The Human Respiratory System

Question 1

When we inhale:
❥ The external intercostal muscles [__] and pull the ribs [__] and [__].
❥ The diaphragm [__], drops downward in the thoracic cage and takes on a [__] shape.
❥ The volume of the thorax [__], the lungs expand, such that the air pressure in the lungs [__], to below atmospheric pressure.
❥ Air is then drawn [__], into the lungs, down a pressure gradient.

Answer 1

❥ contract - upwards - outwards
❥ contracts - flat
❥ increases - decreases
❥ inwards

Question 2

When we exhale:
❥ The internal intercostal muscles [__] and allow the ribs to move
[__] and [__]. At this stage, external intercostal muscles [__].
❥ The diaphragm [__], moves upward and becomes [__] shaped.
❥ The volume of the lungs [__] and the pressure in the lungs [__].
❥ Therefore, air is pushed out of the lungs along pressure gradient.

Answer 2

❥ contract - downwards - inwards - relax
❥ relaxes - dome
❥ decreases - increases

Question 3

❥ The trachea, bronchi, and bronchioles are lined with [__ __] cells and [__] cells that secrete mucus.
❥ Dust and bacteria are trapped by the [__].
❥ The cilia [__] to carry the mucus up the nose and throat where the mucus containing the dust and particles is [__].

Answer 3

❥ ciliated epithelial - goblet
❥ mucus
❥ beat - swallowed

Question 4

The functions of C-shaped cartilage in air passages are:
❥ To hold trachea and bronchi [__].
❥ To prevent the airways from collapsing as you breathe in when the air pressure [__].
❥ To increase [__].
❥ To enable diameter of airways to [__] when coughing to free any obstruction.

Answer 4

❥ open
❥ decreases
❥ flexibility
❥ increase

Question 5

[__ __] is the diffusion of oxygen from the [__] into the [__ __] as well as the diffusion of carbon dioxide in the [__ __], from the blood capillaries into the [__].

Answer 5

Gas exchange - alveoli - blood capillaries - opposite direction - alveoli

Question 6

❥ Human lungs are well adapted for efficient gas exchange. Each lung contains millions of [__] that provide a large surface area for gas exchange to occur.
❥ A vast network of [__] surrounds each alveolus to provide constantly a blood supply.
❥ The alveolar walls and capillary walls are composed of a single layer of cells called [__]. This feature [__] the distance through which gases diffuse.
❥ The [__] walls are moist because they contain special cells that produce a watery fluid. This allows gases to dissolve and then diffuse easily across the [__].
❥ The continuous ventilation maintains a [__] diffusion gradient for the diffusion of oxygen into the
[__] and [__ __] into the alveoli.

Answer 6

❥ alveoli
❥ capillaries
❥ epithelium - reduces
❥ alveolar - membranes
❥ steep - blood - carbon dioxide

Question 7

❥ During physical activity, higher amounts of energy are needed for muscle contraction, this energy is supplied to muscle cells through an increased rate of [__ __].
❥ Levels of carbon dioxide in the blood [__].
❥ This results in a drop in [__ __] which is detected by receptors in the brain.
❥ The brain signals the respiratory muscles, the diaphragm and intercostal muscles, to [__ __] and more forcefully causing breathing to become deeper and faster.

Answer 7

❥ cellular respiration
❥ increase
❥ blood pH
❥ contract faster

Question 8

❥ Emphysema is a disease characterized by the [__ __] of the alveoli and the weakening of the [__] walls. These walls eventually break, causing the alveoli to [__]. This reduces the number of air spaces inside the lungs and decreases the surface area for gas exchange. The patients with emphysema are unable to absorb enough oxygen or remove carbon dioxide efficiently.
❥ Asthma is a disease characterized by the [__] and narrowing of the air passages, mainly the bronchi and the [__].
❥ Bronchitis is the disease caused by the buildup of [__] in the air passages and inflammation of the walls of the [__].

Answer 8

❥ irreversible enlargement - alveolar - merge
❥ inflammation - bronchioles
❥ mucus - bronchi

Question 9

Nicotine is the addictive substance in tobacco smoke. It makes quitting very difficult for smokers.
❥ Nicotine increases [__ __].
❥ Nicotine also contributes to the build-up of [__] deposits in the walls of the arteries. This increases the risk of [__ __] disease.

Answer 9

❥ blood pressure

❥ fatty - coronary heart

Question 10

❥ Carbon monoxide in cigarette smoke combines with the oxygen-carrying pigment [__], reducing the amount of oxygen transported by the blood to the different body organs.
❥ Carbon monoxide causes the [__] to stop beating, consequently causing [__] to build up and collect in the air passages and lungs. As a results smoker’s cough develops.
❥ Carbon monoxide causes a build-up of [__] deposits on the walls of arteries which leads to the formation of [__ __]. This increases the risk of the blockage of some arteries such as the [__ __], thereby contributing to coronary heart disease (CHD) and increasing the risk for heart attacks.

Answer 10

❥ hemoglobin
❥ cilia - mucus
❥ fatty - blood clots - coronary arteries

Question 11

Smoke particles and [_] irritate the lungs, causing inflammation and an increased production of mucus. Tar is also [__] and leads to cancer of the.

Answer 11

tar - carcinogenic