23- 1 Respiratory System - PowerPoint Presentation

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Respiratory System

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Respiration

Ventilation: Movement of air into and out of lungs

External respiration

: Gas exchange between air in lungs and blood

Transport of oxygen and carbon dioxide in the blood

Internal respiration

: Gas exchange between the blood and tissues

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Respiratory System Functions

Gas exchange: Oxygen enters blood and carbon dioxide leaves

Regulation of blood pH

: Altered by changing blood carbon dioxide levels

Voice production

: Movement of air past vocal folds makes sound and speech

Olfaction

: Smell occurs when airborne molecules drawn into nasal cavity

Protection

: Against microorganisms by preventing entry and removing them

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Respiratory System Divisions

Upper tract

Nose, pharynx and associated structures

Lower tract

Larynx, trachea, bronchi, lungs

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Nose and Pharynx

Nose

External nose

Nasal cavity

Functions

Passageway for air

Cleans the air

Humidifies, warms air

Smell

Along with paranasal sinuses are resonating chambers for speech

Pharynx

Common opening for digestive and respiratory systems

Three regions

Nasopharynx

Oropharynx

Laryngopharynx

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Larynx

Functions

Maintain an open passageway for air movement

Epiglottis and vestibular folds prevent swallowed material from moving into larynx

Vocal folds are primary source of sound production

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Vocal Folds

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Trachea

WindpipeDivides to form

Primary bronchi

Insert Fig 23.5 all but b

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Tracheobronchial Tree

Conducting zone

Trachea to terminal bronchioles which is ciliated for removal of debris

Passageway for air movement

Cartilage holds tube system open and smooth muscle controls tube diameter

Respiratory zone

Respiratory bronchioles to alveoli

Site for gas exchange

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Tracheobronchial Tree

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Bronchioles and Alveoli

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Lungs

Two lungs: Principal organs of respiration

Right lung

: Three lobes

Left lung

: Two lobes

Divisions

Lobes, bronchopulmonary segments, lobules

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Ventilation

Movement of air into and out of lungsAir moves from area of higher pressure to area of lower pressure

Pressure is inversely related to volume

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Alveolar Pressure Changes

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Basic Chest X-Ray Interpretation

Deb Updegraff, C.N.S., PICU

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X-rays- describe radiation which is part of the

spectrum which includes visible light, gamma rays and cosmic radiation.Unlike visible light, radiation passes through stuff.

When you shine a beam of X-Ray at a person and put a film on the other side of them a shadow is produced of the inside of their body.

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Different tissues in our body absorb X-rays at different extents:

Bone- high absorption (white)

Tissue- somewhere in the middle absorption (grey)

Air- low absorption (black)

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Film Quality

First determine is the film a PA or AP view.

PA- the x-rays penetrate through the back of the patient on to the film

AP

-

the x-rays penetrate through the front of the patient on to the film.

All x-rays in the PICU are portable and are AP view

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Quality (cont.)

Is the film over or under penetrated if under penetrated you will not be able to see the thoracic vertebrae.

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Quality (cont)

Check for rotationDoes the thoracic spine align in the center of the sternum and between the clavicles?

Are the clavicles level?

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LUNG VOLUMES

The total volume contained in the lung at the end of a maximal inspiration is subdivided into volumes and subdivided into capacities.

There are four volume subdivisions which:

do not overlap.

can not be further divided.

when added together equal total lung capacity.

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Capacities

Lung capacities are subdivisions of total volume that include two or more of the 4 basic lung volumes.

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Basic lung volumes (memorize)

Tidal Volume (TV).

The amount of gas inspired or expired with each breath.

Inspiratory

Reserve Volume (IRV).

Maximum amount of additional air that can be inspired from the end of a normal inspiration

.

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Basic lung volumes (memorize)

Expiratory Reserve Volume (ERV

). The maximum volume of additional air that can be expired from the end of a normal expiration.

Residual Volume (RV).

The volume of air remaining in the lung after a maximal expiration. This is the only lung volume which cannot be measured with a

spirometer

.

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Basic lung capacities (memorize)

Total Lung Capacity (TLC).

The volume of air contained in the lungs at the end of a maximal inspiration. Called a capacity because it is the sum of the 4 basic lung volumes.

