Post on 12-Jan-2016
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Respiratory System
Respiration External Respiration:
exchange of oxygen and carbon dioxide between the air and the cells of the lungs.
Respiration
Internal Respiration: exchange of gases between body cells and blood
Respiration Cellular respiration: chemical
reactions in cells that use oxygen and produce carbon dioxide
Respiration
Breathing or ventilation: the process by which air enters and leaves the respiratory organs
Always involves a moist, thin membrane
Lower Animals Single celled and smaller
animals can use diffusion alone: ‘breathe’ through their moist skin or membrane
Lower Animals
Fish breathe using gills: put moist membrane inside, high surface area
Humans
And terrestrial animals use lungs
also high surface area, moist
Anatomy Nasal
chambers –Air is filtered, warmed, moistened by hairs, mucous and sinus cavities
Anatomy
Oral cavity: second entryway for air
Larger opening, less filtering,
Anatomy
Both nasal and oral cavities open to the pharynx
Anatomy
The epiglottis
prevents foodfrom entering
thetrachea.
Anatomy
The trachea (windpipe) is lined with rings of cartilage for support
Lined with cilia to sweep debris away
Anatomy
Membranes of the upper respiratory passages are ciliated
This helps to remove particles as they enter
Anatomy
The larynx (voicebox) – contains vocal cords
Anatomy
Trachea branches into two bronchi
These branch into smaller bronchioles
Anatomy No cartilage in bronchioles
Contain smooth muscle that contracts and expands with each breath
Anatomy Asthma is the over -constriction
of these muscles
AnatomyAlveoli (sing. Alveolus) are air
sacs at ends of bronchioles Single cell thick, moist surrounded by a capillary bed-
site of gas exchange
AnatomySurfactant – a
lipoprotein secreted by lung tissue to prevent collapse of alveoli
A premature infant with respiratory distress syndrome
Anatomy
Pleural membranes surround the lungs
Fluid between reduces friction
Gas Exchange gas moves from areas of high
pressure to low pressure
pleural pressure = pressure in the lungs
atmospheric pressure = air pressure outside lungs
Gas Exchange
inspiration occurs when pleural pressure is less than atmospheric pressure
expiration occurs when pleural pressure is greater than atmospheric pressure
Muscles Involved in Breathing
Diaphragm is a dome-shaped muscle at base of ribcage
Muscles Involved in Breathing
Intercostal muscles are between ribs
Inspiration diaphragm contracts and moves
downward
intercostals move ribcage up and out
the net result is an increase in lung volume and a decrease in pleural pressure
Air moves into the lungs
Expiration diaphragm relaxes and domes up
intercostal muscles relax
the net is result is a decrease in lung volume and an increase in pleural pressure
gas moves out
Regulation of Breathing
Chemoreceptors in medulla detect carbon dioxide
most
important
Regulation of Breathing
As carbon dioxide levels increase, nerves from brain send messages to respiratory muscles to increase breathing rate
Regulation of Breathing
Oxygen receptors:
- in aorta and carotid arteries
-are a back up for when CO2 stays normal but oxygen is low
ex) high altitude
Oxygen Transport Oxygen binds with hemoglobin to
form oxyhemoglobin
Fact: every RBC carries 265 million molecules of hemoglobin!
Oxygen Transport
Each Hb molecule can carry four oxygen molecules
Hb + O2 Hb(O2 )4 Oxyhemoglobin
Oxyhemoglobin Dissociation
Hemoglobin’s affinity for oxygen decreases as the acidity (carbon dioxide levels) increase
Oxygen delivery increases to tissues in need
Carbon Dioxide Transport 20 times more soluble than oxygen
Carried in three ways:1. some is dissolved in blood plasma
(about 10%) 2. Combines with hemoglobin to form
carbaminohemoglobin (HbCO2)-competes with oxygen
Carbon Dioxide Transport
3. Most carbon dioxide(70%) combines with water in the plasma to form carbonic acid which then breaks down into bicarbonate ions.
Reaction is catalysed by carbonic anhydrase enzyme
Carbon Monoxide
Competes with oxygen for sites on hemoglobin – carboxyhemoglobin
200X more affinity for Hb than oxygen
Carbon Monoxide Hemoglobin combined with CO is
called carboxyhemoglobin Colorless, odorless Skin turns bright pink
Nonrespiratory Air Movements
Coughing and sneezing: contraction of diaphragm with sudden
opening of glottis Dislodges particles on membranes
Nonrespiratory Air Movements
Hiccuping: sudden diaphragmatic contractions
Many causes; may be related to stomach activity
Nonrespiratory Air Movements
Laughing: epiglottis half-closes the larynx, so
that air intake occurs irregularly, making you gasp
A social signal – often initiated by group leaders
Nonrespiratory Air Movements
Yawning: Inspiration with stretching of facial muscles
Contagious, not due to gas levels in blood
Also is a social signal, wolves
High AltitudeBody adapts by:
Short term – increasing force and rate of breathing
Increasing production of RBC’s using hormone erythropoeitin (EPO)
Increases lung capacity
Breathing Disorders
Hyperventilation
Disorder caused by stress, etc. – lowered carbon dioxide levels due to overbreathing
Causes oxygen chemoreceptors to increase in sensitivity
Causes excessive breathing, which further decreases carbon dioxide levels- vicious cycle!
The ‘Bends’ When scuba diving,
nitrogen dissolves in blood – due to increased pressure
When ascending, the pressure drops and the nitrogen gas forms bubbles in blood vessels
Treatment – raise pressure and release it slowly – allowing gas to be diffused out of blood
Hyperbaric Chamber
Bronchitis Inflammation of the airways due
to infection
May be chronic, especially in smokers
Pneumonia Due to infection, lungs produce
fluid Can cause ‘drowning’
Emphysema
Now called COPD (Chronic Obstructive Pulmonary Disease)
Alveoli lose elasticity and can expand but not contract
Eventually lose surface area in lungs
Often due to smoking or mining
May need supplemental oxygen
Lung Cancer
Virtually always due to smoking Takes on average 20 years Usually begins on bronchioles Not diagnosed until spread Poor prognosis