12- Respiratory system 3 Flashcards

1
Q

3 factors that affect the transport of gases

A

partial pressure, pH and temperature

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2
Q

is oxygen or carbon dioxide more soluble in water?

A

carbon dioxide

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3
Q

6 factors affecting O2 binding to and dissociation from haemoglobin

A
Oxygen partial pressure
Acidity (pH)
Carbon dioxide partial pressure
Temperature
2,3-bisphosphoglycerate (BPG)
Foetal haemoglobin
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4
Q

what is the most important factor that determines how much oxygen combines with haemoglobin (Hb)?

A

oxygen partial pressure (PO2)

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5
Q

where is PO2 higher and lower?

A

In the pulmonary capillaries, the PO2 is high.

In the tissue capillaries, PO2 is lower.

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6
Q

the greater the PO2, the more/less oxygen will combine with Hb?

A

more

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7
Q

what is the Bohr effect?

A

the ability for haemoglobin to act as a buffer for hydrogen ions

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8
Q

As acidity increases (pH decreases), the affinity of haemoglobin for O2 (increases/decreases)?

A

decreases

O2 dissociates faster = more available for working muscles

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9
Q

what effect does carbon dioxide partial pressure (PCO2) have on Hb and O2?

A

As carbon dioxide (CO2) enters the blood, much is converted to carbonic acid (H2CO3) which increases hydrogen ions (H+) and decreases pH, causing release of O2 from Hb

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10
Q

as body temperature increases, what happens to Hb?

A

haemoglobin releases O2 more readily

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11
Q

what is 2,3-biphosphoglycerate (BPG) ?

A

a substance formed in red blood cells during glycolysis

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12
Q

what does BPG do to the affinity of haemoglobin for O2

A

BPG decreases the affinity of haemoglobin for O2

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13
Q

how does foetal hemoglobin differ from adult haemoglobin?

A

in structure and in its affinity for O2

it has a higher affinity for oxygen because it binds BPG less strongly and can carry more O2 to offset the low oxygen saturation in maternal blood in the placenta.

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14
Q

how does carbon monoxide poisoning happen?

A

carbon monoxide has a 200 times higher affinity for haemoglobin than oxygen, so it binds to Hb and blood loses its ability to bind O2

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15
Q

3 ways CO2 is carried in blood?

A
Dissolved CO2 (7%)
Carbaminohaemoglobin (23%) combined with the globin part of Hb molecule
Bicarbonate ions (HCO3-) (70%) - CO2 + H2O combine to form carbonic acid that dissociates into H+ and a bicarbonate ion
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16
Q

what maintains the ionic balance between plasma and red blood cells?

A

The conversion of CO2 to HCO3- and the related chloride

17
Q

what is the relationship between CO2 and the pH of our blood?

A

A skeletal muscle cell is metabolising and generating CO2 which diffuses across the capillary wall into the red blood cells. There it combines with H2O and through the action of carbonic anhydrase, it is converted into carbonic acid. This dissociates to the bicarbonate ion and the hydrogen ion. It is the bicarbonate ion that is dissolved in the plasma. So, the CO2 is carried in the form of the bicarbonate ion in this process.

Whenever a CO2 molecule is carried, a hydrogen ion is being generated. As the CO2 in the plasma increases, the amount of hydrogen ions also raises and the pH of our blood decreases.

The opposite process happens in the lungs. The hydrogen ion combines with the bicarbonate ion to form carbonic acid and under the influence of carbonic anhydrase, it forms CO2 and water. This diffuses across the pulmonary capillary wall into the alveolus and is brought out of the body

18
Q

3 areas of the respiratory centre (in the brain)?

A
Medullary rhythmicity area (in the medulla oblongata)
Pneumotaxic area (in the pons)
Apneustic area (in the pons)
19
Q

what happens in the inpiratory and expiratoru areas of the medullary rhythmicity area?

A

The inspiratory area excites autorhythmic neurons for 2 seconds then it is inactive (for 3 seconds).
The expiratory area is inactive during most quiet breathing, it is only active during high ventilation rates.

20
Q

which area coordinates the transition between inspiration and expiration?
how?

A

The pneumotaxic area (in upper pons)

It shortens the duration of inhalation and transmits inhibitory impulses to the inspiratory area; increases the breathing rate

21
Q

what does the apneustic area do?

where is it located?

A

coordinates the transition between inspiration and expiration. In the lower pons

(prolongs the duration of inhalation and sends stimulatory impulses to the inspiratory area that results in a long, deep inhalation. When the pneumotaxic area is active, it overrides signals from the apneustic area)

22
Q

what is cortical regulation responsible for?

A

the voluntary altering of breathing patterns

23
Q

what is a state of increased levels of carbon dioxide in the blood called?

A

hypercapnia

24
Q

What is hypoxia?

A

oxygen deficiency at the tissue level

25
Q

4 types of hypoxia?

A

Hypoxic hypoxia: Caused by a low PO2 in arterial blood (high altitude, airway obstruction, fluid in lungs)

Anaemic hypoxia: Too little functioning haemoglobin in the blood (haemorrhage, anaemia, carbon monoxide poisoning)

Stagnant hypoxia: Inability of blood to carry oxygen to tissues fast enough to sustain their needs (heart failure, circulatory shock)

Histotoxic hypoxia: The blood delivers adequate oxygen to the tissues, but the tissues are unable to use it properly (cyanide poisoning)