Animal Transport Systems: From Hidrolinfa to Human Circulation
Transportation Systems
Acquired nutrients are distributed among all the cells in your body to ensure the proper functioning of animal metabolism. Waste products are expelled outside. Animals with simple structures do not need a transport system, since cells may acquire or expel substances from the environment in which they live. However, animals with highly complex needs require a circulating medium which serves to distribute nutrients and collect metabolic waste. In many cases, it also requires
Read MoreTypes of Environmental Pollutants and Their Health Impacts
Classification of Pollutants
Pollutants can be classified according to their specific characteristics:
- Physical agents
- Chemical agents
- Biological agents
- Psychological pollutants
Physical Pollutants
Physical contaminants alter the environment’s quality by their mere presence. They are characterized by an energy exchange between a person and the environment at a rate the body cannot withstand. Radioactivity (natural or artificial) is a significant example of physical pollution related to environmental geology.
Read MoreCellular Organelles: Functions and Processes
The Endoplasmic Reticulum
The endoplasmic reticulum (ER) is a network of tubules and flattened sacs. Its membrane constitutes about 50% of all cell membranes, and it is continuous with the outer nuclear envelope. There are two types:
- Smooth Endoplasmic Reticulum (SER): Lacks ribosomes.
- Rough Endoplasmic Reticulum (RER): Has ribosomes attached to its cytosolic side.
Functions of the Smooth Endoplasmic Reticulum (SER)
- Lipid Synthesis: Manufactures lipids (phospholipids and cholesterol) and their derivatives,
Five Kingdoms of Life: Characteristics and Classification
Monera: Prokaryotes
Prokaryotes are single-celled organisms with a very simple structure. Bacteria are prokaryotes and come from more primitive groups with similar body structures. Their evolution traces back to a common ancestor, an anaerobic prokaryote.
- Cyanobacteria: Responsible for the increase of oxygen in the atmosphere thanks to their photosynthetic capacity.
Prokaryotes are classified into two major domains:
- Archaea: These bacteria live outdoors, have no murein cell wall, and their lipids are
Proteins, Amino Acids, Enzymes, and Nucleic Acids: Cellular Functions
Proteins
Proteins are the most abundant organic molecules in cells, making up 50% or more of their dry weight. They are found in all parts of all cells, as they are fundamental in all aspects of cellular structure and function. There are many different kinds of proteins, each specialized for a different biological function. Moreover, most genetic information is expressed by proteins. They belong to the class of peptides and are composed of amino acids linked together by peptide bonds. A peptide bond
Read MoreNervous and Endocrine Systems: Structure and Function
Nervous System Organization
Diffuse Network
The diffuse network, a very primitive nervous system found in polyps and jellyfish, is characterized by a network of star-shaped nerve cells distributed throughout the body. There is no cephalic region, but they have sensory organs such as statocysts for balance and ocelli for detecting light and shadow.
Cordlike Nervous System (SN Cordes)
Planaria possess a pair of nodes in the anterior region, forming a primitive brain. From this, two nerve cords run centrally
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