Respiratory System

major funcitions of respiratory system

• supply body with O₂ for cellular respiration and dispose of CO₂, a waste product of cellular respiration

• Respiratory and circulatory system are closely coupled

• Also functions in olfaction and speech

4 processes of respiration

pulmonary ventilation, external respiration, transport of respiratory gasses and internal respiration

pulmonary ventilation

movement of air into and out of the lungs

external respiration

exchange of oxygen and carbon dioxide between the lungs and blood through the circulatory system

transportation of what gases

oxygen and carbon dioxide in blood

internal respiration

exchange of oxygen and carbon dioxide between systemic blood vessels and tissues

nose/nasal cavity

warms, moistens, and filters air as it is inhaled

pharynx (throat)

passageway for air, leads to trachea

larynx

the voice box, where vocal chords are located

trachea (windpipe)

keeps the windpipe “open”; trachea is lined with fine hairs called cilia which filter air before it reaches th elungs

bronchi

two branches at the end of the trachea, each lead to a lung

bronchioles

a network of smaller branches leading from the bronchi into the lung tissue and ultimately to air sacs

alveoli

the functional respiratory units in the lung where gases are exchanged

upper respiratory tract functions

• Passageway for respiration

• Receptors for smell

• Filters incoming air to filter larger foreign material

• Moistens and warms incoming air

• Resonating chambers for voice

paranasal sinuses

mucosa lined air filled cavities in cranial bones surrounding nasal cavity; they lighten skill, may also warm, moisten and filter incoming air

what is the only external portion of the respiratory system

nose

functions of nose

• Provides an airway for respiration

• Moistens and warms entering air

• Filters and cleans inspired air 

• Serves as resonating chamber for speech

  • Houses olfactory receptors

what are the 2 regions of the nose

external nose and nasal cavity

pharynx

• unnel-shaped muscular tube that runs from base of skull to vertebra C₆

  • Connects nasal cavity and mouth to larynx and esophagus

    • Composed of skeletal muscle

3 regions of the pharynx

• Nasopharynx

• Oropharynx

• Laryngopharynx

lower respiratory system

• Larynx, trachea, bronchi, and lungs

what are the 2 zones of the lower respiratory system

respiratory zone and conducting zone

respiratory zone

• site of gas exchange 

Consists of microscopic structures such as respiratorybronchioles, alveolarducts, and alveoli

conducting zone

• conduits that transport gas to and from gas exchange sites

  • Includes all other respiratory structures

    • Cleanses, warms, and humidifies air

lungs

transport air to alveoli for gas exchange

anatomy of the larynx

• extends from 3rd to 6th cervical vertebra and attaches to hyoid bone

  • Opens into laryngopharynx and is continuous with trachea

3 functions of the larynx

 Provides patent airway

2. Routes air and food into proper channels (epiglottis)

3. Voice production

• Houses vocal folds

trachea

• Lined with mucosa, pseudostratified goblet cells that produce mucus to trap dirt and pathogens

• Cilia sweep the mucus upwards towards the larynx

  • Carina: last tracheal cartilage before branching, triggers coughing reflex if object reaches it

alveoli

• Respiratory zone begins where terminal bronchioles feed into respiratory bronchioles, which lead into alveolar ducts and finally into alveolar sacs (bunch of grapes) (saccules)

  • Alveolar sacs contain clusters of alveoli (single grape)

    • ~300 million alveoli make up most of lung volume

    • Sites of actual gas exchange

    • Simple diffusion of gases into and out of capillaries

      • made of simple squamous epithelium

root

• site of vascular and bronchial attachment to mediastinum

costal surface

anterior, lateral, and posterior surfaces

apex

• superior tip, deep to clavicle

base

• inferior surface that rests on diaphragm

cardiac notch

• on left lung, concave space for heart

lobes

• eft lung has two lobes (superior and inferior) right lung has three lobes (superior, middle and inferior)

2 parts of pulmonary ventilation

inspiration and expiration

inspiration

gases flow into lungs (diaphragm and external intercostals)

action of the diaphragm in inspiration

• when dome-shaped diaphragm contracts, it moves inferiorly and flattens out

  • Results in increase in thoracic volume

action of the intercostal muscles in inspiration

• when external intercostals contract, rib cage is lifted up and out, much like when handle on a bucket is raised (outward as it moves upward)

  • Results in increase in thoracic volume

expiration

gases exit lungs

pulmonary ventilation

• Mechanical process that depends on volume changes in thoracic cavity

  • Volume changes lead to pressure changes

  • Pressure changes lead to flow of gases to equalize pressure

respiratory volumes

• can be combined to calculate respiratory capacities, which can give information on a person’s respiratory status

  • Respiratory volumes and capacities are usually abnormal in people with pulmonary disorders

spirometer

• original, cumbersome clinical tool used to measure patient’s respiratory volumes

  • Electronic measuring devices used today

what are the 4 respiratory volumes

tidal volume, inspiratory reserve volume (IRV), expiratory reserve volume (ERV) and residual volume (RV

tidal volume

• amount of air moved into and out of lung with each breath

  • Averages ~500ml 

inspiratory reserve volume

• amount of air that can be inspired forcibly beyond the tidal volume (2100–3200 ml)

expiratory reserve volume

• amount of air that can be forcibly expelled from lungs (1000–1200 ml) 

residual volume

• amount of air that always remains in lungs

  • Needed to keep alveoli open

respiratory capacities

combos of two or more respiratory volumes

inspiratory capacity (IC)

sum of TV and IRV

functional residual capacity (FRC)

sum of RV and ERV

vital capacity VC

sum of TV, IRV, and ERV

total lung capacity

su of all lung volumes (TV, IRV, ERV, and RV)