RESPIRATION

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RESPIRATION
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Anatomical structures

• Upper
• Nose
• Nasal cavity
• Paranasal sinuses
• Pharynx

• Lower
• Larynx
• Trachea
• Bronchi
• Bronchioles
• Alveoli of lungs

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Functional Classification

• Conducting filter, warm, and moisten air
• Nose, pharynx, trachea, bronchi, bronchioles,
  terminal bronchioles
• Respiratory function in respiration, i.e., gas
  exchange
• Respiratory bronchioles, alveolar ducts, alveolar
  sacs, and alveoli

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Respiratory epithelia

• Pseudostratified columnar epithelium with goblet
  cells
• Nasal cavity and superior pharynx
• Stratified squamous epithelium
• Inferior pharynx which acts as a common
  passageway for food
• Pseudostratified columnar epithelium
• Superior portion of lower respiratory system
• Ciliated cuboidal epithelium
• Small bronchioles
• Simple squamous
• Alveoli respiratory exchange surfaces
• Specialized olfactory epithelium

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Lamina propria

• Mucous glands
• Smooth muscle in conducting portions

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Respiratory defense

• Goblet cells
• Mucous glands
• Cilia
• Create a mucous escalator in lower system
• Nasal filtration of larger particles
• Turbulence
• Increased mucous secretion in nasal cavity and
  paranasal sinuses

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The nose filters and warms air and it houses the
olfactory epithelium
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Nose and nasal cavities

• External nares
• Nasal vestibule
• Nasal septum
• Superior, middle and inferior conchae
• Olfactory epithelium
• Hard palate
• floor
• Soft palate
• Boundry of nasopharynx and oropharynx
• Internal nares

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Function of Nose

• Filters air
• Warms air

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Supporting Structures
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Internal Anatomy
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The Pharynx

• Three sections
• Nasopharynx
• Oropharynx
• Laryngopharynx
• Passageway for food and air
• Resonating chamber
• Home to the tonsils
• The eustachian tube opens into the upper part of
  the pharynx

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Tonsils 1 pharyngeal, 2 palatine, 2 lingual, 2
tubular
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Larynx

• Connects pharynx to trachea
• Contains vocal cords
• 9 cartilages

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Unpaired Laryngeal Cartilages

• Thyroid hyaline
• Largest
• Protects glottis
• Cricoid hyaline
• Complete ring
• Protects glottis
• Landmark for tracheotomy (do below)
• Epiglottis elastic
• Guards entrance to trachea
• Hinged

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Paired Laryngeal Cartilages

• Arytenoids hyaline
• Open and close glottis for sound production
• Corniculates
• Open and close glottis for sound production
• Cunieforms
• In folds of tissue between arytenoids and
  epiglottis
• support vocal folds and lateral part of epiglottis

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Laryngeal Attachments

• Thyrohyoid membrane
• Cricothyroid ligament
• Cricotracheal ligament.

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Glottis

• Space bounded by true vocal folds (vocal cords)
• As air passes over folds vibrations are produced
  in air that are sound waves
• Muscles move arytenoids which attach to folds and
  change tension of cords and thus, the distance
  between them
• Narrow distancehigh pitch
• Wide distancelow pitch

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The arytenoids pivot to open And close.
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Other Factors in Sound Production

• Length and thickness of vocal fold
• Thin, shorthigh pitch
• Thick, longlow pitch
• Phayrnx, mouth, nose, paranasal sinuses
• Modify sound

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Whispering

• During the glottis is barely open and no
  vibration occurs in the vocal folds
• The mouth creates the sounds of speech.

