to mechanical stimuli like friction and pressure.
- Photoreceptors: Sensitive to light.
- Thermoreceptors: Sensitive to temperature changes.
- Nociceptors: Sensitive to intense pressure, responsible for pain.
Based on their location, receptors are classified
Read MoreCell Theory: Structure, Function, and Evolution of Cells
Cell Theory
All living organisms are composed of cells. The cell is the structural and physiological unit of living things, where metabolic processes occur. Cells contain hereditary information, passed from mother to daughter cells.
Comparison: Prokaryotes vs. Eukaryotes
Prokaryotes
- Typical of small cells (e.g., monera)
- No defined nucleus
- No cell envelope; may have a capsule
- Genetic material is circular DNA; no mitosis
- Lack cytoskeleton and most organelles
- Small ribosomes
- Cell wall usually present
Eukaryotes
- Typical