TLC=RV+IRV+TV+ERV

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Basic lung capacities (memorize)

Vital Capacity (VC).

The maximum volume of air that can be forcefully expelled from the lungs following a maximal inspiration. Called a capacity because it is the sum of

inspiratory

reserve volume, tidal volume, and expiratory reserve volume. VC=IRV+TV+ERV=TLC-RV

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Basic lung capacities (memorize)

Functional Residual Capacity (FRC)

. The volume of air remaining in the lung at the end of a normal expiration. Called a capacity because it equals residual volume plus expiratory reserve volume. FRC=RV+ERV

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Basic lung capacities (memorize)

Inspiratory

Capacity (IC)

. Maximum volume of air that can be inspired from end expiratory position. Called a capacity because it is the sum of tidal volume and

inspiratory

reserve volume. This capacity is of less clinical significance than the other three. IC=TV+IRV

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Now you are ready

Look at the diaphram: for tenting

free air abnormal elevationMargins should be sharp (

the right hemidiaphram is usually slightly higher than

the left

)

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Check the Heart

SizeShapeSilhouette-margins should be sharp

Diameter (>1/2 thoracic diameter is enlarged heart)Remember: AP views make heart appear larger than it actually is.

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Cardiac Silhouette

R Atrium

R Ventricle

3. Apex of L Ventricle

Superior Vena Cava

Inferior Vena Cava

6. Tricuspid Valve

Pulmonary Valve

Pulmonary Trunk

9. R PA 10. L PA

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Check the costophrenic angles

Margins should

be sharp

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Loss of Sharp Costophrenic Angles

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Check the hilar region

The hilar – the large blood vessels going to and from the lung at the root of each lung where it meets the heart.Check for size and shape of aorta, nodes,enlarged vessels

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Finally, Check the Lung Fields

InfiltratesIncreased interstitial markingsMasses

Absence of normal marginsAir bronchogramsIncreased vascularity

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Hemothorax

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Changing Alveolar Volume

Lung recoil

Causes alveoli to collapse resulting from

Elastic recoil and surface tension

Surfactant: Reduces tendency of lungs to collapse

Pleural pressure

Negative pressure can cause alveoli to expand

Pneumothorax is an opening between pleural cavity and air that causes a loss of pleural pressure

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Pulmonary Volumes

Tidal volume

Volume of air inspired or expired during a normal inspiration or expiration

Inspiratory reserve volume

Amount of air inspired forcefully after inspiration of normal tidal volume

Expiratory reserve volume

Amount of air forcefully expired after expiration of normal tidal volume

Residual volume

Volume of air remaining in respiratory passages and lungs after the most forceful expiration

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Pulmonary Capacities

Inspiratory capacity

Tidal volume plus inspiratory reserve volume

Functional residual capacity

Expiratory reserve volume plus the residual volume

Vital capacity

Sum of inspiratory reserve volume, tidal volume, and expiratory reserve volume

Total lung capacity

Sum of inspiratory and expiratory reserve volumes plus the tidal volume and residual volume

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Spirometer and Lung Volumes/Capacities

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Minute and Alveolar Ventilation

Minute ventilation

: Total amount of air moved into and out of respiratory system per minute

Respiratory rate or frequency

: Number of breaths taken per minute

Anatomic dead space

: Part of respiratory system where gas exchange does not take place

Alveolar ventilation

: How much air per minute enters the parts of the respiratory system in which gas exchange takes place

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Physical Principles of Gas Exchange

Partial pressure

The pressure exerted by each type of gas in a mixture

Dalton’s law

Water vapor pressure

Diffusion of gases through liquids

Concentration of a gas in a liquid is determined by its partial pressure and its solubility coefficient

Henry’s law

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Physical Principles of Gas Exchange

Diffusion of gases through the respiratory membrane

Depends on membrane’s thickness, the diffusion coefficient of gas, surface areas of membrane, partial pressure of gases in alveoli and blood

Relationship between ventilation and pulmonary capillary flow

Increased ventilation or increased pulmonary capillary blood flow increases gas exchange

Physiologic shunt is deoxygenated blood returning from lungs

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Oxygen and Carbon Dioxide

Diffusion Gradients

Oxygen

Moves from alveoli into blood. Blood is almost completely saturated with oxygen when it leaves the capillary

P0

2

in blood decreases because of mixing with deoxygenated blood

Oxygen moves from tissue capillaries into the tissues

Carbon dioxide

Moves from tissues into tissue capillaries

Moves from pulmonary capillaries into the alveoli

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Changes in Partial Pressures

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Hemoglobin and Oxygen Transport

Oxygen is transported by hemoglobin (98.5%) and is dissolved in plasma (1.5%)Oxygen-hemoglobin dissociation curve shows that hemoglobin is almost completely saturated when P0

2

is 80 mm Hg or above. At lower partial pressures, the hemoglobin releases oxygen.