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False Vocal Folds

• Also called vestibular or ventricular folds
• Project into glottis
• Superior to vocal folds
• Help prevent foreign objects from entering
• Protect vocal folds
• When closed, function in holding the breath
  against the thoracic cavity, for example, when
  lifting a heavy object

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Trachea

• C6-T5
• Mediatinum
• Submucosa has extensive mucous glands
• 15-20 C-shaped hyaline cartilage rings
• Completed by elastic ligament and trachialis
  muscle

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Primary bronchi

• Mediatinum
• Right and left
• Carina
• Most sensitive aread
• Cough reflex
• Travels to hilus in root of lung anterior to T5
• Extensive branching after entering lung

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Lungs

• Apex
• Base
• Hilus and root
• Lobes
• Right 3
• Left 2
• Fissures
• Oblique fissure both lungs
• Horizontal fissure right lung
• Cardiac notch left lung
• Anatomical differences
• Right, broader, shorter, 3 lobes

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Branches of Bronchial Tree

• Conducting
• Primary bronchi
• Secondary bronchi
• Tertiary bronchi (segmental bronchi)
• 10 bp segments in right 10 in left during fetal
  life, but reduced to 8 or 9
• Bronchioles of decreasing size
• Terminal bronchioles

• respiratory
• Respiratory bronchioles
• Alveolar ducts
• Alveolar sacs
• Alveoli

About 25 orders of branching of tree
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Bronchial Tree

• Primary bronchi and their branches

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Cartilage

• Complete cartilage rings in primary bronchi
• Secondary and tertiary have plates of cartilage
• Successively reduced until none at bronchiole
  level and beyond
• Cartilage decreases and smooth muscle increases
  as branching progresses.

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Smooth Muscle

• Replaces cartilage at bronchiole level
• Under ANS control
• Sympathetic
• bronchodilation
• PS
• Bronchoconstriction
• Excessiveasthsma

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The Pleurae

• Two layered serous membrane
• Parietal layer extends below apex
• Filled with pleural fluid
• Reduces friction
• Creates attraction between layers

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The visceral layer adheres to the lung and the
parietal layer is closer to the body wall. The
pleural cavity is found between the two layers
it contains pleural fluid, which reduces
friction and causes the layers to be attracted
to each other.
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Branching and Gas Exchange

• Each lung is divided into 10 bronchopulmonary
  segments served by tertiary bronchioles.
• Each segment is divided into many lobules which
  are served by terminal bronchioles.
• Each lobule is wrapped in elastic tissue and has
  a lymph vessel, arteriole and venule in addition
  to the branch of the terminal bronchiole.
• The next orders of branching are where gas
  exchange occurs, the most occurring in the
  alveoli
• Respiratory bronchioles
• Alveolar ducts
• Alveolar sacs and alveoli

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Respiratory bronchioles Alveloar
ducts alveoli
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Aveolar Ducts, Sacs and Alveoli

• Ducts lead to alveolar sacs, which are clusters
  of alveoli
• 150 million alveoli/lung
• Capillaries for gas exchange and elastic tissue
  for recoil

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Alveolar epithelium

• Simple squamous
• Basement membrane
• Alveolar macrophages
• Septal cells
• surfactant

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Respiratory membrane

• Capillary epithelium and basement membrane
• Repiratory epithelium and basement membrane
• Fused basal laminas
• Thin .1-.5 um in thickness

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Blood Supply to Lungs

• Pulmonary circuit
• Systemic circuit
• Some intermixing

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Pulmonary Ventilation Breathing

• Air exchanges between the atmosphere and the
  alveoli due to pressure changes created during
  inhalation and expiration by muscles.

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Pressure Gradients and Air Movement

• Muscles create pressure gradients.
• Air moves into the lungs when the pressure inside
  the lungs is less than the atmospheric pressure.
• Air moves out of the lungs when pressure in the
  lungs exceeds atmospheric pressure.
• Air movement, itself, is passive.

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Boyles Law

• Describes how pressure gradients relate to
  changes in container size.
• The pressue of a gas is inversely proportional to
  the volume of the container.
• As the thorax expands during inhalation, the lung
  volume increases, and the air pressure decreases
  in the lungs relative to the atmosphere. This
  creates the gradient that allows air to rush in.

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The change in volume results in a change in gas
pressure.
(gas laws)
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Diaphragm

• Contraction of the diaphragm increases vertical
  dimension. This produces a pressure differential
  of 1-3 mm of Hg at rest.
• Air flows in.

