Excretory and Nervous Systems: Human Body Functions
Theme 5: The Excretory System
The excretory system includes organs responsible for eliminating waste and foreign substances. It also maintains vital signs, such as the amount of water in the organism and blood acidity.
- Liver: Eliminates products resulting from the destruction of blood hemoglobin.
- Respiratory System: Expels carbon dioxide.
- Sweat Glands: Located in the skin, they produce sweat, which cools the skin when the temperature is high.
- Urinary System: Eliminates waste products through urine.
The
Read MoreHuman 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
Read MoreUnderstanding Human Digestion and Respiration
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
Read MoreMeiosis, Menstrual Cycle, and Histology: Key Concepts
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
Read MoreUnderstanding Heart, Lungs, Puberty, Immunity, and Prevention
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
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