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BIOLOGY OF HUMAN AGING

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BIOLOGY OF HUMAN AGING Chapter 11 The Respiratory System Outline Review of the Structure and Function Nasal Cavity, Pharynx, Trachea, Bronchi, Alveoli, Lungs Age ... – PowerPoint PPT presentation

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Title: BIOLOGY OF HUMAN AGING


1
BIOLOGY OF HUMAN AGING
  • Chapter 11
  • The Respiratory System

2
  • Outline
  • Review of the Structure and Function
  • Nasal Cavity, Pharynx, Trachea, Bronchi, Alveoli,
    Lungs
  • Age-Related Changes
  • Trachea and Bronchi, Alveoli, Lungs Structural
    Changes
  • Age-Related Dysfunctions
  • Chronic Obstructive Pulmonary Disease
  • Emphysema
  • Chronic Bronchitis
  • Pneumonia
  • Tuberculosis
  • Pulmonary Embolism

3
  • Human Respiratory System
  • Functions
  • Works closely with circulatory system, exchanging
    gases between air and blood
  • Takes up oxygen from air and supplies it to blood
    (for cellular respiration).
  • Removal and disposal of carbon dioxide from blood
    (waste product from cellular respiration).
  • Homeostatic Role
  • Regulates blood oxygen and carbon dioxide levels.

4
  • Human Respiratory System
  • Components
  • Nasal cavity, throat (pharynx), larynx (voice
    box), trachea, bronchi, alveoli, and lungs.
  • Pathway of Inhaled Air
  • Nasal cavity
  • Pharynx (Throat)
  • Larynx (Voice Box)
  • Trachea (Windpipe)
  • Bronchi
  • Bronchioles
  • Alveoli (Site of gas exchange)
  • Exhaled air follows reverse pathway.

5
Human Respiratory System
6
Pressure Relationships
Figure 22.12
7
Blood Transports Gases Between Lungs Tissues
8
  • Human Respiratory System
  • Nasal cavity Air enters nostrils, is filtered by
    hairs, warmed, humidified, and sampled for odors
    as it flows through a maze of spaces.
  • 2. Pharynx (Throat) Intersection where pathway
    for air and food cross. Most of the time, the
    pathway for air is open, except when we swallow.
  • 3. Larynx (Voice Box) Reinforced with cartilage.
    Contains vocal cords, which allow us to make
    sounds by voluntarily tensing muscles.
  • More prominent in males (Adams apple).

9
  • Human Respiratory System
  • 4. Trachea (Windpipe) Rings of cartilage
    maintain shape of trachea, to prevent it from
    closing. Forks into two bronchi.
  • 5. Bronchi (sing. Bronchus) Each bronchus leads
    into a lung and branches into smaller and smaller
    bronchioles, resembling an inverted tree.
  • 6. Bronchioles Fine tubes that allow passage of
    air. Muscle layer constricts bronchioles.
    Epithelium of bronchioles is covered with cilia
    and mucus.
  • Mucus traps dust and other particles.

10
  • Human Respiratory System
  • Alveoli (Sing. Alveolus) Grapelike clusters of
    tiny air sacs with very thin elastic walls
    through which gas exchange occurs.
  • Oxygen in air enters blood in capillaries.
  • Carbon dioxide in blood enters air in alveoli.
  • There are several million alveoli in the human
    lungs, with a total surface roughly equivalent to
    a tennis court.
  • The walls of the alveoli are very delicate.
  • Alveolar macrophages are phagocytic cells that
    swallow inhaled particles (dust, bacteria, etc.)
    and digest them.

11
Exchange of Gases Occurs in Alveoli
12
Human Breathing Inhalation and Exhalation
13
Lung volume and using spirometer
14
Lung volume and using spirometer
15
Age-related changes
  • Trachea and Bronchi
  • Progressive calcification
  • Smooth-muscle replaced by fibrous connective
    tissue
  • Reduced elasticity of the lungs
  • VC begin to decrease 40 years of age
  • Mucous membrane lining the trachea and bronchi
    show degenerative changes
  • Decrease activity of cilia and phagocytic
    activity of the macrophages

16
Age-related changes
  • Alveoli
  • Gradual deterioration of the walls of alveoli
  • The size increases but less surface area for the
    gas exchange
  • Cross-linkage
  • More collagen fibers and less elastic fibers
  • Declining oxygen levels in the blood

17
Age-related changes
  • Lungs
  • Lose their elastic recoiling capabilities and
    offer less resistance to expansion
  • Insufficient ventilation? contributing to an
    overall reduction in oxygen saturation of
    arterial blood.
  • Surface area
  • Diminished sensitivity of chemo-receptors that
    monitor oxygen and CO2 levels in the blood.