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Role of the Pleurae

• The intrapleural pressure between the bilayer at
  rest is subatmospheric by about 4mm of hg. It
  drops another 2-4mm during inspiration. Think of
  it as a suction between the two layers.
• This factor in addition to surface tension
  between the layers causes them to adhere to one
  another.

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Function of sub-atmospheric intraplueral pressure

• Keeps the lungs from collapsing
• Pneumothorax opening of pleural cavity leading
  to collapse of lung, atelectasis

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Factors affecting sub-atmospheric pleural pressure

• Relationship between lungs and body wall
• Elastic fibers of lungs oppose fluid bond of
  visceral and parietal pleurae
• Elastic fibers in lungs are stretched even after
  a forced exhalation creating sub-atmospheric
  pressure

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Transmission of Muscle Forces

• As the thorax expands, it pulls on the parietal
  layer
• The parietal layer in turn pulls on the the
  visceral layer
• The visceral layer then pulls on the lungs.
• The lungs then expand.

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The Ribs

• During inspiration the ribs move up and out like
  bucket handles.
• Synovial gliding joints join the ribs to the
  thoracic vertebrae posteriorly and to the sternum
  anteriorly.

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Accessory Muscles of Forced Inspiration

• All are capable of switching origins and
  insertions, if the ribs become the more moveable
  bones
• Scalenes
• Sternocleidomastiod
• External intercostals
• Pectoralis minor
• Serratus anterior

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Expiration

• Normal
• Passive
• Muscles relax, lungs recoil elastically, and
  surface tension pulls lung tissues together.
• Forced
• Internal intercostals and abdominals further
  decrease thoracic volume and expel more air.

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Three Other Factors Affecting Ventilation

• Surface tension
• Compliance
• Airway resistance

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1. Surface Tension

• Alveolar type II cells produce surfactant to
  lower surface tension within the alveoli. This
  helps to prevent collapse.
• A deficiency in surfactant that occurs in
  premature babies is called respiratory distress
  syndrome.

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2. Compliance Ease of Expansion

• High compliance means easy expansion. If the
  elasticity of the alveolar walls is destroyed as
  in emphysema, compliance is too high.
• Low compliance means resistance to expansion. It
  can be a result of scarring, edema, definciency
  of surfactant, or payalysis.

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3. Airway Resistance

• More resistance in the airway means more pressure
  is needed to maintain flow of air.
• Asthma is a condition that increases resistance
  by narrowing or collapsing the airways.
• Emphysema (due to collapse) and bronchitis are
  chronic obstructive pulmonary diseases that
  similarly increase resistance.

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Breathing Patterns

• Eupnea
• Normal breathing
• Costal
• Shallow breathing
• Diaphragmatic
• Deep breathing
• Apnea
• Temporary cessation of breathing
• Modified breathing

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Lung Volumes and Capacities

• Can be measured with a spirometer.

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Tidal-quiet breathing 70 to lungs, 30 to dead
space Inspiratory reserve-deep breath Expiratory
reserve-forced exhalation Residual volume-amount
that cannot be forcefully exhaled Minimal
volume-amount remaining after opening thorax
used to determine death before of after
birth.
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Inspiratory capacitytidalinspiratory reserve
maximum amount that can be inhaled. Functional
residual capacityresidual volumeexpriatory
reserve volume amount left after quiet
expiration. Vital capacity-inspiratory
reservetidal volumeexpiratory reserve
maximum amount that can move in and out Total
lung capacity-sum of all volumes
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Respiration

• Exchange of gases

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Three Steps of Respiration

• Pulmonary ventilation
• External respiration
• Exchange of gas in the lungs between alveoli and
  blood
• Internal respiration
• Exchange of gas between capillaries and tissues
• Note only 25 of available oxygen is needed in
  resting tissue more is needed during exercise.

