Human Body Systems: Circulatory, Excretory, and Nervous
Circulatory System
The circulatory system involves a continuous loop:
Left auricle → bicuspid valve → left ventricle → aorta artery → vena cava → right auricle → tricuspid valve → right ventricle → pulmonary artery → lungs (alveoli) → pulmonary vein → left auricle.
Blood
Types of Blood Cells
- RBC (Red Blood Cells): No nucleus, contains hemoglobin.
- WBC (White Blood Cells):
- Phagocytes: Engulf bacteria and viruses (phagocytosis).
- Lymphocytes: Produce antibodies.
- Platelets: No nucleus.
Functions
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The Digestive System: A Detailed Look
Chewing: This is a mechanical process that involves grinding food into smaller pieces to facilitate digestion. Chewing is performed by the teeth, aided by the tongue. Teeth are hard structures containing calcium and fluoride, responsible for crushing food. Types of teeth include:
- Incisors: Used to cut food.
- Canines: Also called tusks, used to tear food.
- Premolars and Molars: Known as molars, their function is to grind food.
Salivation: Saliva, secreted by the salivary
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Meiosis
Meiosis: Duplication of DNA, with 2 successive divisions, a mechanism which maintains variability.
Meiosis involves:
- One duplication of DNA, variability through crossing over (metaphase I).
- Two successive divisions: 1st meiotic (prophase I, metaphase I, anaphase I, telophase I, cytokinesis I), 2nd meiotic (II).
Haploid Cells
Haploid cells include sperm and oocytes.
Crossing Over
Crossing over is the exchange of chromatid segments between chromatids.
Prophase I
During prophase I, chromosomes have doubled
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Heart Anatomy and Physiology
The heart, a muscular organ, is located below the sternum and between the lungs. Its bottom part is in contact with the diaphragm. It is composed of two atria and two ventricles. The heart also has four valves: the tricuspid valve, pulmonary valve, mitral valve, and aortic valve.
The heart’s physiology involves two circulations. The large systemic circulation is the movement of blood that leaves the heart and supplies the body. The small pulmonary circulation is the movement
Read MoreEvolutionary Biology: Key Concepts and Theories
Key Concepts in Evolutionary Biology
PUNT (Punctuated Equilibrium): The theory suggests that there are certain periods of intense speciation which interrupt the equilibrium of normal adaptation.
Fixism: Upholds the idea that species on Earth were created by God.
Catastrophism: Proposed by Cuvier, it maintained that fossils were the remains of extinct species that had died out as a result of catastrophes.
Evolution: Maintains that species undergo a process of transformation which results in the appearance
Read MoreTaste and Hearing: Anatomy, Function, and Disorders
Taste
- Taste receptors are chemoreceptors.
- Taste buds are directly related to nerve fibers.
- The structure of language is important in taste perception.
- Monosodium glutamate is responsible for the umami flavor.
- Flavors are perceived in the palatal portion of the tongue.
- The tongue structure is flexible, not rigid.
- Filiform papillae are also known as conical papillae.
- Taste buds are inside the taste bud.
- Saliva contributes to, rather than decreases, the perception of taste by degrading food and chemical substances.