A shift of the curve to the left because of an increase in pH, a decrease in carbon dioxide, or a decrease in temperature results in an increase in the ability of hemoglobin to hold oxygen

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Hemoglobin and Oxygen Transport

A shift of the curve to the right because of a decrease in pH, an increase in carbon dioxide, or an increase in temperature results in a decrease in the ability of hemoglobin to hold oxygenThe substance 2.3-bisphosphoglycerate increases the ability of hemoglobin to release oxygen

Fetal hemoglobin has a higher affinity for oxygen than does maternal

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Oxygen-HemoglobinDissociation Curve at Rest

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Oxygen-HemoglobinDissociation Curve during Exercise

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Shifting the Curve

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Transport of Carbon Dioxide

Carbon dioxide is transported as bicarbonate ions (70%) in combination with blood proteins (23%) and in solution with plasma (7%)Hemoglobin that has released oxygen binds more readily to carbon dioxide than hemoglobin that has oxygen bound to it (Haldane effect)

In tissue capillaries, carbon dioxide combines with water inside RBCs to form carbonic acid which dissociates to form bicarbonate ions and hydrogen ions

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Transport of Carbon Dioxide

In lung capillaries, bicarbonate ions and hydrogen ions move into RBCs and chloride ions move out. Bicarbonate ions combine with hydrogen ions to form carbonic acid. The carbonic acid is converted to carbon dioxide and water. The carbon dioxide diffuses out of the RBCs.

Increased plasma carbon dioxide lowers blood pH. The respiratory system regulates blood pH by regulating plasma carbon dioxide levels

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Carbon Dioxide Transportand Chloride Movement

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Respiratory Areas in Brainstem

Medullary respiratory centerDorsal groups stimulate the diaphragm

Ventral groups stimulate the intercostal and abdominal muscles

Pontine (pneumotaxic) respiratory group

Involved with switching between inspiration and expiration

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Respiratory Structures in Brainstem

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Rhythmic Ventilation

Starting inspiration

Medullary respiratory center neurons are continuously active

Center receives stimulation from receptors and simulation from parts of brain concerned with voluntary respiratory movements and emotion

Combined input from all sources causes action potentials to stimulate respiratory muscles

Increasing inspiration

More and more neurons are activated

Stopping inspiration

Neurons stimulating also responsible for stopping inspiration and receive input from pontine group and stretch receptors in lungs. Inhibitory neurons activated and relaxation of respiratory muscles results in expiration.

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Modification of Ventilation

Cerebral and limbic systemRespiration can be voluntarily controlled and modified by emotions

Chemical control

Carbon dioxide is major regulator

Increase or decrease in pH can stimulate chemo- sensitive area, causing a greater rate and depth of respiration

Oxygen levels in blood affect respiration when a

50%

or greater decrease from normal levels exists

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Modifying Respiration

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Regulation of Blood pH and Gases

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Herring-Breuer Reflex

Limits the degree of inspiration and prevents overinflation of the lungsInfants

Reflex plays a role in regulating basic rhythm of breathing and preventing overinflation of lungs

Adults

Reflex important only when tidal volume large as in exercise

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Ventilation in Exercise

Ventilation increases abruptly

At onset of exercise

Movement of limbs has strong influence

Learned component

Ventilation increases gradually

After immediate increase, gradual increase occurs (4-6 minutes)

Anaerobic threshold is highest level of exercise without causing significant change in blood pH

If exceeded, lactic acid produced by skeletal muscles

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Effects of Aging

Vital capacity and maximum minute ventilation decreaseResidual volume and dead space increaseAbility to remove mucus from respiratory passageways decreases

Gas exchange across respiratory membrane is reduced