Biology 3.2

Question 1

Methods of respiration

Answer 1

Diffusion of gases directly with environment, gills, tracheae and lungs

Question 2

Diffusion of gases directly with environment

Answer 2

in small animals with most cells exposed to the environment with some O2 diffusion

Question 3

Gills

Answer 3

these are evaginated structures, large SA for gas exchange. Has circulatory system to maximize level of countercurrent exchange between water and blood. Can be internal or external. Fish have gill covers called operculum.

Question 4

Tracheae

Answer 4

Tubular system lined with chitin in insects. O2 enters and CO2 leaves through openings in tracheae called spiracles

Question 5

Lungs

Answer 5

Invaginated structures/cavities. Spiders have book lungs that are like a stack of leaf-like membranes

Question 6

Respiration in humans

Answer 6

1) Air enters through nasal cavity, passing pharynx and larynx
2) O2 enters trachea, epiglottis is a flap preventing fluids and solids in lungs
3) Trachea branches off to bronchus, bronchioles, alveolus covered in capillaries
4) Diffusion occurs between air in alveoli and blood in capillaries
5) RBCs bind to O2 using hemoglobin. RBC carries O2 to the rest of the body where it is diffused across capillary walls, interstitial fluid and to the cells
6) When CO2 enters RBC, the carbonic anhydrase enzyme converts the gas to carbonic acid (H2CO3). CO2 travels in blood as bicarbonate ions (HCO3-).

Equation: CO2 + H2O > H2O3 > H+ + HCO3-

Question 7

Inspiration

Answer 7

Diaphragm contracts downwards and external intercostal muscles contract upwards and outwards. Lung volume increases and negative pressure created in the lungs. Air from outside of the body travels down the pressure gradient (bulk flow)

Question 8

Exhalation

Answer 8

diaphragm contracts upwards and external intercostal muscles relax downwards and inwards. Lung volume decreases and there is a high positive pressure in the lungs. Internal intercostal muscles may be contracted further to push out air

Question 9

Medulla oblongata

Answer 9

regulates respiration, is in the brain stem, regulates depth and rate of breathing. Consists of chemoreceptors and mechanoreceptors.

Question 10

Chemoreceptors

Answer 10

Part of medulla oblongata. Found in medulla, aorta and carotid arteries. Monitors partial pressure of O2 in blood and the pH of blood and cerebral spinal fluid. If partial pressure of O2 drops, respiratory rate increases. High levels of CO2 waste indicates low pH levels, respiration rate increases

Question 11

Mechanoreceptors

Answer 11

Part of medulla oblongata. Stretch receptors in respiratory tract are stimulated if lungs reach their physical capacity and may trigger exhalation.