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Daltons Law

• Describes independence of each gas within a mix
  of gases, like air.
• Each gas travels down its own gradient in the
  alveolus (and between the capillary and
  interstitial fluid in the body, as we will see).
• Describes the contribution of the individual gas
  pressures to the total pressure
• atmospheric pressure PNPOPH2OPCO2POTHER
  

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Daltons Law and External Respiration

• Blood arriving in the alveoli is oxygen poor,
  because the body has used it primarily for
  aerobic respiration.
• Oxygen levels are higher in the inhaled air, so
  oxygen travels down its gradient from the air to
  the blood.
• Carbon dioxide level in the alveolar blood are
  high. It is a waste product of aerobic
  respiration.
• Carbon dioxide travels down its own gradient from
  the blood to the lungs.

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Daltons Law and Internal Respiration

• Once inside the body, these patterns of gas
  exchange are reversed at the capillary level.
• Oxygen is unloaded and carbon dioxide is picked
  up by the blood.
• The blood now returns to the lung and the process
  repeats.

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Henrys Law

• Describes how much of an individual gas will
  dissolve in a liquid.
• The quantity of gas that will dissolve in a
  liquid is proportional to its partial pressure
  and its solubility coefficient.
• Carbon dioxide has a much higher solubility
  coefficient than oxygen.
• Nitrogen has a very low solubility
• High pressure created during deep diving causes
  nitrogen to dissolve into the blood. When a
  diver surfaces without decompression time,
  nitrogen bubbles out of the blood causing great
  damage remember boyles law! (Boyles)

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Factors Affecting Rate of Exchange During
External Respiration

• PP of gases
• Surface area for exchange
• Diffusion distance-greater with edema
• Solubility and molecular weight of gases

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Oxygen Transport

• Oxygen has a low coefficient of solubility.
• Hemoglobin in RBCs solves this problem by
  binding to oxygen so that it may be easily
  transported.
• Hemoglobin has 4 heme groups, each has an iron
  atom that can bind to oxygen.
• Therefore, at saturation, a Hb can carry 4
  molecules of oxygen gas.
• Hb then releases the oxygen at the tissue level
  and it diffuses out of the RBC into the
  interstitial fluid.

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Binding of Oxygen to Hb in Relation to PP of
Oxygen

• As oxygen pp increases, binding increases
• Highest in pulmonary capillaries
• As oxygen pp decreases, binding decreases oxygen
  is released
• Lower in systemic circulation

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Effects of pH

• As acidity increases, affinity for oxygen
  decreases (binding), and oxygen is released to
  the tissues.
• The right shift that occurs when results are
  graphed is called the Bohr effect.
• Hb acts as a buffer for hydrogen ion.

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BOHR EFFECT
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Effects of CO2 on Hb

• As pp of carbon dioxide increases, affinity for
  oxygen decreases.
• This is the same effect that a decrease in pH
  has. (In fact, as carbon dioxide increases, more
  carbonic acid is formed resulting in a pH
  decrease.)

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Effect of Temperature on Hb

• As temperature increases affinity for oxygen
  decreases.

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Effects of 2,3 Bisphosphoglycerate (BPG) on Hb

• This substance is found in RBCs.
• It decreases the affinity of Hb for oxygen.
• Fetal RBCs have less This enables them to bind
  30 more oxygen than maternal blood.

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Effects of Carbon Monoxide

• CO has an affinity for Hb.
• Its binding is over 200x stronger than that of
  oxygen.
• Death can result because insufficient oxygen is
  available.

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Transport of Carbon Dioxide in the Blood

• Dissolved
• Smallest amount only 7 dissolved in plasma
• Carbamino compounds
• 23, mostly bound to hg
• Bicarbonate
• 70 as HCO3- in plasma

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RBCs and Formation of HCO3-

• Carbon dioxide enters the RBC.
• Here it combines with water to form carbonic
  acid, H2CO3 with the help of the enzyme carbonic
  anhydrase.
• Carbonic acid dissociates into hydrogen ion and
  bicarbonate ion--H and HCO3-
• The HCO3- diffuses out of the RBC into the
  plasma.
• The electrical balance is kept by the diffusion
  of Cl- into the RBC as it replaces the HCO3-
  this is called the chloride shift.

