The Plan Introduction general concepts Anatomy Mechanics moving

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The Plan • Introduction – general concepts • Anatomy • Mechanics – moving air

The Plan • Introduction – general concepts • Anatomy • Mechanics – moving air into the lungs – Structures, pressure changes • Gas Exchange – moving air from the lungs to blood and tissues – Moving O 2 in and CO 2 out of tissues • Control mechanisms – Local – CNS 1

Readings - Respiratory • Mc. Kinley, O’Loughlin, and Bidle, Anatomy and Physiology An integrative

Readings - Respiratory • Mc. Kinley, O’Loughlin, and Bidle, Anatomy and Physiology An integrative Approach, p 883 -931. • Control mechanisms: nervous and others 911 -915 2

Objectives • Describe the general controls of the respiratory system involving skeletal muscles. •

Objectives • Describe the general controls of the respiratory system involving skeletal muscles. • Understand local controls involving dilation and constriction of blood vessels and bronchioles • Explain inputs and controls involving voluntary and involuntary centers in the CNS • Describe the functions of the dorsal and ventral respiratory groups 3

Controls of Respiration cognition Higher CNS centers brain stem Respiratory control center body respiratory

Controls of Respiration cognition Higher CNS centers brain stem Respiratory control center body respiratory system Respiratory Centers and Reflex Controls spinal cord Motor neurons 4

Control of Respiration • How do you control respiration? – what cells directly control

Control of Respiration • How do you control respiration? – what cells directly control inhalation & exhalation? – Control = skeletal muscles involved in inhalation and exhalation • These cells control respiratory minute volume. How do you control these cells? – Motor neurons control skeletal muscle. Respiratory minute volume involves the frequency and volume of a respiratory cycle. • Is this control voluntary or involuntary? – Both … from several CNS control centers 5

Control of Respiration • How does one know when control is needed? Where do

Control of Respiration • How does one know when control is needed? Where do the signals originate? – Cognitive input & input from the 5 senses (visual, auditory, olfactory, gustatory, touch) – function through control centers in the brain stem – Sensory inputs from the body also function through control centers in the brain stem • Chemoreceptors • Baroreceptors • others 6

Mechanisms that control breathing 1. Motor neurons control skeletal muscles (diaphragm, intercostals and accessory

Mechanisms that control breathing 1. Motor neurons control skeletal muscles (diaphragm, intercostals and accessory muscles for increased breathing) 2. ● Local controls for systemic blood flow in arterioles. ● Local controls in the lung for blood flow and air flow in the lung. 3. Input from (peripheral) sensory receptors: chemo-, baro-, and proprio-receptors 4. Control centers within the CNS 7

1. Controls of ‘Respiratory’ muscles 8

1. Controls of ‘Respiratory’ muscles 8

Control Mechanisms & Respiration • The distribution of gases (O 2 and CO 2)

Control Mechanisms & Respiration • The distribution of gases (O 2 and CO 2) associated with blood or the spaces in the lung is carefully coordinated. • The movement of gases is influenced by: – Partial pressures, gradients, p. H, temperature, gas solubilities – Changes in blood flow – Changes in depth and rate of respiration • This involves: – responses to stimuli from a systemic (the body) location & – excellent coordination between the respiratory and cardiovascular systems called - – Ventilation-Perfusion Coupling Air/Gas flow Blood flow 9

t p e c n o c • Controls: flow of a gas or

t p e c n o c • Controls: flow of a gas or liquid To increase the amount of a gas or liquid, you open up the tube – you dilate that tube … faster • = vasodilate & bronchiodilate To slow (restrict) flow of a gas or liquid, you constrict the tube … slower • = vasoconstrict or bronchioconstrict Remember: O 2 is good and CO 2 is bad so … – • you want to remove CO 2 and bring in O 2 Scenerio: muscle cells in interstitium are very active, so … – O 2 is needed for metabolism; O 2 is donated to cells so O 2 in blood decreases … also – CO 2 is produced after metabolism and PCO 2 in blood increases 10

