The document summarizes the regulation of respiration through nervous and chemical mechanisms. The nervous mechanism involves respiratory centers in the medulla and pons that receive sensory information and control respiratory muscles. The chemical mechanism involves chemoreceptors that detect changes in blood oxygen, carbon dioxide, and hydrogen ion levels. Central chemoreceptors in the brainstem are sensitive to increased carbon dioxide levels, while peripheral chemoreceptors respond to decreased oxygen levels. Together the nervous and chemical mechanisms work to regulate breathing and maintain appropriate gas exchange.
This presentation is an overview of the description of the 4 stages of the cardiac cycle (atrial diastole, atrial systole, ventricular systole, ventricular diastole) as well as explaining the mechanism of the cardiac cycle.
The apparatus used to measure
Volume of air exchanged during breathing
Respiratory rate
The record is called a spirogram
Upward deflection inhalation
Downward deflection exhalation
Regulation of Respiration - Animal PhysiologyMuhammad Yousaf
This document contain detailed study about The Regulation of Respiration and it covers all of the aspects of terms and topics related to regulation of respiration.
This presentation is an overview of the description of the 4 stages of the cardiac cycle (atrial diastole, atrial systole, ventricular systole, ventricular diastole) as well as explaining the mechanism of the cardiac cycle.
The apparatus used to measure
Volume of air exchanged during breathing
Respiratory rate
The record is called a spirogram
Upward deflection inhalation
Downward deflection exhalation
Regulation of Respiration - Animal PhysiologyMuhammad Yousaf
This document contain detailed study about The Regulation of Respiration and it covers all of the aspects of terms and topics related to regulation of respiration.
This a presentation on regulation of respiration, control of the rate of increase of the the ramp signal, control of the limiting point at which ramp suddenly ceases
Regulation of respiration (the guyton and hall physiology)Maryam Fida
Normal respiration is spontaneous and unconscious.
There are 4 groups of neurons on each side in the Pons and medulla oblongata which are involved in regulation of respiration. These include
1. Medullary centers
Dorsal respiratory group of neurons
Ventral respiratory group of neurons
2. Pontine centers
Pneumotaxic centre
Apneustic centre.
It contains “I”neurons which are inspiratory neurons.
It’s located in dorsal portion of medulla oblongata.
It also includes the nucleus of tractus solitarius which is the sensory termination of afferent fibers in 9th ( GLOSSOPHARYNGEAL NERVE) and 10th (VAGUS NERVE) cranial nerves.
They receive impulses from peripheral chemoreceptors, carotid and aortic baroreceptors and also other receptors in the lungs.
In this group inspiratory ramp signals are produced spontaneously.
If we cut the medulla oblongata from other parts of brain and also the afferent nerves which enter the medulla, still inspiratory ramp signals are produced which indicate it’s the inherent property of medulla.
Initially the signal is weak and then it progressively increases and then fades away.
Each ramp signal’s duration is 2 sec and then for 3 seconds there is no ramp signal.
So each cycle lasts for 5 seconds and there are 12 cycles /minute which is the respiratory rate.
Significance of the signal in the form of ramp is that it causes progressive expansion of the lungs. After production, these ramp signals are transmitted to the contra lateral motor neurons supplying the inspiratory muscles.
Rate and duration of inspiratory ramp signals is controlled by impulses from the Pneumotaxic centre and impulses from the lungs via vagi.
Like heartbeat, breathing must occur in a continuous, cyclic pattern to sustain life processes.
Inspiratory muscles must rhythmically contract and relax to alternately fill the lungs with air and empty them.
The rhythmic pattern of breathing is established by cyclic neural activity to the respiratory muscles
2. Respiration is regulated by two mechanisms: Nervous or neural mechanism Chemical mechanism Nervous Mechanism: It involves respiratory centers, afferent and efferent nerves. Respiratory centers: The centres in the medulla oblongata and pons that collects sensory information about the level of oxygen and carbon dioxide in the blood and determines the signals to be sent to the respiratory muscles. Stimulation of these respiratory muscles provide respiratory movements which leads to alveolar ventilation. Respiratory centers are situated in the reticular formation of the brainstem and depending upon the situation in brainstem, the respiratory centers are classified into two groups: Medullary centers Pontine centers
3. There are two centers in each group: Medullary Centers: Inspiratory center Expiratory center Pontine Centers: Pneumotaxic center Apneustic center
4. Inspiratory center: Inspiratory center is situated in upper part of medulla oblongata This center is also called dorsal group of respiratory neurons It is formed by nucleus of tractus solitarius Function: it is concerned with inspiration. Expiratory center: It is situated in medulla oblongata anterior and lateral to the inspiratory center It is also called ventral group of respiratory neurons It is formed by neurons of nucleus ambiguous and nucleus retro ambiguous Function: this center is inactive during quiet breathing and inspiratory center is the active center, but during forced breathing or when the inspiratory center is inhibited it becomes active.
5. Pneumotaxic center: It is situated in upper Pons. It is formed by nucleus parabrachialis. Function: it controls medullary respiratory centers, particularly the inspiratory center through apneustic center. It always controls the activity of inspiratory center so that duration of inspiration is controlled. Apnuestic center: It is situated in lower Pons. Function: this center increases depth of inspiration by acting directly on the inspiratory center.
