M2.2.3 - Respiratory systems

Question 1

Respiration vs. Breathing

Answer 1

Respiration: chemical reactions that provide energy for an organism to function

Breathing: mechanical process using muscles and skeletons, which facilitates exchange of gases, oxygen in, carbon dioxide out

Question 2

Gas exchange

Answer 2

Process of dissolved gas diffusion between cells
- Affected by concentration gradient of gases in blood

Question 3

Respiratory system structures

Answer 3

1. Trachea (windpipe)
2. Bronchi (primary, secondary, tertiary)
3. Bronchioles
4. Alveoli (air sacs): thin walled cells in direct contact with capillaries → easy + fast gas exchange

Question 4

Alveoli (singular alveolus)

Purpose, features that allow it to achieve this purpose

Answer 4

• Site of gas exchange
• Thin walls + proximity to capillaries → easy and fast gas exchange
• Circulation of blood by heart pumping → constant gas exchange (low-oxygenated blood passing through alveoli)
• Moist surface facilitates diffusion as the gas dissolves into the fluid

Question 5

Haemoglobin

Answer 5

• Red blood cell pigment
• Can carry up to 4 O2 molecules
• Haemoglobin + 4 O2 → oxyhaemoglobin. Hb + 4O2 → Hb(O2)4
• This process is reversible, allowing for constant uptake of oxygen by haemoglobin

Question 6

Insect Respiration

Answer 6

Tracheal system:
1. Spiracles (holes) form a row on both sides of the body → gases can enter or be expelled by diffusion, or pumping the abdomen, or using flight muscles
2. Spiracles connect to trachaea, a seres of tubes, which lead to smaller tubes called tracheoles, which reach the surface of most cells in the body

Spiracles (holes) → trachaea (tubes) → tracheoles (smaller tubes)

Question 7

Fish respiration

Answer 7

• Water enters through the mouth and over the gills
• Countercurrent movement of blood against the flow of water → concentration gradient of oxygenated water + deoxygenated blood → constant uptake of oxygen.
• Increases efficiency of gas exchange so 95% of oxygen can be obtained from water passing over the gills.

Structure:
- Gills are covered by an operculum.
- 4 gill arches on either side of the head, each arch is composed of 2 rows of gill fillaments, which are covered by gill lamellae
* When fish are not in fluid, the gill structure collapses, which is why they cannot survive out of water.

Question 8

Requirements of respiratory surface

Answer 8

1. Moist: so gases can dissolve and hence diffuse across the membrane
2. Large surface area: allows maximum diffusion
3. Rich blood supply: oxygen can be removed once it has been abosrb, allowing a fresh round of oxygen intake
4. Thin: reduces amount of diffusion needed

Question 9

Frog respiration

Answer 9

• Gas exchange occurs on the skin (cutaneous)
• Skin is a thin membranous tissue with a rich blood supply → facilitates gas exchange
• Frogs must be moist so gas exchange can occur on the skin
• Sac-like lungs connected to buccal cavity → lungs (pulmonary) are used to absorb oxygen and excrete CO2 when on land, skin is used to absorb O2 and excrete CO2 when completely submerged
• Buccal cavity is used to force air into the lungs → ventilation is tidal and periodic

Question 10

Autotroph nutrient and gas requirements

And how they obtain them

Answer 10

• O2 and CO2 diffuses into plant across cell surfaces
• Water diffuses through roots
• Glucose produced by photosynthesis
• Protein and lipids produced by plants from glucose and ions
• Mineral ions move into plant through roots by diffusion and active transport.

Autotrophs produce their own gluocse, proteins, and lipids. Water Mineral ions are transported through roots by diffusion and active transport. Autotrophs require both oxygen and carbon dioxide for respirations and photosynthesis

Question 11

Heterotroph nutrient and gas requirements

And how they get them

Answer 11

• O2 diffuses through respiratory surfaces, CO2 not required
• Water ingested through digestive system
• Glucose ingested into digestive system as either simple or complex carbohydrates and absorbed into the bloodstream
• Protein, lipids ingested and absorbed into the bloodstream as amino acids, fats and glycerol
• Mineral ions ingested and absorbed into bloodstream

Heterotrophs obtain water, glucose, proteins, and lipids by ingestion and abosrbtion into the bloodstream. Heterotrophs require only oxygen.