Respiration

Question 1

What are the steps of respiration?

Answer 1

VEntilation
gas exchange
gas transfer
gas exchange
Cellular respitation

Question 2

What happens during gaseous exchange?

Answer 2

O2 transferred via diffusion from alvaeoli into the pulmonary vein.
CO2 transferred from the pulmonary artery into the alveoli.
O2 transported towards tissues, diffuses from blood into the cells.
CO2 diffuses from cells into circulatory system towards lungs.

Question 3

What is partial pressure?

Answer 3

The percentage of a specific gas in a mixture. The % of gas timesed by the atmospheric pressure.

Question 4

What is the PO2 at sea level?

Answer 4

160mmHg

Question 5

What is the PCO2 at sea level?

Answer 5

0.2mmHg

Question 6

What does the atmosphere weight support at sea level?

Answer 6

Column of mercury (Hg) = 760mmHg

Question 7

What does dalton’s gas law state?

Answer 7

a specific gas in a mixture will exert pressure as if there are no other gases present.

Question 8

What does boyle’s law state?

Answer 8

increasing the volume of a qunantity of gas, decreases the pressure of the gas.

Question 9

What does Henry’s law state?

Answer 9

a quantiy of gas that dissolves at a certain temperature is proportional to the partial pressure of that gas in gaseous state.

Question 10

What is fick’s law of diffusion?

Answer 10

allows us to calculate the rate of diffusion.

Question 11

What affects diffusion rates?

Answer 11

BOdy size:
The larger the animal the smaller the surface-to-volume ratio and the larger the diffusion distance. Therefore larger animals had to evolve structures and organ specialised for respiration.

Question 12

NAme the different types of respiratory organs.

Answer 12

Gills
Trachea
Lungs

Question 13

How do fish with gils breahte?

Answer 13

Gils have a large surface area for highly efficient gaseous exchange. Undergoes counter current exchange = blood flows through the gills and passes by water flowing in the opposite direction over the gils. O2 is transferred from the water into the blood continuously as equilibrium is never reached.

Question 14

How do insects with trachea breathe?

Answer 14

The trachea consists of a network of air-filled passages that transfer O2 directly to the body tissues and cells, which allows O2 and CO2 to be diffused faster. There is no circulatory systems.

Question 15

How do amphibians breathe?

Answer 15

Breathe with lungs and positive pressure breathing.
Air is forced into the lungs, nostrils open air flows in and buccal cavity expands. Nostrils close, glottis opens, buccal cavity contracts and air flows into expanded lungs.
Buccal cavity expands and the lungs contract = air flows from lungs into buccal cavity. Nostrils open and glottis closesand buccal cavity contracts = air flows out of buccal cavity into environment.

Question 16

How do mammals breathe?

Answer 16

Mammals have lungs and breathe via negative pressure breathing.
Lungs have negative pressure so that air can flow into the low pressured area. Respiration rhythm is determined by nerve impulses that fire for 2sec and rest for 3sec. During firing, respiratory muscles contract, when neuron stops respiratory muscles relax.
Lungs have a branched system of passages that end in alveoli where gas exchange occurs. Gases can only diffuse dissolved in aqueous solution due to moist respiratory surfaces.
Lungs are filled and controlled by pulmonary stretch receptors which prevents over inflation.
Hering-Breur refllux - control of breath-by-breath breathing.
Gas in blood ins controlled by chemoreceptors to regulate blood acidity and pH.

Question 17

What are the advantages and disadvantages of mammals lungs?

Answer 17

Advantages:
Reduces water loss
High SA:V
blood vessels around the alveoli decreases the diffusion distance.

Disadvantages:
Tidal ventialation
Residual volume
Concurrent
O2 cannot diffuse over bronchi
O2 concentration in lungs is lower that environmental O2 concentration due to water vapor and residual volume.

Question 18

What are the adption of mammalian lungs?

