Postmortem Skin Findings: Discoloration, Bruising, Abrasions
Postmortem Body Surface Changes
Examining the body surface reveals various postmortem changes, including discoloration similar to bruising (pseudo-ecchymotic discoloration):
- Cyanotic Spots: These appear on the face and, more rarely, in the neck region in cases of death from acute cardiorespiratory failure.
- Livor Mortis (Cadaveric Lividity): These discolorations are linked to body position after death, forming only in dependent areas. They are not prominent, the blood is not extravasated outside vessels
Advances in Biology: Cells, Immunity, and Reproduction
Stem Cells and Differentiation
Stem cells are pluripotent, meaning they can differentiate into any of the approximately 200 cell types that exist in the organism. Their differentiation into a specific cell type depends on chemical signals – substances that induce changes in gene expression, protein production, or other cellular processes. For example, they can become:
- Cardiac cells
- Retinal epithelial cells
- Pancreatic beta cells
Embryonic stem cells are obtained from blastocysts, a very early stage
Read MoreEnzymes, Carbohydrates, and Spectrophotometry: A Review
Enzymes: Proteinaceous Catalysts
Enzymes are proteinaceous substances involved in biochemical reactions. They are proteins formed from amino acids. When the number of amino acids is between -100 and +100, they are called polypeptides. The linear sequence of amino acids, known as the primary structure, is unique for each protein and dictates its function.
Enzymes can only bind to a specific substrate, forming a reversible enzyme-substrate complex. They are used as reagents in clinical chemistry because
Read MoreEndoplasmic Reticulum: Key Cellular Functions
Rough ER: Exportable Protein Synthesis
Proteins destined for export enter the Rough Endoplasmic Reticulum (RER) lumen through a channel. The signal peptide is cleaved by a signal peptidase, leaving the mature protein ready for further processing and export.
Smooth ER: Lipid Synthesis and Metabolism
Lipid synthesis and metabolism primarily occur in the Smooth Endoplasmic Reticulum (SER), although some fatty acids and phospholipids are synthesized in mitochondria. The SER is crucial for synthesizing:
Read MoreHuman Blood: Components and Functions
Blood
The human body contains several extracellular fluids that constitute the internal environment. These include the interstitial fluid of the intercellular matrix and circulating fluids such as blood and lymph. These fluids act as intermediaries between the highly variable external environment and the intracellular environment, where metabolic reactions occur.
Blood is a liquid tissue, part of the internal environment, that circulates through blood vessels.
Blood performs a wide variety of functions:
Read MoreMollusk and Annelid Characteristics & Classes
Mollusks: Diverse Invertebrates
Mollusks are a diverse group of invertebrates, including snails, clams, squids, and octopuses. They have soft bodies, often protected by a shell, and exhibit a wide range of adaptations.
Mollusk Body Plan
- Head-foot: Includes the sensory organs and movement structures.
- Visceral mass: Contains internal organs like the heart, digestive system, and reproductive organs.
- Mantle: Secretes the shell and forms the mantle cavity, housing gills or lungs.
- Radula: A specialized feeding