18
Human Breathing is Automatically Controlled
19
Age-related changes
  • Structural changes
  • Kyphosis and the hunching over reduces the volume
    of the thoracic cavity and make it more difficult
    to expand the lungs
  • Loss of Ca and weakening of muscles
  • Diminished elasticity and increases fibrosis of
    the lungs
  • Stiffness of the rib cage
  • Older individual rely more on the diaphragm

20
  • Age-related dysfunctions
  • Dysfunctions of respiratory system are more
    common in older individuals
  • These are not merely a result of aging, rather
    due to constant exposure to environmental stimuli
    (air pollution smoking)
  • Air pollutants damage trachea, bronchi, alveoli
  • Most frequently occurring pulmonary disorders
  • Restrictive (hinder lung expansion)
  • Obstructive (involve respiratory airways ?
    increased resistance to air flow

21
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22
  • Chronic Obstructive Pulmonary Disease (COPD)
  • Characterized by chronic air flow obstruction in
    lungs
  • Reduction in the ratio of forced expiratory
    volume in the first second to forced vital
    capacity (FEV1/FVC)
  • Symptoms
  • Difficulty breathing, wheezing, cough, etc
  • Increase rapidly in gt50 years of age, frequent in
    men
  • Cause
  • Environmental factors and age (also genetic
    predisposition)
  • 80 of cases is due to cigarette smoking
  • Two most common types Emphysema Chronic
    bronchitis

23
  • Emphysema
  • Excessive air accumulates in lungs as they lose
    their ability to ventilate properly
  • More prevalent in older people
  • Gradual development in response to smoking,
    bronchitis, pulmonary irritants
  • Mechanism
  • Chronic irritation, smoking, infections ?
    paralyze deteriorate mucus membrane cilia ?
    excessive mucus production w/in airways to the
    lungs ? persistent cough
  • ? collapse of airways ? hinders air flow through
    lungs ? air becomes trapped in alveoli
  • Trapped air ? alveoli remain inflated ?
    expiration (normally passive action) requires
    muscular resistance ? significant energy needed
    to exhale ? development of Barrel Chest

24
  • Over-inflated alveoli destroy alveolis wall ?
    replaced by fibrous tissue ? hinder gaseous
    exchange
  • Early stages gaseous exchange fairly adequate ?
    no cyanosis
  • Later stages great reduction in area where gas
    exchange occurs ? cyanosis even w/ mild physical
    effort
  • Patients often have low maximum breathing
    capacity and high residual air volume
  • The disease can not be reversed and gradually
    worsens
  • Therapy positive-pressure oxygen therapy to
    force O2 into alveoli
  • Emphysema puts extra load on heart (attempts to
    pump more blood into lungs to compensate for O2
    deficiency)
  • Patients suffering from emphysema die from heart
    failure

25
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26
Dirty lung of an Emphysema (smoking) patient
27
  • Bronchitis
  • Acute or chronic inflammation of the bronchial
    tree
  • Caused by bacterial infection or by irritants
    (smoke in inhaled air)
  • Chronic bronchitis is due to long-term exposure
    to environmental insults ? more common in elderly
  • Similar to emphysema airway irritation responds
    by mucus production
  • In severe cases, mucus membrane becomes swollen
    and partially obstruct airway ? severe hindrance
    of gas exchange ? cyanosis
  • Excess mucus buildup is removed by persistent
    coughing

28
  • Pneumonia
  • Inflammation of the lower airways of the lungs
  • Symptoms Fever, cough, sputum production (not
    restricted to older individuals)
  • Classification (due to variability in causative
    agents)
  • Community acquired viruses (influenza) or
    pneumococcus
  • Hospital acquired gram negative bacilli (E.
    Coli) or Enterobacter
  • Aspiration pneumonia inhalation of foods or
    foreign bodies that obstruct bronchus
  • causes lung collapse, fluid accumulation,
    infection
  • More common in older (bedridden) individuals

29
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30
Classification of Pneumonia
31
  • Tuberculosis
  • Caused by mycobacterium tuberculosis enters
    body with inspired air ? lung tuberculosis is the
    most common form
  • Symptoms early (subtle) weight loss, fever,
    cough
  • Diagnosis skin test, chest x-ray, sputum
    culture
  • Lung phagocytes ? destroy the bug ? alive
    bacteria are walled off in small or calcified
    nodules (Tubercle)
  • Evading bacteria ? spread ? lung tissue replaced
    by fibrous tissue ? reduced vital capacity and
    difficulty breathing
  • Antibiotics harnessed TB till mid-80s ?
    resurgence due to AIDS
  • Role of immune system in controlling outward
    signs of the disease
  • Dormancy ? impaired immune system ? Reactivation
    tuberculosis

32
Causative agent mycobacterium tuberculosis
X-ray film of infected lung
33
  • Pulmonary Embolism
  • Ambolus blood clot or foreign objects that flows
    freely w/in blood vessels
  • Can reach vessels with small diameter, can not
    pass through them ? partial or complete block ?
    reduced blood flow to the tissue ? tissue dies
  • Pulmonary embolism a clot that blocks a branch
    of pulmonary artery
  • Symptoms shortness of breath, chest pain,
    spitting blood, accelerated heart beat and
    breathing rate, anxiety
  • Can occur at any age, more common in bedridden
    older individuals
  • Immobile patients tend to develop clots in leg
    veins (low blood flow)
  • Treatment
  • Anticoagulant drugs (streptokinase)

34
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