Circulatory and Excretory Systems in Animals
Lymphatic Circulatory System
The lymphatic circulatory system, characteristic of vertebrates, is made up of lymphatic vessels and lymph nodes. Lymph is the circulating fluid. The lymphatic vessels are formed as terminal hairs, with one end closed. They are found in almost all tissue spaces and merge to form larger lymphatic vessels containing valves inside that prevent the backward flow of lymph. The lymphatic vessels drain into the blood circulatory system.
Lymph nodes are structures located along
Read MoreUnderstanding Depressants, Narcotics, and Genetic Engineering
Depressants and Narcotics
Depressants: reduce activity and promote relaxation. Small doses can produce euphoria. Abuse causes damage to the central nervous system. Examples include sedatives, anxiolytics, alcohol, and inhalants.
Narcotics: reduce central nervous system activity and relieve pain. Examples include opioids, morphine, and heroin.
Common Health Conditions
Stress: the body’s response to problems, causing physical and psychological changes that can severely affect health.
Alzheimer’s: a process
Read MoreThe Genesis of Life: From Primordial Soup to Complex Organisms
Act II. The Life
Scene I. The Early Word
Pasteur, Darwin, and the Origin of Life
What roles did Pasteur and Darwin play in explaining the origin of life?
Pasteur demonstrated that microscopic germs are everywhere. In an experiment, he isolated a meat and vegetable broth, boiled it for sterilization, and concluded that life does not arise spontaneously but is a process that takes time.
Darwin championed the principle of evolution, where species are modified by natural selection—nature selects the fittest
Read MoreCellular Biology: DNA, RNA, Chromosomes, and Genetics
Cellular Components and DNA
Cell: The DNA resides within the cell. During cell reproduction, DNA is maintained in both daughter cells, ensuring they inherit the same characteristics as the parent cell. A cell contains three organelles within the nucleus and two outside. Eukaryotic cells possess a nuclear envelope, while prokaryotic cells do not. The main components of a cell are the nucleus, cytoplasm, and cell membrane.
DNA: The term DNA stands for deoxyribonucleic acid. It carries all genetic information.
Read MoreAnimal and Human Digestive System Structures
Nutrition: Different Structures
- Snakes: They have a specialized adaptation of their oral equipment. Their fangs are hollow and connected to the venom gland, a modified salivary gland. The poison is used to immobilize prey.
- Butterflies: They have highly specialized mouthparts that enable them to extract nectar from flowers.
- Sharks: Their teeth grow continuously. As teeth are worn, new rows form.
- Hippos: They spend all day in the water, gathered in groups of up to 150 individuals, and disperse to feed
Cellular Nutrition: Processes, Types, and Metabolism
Cellular nutrition consists of all the processes in which cells obtain matter and energy to perform their vital functions. Cells need energy to carry out their activities and matter to build their components.
Substance Interchange
- Osmosis: This is the normal way of interchanging water. Water passes through the cell membrane from a less concentrated solution to a more concentrated one, separated by a semi-permeable membrane, such as the plasmatic membrane of cells, which allows its passage but not