Basic Science 2
Prepared by: Maria Johanna Baguio Testa
Chapter 1. Human Body Systems
By the end of this chapter, you should be able to:
- Identify the organs and describe the functions of the organs involved in the respiratory system.
- Explain the mechanisms of inhalation and exhalation and the process of gas exchange.
- Identify the organs and describe the functions of the organs in the excretory system for the elimination of waste products in kidneys.
- Describe the structures and functions of the heart, blood vessels and blood.
- Explain the process of circulatory system using a model.
- Design and conduct an experiment to compare the normal heart rate and the heat rate after doing activities.
- Identify and describe the functions of organs in CNS that control and coordinate the human body
- Realize the importance of our systems by suggesting guidelines how to take care of them.
Human Body Systems
Human body - the physical substance of the human organism, composed of living cells and extracellular materials and organized into tissues, organs, and systems. (cell - is the basic unit of life)
- cell
- tissue
- organ
- organ system
- organism
1.1 Respiratory System
The human respiratory system provides an area for gas exchange between the blood and the environment.
The gas exchange in lungs is called breathing (external respiration). This exchange involves inhalation [1. breathing in O2 (oxygen)] and exhalation [2. breathing out CO2 (carbon dioxide)].
Structure of the Human Respiratory System
*note: need to memorize. The air we breath travels from nasal cavity down to the capillaries (where the exchange of gases (O2, CO2) takes place)
Follow oxygen through the nose or mouth, down the pharynx and larynx, and past the trachea to the lungs
The respiratory tract conveys air from the mouth and nose to the lungs, where oxygen and carbon dioxide are exchanged between the alveoli and the capillaries.
Structure of The Lungs
The lungs are made up of alveoli (are tiny air sacs), bronchioles and blood capillaries. The lungs are located in a space called thoracic cavity. The lungs are protected by the rib cage which consists of ribs and intercostal muscle. A sheet of muscle called the diaphragm separates the thoracic cavity from the abdomen.
Adaptation of the Alveoli for Efficient Gas Exchange
- Large surface area
Lungs have millions of alveoli to provide a large surface area for gas exchange.
- Very thin walls
Alveolus is one cell thick to provide a very short distance for diffusion of gases
- Moist inner surface
The inner surface of each alveolus is moist so that oxygen can dissolve in the moisture before diffusing across the alveolar wall.
- Surrounded by numerous blood capillaries
The blood capillaries help to transport gases to and from the alveoli quickly.
Adaptation of the Alveoli for Efficient Gas Exchange
Mechanism of Human Breathing
The breathing mechanism consists of two phases. The taking in of air is called inhalation. The letting out of air is called exhalation.
Gas Exchange
- The diffusion of oxygen from the alveoli into the blood capillaries.
Gas exchange takes place in lungs by diffusion.
- The transport of oxygen by blood.
The red blood cells contain the oxygen-carrying pigment called hemoglobin. Oxyhemoglobin oxygen combines with hemoglobin.
- The diffusion of oxygen from the blood capillaries into the body cells.
Gas exchange also takes place between capillaries and the body cells
Mechanism of Human Breathing
The breathing mechanism consists of two phases. The taking in of air is called inhalation. The letting out of air is called exhalation.
Taking Care of Our Respiratory System
- Harmful Substance
The air we breathe in may contain substances that are harmful to our respiratory system. The table below shows the types of harmful substances and their effects on our respiratory system.
Diseases of the Respiratory system
- Asthma is a chronic disorder of lungs in which the airways are prone to constrict. This may due to the patient’s sensitivity to air pollutants. The patient may suffer from: wheezing, chest tightness, coughing and breathlessness.
- Bronchitis is the inflammation of the bronchi. This may due to the infection by bacteria or viruses, or chemicals such as those in cigarette smoke.
- Emphysema is a condition due to the loss of air within the lungs. This reduces the surface area for gas exchange, leaving the person constantly short of breath.
- Lung cancer is caused by uncontrolled growth of cells in the lungs. Cigarette smoking is the leading cause of lung cancer.
Practice Test (write your answers in your notebook)
Q1. (a) Name the muscles that are used for breathing.
(b) Explain how the muscles mentioned in (a) are involved in inhalation.
Q2. If there is a hole in the chest wall, a person may not be able to breathe even though his lungs are not damaged. Explain.
Q3. By what physical process does oxygen enter the capillaries from the alveoli?
Q4. How does blood supply the body tissues with oxygen?
Q5. How do we keep our respiratory system healthy?