HSF: The Respiratory System

Main structures of respiratory system

Conducting zone:

• Nose (U)

• Pharynx (U)

• Larynx

• Trachea

• Bronchi

Respiration zone:

• Lungs

Nose

• External portion of nose = cartilage + skin + lined with mucous membrane

  • protects functional part inside

• Bony framework formed by = frontal + nasal + maxillary bones

Internal Structures of Nose

• 3 functions:

  • filter air

  • detect olfactory stimuli

  • speech

• Superior nasal concha = has blood capillaries = warms air up

1. air enters vestibule

2. hairs in nostril filter dust (first barrier defence to stop getting into body)

3. conchae form 3 passages (incr SA)

4. air warmed by blood capillaries in SNC + mucus from goblet cells trap dust

5. Cilia move mucus to pharynx (spit or swallow)

Pharynx

• Functions as a passageway for air + food

• Provides a resonating chamber for speech sounds

• Houses tonsils - participate in immunological reactions against foreign invaders

Larynx

• AKA voice box

• passageway that connects pharynx + trachea

• air pressure = controls sound volume

• tension of vocal folds = determines pitch

Trachea

• Extends from larynx to the primary bronchi

• Branches into a right primary bronchus (enters right lung) + a left primary bronchus (enters the left lung)

• Lungs = paired organs in the thoracic cavity

Bronchi

• Upon entering lungs - primary bronchi divide to form smaller branches

• The terminal bronchioles are the end of the conducting zone

• Branching of Bronchial Tree

  • Trachea

  • Main Bronchi

  • Lobar Bronchi

  • Segmental Bronchi

  • Bronchioles

  • Terminal Bronchioles

Branching of Bronchial Tree

Alveoli

• When the conducting zone ends at the terminal bronchioles = the respiratory zone begins

• The respiratory zone = terminates at the alveoli

• Alveoli = ‘air sacs’ found within the lungs

Sighing

• a long drawn-out deep inhalation

• followed by a shorter, forceful exhalation

Crying

• an inhalation followed by many short exhalations

• vocal cords remain open + vibrate

Coughing

• long-drawn, deep inhalation

• full closure of vocal cords

• causing a strong exhalation which sends out a blast of air

• maybe caused by blockage of windpipe

Lung Volume and Capacities: IMAGE

Lung Volume and Capacities: TIDAL VOLUME

Amount of air passing in / out of lungs during each cycle

Lung Volume and Capacities: INSPIRATORY RESERVE VOLUME

Extra volume of air that can be inspired during maximum inspiration

Lung Volume and Capacities: INSPIRATORY CAPACITY

Amount of air that can be inspired at max effort (TV + IRV)

Lung Volume and Capacities: FUNCTIONAL RESIDUAL CAPACITY

Air remaining in air passages + alveoli after quiet expiration

Lung Volume and Capacities: EXPIRATORY RESERVE VOLUME

maximum volume of air that can be exhaled after a normal, quiet exhalation.

Lung Volume and Capacities: RESIDUAL VOLUME

Volume of air that can be expired during max. expiration

Lung Volume and Capacities: VITAL CAPACITY

max volume of air that can be moved into and out of lungs

Control of Respiration

Cortical influences:

• Allow conscious control of respiration that may be needed to avoid inhaling noxious gases or water

Chemoreceptor:

• Central + peripheral chemoreceptors monitor levels of O2 + CO2 = provide input to the respiratory center

Chronic Obstructive Pulmonary Disorder (COPD)

Symptoms:

• Shortness of breath

• Persistent cough

• Wheezing

• Increased Phlegm / sputum

COPD

• Caused by inhalation of toxic gases + particulate matter into the lungs

• Damage to lung tissue:

  • more prevalent in smokers (not all lead to COPD)

  • inflammatory response = release of plasma + immune cells into bronchi

• Forced Expired Volume in 1 sec (FEV1) / forced vital capacity (FEV)

  • GOLD criteria: <70% = indicative of COPD

  • GOLD = Global initiative for chronic Obstructive Lung Disease

  • basc usually in 1st second = 75-85% of air is out so if its less than 70% = COPD sign

Global initiative for chronic Obstructive Lung Disease (GOLD): CRITERIA (severity)

• GOLD 1 - mild

  • FEV > 80% predicted

• GOLD 2 - moderate

  • 50% < FEV1 < 80% predicted

• GOLD 3 - severe

  • 30% < FEV1 < 50%

• GOLD 4 - very severe

  • FEV1 < 30%

COPD: What causes the symptoms?

Follow as flowchart: (1)

• Long expiration time

• Stimulus to take breath = occurs before lung returned to previous resting level of inflation

• Hyperinflation of lungs during exercise

• Hyperinflation of lungs during rest

• Long expiration time

(2)

• Long expiration time

• Increased intrathoracic pressure

• Increased pulmonary vascular pressure

• If alveolar pressure > pleural pressure

• Pulmonary hypertension

COPD: Pathology (IMAGE)

COPD: Immune Response (1)

• The innate immune response = primarily functions to maintain the sterile environment in the lungs

• Mucous clearance apparatus = clear out lower respiratory tract = into lymphatic system

toxic materials inhaled

tightly joined epithelial cells = detect foreign material on surface

COPD: Immune Response (2)

• innate immune system = also functions to increase no. of plasma cells + circulating effector cells to the site of tissue damage

Steps:

• Inflammatory response

• Increase in chemokines + cytokines

  • e.g. IL-8 interacts with receptors = to increase polymorphonuclear neutrophil (PMN) infiltration of damaged tissue

• Activation of PMN, monocytes, basophils, T-lymphocytes

• Infiltration by PMN, macrophages, NK cells, dendritic cells, CD-4, CD-8 + B Cells

• Accumulation of dendritic cells = adaptive immune response

Immune response: Dendritic cells

• DCs transport antigen to lymph node where they are presented to lymphocytes

Chronic Bronchitis

• Chronic cough + sputum on most days

  • for 3 months in 2 consecutive years

• Size of mucus gland increases

• Caused by:

  • inhalation of toxins

  • inflammatory response

  • enlargement of mucus glands

  • tissue remodeling

COPD: Bronchioles

Small bronchi + bronchioles (<2mm diameter) = main obstruction sites for COPD

Airflow limitation:

• Thickening walls

• Reduction lumen

Summary

• The respiratory system has roles in the control of:

  • gas exchange

  • immune defence

  • detect olfactory stimuli

  • speech

• Gas exchange occurs in the lungs in specially adapted structures called alveoli

• Obstruction or destruction of airways can cause respiratory problems