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Human Biology Unit 3 > Chapter 6.2 Regulation of Gas Concentrations ✔ > Flashcards

Chapter 6.2 Regulation of Gas Concentrations ✔ Flashcards

1
Q

Why does cellular respiration occur?

A

To provide energy for cellular functions

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2
Q

What gases do cells need to continuously remove and take in?

A

Remove CO2
Take in O2

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3
Q

What system is responsible for the exchange of gases?

A

The Respiratory system

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4
Q

What system carries oxygen to the cells and removes carbon dioxide from the cells?

A

The circulatory system

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5
Q

What muscles in the body causes air to move in and out of the lungs?

A

-Diaphragm: A muscles that separates the thorax from the abdomen
-Intercostal muscles: The muscles between the ribs

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6
Q

What initiates the contraction of the diaphragm and intercostal muscles?

A

Nerve impulses, more specifically:
-Diaphragm: Stimulated by impulses from the phrenic nerve
-Intercostal muscles: Stimulated by impulses from intercostal nerves

-These spinal nerves have their origin in the spinal cord at the level of the neck and thorax

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7
Q

Define respiratory centre

A

The part of the brain that regulates breathing rate; located in the hypothalamus

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8
Q

Where is the respiratory centre that controls nerve impulses to the diaphragm and intercostal muscles located?

A

The respiratory centre is located in the medulla oblongata of the brain

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9
Q

What are the two regions within the respiratory centre responsible for?

A

One region controls inspiration (breathing in), and the other controls expiration (breathing out).

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10
Q

How is breathing coordinated between the two regions of the respiratory centre?

A

Messages pass back and forth between neurons in the inspiration and expiration regions to coordinate breathing.

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11
Q

Concentrations of what gases affect the breathing rate and depth?

A

The concentrations of oxygen and carbon dioxide in the blood

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12
Q

Concentration of what gas affects the concentration of hydrogen ions in the blood plasma and why?

A

Carbon dioxide because when carbon dioxide dissolved in water, it forms carbonic acid (H2CO3), which breaks down readily to form hydrogen ions and bicarbonate ions (HCO-) as shown in the following chemical equation.

CO2 + H2O ⇌ H2CO3 ⇌ H + HCO

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13
Q

What are the two types of chemoreceptors?

A

-Peripheral chemoreceptors
-Central chemoreceptors

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14
Q

Define peripheral chemoreceptors

A

Groups of cells within the walls of the aorta and carotid arteries that are sensitive to changes in the concentration of oxygen, carbon dioxide and hydrogen ions in the blood plasma. These are known as aortic and carotid bodies

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15
Q

Define central chemoreceptors

A

Receptors that are sensitive to changes in the concentration of carbon dioxide in the blood and hydrogen ions in the cerebrospinal fluid

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16
Q

Where are central chemoreceptors located?

A

Medulla oblongata

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17
Q

Where are peripheral chemoreceptors located

A

Located in the aortic and carotid bodies

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18
Q

In this chapters context, where does the nerve impulses go when chemoreceptors are stimulated?

A

When chemoreceptors stimulated, they send a nerve impulse to the area of the respiratory centre that regulates breathing

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19
Q

What happens when there is a large decrease in oxygen concentration?

A

The peripheral chemoreceptors are stimulated and nerve impulses are transmitted to the respiratory centre.
These nerve impulses stimulate the transmission of messages to the diaphragm and intercostal muscles and so the breathing rate and depth increases

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20
Q

What happens when there is a large increase in oxygen concentration?

A

The peripheral chemoreceptors are not strongly stimulated and fewer nerve impulses are transmitted to the respiratory centre.
These reduced nerve impulses lead to less stimulation of messages to the diaphragm and intercostal muscles and so the breathing rate and depth decreases.

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21
Q

How does an increase in carbon dioxide concentration affect breathing?

A

Even a small increase in carbon dioxide concentration causes a marked increase in the rate and depth of breathing

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22
Q

: What is the relationship between carbon dioxide concentration and hydrogen ion concentration in the blood?

A

An increase in carbon dioxide concentration causes an associated increase in hydrogen ion concentration.

