Regulation of Breathing/ Neural Regulation
Control of Respiration
The medulla oblongata is the primary respiratory control center.
Structure involved in control of Respiration.
Respiratory center
Medullary rhythmicity area (center)
Location- this center is located in medulla oblongata.
Function- to control the basic rythm of Respiration.
Medullary Rhythmicity area, two circuit of neuron-
1. Inspiratory area; stimulating inhalation
2.Expiratory area; stimulating exhalation
Inspiratory area
When inspiratory area is active, it generates nerve impulses for about 2s which travel to muscles of Respiration.
Nerve impulses from inspiratory center
Contraction of muscles of Respiration (internal intercostal muscle relax)
Expansion of rib cage
Air rushes into lung
Flowchart- role of inspiratory area in respiratory
During in 2s Inspiratory neurons cause contraction of diaphragm (via phrenic nerve) and contraction of external intercostal muscle (via intercostal nerves).
Expiratory area
When expiratory circuit activated. It's neuron send inhibitory impulse to the inspiratory circuit to prevent inspiration.
So, at the beginning of expiration, inspiratory area is inactive but after 3 second become active.
Nerve impulses from expiratory center
Contraction of internal intercostal muscles and relaxation of external intercostals and diaphragm.
(Diaphragm and external intercostal muscle relax for 3 second)
Rib cage becomes smaller
Increased pressure in the lungs
Air expelled from the lungs
Flowchart - role of expiratory area in respiration
Pontine Respiratory Group
Pontine respiratory group is a collection of neurons in the Ponds.
Pontine respiratory group connection with medullary respiratory centers, play a role in switching between inspiration and expiration.
Pontine respiratory group has -
1. Apneustic area (lower pond)
2. Pneumotaxic area (upper pond)
1. Apneustic area (lower pond)
Located in the lower ponds.
Function - it coordinate the transition between inspiration and expiration.
It causes strong inhalation and weak exhalation.
Apneustic area - sends stimulatory impulses- to inspiratory area, activate it - prelong respiration and inhibit expiration- when pneumotaxic area is inactive.
2. Pneumotaxic area
Located in the upper ponds.
Function - it coordinate the transition between inspiration and expiration.
It limit duration of inspiration and thus facilitates expiration.
When this area is more active, breathing rate is quicker.
It transmits inhibitory impulses to inspiratory area.
Regulation of Respiration
1. Nervous regulatory mechanism
2. Chemical regulatory mechanism
Nervous regulatory mechanism
1. Automatic control (involuntary)
Medulla
A. Dorsal respiratory group (DRG)
Made up inspiratory neuron
B. Ventral respiratory group (VRG)
Made of inspiratory and expiratory neuron
Pons
1. Apneustic center (lower pons)
2. Pneumotaxic center (upper pons)
2. Voluntary control
Cerebral cortex
2. Chemical Regulatory mechanism
1 Peripheral chemoreceptors
Present in carotid and Aortic body
2. Central/ medullary chemoreceptors
Present in medulla
Regulation of Respiration
Breathing is controlled by the central neuronal network to meet the metabolic demand of the body.
1. Neural Regulation
2. Chemical Regulation
Respiratory centers
A collection of functionally similar neurons that help to regulate the respiratory center's.
Basic respiratory centers,
1. Medulla
2. Pons
3. Higher respiratory center,
Cerebral cortex,
Hypothalamus and limbic system
4. Spinal cord, respiratory motor neurons
1. Cerebral and limbic system control
Cerebral cortex , cerebral cortex of brain controls voluntary respiration.
It has connections with respiratory center.
Voluntary control is protective, because it enables is to prevent water or irritating gases from entering the lungs.
Increased CO2 and H+ ions in the Blood.
Inspuratory area is strongly stimulated
Send nerve impulses to inspiratory muscles
Breathing
Hypothalamus and limbic system
Nerve impulses from hypothalamus and limbic system also stimulate respiratory center.
Structure and interacting areas of limbic system are involved in -
Motivation
Emotion
Learning
Memory
These pathway permit emotional stimulus to after respiration.
Excess breathing creates low level of CO2 in blood.
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