Respiratory system (Chapter 4)

Question 1

Define cellular respiration

Answer 1

Process by which organic molecules are broken down in the cells to release energy for the cell’s activities.

Question 2

Where does the energy from cellular respiration go?

Answer 2

Approx 60% of the energy released from respiration is in the form of heat.
- Useful in maintaining body temperature.
- Also acts as a catalyst for reactions.
The remaining 40% of the energy is released as
ADENOSINE TRIPHOSPHATE (ATP)

Question 3

Explain how ATP is formed and how it releases energy

Answer 3

• ATP is formed when a phosphate molecule bonds to ADP (adenosine diphosphate).
• Building molecules (anabolism) requires energy, so energy is stored in the bond between the 2nd and 3rd phosphate molecules.
• When the energy is required, the ATP molecule
  breaks its bond which releases stored energy

Question 4

How is energy from ATP used?

Answer 4

• Cell division and growth (mitosis)
• Movement of organelles
• Movement of whole cell

Question 5

lungs structure and function

Answer 5

• Elastic connective tissue, held to chest cavity by pleural fluid
• transports air in and out of body

Question 6

What is the function of the nasal cavity in the respiratory system?

Answer 6

The nasal cavity filters, warms and moistens the air in preparation for entering the lungs. Hairs and mucous trap foreign particles.

Question 7

What is the function and structure of the trachea?

Answer 7

The trachea carries air from larynx to lungs. It is made of c-shaped bands of cartilage that give
flexibility and support. It is lined with mucous membrane and cells with cilia to trap any solid particles.

Question 8

Function of bronchi, bronchioles

Answer 8

air passage

Question 9

What are bronchioles?

Answer 9

Very fine tubes that pass air from bronchi to alveoli. They end in tiny air sacs which is the alveoli.

Question 10

What is the function and structure of the alveoli, and what do the cells of the alveoli secrete?

Answer 10

• Tiny air sacs with thin walls, surrounded by blood capillaries
• Function is the exchange of oxygen and carbon dioxide between the lungs and the blood
• The cells of the alveoli secrete alveolar fluid that keeps the surface of the alveoli moist.
• The fluid contains surfactant which helps prevent the alveoli from collapsing and assists in the diffusion of gases

Question 11

What is gas exchange?

Answer 11

The process of oxygen diffusing from the alveoli into the blood and carbon dioxide diffusing from the blood into the alveoli in the lungs.
- When we inhale, there is a high concentration of
oxygen in the alveoli and a low concentration of
oxygen in the blood coming to the lungs (from the heart) - so oxygen diffuses from alveoli into the blood.
- At the same time, there is a high concentration of carbon dioxide in the blood (waste product of
respiration in the cells) and a low concentration in the alveoli - so it diffuses from blood into alveoli and is exhaled.

Question 12

How is the concentration gradient maintained

Answer 12

• Blood constantly moving through the capillaries
  surrounding the alveoli
• Constant inhaling and exhaling, bring ‘new’ air
  into the alveoli to be exchanged

Question 13

What are the steps in Inspiration?

Answer 13

• Diaphragm contracts moving downwards
• Intercostal muscles contract moving up and outwards
• This increases lung volume
• Which decreases air pressure inside lungs
• Air flows into lungs from a higher pressure (outside body) to a lower pressure (inside lungs) until pressure becomes equal

Question 14

What are the steps in expiration?

Answer 14

• Diaphragm relaxes moving upwards
• Intercostal muscles relax moving down and inwards
• This decreases lung volume
• Which increases air pressure inside lungs
• Air flows out of lungs from a higher pressure (inside lungs) to a lower pressure (outside body) until pressure becomes equal

Question 15

What is the epiglottis?

Answer 15

A flap of tissue that during swallowing, closes off the trachea so food and liquid cannot enter the lungs

Question 16

What is the diaphragm?

Answer 16

A dome-shaped muscle that separates the chest from the abdomen. It contracts and relaxes, thereby increasing and decreasing the volume of the chest cavity and lungs during breathing in and out.

Question 17

Anaerobic respiration

Answer 17

Glycolysis occurs:
- occurs in the cytoplasm
- glucose is broken down into two pyruvate molecules and two ATP molecules
As no oxygen is present, pyruvate molecules are converted to Lactic acid

Question 18

Aerobic respiration (equation needed in answer)

Answer 18

• requires oxygen
• occurs in the inner folds of the mitochondria called the christae
• Krebs cycle: the two pyruvate enter the mitochondria and are broken down into hydrogen ions and waste CO2. 2 ATP molecules are released in this action
• the hydrogen ions are then passed through electron transport chain, producing a small amount of energy at each step, resulting in 32-34 ATP, and water and CO2 as by-products
• and so final result is 36-38 ATP, two from glycolysis, two from krebs cycyle and 32-34 from electron transport chain.
  -C6 H12 O6 + 6O2 -> 6H2O + 6 CO2 +36-38ATP

Question 19

Why are the lungs suited to their function of gas exchange?

Answer 19

Millions of alveoli and convoluted structure = large surface area, meaning large amounts of gas can be exchanged quickly

Each alveoli is covered by capillaries, meaning blood is close to the air in alveolus and so gases don’t have to travel very far

Walls of alveoli and capillaries are only 1 cell thick, means gases don’t have to travel very far in and out of blood

lungs are deep inside body, prevents excessive evaporation of the fluids that cover the alveoli surfaces

the lung volume can be changed by movements of the muscles so air flows in and out of the lungs. this ensures there is always a concentration difference of the gases

Question 20

How is oxygen transported around the body

Answer 20

• 3% dissolved in the plasma of the blood
• The other 97% is carried attached to haemoglobin molecules of the red blood cells (Oxyhaemoglobin)

Question 21

How is CO2 transported around the body?

Answer 21

• 7-8% –>dissolved in the plasma of the blood.
• 22% –> bound to haemoglobin molecules forming a substance known as carbaminohaemoglobin
• 70% –> carried in the plasma as bicarbonate ions