Respiratory System II

Question 1

Secretion of EPO is stimulated by

Answer 1

Testosterone

Question 2

In an O2 poor envionment EPO begins to be produced and reahed peak levels in

Answer 2

24 hours

takes days for mature RBCs to appear in circulation as a result of low O2 levels

Large amount of EPO in the blod increases RBC production rate 10x over the normal level

Question 3

Hemoglobin

Answer 3

Produced in immature RBC containing a nucleus

once mature the nucleus is lost (no more hemoglobin is produced)

24 pg of hemoglobin in each RBC

Question 4

Hemoglobin Structure

Answer 4

Each hemoglobin contains 4 subunits

Each subunit contains a single heme molecule attached to a polypeptide

4 polypeptides are called a globin

each heme carries one oxygen atom attached to the central iron atom

each hemoglobin can carry four oxygen molecules

iron atom makes blood red in colour

Question 5

When Blood Leaves the Lungs after picking up oxygen

Answer 5

Hemoglobin is almost completely saturated with oxygen

Question 6

O2 and Hemoglobin

Answer 6

O2 easily binds w/ Hb in a reversible reaction to produce oxyhemoglobin (HbO2)

Reaction is driven in each direction either by the amount of O2 or HbO2 at either end of the reaction

Question 7

______ determines if we are loading or unloading oxygen

Answer 7

Amount of PO2 dissolved in the blood

Question 8

PO2 is high

Answer 8

In the lungs

O2 loads onto hemoglobin

Question 9

PO2 is low

Answer 9

In the tissues

O2 unload into the tissues

Question 10

Temperature and Acidity

Answer 10

When the body warms up and is working muscles produce lactic acid this increases the acidity of the blood

Increase the unloading of oxygen from hemoglobin

Question 11

Three Ways to Transport Carbon Dioxide

Answer 11

Dissolved in the Plasma
Carried as a Bicarbonate ion
Bound to Globin forming a carbamino compound

Question 12

Dissolved in Plasma (CO2)

Answer 12

20% more soluble in plasma and will dissolve much easier

7%-10% of all the CO2 is carried dissolved in plasma

Question 13

PCO2 levels (Veneous v Arterial)

Answer 13

40 mmHg on the arterial side

46 mmHg on the venous side

the significant amount of CO2 in the arterial blood passes through the lungs without all beng removed it helpsmaintain blood flow by keeping arterioles dilated

Question 14

Bicarbonate Ion

Answer 14

70% of the total CO2 is carried in the blood as bicarbonate ions (HCO3-)

CO2 reacting w/ water produced carbonic acid

Carbonic anhydrous acts as an enzyme

Carbonic acid dissociated into bicarbonate ions and hydrogen ions

CO2 released from the cells diffuses into the blood and then into RBCs

Carbonic anhydrase found in RBCs catalyzes the first step of the reaction inside the cell

Question 15

H+

Answer 15

After CO2 has been converted to bicorbonate ions most of the H+ will bind w/ hemoglobin (Hb) found inside the red blood cell

important since h+ is able to diffuse out of the cell making the blood acidic

Bicarbonate ions diffuse out of the RBC into the plasma to act as a buffer to help stabilize the pH of the blood

Question 16

Chloride Shift

Answer 16

HCO3- leaving the RBC makes inside of the RBC more (+)ve

To balance the (+)ve charge Cl- must diffuse into the cell

Chloride shift can occur very quickly because the membrane is permeable to (-ve) charge

Question 17

Carbocamino compounds

Answer 17

20% to 30% of all carbon dioxide is transported in the blood attached to proteins forming carbamino compounds

Hemoglobin which has unloaded some of its O2 to the tissue is one of the most abundant proteins that can carry CO2

CO2 attaches to the globin portion of hemoglobin

HbCO2 will return to the lungs on the RBC

Once in the lungs CO2 detaches from Hb and will diffuse into the alveolar space

Oxygen then diffuses into the RBC and will attach to the heme portion of hemoglobin

Question 18

In the tissues high PCO2

Answer 18

Moves the reaction to the reight to form HbCO2 and HCO3-

Question 19

In the lungs the low PCO2

Answer 19

Moves the reaction to the left to form CO2 and Hb/H20

Question 20

Control of Breathing

Answer 20

We can increase, decrease or stop respiration at will

Most breathing done spontaneously

Question 21

Spontaneous Respiration

Answer 21

Originates in the medullary respiratory center of the medulla oblongata of the brainstem

Produced by rythmic activity from neurons

Question 22

Voluntary Center

Answer 22

Located in the cerebral cortex

Capable of overriding the center in the brainstem (when holding your breath)

Question 23

Inhalation

Answer 23

Inspiratory center in the MRC activates inspiratory muscles during inhalation

Inspiration is an active process

requiring the contraction of the diaphragm and external intercostal space

Inspiratory center stimulates the contraction of these inspiratory muscles at the same time it also inhibts the expiratory center

Question 24

Exhalation

Answer 24

Quiet exhalation is a passive process involuntary only the relaxation of the inpiratory muscles

the lungs own elastic properties and recoiling of muscle causes exhalation at rest

Forceful exhalation requires contraction of the abdominal muscle + internal intercostal muscles of the ribs

signals to these muscles originate in the expiratory center of the medulla

while this center is active the inspiration center is inhibted

Question 25

Apneustic + Pneumotaxic Centers

Answer 25

Centers regulate respiration to ensure that there is sufficient oxygen and not too much carbon dioxide in the blood

Centers are above the medulla in the pons and can modify spontaneous signals from the centers in the medulla

Question 26

Pneumotaxic Area

Answer 26

Regulates the rate of breathing

Question 27

Apneustic Area

Answer 27

regulates the depth of breathing

Question 28

Voluntary Center

Answer 28

The site of voluntary ventilation is the cerebral cortes which can modify ventilation by effecting signals originating in either the apneustic center or pneumotaxic center

Question 29

Importance of Regulating gas concentration in the blood

Answer 29

Holding your breath: not enough oxygen is entering the bloodstrean abd you will pass out

Hyperventilating: CO2 levels in the blood drop resulting in vasoconstriction blood vessels less blood and oxygen are heading to the brain leading you to pass ou

Question 30

Regulation of Respiration Feedback Loop

Answer 30

Setpoint: PO2 or PCO2

Control Center: Medullary respiratory center

Effector: muscle of respiration

Controlled Variable: Lung ventilation

Sensor: Chemoreceptor

Question 31

Chemoreceptor

Answer 31

Special receptors that detect the concentration of oxygen, CO2 or H+ ions in the blood

Question 32

Two Groups of Chemoreceptors

Answer 32

Peripheral

Central

Question 33

Peripheral Chemoreceptor

Answer 33

Aortic Arch + Carotid Sinus

Primarily sensitive to O2 concentrations

Slightly sensitive to CO2 concentrations in the blood

sends signals back to respiratory center in the brain

Question 34

Central Group

Answer 34

Medulla of the brainstem

Sensitive to H+ ion levels in the intersitial space of the brain

since central chemoreceptors are located in the medulla gases must diffuse into the interstital space crossing the BBB

BBB is permeable to CO2 but not H+

CO2 crosses the BBB and reacts with waterin the interstitial space fo the brain to produce bicarbonate and H+

H+ will be detected by central chemoreceptors

An increase in CO2 in the blood will be detected indirectly through those chemoreceptors to signal the respiratory center in the brainstem in the brainstem increasing ventilation