6. Nervous connections of respiratory centers: Afferent pathway: Respiratory center receive afferent impulses from different parts of the body according to movements of thoracic cage and lungs. From peripheral chemoreceptor and baroreceptor impulses are carried by glossopharyngeal and vagus nerves to respiratory center. Efferent pathway: Nerve fiber from respiratory center leaves the brain and descend in anterior part of lateral column of spinal cord. These nerve fibers terminate in the motor neurons in the anterior horn cells of the cervical and thoracic segments of spinal cord. From motor neurons two sets of nerve fiber arise which supplies particular muscle: Phrenic nerve fibers: supplies diaphragm The intercostal nerve fibers: supplies intercostal muscles.
7. Factors affecting respiratory centers: Impulses from higher centers: impulses from higher center can stimulate or inhibit respiratory centers directly. Impulses from stretch receptors of lung:
8. 3) Impulses from ‘J’ receptors of lungs: ‘J’ receptors are juxtacapillary receptors which are present in wall of the alveoli and have close contact with the pulmonary capillaries. These receptors get stimulated during conditions like pulmonary edema, pulmonary congestion, pneumonia as well as due to exposure of exogenous and endogenous chemicals like histamine, serotonin. Stimulation of ‘J’ receptor produces a reflex response called apnea. 4) Impulses from irritant receptors of lungs: Irritant receptors are situated on the wall of bronchi and bronchioles of lungs. They got stimulated by harmful chemicals like ammonia and sulfur dioxide. Stimulation of irritant receptors produces reflex hyperventilation along with bronchospasm which prevents entry of harmful chemicals into the alveoli.
9. 5) Impulses from Proprioceptors: Proprioceptors are the receptors which give response to the change in the position of different parts of the body. This receptors are situated in joints, muscles and tendons. They get stimulated during exercise and sends impulses to the cerebral cortex. Cerebral cortex in turn by activating medullary respiratory centres causes hyperventilation. 6) Impulses from Thermoreceptors: Thermoreceptors give response to change in the body temperature. They are cutaneous receptors namely cold and warmth When this receptors get stimulated they send signals to cerebral cortex Cerebral cortex in turn stimulates respiratory centres and causes hyperventilation.
10. 7) Impulses from pain receptors: Pain receptors give response to pain stimulus. Like other receptors this receptors also send impulses to the cerebral cortex. Cerebral cortex in turn stimulates the respiratory centers ad causes hyperventilation. 8) Cough reflex: This is a protective reflex caused by irritation of parts of the respiratory tract beyond nose like larynx, trachea and bronchi. Irritation of any of this part causes stimulation of vagus nerve and cough occurs. Cough begins with deep inspiration followed by forceful expiration with closed glottis. So the intrapleural pressure rises above 100 mm Hg. Then, glottis is suddenly opened with explosive outflow of air at a higher velocity. So the irritants may be expelled out of the respiratory tract.
11. 9) Sneezing reflex: It is also a protective reflex which occurs due to the irritation of nasal mucus membrane. During irritation of nasal mucus membrane, the olfactory receptors and trigeminal nerve endings present in the nasal mucosa are stimulated leading to sneezing. Sneezing starts with deep inspiration, followed by forceful expiratory effort with opened glottis and the irritants are expelled out of the respiratory tract. 10) Deglutition reflex: During swallowing of the food, the respiration is arrested for a while. Temporary arrest of the respiration is called apnea and apnea which occurs during swallowing called swallowing apnea or deglutition apnea. This prevents entry of the food particles into the respiratory tract.
12. Chemical Mechanism: The chemical mechanism of the respiration is operated through the chemoreceptors. Chemoreceptors: They are the receptors which give response to change in the chemical constituents of blood like.. Hypoxia Hypercapnea Increased hydrogen ions concentration (decreased blood pH) Chemoreceptors are classified into two groups: Central chemoreceptors Peripheral chemoreceptors
13. Central chemoreceptors The chemoreceptors present in the brain are called central chemoreceptors. Situation: They are situated in deeper part of medulla oblongata, close to the dorsal group of neurons. This area is known as chemosensitivearea and neurons are called as chemoreceptors. They are in close contact with blood and CSF. Action: They are very sensitive to increase in hydrogen ion concentration. Hydrogen ion cannot cross the blood brain barrier and blood cerebrospinal fluid barrier. On the other hand if carbon dioxide increases in the blood as it is a gas it can cross both the barrier easily and after entering the brain it combines with water to form carbonic acid. As carbonic acid is unstable, it immediately dissociates into hydrogen and bicarbonate ions. The hydrogen ion now stimulates the central cemoreceptors which stimulates dorsal group of respiratory center (inspiratory group) and increase rate and force of breathing.
14. Peripheral chemoreceptors: Situation: The receptors are present in peripheral portions of the body that’s why called as peripheral chemoreceptors. Action: They are very sensitive to reduction in partial pressure of oxygen. Whenever, the partial pressure of oxygen decreases these chemoreceptors become activated and send impulses to inspiratory center and stimulate them. Thereby increases rate and force of respiration and rectifies the lack of oxygen.