Human Body Systems: Respiration, Excretion, and Circulation
The Respiratory System: Air Circulation and Gas Exchange
The respiratory system is responsible for circulating air.
Components of the Respiratory System
- Upper Tract: Pharynx.
- Lower Tract: Bronchioles.
- Air Entry: Nose and Mouth (air passes to the pharynx).
- Trachea: Flexible tube, kept open.
- Larynx: Funnel-shaped structure with internal hard walls. Note: The text states 'No vocal strings.'
- Lungs: Located in the thoracic cavity, protected by ribs, resting on the diaphragm.
- Bronchi: Two main bronchi branch into increasingly thin bronchioles.
Alveolar Gas Exchange (Interchange)
Gas exchange occurs easily across the surface of the alveoli. Alveoli are thin-walled and surrounded by blood capillaries.
- Oxygen (O₂) from the air passes into the blood.
- Carbon Dioxide (CO₂) from the blood passes from the walls into the alveoli.
This transfer happens via diffusion, moving from areas of higher concentration to lower concentration.
Respiratory Movement (Ventilation)
Movement involves the elastic walls of the lungs, the diaphragm, and muscles between the ribs.
- Inspiration: Diaphragm and intercostal muscles contract, increasing the thoracic cavity volume. Air enters.
- Expiration: Muscles relax, lung elasticity causes volume to decrease. Abdominal muscles are involved. The text mentions 'spiral columns decreases' in relation to expiration.
Respiratory Infections and Damage
Common Respiratory Illnesses
These are sometimes referred to simply as "breathing infections": colds, flu, bronchitis, and pneumonia.
Damage Caused by Smoking
- Chronic Bronchitis: Substances in smoke obstruct the airways.
- Lung Cancer: Uncontrolled growth of malignant cells.
Hygiene for the Respiratory System
Recommendations for respiratory health:
- Inspiring air through the nose.
- Avoiding polluted indoor environments.
- Covering the mouth when coughing or sneezing (using a cloth or handkerchief).
The Excretory System and Urinary Function
Excretion and Urine Composition
Excretion is the process of removing waste substances. Urine consists primarily of water, salts, and urea.
Components of the Urinary System
- Kidneys: Located near the spine; they form urine.
- Kidney Structure: The text identifies three parts: Cortex (Bark), Medulla (Bone), and the Renal Artery and Vein.
- Ureters: Two thin tubes carrying urine from the kidneys.
- Bladder: Collects urine; contracts when the need to urinate arises.
- Urethra: Carries urine out of the body.
Urine Formation: The Nephron
The basic functional unit of the kidney is the nephron, formed by a capsule and a tubule. Urine formation is the result of the nephrons' work.
The Filtration Process
Blood capillaries filter small molecules (water, salts, glucose, urea). Glucose and 99% of the filtered substances are returned to the blood.
Water Regulation and Kidney Function
The kidney has a dual function:
- Cleaning the blood.
- Controlling the amount of water and salts contained in the blood.
Urinary System Issues and Care
Urinary Infections and Calculi
- Cystitis: Inflammation of the bladder.
- Calculi (Stones): Stones block the ducts, leading to very painful expulsion known as renal colic.
Kidney Failure Treatment
If the kidneys do not work, Hemodialysis is performed using an artificial kidney machine.
Care for the Urinary System
- Consume nitrogenous foods in moderation.
- Drink plenty of water to dissolve waste.
Homeostasis and Internal Stability
Homeostasis refers to the set of mechanisms by which living beings tend to reach stability in the properties of their internal environment.
- Lungs: Regulate O₂ and CO₂ levels.
- Liver: Regulates blood glucose.
- Skin: Regulates temperature (Tº).
Blood Circulation Path
The Journey from the Right Ventricle
The path of blood flow starting from the Right Ventricle:
- Right Ventricle
- Pulmonary Artery
- Tricuspid Valve (as listed in the original text)
- Lungs
- Pulmonary Vein
- Left Atrium
- Left Ventricle
- Aortic Valve
- Aorta (Aortic Artery)
- Organ/Body
- Vena Cava
- Right Atrium and Right Ventricle