Gases Exchange

What is gaseous change? Gaseous exchange basically is the change of gases which occur between living organism and the surrounding environment. In animals what are the gases which are ‘exchanged’ and where are they produced?

What is the importance of gaseous exchange in man? Respiring cells need a continuous supply of _______.They must also get rid of _______. That is being produced constantly. what transports these two gases to the cells? Blood. Where do u this gaseous exchange take place in humans? lungs

The lung and gaseous exchange

The human respiratory system This system includes the lungs, pathways connecting them to the outside environment, and structures in the chest involved with moving air in and out of the lungs Use the following diagram to label the diagram of the human respiratory system giving

The lung The lungs are very important and are made up of tiny air spaces or sacs called alveoli.

Lets follow the passage of air that enters the body Air enters the body through the nose, is warmed, filtered, and passed through the nasal cavity. Air passes the pharynx (which has the epiglottis that prevents food from entering the trachea). The upper part of the trachea contains the larynx. The vocal cords are two bands of tissue that extend across the opening of the larynx. After passing the larynx, the air moves into the bronchi that carry air in and out of the lungs.

Bronchi are reinforced to prevent their collapse by rings of cartilage The bronchi are lined with ciliated epithelium (cilia)and mucus-producing cells. Bronchi branch into smaller and smaller tubes known as bronchioles. Bronchioles terminate in grape-like sac clusters known as alveoli. alveoli full

Alveoli The walls of the alveoli are the gaseous exchange surfaces. The smallest blood vessels, capillaries, are closely wrapped around each alveolus. Oxygen diffuses across the walls of the alveolus into the capillary and the blood becomes oxygenated. Carbon dioxide diffuses from the capillary into the alveolus and is exhaled out of the body The walls of the alveolus and capillary are very thin (one cell thin) so that diffusion can occur readily

What do cilia and mucus do? The trachea is lined with mucus a slimy substance which traps and holds dust and micro-organisms. The trachea is also lined with cilia which beat in a wave-like manner, moving the mucus containing dust and micro-organisms upward and out of the lungs

Sneezing Irritating substances like dust stimulate a sneeze which ejects the irritant out of the lungs

The Mechanism of gaseous exchange in animals Breathing in is called inspiration Breathing out is called expiration

Adaptations for efficient gaseous exchange Large surface area Thin surface for gaseous exchange Constant moving transport medium

The effects of cigarette smoking

Facts About smoking Causes over 3 million deaths worldwide a year Deaths are mainly from lung cancer, but heart disease is also associated with smoking Cigarette smoke contains tar, nicotine and carbon dioxide

Nicotine Makes cigarettes highly addictive. Reduces air flow in and out of the lungs. Paralyses the cilia lining the trachea, which remove dirt and bacteria. Raises blood pressure. Raises heart rate. Increases the risk of osteoporosis

Tar Sticks to cells in the lungs Causes the development of cancer. Breaks down the alveoli, thus decreasing the surface area for gaseous exchange. . Causes bronchitis or inflammation of the lining of the air passages. Causes 'smokers cough'.

Carbon monoxide Combines irreversibly with haemoglobin in the blood. Causes less oxygen to be transported by blood. Reduces the smoker's ability to take strenuous exercise Causes breathlessness. If a pregnant woman smokes, carbon monoxide gets into the blood of the fetus and combines with the haemoglobin. Less oxygen gets to the growing tissues, resulting in a smaller birth weight which is associated with greater risk of health

Appearance of lungs