Ianowski - theme 10

Question 1

How is O2 transported in the blood? CO2?

Answer 1

O2 is bound by Hb. CO2 travels as bicarbonate ion.

Question 2

Hb curve:

Answer 2

Sigmoidal - high in lungs, low in extremities

Question 3

How much O2 can Hb bind?

Answer 3

1g Hb binds 1.39 mL O2

Question 4

Structure of Hb:

Answer 4

4 binding sites. 2 alpha chains, 2 beta chains. Fe2+ in the middle.

Question 5

Hb-O2 dissociation curve:

Answer 5

Sigmoidal due to cooperativity.

Question 6

Hb affinity for O2 depends on:

Answer 6

Temp, H+, CO2. Increasing them lowers affinity.

Question 7

How does O2 get into body cells?

Answer 7

Follows its concentration gradient down into interstitial fluid and into cells. Passive.

Question 8

How does CO2 get out of the body?

Answer 8

Going into blood: Active. 10% is dissolved, 70% is converted to HCO3-, and 20% combines with Hb (carbaminoblahblah)
Going into air: Passive. CO2 packing reactions are reversed.

Question 9

Who has Hb in RBCs?

Answer 9

Vertebrates

Question 10

Involuntary neural control of breathing at rest:

Answer 10

In the brain stem. Inspiratory neurons initiate breathing. Phrenic nerve causes diaphragm contraction and intercostal motorneurons cause intercostal muscle contraction. Stretch receptors inactivate inspiratory neurons. This is the Hering-Breuer reflex.

Question 11

Involuntary neural control of breathing when exercising:

Answer 11

All the same as rest except there are also expiratory neurons.

Question 12

Voluntary neural control of breathing:

Answer 12

Cortex

Question 13

Neural regulation of breathing: the chemicals

Answer 13

Chemoreceptors: peripheral carotid bodies and aortic bodies sense O2 in arteries. Central senses CO2 in cerebrospinal fluid.

Question 14

Breathing and juxtacapillary receptors:

Answer 14

Engorged capillaries causes dyspnea, the sensation of difficulty breathing

Question 15

What can sense PO2? What can’t?

Answer 15

Peripheral chemoreceptors can. The medullary respiratory centre and central chemoreceptors cannot.

Question 16

Glomus cells:

Answer 16

Increased nerve firing when O2 drops. THEY FREAK OUT WHEN O2 IS LOW!!!

Question 17

Importance of carotid bodies: experiment

Answer 17

Normal: when PO2 drops, breathing increases.
Remove carotid bodies: when PO2 drops, there is no response.
They are the ONLY source of hypoxic ventilatory drive.

Question 18

Central chemoreceptors vs breathing regulation:

Answer 18

Sense increased CO2 in arterial blood -> increase breathing. Located in the medulla oblongata.

Question 19

Humans respond to which chemoreceptor activity the most?

Answer 19

Central CO2 receptors. Response is linear and VERY STEEP. Small changes in CO2 cause a huge breathing change.

Question 20

What is the desire for air driven by in land vs aquatic animals?

Answer 20

Land animals are driven by CO2. O2 is pretty available, as long as CO2 levels are good.
Aquatic animals are driven by O2. CO2 is pretty soluble, so if O2 levels are good them CO2 will be fine.