Control of breathing Central rhythm Lecture 13 Flashcards
Describe the muscles used in breathing
Inspiration- diaphragm is the only major inspiratory muscle External muscles- scalene and sternocleomastoid muscle used in exercise, coughing and vomiting Expiration- passive diaphragm relaxation Internal muscles- abdominal and oblique muscle involved only in forced breathing
Briefly describe central control of timing breathing and rhythm
PRG in the pons important for timing DRG and VRG in the medulla important for rhythm generation DRG- inspiratory neurones, in the nucleus tractus solitarius (NTS)- spontaneous activity synchronised with breathing VRG- inspiratory/expiratory motor neurones, activity in the DRG excites inspiratory neurones and inhibits expiratory neurones
What causes inspiration during quiet breathing?
DRG- self-excitable neurones, repetitively generating action potentials to cause inspiration ➡️C spinal cord ➡️phrenic nerves ➡️diaphragm contracts ➡️inspiration
What causes expiration?
Entirely passive DRG inactive➡️ diaphragm relaxes➡️ expiration
What neural control causes forced breathing?
Inspiratory neurones in the VRG via the T spinal cord causes other inspiratory muscles to contract Expiratory neurones causes expiratory muscles to contract
Describe the involvement of higher brain centres in respiration
Hypothalamus- temperature, fight/flight response Limbic system and cerebral cortex- emotion/pain Motor cortex- limb receptors, excercise
Give a brief overview of CNS in respiratory control
Brainstem- automatic- metabolic Cortical- voluntary- behavioural