Respiration and Gas exchange

What are the main gases in earths atmosphere?

• 79% nitrogen

• 21% oxygen

• 1% carbon dioxide

What are the roles of Nitrogen, Oxygen and carbon dioxide?

• Nitrogen helps plants grow

• Oxygen helps respiration

• Carbon dioxide helps photosynthesis

Explain resource or waste products?

• Oxygen and carbon dioxide can act as a waste product

• Animals use oxygen for cellular respiration and carbon dioxide as a waste product

• Plants use carbon dioxide as a resource

Explain partial pressure?

• units is mm/Hg

• Is the percentage that each gas contributes to the total pressure

• Example, partial pressure of oxygen is 160mm/Hg, nitrogen is 600mm/Hg, CO2 is 0.03mm/Hg

• Total atmospheric pressure is 760mm/Hg

• Gases diffuse from high partial pressure to low partial pressure

Explain aquatic respiratory systems?

• Gills are a common adaption for gas exchange

• Can happen 2 ways, pumping water through gills, or swimming with their mouth open

• Water flows over gills

• Passes over lamellae, dense network of capillaries, provide large surface area for gas exchange

• Water flows over lamellae in opposite direction of blood flow, countercurrent exchange, maximises diffusion

Describe the human respiratory system

• Nasal cavity - filters, warms and humidifies air

• Pharynx - shared space for food and air

• Larynx - important for voice production

• Trachea - tube that connects trachea to bronchi

• Bronchi - airway before lung

• Bronchioles - muscular tubes that contract or dilate

• Alveoli - site of gas exchange, covered in pulmonary capillaries

• Lungs - organ that facilitates gas exchange

• Diaphragm - muscle underneath lungs`

Explain surfactant?

• To facilitate gas exchange, alveoli is lined with water, however water causes surface tension, causing it to collapse

• A mixture of protein and phospholipids that breaks surface tension of water

• HB in water is broken, preventing alveoli from collapsing, making gas exchange easie

Describe positive and negative pressure breathing?

• Positive pressure breathing - air is pushed into lungs

• Negative pressure breathing - air is pulled into lungs

Describe human breathing?

• Inspiration - chest walk expands when rub muscles and diaphragm contract

• This increases the volume of lungs, reducing air pressure in lungs

• Air is pulled into lungs from higher pressure atmosphere into the lower pressure lungs

• Expiration - rib muscles and diaphragm relax, decreases the volume of chest, therefore pressure in lunch is higher, forces air out of lungs

Describe Lung volume?

• Tidal volume - amount of air moved in during normal breath

• Inspiratory reserve volume - excess air breathed in

• Expiratory - excess air breathed out

• Residual volume - air leftover in lungs

• Vital capacity - inspiratory + tidal + expiratory = 4800mL

• Total lung capacity - inspiratory + tidal + expiratory + residual = 6000mL

Describe the gas exchange?

• Body produced ATP, which consumes oxygen and produced carbon dioxide

• Tissue has low oxygen and high carbon dioxide partial pressure

• Lungs get constant air, so high in oxygen and low in carbon dioxide

• Oxygen moves from lungs, to blood to tissue

• Carbon dioxide opposite way

Describe gas transport?

• Refers to the movement of oxygen and carbon dioxide between lungs and tissue

• Oxygen is a challenge to transport due to low solubility

• Due to this, oxygen is transported through haemoglobin

Describe the pH levels in blood?

• lower pH reduces haemoglobins affinity for oxygen

• Higher blood pressure increases haemoglobins affinity for oxygen

Describe the regulations of breathing?

• If breath is held, brain detects it, might be due to lack of oxygen, but actually due to build up of carbon dioxide which lowers pH

• pH drop is detected by chemoreceptors

• In response, breathing control centre sends action potentials to respiratory muscles, helps rate and depth of breathing

Describe stomata?

• microscopic pores which open and close for gas exchange

• Each stomata has guards which regulate size of pore

• When stomata is open, CO2 diffuses for photosynthesis, while O2 diffuses out, water is lost

Describe how stomata open and close?

• Open and close due to turgor pressure

• Potassium ions gather up, causes water to come in, allowing pore to open

Describe C3 photosynthesis?

• Stomata opens during the day

• CO2 diffuses into the leaf

• Works in cool and moist conditions

• Water Vapor can escape through

Describe CAM photosynthesis

• Used in hot dry environments

• CO2 is taken in at night and stored

• Released and used in the day

• Stomata is open at night to allow CO2 (malic acid) in

• In day, stomata closes, water loss is prevents, malic acid is converted into CO2, requires energy

Describe pH in C3 and CAM plants?

• C3 plants dont have changes in pH levels

• CAM plants have low pH at night, high pH in day

Describe C4 synthesis?

• Use spatial separation

• Stomata open in day

• Minimised photorespiration

• Uses extra energy