Control of gas movement in blood or air spaces • Constriction & dilation occurs

Control of gas movement in blood or air spaces • Constriction & dilation occurs in arterioles and bronchioles – these are the ‘control’ points for the cardiovascular and respiratory systems – because they have smooth muscles oriented around their small lumens and their branches support many cells • Constriction or dilation in arterioles or bronchioles results in: – altered blood flow through capillaries. – altered air flow into and out of alveoli. 11

2. Controls: Systemic Gas flow in the organ systems, eg. muscle cells Muscle cells

2. Controls: Systemic Gas flow in the organ systems, eg. muscle cells Muscle cells in interstitium are very active. According to the partial pressure gradients: Systemic capillary - O 2 is given to muscle cells for metabolism - CO 2 is being produced after metabolism and released In the systemic capillary: - PO 2 is decreased from 95 to 40 mm Hg - PCO 2 is increased from 40 to 45 mm Hg The control Released CO 2 causes smooth muscle cells around systemic BVs to relax = vasodilation Blood flow increases, CO 2 leaves & more O 2 enters via blood 12 Copyright 2009 Pearson Education Inc. publishing as Pearson Benjamin Cummings

2. Controls: within the lungs Ventilation-Perfusion Coupling 1. 2. Blood flow through alveolar capillaries

2. Controls: within the lungs Ventilation-Perfusion Coupling 1. 2. Blood flow through alveolar capillaries is directed toward lung lobules where PO 2 levels are relatively high and (CO 2 levels are low) Smooth muscle cells in walls of bronchioles are sensitive to CO 2 1. Increased PCO 2 causes bronchiodilation 13

Ventilation-Perfusion Coupling § For gas exchange to be optimal in the lung, perfusion through

Ventilation-Perfusion Coupling § For gas exchange to be optimal in the lung, perfusion through blood vessels has to match air compositions in the alveoli - if alveoli are well ventilated = high O 2 and low CO 2 – pulmonary arterioles dilate and blood flow is directed to that area to pick up O 2. - if alveoli are poorly ventilated = low O 2 and high CO 2 – pulmonary arterioles constrict and blood flow to that area is decreased. § Bronchiole diameter parallels CO 2 levels a. if CO 2 bronchioles dilate -- CO 2 and O 2 enters b. if CO 2 bronchioles constrict 14

Ventilation-Perfusion Coupling BVs lung = CO 2 increased Increased O 2 in lungs correlates

Ventilation-Perfusion Coupling BVs lung = CO 2 increased Increased O 2 in lungs correlates with increased blood flow = vasodilation 15

Controls: bronchioles and arterioles in the lung (a) Changes in bronchioles (b) Changes in

Controls: bronchioles and arterioles in the lung (a) Changes in bronchioles (b) Changes in arterioles Increase CO 2 causes bronchioles to dilate and arterioles to constrict 16

3. Controls: (peripheral) sensory information into the CNS • Sensory Modifiers of Respiratory Center

3. Controls: (peripheral) sensory information into the CNS • Sensory Modifiers of Respiratory Center Activities – Chemoreceptors are sensitive to PCO 2, PO 2, or p. H of blood or cerebrospinal fluid – Baroreceptors in aortic or carotid sinuses are sensitive to changes in blood pressure • Stretch receptors respond to changes in lung volume – Proprioceptors from the periphery – signals indicating position in space of limbs – Irritating physical or chemical stimuli in nasal cavity, larynx, or bronchial tree - COUGHING AND SNEEZING – Other sensations including pain, changes in body temperature, abnormal visceral sensations 17

Controls of Respiration Peripheral – monitors changes p. H either induced by PCO 2

Controls of Respiration Peripheral – monitors changes p. H either induced by PCO 2 or independent of PCO 2 (kidney failure) – in carotid or aortic bodies (in carotid & aortic blood vessels) – leads to increased rate and depth of respiration when p. H goes down • Chemoreceptors Central – monitors changes in p. H due to changes in blood PCO 2 in the CSF – sensitive to 5 mm Hg change – on ventrolateral surface of medulla oblongata – increased blood PCO 2 causes a decrease in CSF p. H – causes increased rate and depth of breathing 18

