Respiratory system 3: control of respiration

Question 0

what is the function of medullary rhythmicity area

Answer 0

to control the basic rhythm of respiration
Dorsal respiratory group (Inspiratory area) has an intrinsic excitability of auto rhythmic neurons that sets the basic rhythm of respiration

Ventral respiratory group (Expiratory area) neurons remain inactive during most quiet respiration but are probably activated during high levels of ventilation to cause contraction of muscles used in forced expiration.

Question 1

Respiratory center

Answer 1

1. Medullary rhythmicity (medulla oblongata)
2. pneumotaxic area (pons)
3. apneustic centers (pons)

Question 2

During normal quiet breathing what activates what

Answer 2

Dorsal respiratory group activate Diaphragm, external intercostals actively contract (2 seconds) = normal quiet inhalation

For exhalation DRG is inactive. Diaphragm, external intercostals relax, followed by elastic recoil of chest wall and lungs

Question 3

During forceful breathing what activates what

Answer 3

DRG activate diaphragm and external intercostal muscles contracts for forceful inhalation

DRG also activates VRG to activate accessory muscle of inhalation (SCM, scalene, pec minor) to contract to inhale

For exhalation, VRG activates accessory muscles of exhalation (internal intercostal, external oblique, internal oblique, transversus abdominis and rectus abdominis muscle) to contract

Question 4

Pneumotaxic area

Answer 4

Pontine respiratory group in the upper pons helps coordinate the transition between inspiration and expiration

Question 5

Ventral respiratory group is also known as

Answer 5

Pre Botzinger complex

Question 6

Apneustic area

Answer 6

The apneustic area sends impulses to the inspiratory area that activate it and prolong inspiration, inhibiting expiration

Question 7

Regulation of respiratory center

Answer 7

Cortical influences

Voluntarily alter breathing patterns

Question 8

Cortical influences allows

Answer 8

conscious control of respiration that may be needed to avoid inhaling noxious gasses or water

Question 9

Voluntary breath holding is limited by

Answer 9

the overriding stimuli of increase H+ and CO2

Question 10

Chemoreceptor regulation of respiration is stimulated when….

Answer 10

Increase of PCO2 (and thus H+) will stimulate…
1. Central chemoreceptors (hypercapnia) in Medulla oblongata in the central nervous system
Then O2 decreases…
2. is activated and hyperventilation, rapid and deep breathing occur.

Question 11

When the chemoreceptors are not stimulated

Answer 11

Hypocapnia. Arterial PCO2 is lower than 40 mmHg.

Question 12

Severe deficiency of O2 will…

Answer 12

depress activity of the central chemoreceptors and respiratory center.

Question 13

Peripheral chemoreceptors (2 bodies)

Answer 13

respond to changes in H+, PO2 or PCO2

1. aortic body in the wall of aorta.
2. in walls of common carotid arteries.

Question 14

Where does aortic body of chemoreceptors join?

Answer 14

nerves join vagus

Question 15

Where does carotid bodies of chemoreceptors join?

Answer 15

nerves join glossopharyngeal nerve

Question 16

Negative feedback regulation of breathing

Answer 16

1. Increase in arterial pCO2
2. Stimulates receptors
3. respiratory center receives input
4. Muscles of respiration contract more frequently and forcefully
5. PCO2 decrease

Question 17

What will activate the inspiratory center to increase ventilation prior to exercise induced oxygen need.

Answer 17

Proprioceptors of joints and muscles

Question 18

what detects lung expansion with stretch receptors and limits it depending on ventilatory need and prevention of damage

Answer 18

Inflation (Hering-Breuer) reflex

Stretch receptors = baroreceptors

Question 19

where does stretch receptors located

Answer 19

in the walls of bronchi and bronchioles, also called as baroreceptors

Question 20

what makes ventilation rate and depth increase (8)

Answer 20

1. Voluntary hyperventilation controlled by cerebral cortex
2. Anticipation of activity via stimulation of the limbic system
3. Increase in arterial blood H+ level or pCO2 above 40mm Hg and decrease in arterial blood pO2
   from 100 to 50 mmHg. Detected by central and peripheral chemoreceptors
4. Increase in sensory impulses from proprioceptors in muscles and joints and increase in motor impulses from the motor cortex.
5. Decrease in blood pressure detected by baroreceptors
6. Increase in body temperature
7. Prolonged (somatic) pain
8. stretching anal sphincter

Question 21

what makes ventilation rate and depth decrease with

Answer 21

1. Voluntary hypoventilation controlled by cerebral cortex (limited by buildup of CO2 and H+)
2. Decrease in arterial blood H+ level or pCO2 below 40mm Hg and decrease in arterial blood pO2 below 50 mm Hg, detected by central and peripheral chemoreceptors
3. Decrease in sensory impulses from proprioceptors in muscles and joints and decrease in motor impulses from the motor cortex
4. Increase in blood pressure detected by baroreceptors
5. Decrease in body temperature (sudden cold stimulus causes apnea)
6. severe pain causes apnea
7. Irritation of pharynx or larynx by touch or chemicals causes apnea followed by coughing or sneezing

Question 22

4 different type of hypoxia

Answer 22

1. Hypoxic hypoxia - low pO2 in arterial blood (high altitude, airway obstruction, fluid in lungs)
2. Anemic hypoxia - to little functioning hemoglobin in the blood (hemorrhage, anemia, carbon monoxide poisoning)
3. Stagnant/Ischemic hypoxia - results from the inability of blood to carry oxygen to tissues fast enough to sustain their needs (heart failure, circulatory shock)
4. In histotoxic hypoxia, the blood delivers adequate oxygen to the tissues, but the tissues are unable to use it properly (cyanide poisoning)

Question 23

how exercises will increase the respiration

Answer 23

• blood flow increases with lower O2 and higher CO2 content
• is matched by increased ventilation and oxygen diffusion capacity as more pulmonary capillaries open
• ventilatory modifications can increase 30 times above resting levels initially neural influences and then gradually due to chemical stimulation from changes in cell metabolism

Question 24

why smokers have difficulty breathing

Answer 24

1. nicotine constricts terminal bronchioles
2. carbon monoxide in smoke binds to hemoglobin
3. irritants in smoke cause excess mucus secretion
4. irritants inhibit movements of cilia
5. in time destroys elastic fibers in lungs and leads to emphysema (trapping of air in alveoli and reduced gas exchange)

Question 25

when fetus develops lungs with sufficient surfactant for survival

Answer 25

26 - 28 weeks

Question 26

Aging of respiratory system (6)

Answer 26

1. Respiratory tissue and chest wall become more rigid
2. vital capacity decreases to 35% by age 70
3. Decreases in macrophage activity
4. Diminished ciliary action
5. Decrease in blood levels of O2
6. Result is an age-related susceptibility to pneumonia or bronchitis