Answer 18

Thin layer of lung lining fluid
Aveoli produce surfactants
Other cells produce mucous that captures dirt
Cilia moves the mucous.

Question 19

Quiet breathing

Answer 19

Resting respitation

Question 20

Vigorous breathing

Answer 20

forced in and exhalation
Strenuous excersise

Question 21

How do birds breathe?

Answer 21

Unidirectional and continuous = allows birds to maximise the environmental O2 on external side of exchange surfaces.
I breath takes 2 cycles to be exhaled
2 volumes are inhaled to make breathing continuous
Air moves into posterior sac into lungs and into anterior sac.
Lungs are small with maximised gaseous exchange and cross current flow between blood and air.
PO2 of lung surface = PO2 atm
NOt sensitive to blood CO2

Question 22

How is O2 transported in the body?

Answer 22

Bound to respiratory pigments -heamoglobin (98.5%) or present as gas (1.5%).
O2 is poorly soluble in blood.
Heamoglobin can bind to 4 O2 molecules - binding to the first makes the second easier but the 3rd and 4th a high PO2 is needed.

Question 23

What determines the Hb-O2 affinity?

Answer 23

PO2 of environment
A high Po2 increases the affinity - will bond to O2, at lungs
A low PO2 decreases the affinity - will release O2, at body cells

Question 24

O2-Hb dissociation curve

Answer 24

S-shaped curve shows the O2 saturation of Hb and the corresponding PO2.
Curve plateau = Hb is highly saturated and favours O2 loading at lungs
Curve Steep slope = drop in PO2 leads to a decrease in O2 saturation, favours release of O2 in body cells

Question 25

Changes in the dissociation curves with respect to?

Answer 25

Acidity - high blood acidity curve moves right
Temp - high temp curve move right
Organic phosphates - lots of DPG curve moves right
Size - smaller animals curve move right
Pregnancy and foetal Hb - foetus’ have a higher Hb affinity curve moves right for mother.

Question 26

Myoglobin dissociation curve

Answer 26

Myoglobin is the protein in muscles that O2 binds to.
Allows muscles to produce ATP
A Single poly peptide with 1 heme group. Has a higher affinity for O2 than hemoglobin - it is saturated at lower levels.

Question 27

How is CO2 transported in the body?

Answer 27

Plasma (7%) - CO2 dissolved in blood
carbino-heamoglobin (23%) - Bound to Hb
Bicarbonate (70%):
CO2 enters RBC and combines with H2O and forms H2CO3
This dissociates into H+ and HCo3-
HCO3- moves out of cell and Cl- move in = chloride shift
H+ inside RBC = more acidic and Hb releases O2
H+ bind to Hb and acts as a buffer
When RBC reach lungs, HCO3- is pumped back into the cell and the entire process is reversed.

Question 28

CO2 as an important regulator

Answer 28

Cnetral chemoreceptos detect a change in CSF pH
CO2 diffuses access blood-brain barrier
Triggers an increase in ventilation so that more CO2 can be exhaled
Blood and CSF CO2 decreases
Breathing returns to normal. .

Question 29

Why is climbing mount Everest difficult?

Answer 29

Lungs are not efficient at breathing at such high altitudes.
Tidal breathing - lungs can only use 67% of PO2 than Ambient PO2.
At higher altitudes the air density and atmospheric pressure is lower.
Sea level = 760mmHg
Summit = 253mmHg
PO2 is low in the lungs is greater than that of the atm due to water vapour.

Question 30

What happens to our breathing when we are at higher altitudes?

Answer 30

BR increases:
Peripheral chemoreceptors detect low O2 levels
Results in a moderate increase in BR.

Secondary rise in respiration:
Removes the break on breathing initially composed by low CO2 In blood and low pH
Blood acidity is partially restored by the kidneys which enables higher BR

Increase in RBC production:
Blood viscosity increases
Heart rate increases to pump blood

Production of DPG:
Binds to HB and reduces the HB-O2 affinity
VUrve shifts right
All essential organs get sufficient O2.