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23
Q

What do increased levels of carbon dioxide and hydrogen ions in the blood stimulate?

A

They stimulate central and peripheral chemoreceptors.

24
Q

What is the effect of chemoreceptor stimulation on breathing?

A

Chemoreceptors send nerve impulses to the respiratory centre, increasing the rate and depth of breathing.

25
Where are the chemoreceptors most sensitive to carbon dioxide located?
In the medulla oblongata.
26
How much do central chemoreceptors contribute to the increase in breathing rate due to rising carbon dioxide levels?
They are responsible for 70–80% of the increase in breathing rate.
27
How quickly do central chemoreceptors respond to increased carbon dioxide?
Their response takes several minutes.
28
What happens to blood pH as hydrogen ion concentration increases?
As hydrogen ion concentration increases, blood pH decreases.
29
Which chemoreceptors are directly stimulated by a decrease in pH?
Chemoreceptors in the aortic and carotid bodies.
30
What is the effect of stimulating aortic and carotid body chemoreceptors?
They send impulses to the respiratory centre, increasing the rate and depth of breathing.
31
Are oxygen, carbon dioxide, and hydrogen ion concentrations independent in regulating breathing?
No, they interact with each other and work together in the regulation of breathing rate
32
Are oxygen, carbon dioxide, and hydrogen ions the only factors that regulate breathing rate?
No, other factors also play a role in the control of breathing.
33
Which factor has the greatest sensitivity in regulating breathing—oxygen or carbon dioxide?
Carbon dioxide generally has greater sensitivity than oxygen in regulating breathing.
34
Why are oxygen, carbon dioxide, and hydrogen ion concentrations not considered independent in regulating breathing?
Because they interact with each other, for example, increased carbon dioxide raises hydrogen ion concentration and lowers pH so breathing is regulated by their combined effects, not separately.
35
Why is voluntary control of breathing important?
It allows us to speak and protect the lungs by preventing entry of irritating gases or water.
36
Why can’t we stop breathing forever?
A buildup of carbon dioxide in the plasma stimulates the inspiratory center, forcing us to breathe.
37
What is hyperventilation?
Rapid deep breathing that provides more oxygen and removes more carbon dioxide than necessary.
38
What can cause hyperventilation?
Voluntary actions, physical stress (like severe pain), or emotional stress (like extreme anxiety).
39
How does hyperventilation usually correct itself?
Reduced carbon dioxide levels mean chemoreceptors are not stimulated, decreasing the rate and depth of breathing.
40
Why is hyperventilating before underwater swimming dangerous?
It reduces carbon dioxide levels, delaying the urge to breathe and increasing the risk of unconsciousness and drowning from oxygen deprivation.
41
What happens to breathing during exercise?
Both the rate and depth of breathing increase to meet higher oxygen demands and remove more carbon dioxide.
42
By how much can ventilation increase during heavy exercise?
It can increase 10- to 20-fold (meaning it increases by 10-20 times)
43
What factors influence breathing during exercise and at rest?
Levels of carbon dioxide, hydrogen ions, and (to a lesser extent) oxygen in the blood plasma.
44
How do humans control their breathing voluntarily?
The cerebral cortex sends signals through the spinal cord that bypass the medulla oblongata, allowing conscious control over the rate and depth of breathing.
45
Write the word equation for cellular respiration
Glucose + Oxygen -> Carbon dioxide + Water + Energy (ATP)
46
Which chemoreceptors detect changes in: a) Oxygen? b) Carbon dioxide? c) Hydrogen ions?
a) Oxygen: Peripheral chemoreceptors (carotid and aortic bodies) b) Carbon dioxide: Central and peripheral chemoreceptors c) Hydrogen ions: Central chemoreceptors (indirectly) and peripheral chemoreceptors (directly)
47
Explain how an increased rate and depth of breathing is able to decrease the concentration of carbon dioxide in the blood.
Faster and deeper breathing increases the amount of air exchanged in the lungs, allowing more carbon dioxide to diffuse from the blood into the alveoli and be exhaled. This reduces carbon dioxide concentration in the plasma, leading to a decrease in hydrogen ion concentration and helping restore normal blood pH.
