Ch.30 - Human Breathing

Question 1

What separates the thoracic cavity from the abdominal cavity?

Answer 1

The diaphragm separates the thoracic and abdominal cavities.

Question 2

Draw a diagram of the parts of the respiratory system.

Answer 2

Question 3

What is the pathway for air entering the nose?

Answer 3

Air enters the nostrils then passes through the trachea, after the epiglottis, pharynx and then larynx. The base of the trachea branches into 2 bronchi (for RHS and LHS of lung). From the bronchus, air enters bronchioles, where rings of cartilage keeps the bronchioles from falling in. The bronchus and bronchioles are lined with cilia. Finally, the air reaches the alveoli, where gases are exchanged.

Question 4

What are the functions of the nose?/Why is breathing through the nose beneficial?

Answer 4

Air in the nasal passages is filtered by the hair and mucus in the nostrils, it is moistened and warmed. Moist, warm air passes more easily from the lungs into the bloodstream.

Question 5

What is the pharynx and the larynx?

Answer 5

The pharynx is the throat. The larynx(Adam’s apple) is the voice box, it makes sound.

Question 6

What is the epiglottis?

Answer 6

The epiglottis is a flap of tissue in the pharynx. It closes over the trachea when we swallow. This prevents food and drink from passing into the trachea.

Question 7

What are trachea, bronchi and the higher bronchioles made of?

Answer 7

They are all made of muscle and elastic fibres along with C-shaped rings of cartilage. Cartilage is a strong, rigid material which prevents the tubes from caving in. Lower, smaller bronchioles do not contain cartilage.

Question 8

What defends infection in the lungs?

Answer 8

The tubes in the respiratory system are lined with mucus and cilia. The mucus is sticky so it traps dust, bacteria and viruses. The cilia beat and create an upward current, moving the mucus past the epiglottis and down the oesophagus to the stomach.

Question 9

What are the lungs enclosed with?

Answer 9

The lungs are enclosed by a pair of pleural membranes. The outer pleura lines the chest wall and the diaphragm. The inner pleura lines the lungs. The pleural cavity is the gap between the pleura, it contains a liquid which reduces friction when breathing(by lubricating the pleura).

Question 10

What are alveoli? What are their function? How are they adapted for their function?

Answer 10

Alveoli are tiny air sacs in which gas exchange takes place. Their are many alveoli which provides a huge surface area for gas exchange, they are thin walled, ideal for diffusion. They have moist surfaces and they are enclosed in a network of capillaries.

Question 11

Describe the chemical reaction involved in respiration.

Answer 11

In body cells, respiration occurs to release energy. They use up glucose and oxygen to produce CO2 and water.

Question 12

Describe gaseous exchange in the alveoli.

Answer 12

The exchange of gases occurs by diffusion.
The concentration of oxygen in the alveoli is high but low in the pulmonary capillary. So oxygen diffuses from the alveoli in to the pulmonary capillaries.
The concentration of CO2 and water in the alveoli is low but high in the pulmonary capillaries. So CO2 diffuses from the capillaries into the alveoli. Water goes from the capillaries to the alveoli by osmosis.

Question 13

How are gases(and water) transported through the body?

Answer 13

Oxygen is transported by combining with haemoglobin to form oxyhaemoglobin. Carbon dioxide and water are dissolved in the blood plasma. (Around 3% of oxygen is carried dissolved in plasma).

Question 14

Draw a diagram of the gas exchange in an alveolus.

Answer 14

Question 15

What is inhalation and exhalation?

Answer 15

Inhalation is breathing in. Exhalation is breathing out. Inhalation is an active process. Exhalation is a passive process.

Question 16

What controls the rate of breathing?

Answer 16

The medulla oblongata controls the rate of breathing. The brain detects decreases in pH which triggers the brain to cause breathing. Respiration produces water and carbon dioxide. Carbon dioxide dissolves in water to form carbonic acid. This decreases the blood’s pH. High carbon dioxide concentration operates as a controlling factor in gas exchange rather than low oxygen concentration.

Question 17

Describe the mechanism of breathing.

Answer 17

The medulla oblongata sends impulses to the intercostal muscles and the diaphragm muscle to contract and relax.

Question 18

What is asthma? Symptoms, causes, prevention, treatment?

Answer 18

Asthma is a respiratory disease. Symptoms include breathlessness and wheezing. Asthma is caused by inhaled allergens, such as pollen, animal dander and tobacco smoke. In asthma attacks, the lower bronchioles become inflamed and constricted. Asthma attacks may be prevented by avoiding known allergens. (preventative inhalers that prevent bronchioles from reacting to allergens may be used). The treatment for asthma is inhaling bronchodilators which dilate the bronchioles. (Steroid may be inhaled, reducing inflammation and drugs may be given by injection).

Question 19

How does the breathing system respond to a high level of CO2?

Answer 19

Excess CO2 increases blood pH due to its dissolving in water and forming carbonic acid. Chemoreceptors in the brain detect high blood pH and increases the rate and depth of breathing.