Respiration in Humans (chapter 7)

Aerobic respiration

Aerobic respiration is the release of energy by the breakdown of glucose in the prescience of oxygen. Carbon dioxide and water are released as waste products. Aerobic respiration releases large amount of energy.

Anaerobic Respiration

Anaerobic Respiration is the release of energy by the breakdown of glucose in the absence of oxygen. Anaerobic respiration releases relatively small amounts of energy.

The nose

• Dust Foreign particles, including bacteria in the air, are trapped by the hairs in the nostrils as well as by the mucus on the mucous membrane.

• As air passes through the nasal passages, it is warmed and moistened

• Harmful chemicals may be detected by small sensory cells in the mucous membrane

Trachea

The membrane next to the lumen is the epithelium which contains two types of cell:

• Gland cells- secret mucus to trap dust particles and bacteria

• Ciliated cells- have hair-like structure called cilia on their surfaces. The cilia sweep the dust-trapped mucus up the trachea.

How the lungs adapted for efficient Gas exchange

• numerous alveoli in the lungs provide a larger surface area (only for alveoli not alveolus)

• the wall of the alveolus is only one cell thick, provides a shorter diffusion distance for gases, ensuring a higher rate of diffusion.

• A thin film of moisture covers the inner wall of the alveolus, allowing oxygen to diffuse in it.

• The walls of the alveoli are richly supplied with blood capillaries. The flow of blood maintains the concentration gradient of gases.

how does gas exchange occur in the alveoli

• Oxygen dissolves into the thin film of moisture on the wall of the alveolus.

• The dissolved oxygen then diffuses through the wall of the alveolus and the wall of the blood capillary into the red blood cells.

• The oxygen combines with the haemoglobin to form oxyhaemoglobin.

• carbon dioxide diffuses from the blood into the alveolar air.

The oxygen and carbon dioxide concentration gradients between the alveolar air and the blood are maintained by

• a continuous flow of blood through the blood capillaries

• continuous breathing, causes air in the lungs to be constantly refreshed.

Inspiration (Inhalation)

1. Your diaphragm muscles contract, and the diaphragm flattens.

2. Your external intercostal muscles contract while your internal intercostal muscles relax.

3. Your ribs move upwards and outwards. Your sternum also moves up and forward.

4. The volume of your thoracic cavity increases.

5. Your lung expand and air pressure inside them decreases as the volume increases.

6. Atmospheric pressure is now higher than the pressure within your lungs

7. Air moves into your lungs.

Expiration (exhalation)

1. Your diaphragm muscles relaxes and the diaphragm arches upwards.

2. Your internal intercostal muscles relaxes.

3. Your ribs move downwards and inwards. Your sternum also moves down to it’s original position.

4. The volume of your throat cavity decreases

5. Your lungs are compressed and air pressure inside them increases as the volume decreases. Pressure within the lungs is now higher than the atmospheric pressure. The air ids forced out of your lungs to the exterior environment.

Effect of Nicotine on the Human Health

• increases heartbeat rate and blood pressure

• increases the risk of blood clots in the arteries, leading to risks of coronary heart diseases

• increases the risk of arteries to narrow

Effect of Carbon monoxide on Human Health

• reduces ability of blood to transport oxygen as carbon monoxide binds permanently with haemoglobin. less haemoglobin available yo transport oxygen

• increases risk of coronary heart disease

effect of Tar on the human health

• increases the risk of cancer in the lungs as tar can cause uncontrolled cell division.

• increases the risk of chronic bronchitis and emphysema.

• Tar paralyses the cilia lining air passages. Hence, dust particles are trapped in the musics lining can not be removed

Diseases caused by tobacco smoke

Chronic Bronchitis:

• The epithelium lining of air passages

• Excessive mucus is secreted by the epithelium

• The cilia on the epithelium are paralysed and mucus and dust cannot be removed

• air passages become blocked, making breathing difficult,

• Persistent coughing occurs to clear air passages.

Emphysema:

• The partition walls between the alveoli break down due to persistent and violent coughing

• results in a decreased surface area for gaseous exchange.

• The lungs lose their elasticity and becomes inflates with air

• Breathing becomes difficult. Wheezing and serve breathlessness result.