48
Explain why it is not possible to die from holding your breath unless you are under water
When you hold your breath, carbon dioxide builds up in the blood. This rise in carbon dioxide stimulates the central chemoreceptors, which trigger the inspiratory centre in the brain to force you to breathe. On land, this reflex overrides voluntary breath-holding before oxygen levels drop to a life-threatening level. However, underwater, this forced breath cannot happen without inhaling water, which can lead to drowning.
49
Use a flow chart to show the pathway of messages from the respiratory centre to the diaphragm during inspiration.
Respiratory centre (medulla oblongata) -> Motor neurons in spinal cord -> Phrenic nerve (from cervical spinal cord) -> Diaphragm muscle fibres -> Diaphragm contracts (moves down) -> Thorax volume increases -> Air drawn in
50
Why is it important that the muscles responsible for breathing are skeletal muscles?
It is important because skeletal muscles, like the diaphragm and intercostal muscles, can be controlled both involuntarily and voluntarily. This allows automatic breathing regulated by the brain for survival, while still enabling conscious control—for example, during speech, singing, or holding your breath.
51
Both central and peripheral chemoreceptors respond when there is an increase in carbon dioxide levels. Explain why it is important that both of these receptors are stimulated.
It is important because central and peripheral chemoreceptors work together to provide a faster and more accurate response to rising carbon dioxide levels. Central chemoreceptors (in the medulla) respond to changes in pH of cerebrospinal fluid caused by CO₂, while peripheral chemoreceptors (in the carotid and aortic bodies) detect changes directly in the blood. This dual detection ensures the respiratory centre receives strong signals to increase breathing rate and depth, helping quickly remove excess CO₂ and maintain stable blood pH.
52
People with chronic obstructive pulmonary disease have inflamed airways that make it difficult to breathe. This can lead to a condition known as hypercapnia, an increased level of carbon dioxide. a) One symptom of hypercapnia is that the blood becomes acidic. Explain why this would occur.
In hypercapnia, excess carbon dioxide (CO₂) in the blood reacts with water to form carbonic acid. This acid dissociates into hydrogen ions and bicarbonate ions. The increase in hydrogen ions lowers the blood pH, making it more acidic.
53
People with chronic obstructive pulmonary disease have inflamed airways that make it difficult to breathe. This can lead to a condition known as hypercapnia, an increased level of carbon dioxide. b) Explain why giving oxygen to a patient with hypercapnia could be dangerous.
In patients with chronic hypercapnia, their bodies rely more on low oxygen levels—not high CO₂—to trigger breathing (this is called hypoxic drive). Giving too much oxygen can reduce this low oxygen stimulus, causing their breathing rate to drop. This may lead to further CO₂ build-up and even respiratory failure.
54
Draw a feedback loop to show what would happen in the body if the concentration of oxygen decreased by a small amount.
Stimulus: -Decrease in oxygen concentration in the blood Receptor: -Peripheral chemoreceptors (carotid and aortic bodies) Message: -Nerve impulses sent to the respiratory centre Modulator: -Respiratory centre in the medulla oblongata Message: -Motor impulses sent via phrenic and intercostal nerves Effector: -Diaphragm and intercostal muscles Response: -Increased rate and depth of breathing Feedback: -Oxygen concentration in the blood increases back to normal -Negative feedback
55
Draw a feedback loop to show what would happen in the body if the concentration of oxygen decreased by a large amount.
Stimulus: -Significant decrease in oxygen concentration in the blood Receptor: -Peripheral chemoreceptors (strongly stimulated) Message: -Frequent, strong nerve impulses to respiratory centre Modulator: -Respiratory centre in the medulla oblongata Message: -Strong motor signals to breathing muscles Effector: Diaphragm and intercostal muscles (strong contractions) Response: -Rapid, deep breathing (possibly gasping) Feedback: -Oxygen levels begin to rise, but may take longer or remain low if underlying cause is severe -Negative feedback

Human Biology Unit 3 (18 decks)

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