Controls of Respiration • Baroreceptors 1. monitor blood pressure; located in carotid sinuses and

Controls of Respiration • Baroreceptors 1. monitor blood pressure; located in carotid sinuses and aortic arch – when blood pressure falls - respiration rate increases 2. baroreceptors in bronchioles and visceral pleura also monitor pressure and inhibit over stretching of lungs (Hering-Breuer reflex) • Proprioreceptors – monitor limb position is space – Increase breathing when body movements increase • Irritant receptors – coughing and sneezing – require elevated intake of breath 19

3. Controls of the Respiratory System Irritant receptors Baroreceptors Receptors of other Reflexes Internal

3. Controls of the Respiratory System Irritant receptors Baroreceptors Receptors of other Reflexes Internal Chemoreceptors Proprioceptors 20

4. Controls of the Respiratory System Pontine respiratory center Dorsal Respiratory Group (DRG) Ventral

4. Controls of the Respiratory System Pontine respiratory center Dorsal Respiratory Group (DRG) Ventral Respiratory Group(VRG) 21

4. CNS Control of Respiration The Respiratory Center = brain stem nuclei • Pontine

4. CNS Control of Respiration The Respiratory Center = brain stem nuclei • Pontine respiratory system – modifies information into the medullary center and regulates transition from inspiration to expiration • Medullary respiratory system – Dorsal respiratory system (DRG) • Receives sensory information and relays information to the VRG – **Ventral respiratory group (VRG) • Initiates neural impulses for quiet breathing via the spinal cord and the diaphragm and internal intercostal muscles 22

Controls: from the CNS • Voluntary Controls – input from higher brain centers –

Controls: from the CNS • Voluntary Controls – input from higher brain centers – Cognition into cortex; emotions from frontal cortex; limbic system; hypotha. Iamus. • into medullary respiratory system then to motor neurons in spinal cord OR • directly to motor neurons that control skeletal muscles associated with respiration • Involuntary Controls – input into brain stem nuclei – Input from receptors (chemo-, baro-, proprio, etc. ) in the body into DRG of the medullary respiratory system. Output to VRG – VRG signals the motor neurons controlling skeletal muscles associated with respiration 23

Control of Respiration • Ventral Respiratory Group (VRG) - Inspiratory center – controls diaphragm

Control of Respiration • Ventral Respiratory Group (VRG) - Inspiratory center – controls diaphragm and external intercostals - Functions in quiet and forced breathing • Dorsal Respiratory Group (DRG) - relays information to VRG 24 Copyright 2009 Pearson Education Inc. publishing as Pearson Benjamin Cummings

Respiratory Rhythmicity • Quiet Breathing – VRG (ventral respiratory group: inspiratory neurons) activated for

Respiratory Rhythmicity • Quiet Breathing – VRG (ventral respiratory group: inspiratory neurons) activated for 2 sec. • Stimulates motor neurons and inspiratory muscles (diaphragm and ext. intercostals) – VRG inspiratory neurons inactivated by VRG expiratory neurons for 3 sec. • Allowing passive exhalation • Altered Breathing Rate and Depth – Sensory inputs (chemo, baro, proprio, etc. ) into DRG – Rate varies by altering inspiration vs expiration times – Depth varied by engaging accessory muscles 25

Control of Respiration • SIDS (sudden infant death syndrome) • marked by the sudden

Control of Respiration • SIDS (sudden infant death syndrome) • marked by the sudden death of an infant that is not predicted by medical history (wikipedia) – Some evidence of a disruption of the normal respiratory reflex pattern – May result from connection problems between pacemaker complex and respiratory centers – http: //en. wikipedia. org/wiki/Sudden_infant_death_syndrome 26

Controls of the Respiratory System 27

Controls of the Respiratory System 27