Chap. 42 Circulation and Gas Exchange AP Biology Mr. Orndorff March 2004.
Chap 42
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Transcript of Chap 42
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Disturbances of respiration
These are due to Abnormal respiratory
pattern Disturbances related to
respiratory gasses
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Abnormal respiratory pattern
Tachypnea … Increase rate of respiration..
Apnoea …Temporary cessation of breathing
Dyspnoea…distressed breathing Periodic breathing…alternate
periods of respiratory activity and apnea e.g. Cheyne stokes breathing
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Cheyne-Stokes Breathing
Is periodic type of breathing in which alternate periods of respiratory activity and apnoea occur at regular intervals
And during the period of respiratory activity there is waxing and waning of tidal volume
Duration is of 1 minute PO2 is lowest and the PCO2 is highest
at the end of apnoea.
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causes
PHYSIOLOGICAL CAUSES Voluntry hyperventilation High altitude During sleep PATHOLOGICAL CAUSES Chronic heart failure Brain damage Uraemia Poisoning by narcotics
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Sleep Apnea
Apnea is the temporary suspension of breathing.
Normally, some episodes of apnea occur. In people with sleep apnea, the episodes are longer and more frequent.
2 types of sleep apnea are: Obstructive sleep apnea
Central sleep apnea
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Obstructive Sleep Apnea In patients with sleep apnea, the pharynx
is collapsed while the muscles relax. Some of the factors that cause this collapse include: Excess fat deposits in the soft tissues of the
pharynx or fat masses in the neck. Nasal obstruction Enlarged tonsils Very large tongue Certain shapes of the palate
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Symptoms of Obstructive Sleep Apnea
Loud snoring and labored breathing that often progressively worsens.
Long silent periods (apnea) that cause increases in PCO2 and decreases in PO2.
This stimulates respiration, which results in loud snorts and gasps.
This repeats.
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Central Sleep Apnea
Less common than obstructive sleep apnea.
The CNS signal to the respiratory muscles stops.
Can be caused by damage to the central respiratory center or respiratory neuromuscular junction.
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Disturbances related to respiratory gases Respiratory disturbances are
related to respiratory gases include
Hypoxia Hypercapnia Asphyxia Carbon monoxide poisoning
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HypoxiaTissue hypoxia means
that the amount of oxygen available for cellular metabolism is inadequate.
Hypoxia leads to anaerobic mechanisms that eventually produces lactic acid and cause the blood pH to decrease.
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CAuses Decreased oxygen tension of the arterial blood Decreased oxygen carrying capacity
of lungs Decreased rate of blood flow to the
tissues Decreased tissue utilization of
oxygen
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types Hypoxic hypoxia Anemic hypoxia Circulatory hypoxia Histotoxic hypoxia
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Hypoxic Hypoxia Hypoxic hypoxia or hypoxemic hypoxia
refers to the condition in which the PO2 is abnormally low.
This form of hypoxia is better known as hypoxemia (low oxygen concentration in the blood).
This form of hypoxia can develop from: pulmonary shunting - low alveolar
PO2 diffusion impairment - V/Q mismatch
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Anemic Hypoxia Anemic hypoxia is when the oxygen
tension in the arterial blood is normal, but the oxygen-carrying capacity of the blood is inadequate.
This form of hypoxia can develop from: a low amount of Hb in the blood a deficiency in the ability of Hb to carry
O2 Increased cardiac output is the main
compensatory mechanism for anemic hypoxia. 16
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Circulatory Hypoxia
In circulatory hypoxia, the arterial blood that reaches the tissue cells may have a normal O2 tension and content, but the amount of blood--and therefore the amount of O2--is not adequate to meet tissue needs.
The two main causes of circulating hypoxia are: stagnant hypoxia arterial-venous shunting
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Histotoxic Hypoxia
Histotoxic hypoxia develops in any condition that impairs the ability of tissue cells to utilize oxygen.
May be due to cyanide or sulphide poisoning
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Characteristic features of hypoxia
Features Hpoxic hypoxia
Anemic hypoxia
Circulatory hypoxia
Histotoxic hypoxia
PO2 in arterial blood
Reduced
Normal Normal Normal
O2 carrying capacity of blood
Normal Reduced
Normal Normal
Velocity of blood flow
Normal Normal Reduced Normal
Utilization of blood flow
Normal Normal Normal Reduced
Efficiency of O2 therapy
100% 75% >50% Not useful
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Cyanosis
Cyanosis is the term used to describe the blue-gray or purplish discoloration seen on the mucous membranes, fingertips, and toes whenever the blood in these areas is hypoxemic.
When level of deoxy Hb ≥5g/dl signs of cyanosis may develop
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Types of hypoxia
Peripheral cyanosis Central cyanosis
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Treatment of cyanosis
Warming of the affected areas Peripheral cyanosis brought about by
exposure to cold or Raynaud’s phenomenon may be treated symptomatically using gentle warming of the fingers and toes.
Oxygenation as a treatment for cyanosis Initial stabilization requires oxygenation.
Sometimes a breathing machine or ventilator might be required.
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Surgery as a treatment for cyanosis Treatment of central cyanosis due to
congenital heart defects may often involve surgery.
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Asphyixa
Refers to the condition in which there is hypoxia associated with hypercapnia
May be due to strangulation drowning tracheal obstruction due to foreign body paralysis of diaphragm
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treatment
First aid to remove foreign body Emergency resuscitation Expired Air Resuscitation (EAR) Cardio-Pulmonary Resuscitation
(CPR)
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pneumonia
Inflammatory condition of the lung in which alveoli are filled with fluid and blood cells
There is hypoxemia and hypercapnea
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treatment
Most cases of pneumonia can be treated at home. However babies, children, and people with severe pneumonia may need to be admitted to hospital for treatment.
Pneumonia is usually treated with antibiotics, even if viral pneumonia is suspected as there may be a degree of bacterial infection as well. The type of antibiotic used and the way it is given will be determined by the severity and cause of the pneumonia.
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asthma
Asthma is a common chronic inflammatory disease of the airways characterized by variable and recurring symptoms, reversible airflow obstruction, and bronchospasm.
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symptoms
Common symptoms include wheezing, coughing, chest tightness, and shortness of breath.
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Treatment
Bronchodilators Nebulization
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tuberculosis Tuberculosis) is a
common infectious disease caused by various strains of mycobacteria, usually Mycobacterium tuberculosis. Tuberculosis typically attacks the lungs, but can also affect other parts of the body
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Symptoms of TB
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Treatment
Anti tuberculous drugs
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