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Haldane Effect

• The lower the amount of HbO2, the higher the
  amount of CO2 carried by the blood.
• This is called the Haldane effect.

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SUMMARY OF GAS TRANSPORTS
ABOUT 200 ml/MIN. OF OXYGEN ARE USED AT REST
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Regulation of Respiration in the CNS
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-The medullary rhythmicity area determines basic
rhythm by sending signals via phrenic nerve to
the diaphragm. -It has and inspiratory area and
an expiratory area. -the expiratory area is
active during forceful expiration and causes
contraction of the internal intercostals and
abdominals. -the expiratory area is inactive
during quiet breathing when recoil and passive
relaxation are sufficient.
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-The repiratory centers of the pons aid in the
transition between inspiration and expiration.
-The pneumotaxic area inhibits inspiration. This
prevents the lungs from overfilling. It is
active during rapid breathing. -The apneustic
area inhibits expiration by activating the
inspiratory area of the medulla. This occurs if
the pneumotaxic area is inactive. If pneumotaxic
area is active, it overrides the apneustic area,
keeping the lungs from overfilling.
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Regulation of Respiratory Center

• Cortical signals can voluntarily modify breathing
  to some extent.
• The limbic and hypothalamus can modify breathing
  due to emotions.
• No, you cannot kill yourself by holding your
  breath because increased CO2 and H stimulate the
  inspiratory area.

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Monitoring of CO2 and O2

• CNS-central chemoreceptors in medulla monitor CSF
  for changes in hydrogen ion and partial pressure
  of carbon dioxide.
• PNS-monitor hydogen ion and partial pressures of
  both carbon dioxide and oxygen.
• Aortic body in wall of aorta
• Via CN X to medulla
• Carotid body in walls of carotids
• Via CN IX to medulla

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Hypercapnia

• Hypercapnia (increased CO2) stimulates receptors
  in CNS via the CSF.
• Hypercapnia quickly causes an increase in H in
  CSF because less buffers are present.
• The inspiratory center is stimulated, rate and
  depth of breathing increase thus releasing CO2
  and restoring acceptable levels.

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Hypocapnia

• Hypocapnia occurs when arterial CO2 falls below
  40 mg.
• There is no stimulation of receptors in CNS or
  PNS.
• No signals are sent to the inspiratory area.
• The inspiratory area sets its own pace until CO2
  rises.

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Hyperventilation

• Hyperventilation leads to hypocapnia as too much
  carbon dioxide is lost from the body.
• Can be dangerous fainting can occur, or worse,
  death due to insufficient oxygen.
• Swimmers used to do this to increase time they
  could hold their breath. This practice is now
  discouraged for obvious reasons.
• Breathing into a bag and rebreathing the exhaled
  air which is rich in carbon dioxide can help
  reverse hypocapnia.

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Hypoxia

• When oxygen levels drop severely the central
  chemoreceptors are depressed, the inspiratory
  center does not respond.
• A positive feedback occurs and death can result
  if intervention does not take place.

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Effects of Proprioceptors

• The body constantly monitors its position during
  movement.
• Signals from proprioreceptors can stimulate the
  inspiratory center, for instance, during exercise.

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Inhalation Reflex

• Baroreceptors in walls of bronchi and bronchioles
  respond to stretch.
• They send inhibitory signals via CN X to
  inspiratoryarea and apneustic area.
• Inhalation is inhibited.

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OTHER INFLUENCES

• Limbic
• Emotions up, resp. depth and rate up
• Temperature
• Temp up, resp. depth and rate up
• Pain
• Pain up initially resp. decrease, then resp.
  depth and rate up
• Stretching anal sphincter
• resp. depth and rate up
• Irritation of airways
• Cough or sneeze up, resp. down
• Blood pressure
• Bp up resp. down, bp down, resp. up

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Ondines Curse

• named after a cursed germanic water nymph who had
  automatic functions taken away. he had to
  remember to breath.
• can occur if there is damage to brain stem due to
  trauma or disease, e.g., polio.

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THE END.