Science CT3 Respiratory System

What is the word equation for aerobic respiration?

Glucose + Oxygen → Carbon Dioxide + Water + Energy (ATP)

Where does aerobic respiration occur in the cell?

Mitochondria

What is the difference between breathing and respiration?

Breathing is the mechanical process of moving air in and out; respiration is the chemical process that releases energy from glucose

What are the five main parts of the respiratory system in order from nose to gas exchange surfaces?

Nose (nasal cavity) → Trachea → Bronchi → Bronchioles → Alveoli

What is the function of the nasal cavity?

Warms, moistens, and filters incoming air (using hairs and mucus)

What is the function of the trachea (windpipe)?

Carries air from the nose/mouth to the lungs; lined with ciliated epithelium and mucus

What are the bronchi?

Two tubes that branch from the trachea into each lung

What are the bronchioles?

Smaller tubes that branch from the bronchi throughout the lungs

What are the alveoli?

Tiny air sacs at the end of bronchioles where gas exchange occurs

What is the function of the diaphragm?

A sheet of muscle below the lungs that controls breathing

What are the intercostal muscles?

Muscles between the ribs that help move the ribcage during breathing

What happens to the diaphragm during inhalation?

Contracts (flattens, moves down)

What happens to the intercostal muscles during inhalation?

Contract (ribs move up and out)

What happens to the volume of the chest cavity during inhalation?

Increases

What happens to the pressure inside the lungs during inhalation?

Decreases (below atmospheric pressure)

Why does air move into the lungs during inhalation?

Air moves from high pressure outside to low pressure inside the lungs (pressure gradient)

What happens to the diaphragm during exhalation?

Relaxes (moves up into a dome shape)

What happens to the intercostal muscles during exhalation?

Relax (ribs move down and in)

What happens to the volume of the chest cavity during exhalation?

Decreases

What happens to the pressure inside the lungs during exhalation?

Increases (above atmospheric pressure)

Why does air move out of the lungs during exhalation?

Air moves from high pressure inside the lungs to low pressure outside

Name two features of the alveoli that make them efficient for gas exchange

Thin walls (one cell thick) for short diffusion distance; large surface area (millions of alveoli); surrounded by capillaries (rich blood supply); moist surface (gases dissolve); ventilated (fresh air constantly brought in)

What is the function of the cilia in the trachea and bronchi?

Beat in waves to sweep mucus upwards towards the throat (part of the mucus escalator)

What is the function of mucus in the trachea and bronchi?

Traps dust, bacteria, and pathogens (preventing them from reaching the lungs)

What are the two components of the mucus escalator?

Cilia (sweeps mucus upwards) and mucus (traps pathogens)

What happens to mucus after it is swept up by cilia?

It is either swallowed (into the stomach, where acid kills pathogens) or coughed out (expelled from the body)

Why is the mucus escalator important?

Prevents infections and keeps the airways clear for efficient gas exchange

What gas moves from the alveoli into the blood, and in which direction does it diffuse?

Oxygen diffuses from alveoli (high concentration) → blood (low concentration)

What gas moves from the blood into the alveoli, and in which direction does it diffuse?

Carbon dioxide diffuses from blood (high concentration) → alveoli (low concentration)

What is the protein in red blood cells that carries oxygen?

Haemoglobin

What is it called when haemoglobin has oxygen bound to it?

Oxyhaemoglobin

Define diffusion

The net movement of particles from a region of higher concentration to a region of lower concentration, down the concentration gradient, until equilibrium is reached

Does diffusion require energy?

No, diffusion is a passive process (no energy required)

What is the percentage of oxygen in inhaled air?

Approximately 21%

What is the percentage of oxygen in exhaled air?

Approximately 16%

What is the percentage of carbon dioxide in inhaled air?

Approximately 0.04%

What is the percentage of carbon dioxide in exhaled air?

Approximately 4%

Why does exhaled air have less oxygen than inhaled air?

Oxygen is used for aerobic respiration in the body's cells

Why does exhaled air have more carbon dioxide than inhaled air?

Carbon dioxide is produced as a waste product of aerobic respiration

Why does the percentage of nitrogen stay the same in inhaled and exhaled air?

The body does not use nitrogen, so it is simply inhaled and exhaled unchanged

Why is exhaled air warmer than inhaled air?

The air is warmed by the body as it passes through the respiratory system

Why is exhaled air more moist than inhaled air?

The body adds water vapour to the air as it passes through the respiratory system

What happens when you breathe out through a straw into limewater?

The limewater turns cloudy (milky)

Why does limewater turn cloudy when you breathe into it?

Exhaled air contains carbon dioxide, which reacts with limewater (calcium hydroxide) to form calcium carbonate (a white precipitate)

Name three harmful substances in cigarette smoke

Tar, nicotine, carbon monoxide

What is tar?

A sticky, brown substance in cigarette smoke that damages cilia and contains carcinogens (cancer-causing chemicals)

What is nicotine?

An addictive drug in cigarettes and vapes that narrows blood vessels and increases heart rate

What is carbon monoxide?

A poisonous gas in cigarette smoke that binds irreversibly to haemoglobin

How does tar damage the lungs?

Damages/destroys cilia (mucus builds up), coats alveoli (thickens walls, slower diffusion), contains carcinogens (causes lung cancer)

What is a carcinogen?

A substance that causes cancer (damages DNA, leading to uncontrolled cell division)