Respiratory System

Functions of Respiratory System

Intake of Air, Exchange gases between air and blood, Exhalation

Respiration

the process of taking air in, exchanging gases, and ridding the body of waste

Ventilation

air entering the lungs or exits the lungs

External respiration

exchange of gas between the air and blood within the lungs, O2 →lungs to the blood. CO2 → blood to the lungs

Transport

O2 is carried throughout the body, Reaches all body tissues

Internal respiration

exchange of gas between the blood and body tissues, O2 →blood → tissues, CO2 → tissues →blood

Cellular Respiration

uses O2 to make ATP and produces CO2 as a byproduct

Nose

opening and passageway for air to enter the body, Contains mucus membrane and hairs, Filter air, Warms and humidifies air

Nasal Cavity

Behind nose, Contains nasal conchae (bones that divide nasal cavity), Covered by the mucous membrane, Increase the surface area for filtration and warming of the air

Sinuses

hollow cavities within the skull, Lined with mucus membranes, Reduce weight of the skull, Serves as a resonance chamber for voice

Pharynx

throat, passageway for air and food, Subdivisions

Nasopharynx

only air, connects nasal cavity to pharynx

Oropharynx

food/liquid and air, connects mouth to pharynx

Laryngopharynx

Connects pharynx to larynx (air) and esophagus (food), Controlled by epiglottis

Larynx

voice box or Adam’s Apple, Enlargement in the airway superior to the trachea, Houses vocal cords, Composed of smooth muscle and cartilage

Vocal Chords

2 pairs of ligaments, False vocal cords, Hold the true vocal cords in place, True Vocal Chords, Vibrate to produce sound waves

Vocal Chords

Sound Production

Sound

vibration in mouth turns into words

Loudness

more air→louder the voice

Pitch

length or tension in the vocal cords, shorter/tighter →higher pitch

Trachea

windpipe, Lined with mucus membrane and cilia, Composed of cartilage

Tracheotomy/Tracheostomy

performed to allow air to bypass an obstruction within the larynx

Bronchial Tree

branches from trachea and carries air into lungs, Primary Bronchi → Secondary Bronchi→Bronchioles

Alveoli

air sacs, Site of gas exchange, Surrounded by capillaries, Contain alveolar pores

Alveolar macrophages

clear inhaled pathogens

Alveolar Wall

Are a single layer of type I pneumocytes, Squamous cells (flat walls) allow the diffusion of gases easily, Also contain type II pneumocytes, Cube shaped walls, Release surfactant so they don’t fully collapse

Respiratory Membrane

where gas exchange between air and blood occurs, it is very thin to facilitate the diffusion of gasses, Consists of alveolar wall and capillary wall

Lungs

house bronchial tree and the alveoli, Soft spongy organs, Right lung is larger because heart tilts towards the left

Ventilation

movement of air into and out of the lungs, Dependent on changes in thoracic pressure, Lungs at rest when the pressure in the thoracic cavity is equal to atmospheric pressure

Major Events in Inspiration

Diaphragm contracts and moves downward, Intercostal muscles (between ribs) and rib cage moves up, Thoracic cavity increases in size and pressure inside decreases, Atmospheric pressure is greater than thoracic pressure, Air moves in

Major Events in Expiration

Diaphragm relaxes and moves upwards, Intercostal muscles relax and rib cage moves down, Thoracic cavity decreases in size and pressure increases, Atmospheric pressure is less than thoracic pressure, Air moves out

Measurement of Lung Function Purpose

Diagnose disease, Track progress of a disease, Track recovery from a disease; Ex. Lung compliance, Pulmonary volumes and capacities, Minute ventilation, Alveolar ventilation

Lung Compliance

Measurement of the ease with which the lungs and thorax expand, Volume increases for each unit of pressure change in alveolar pressure

Spirometry

the process of measuring volumes of air that move into and out of the respiratory system

Spirometer

a device used to measure these pulmonary volumes

Tidal volume (TV)

volume of air inhaled or exhaled during a normal breath

Inspiratory reserve volume (IRV)

amount of air that can be forcefully inhaled after a normal inhale

Expiratory reserve volume (ERV)

amount of air that can be forcefully exhaled after a normal exhale

Residual volume (RV)

amount of air remaining in the lungs after the most forceful exhale

Pulmonary Capacities

Sum of two or more pulmonary volumes

Inspiratory capacity (IC=IRV + TV)

amount of air a person can maximally inhale after a normal exhale

Functional Residual Capacity (FRC = ERV +RV)

amount of air remaining in the lungs, doesn’t include air in the trachea or bronchial tree

Vital Capacity (VC = IRV +TV +ERV)

max volume of air that can be exhaled after a maximum inhale

Total Lung Capacity (TLC = IRV + ERV + TV + RV)

all of the air the lungs can hold

Minute Ventilation

Equals tidal volume (~500mls) times respiratory rate (~12 breaths/min), Average ~ 6 L/min, Only measures movement of air into and out of the lungs, not amount of air available for gas exchange

Dead space

Areas of the respiratory system where gas exchange does not take place, Includes the nasal cavity, pharynx, larynx, trachea. Bronchi, bronchioles, and terminal bronchioles

Alveolar Ventilation (VA)

Volume of air available for gas exchange, Slow, deep breathing increases AVR and rapid, shallow breathing decreases AVR, VA (mLs/min) = (frequency breaths)(TV

Sneeze

Clear the upper respiratory tract

Cough

Clears the lower respiratory tract

Laugh

1 normal exhale released as a series of short exhale with a smile

Hiccup

Spasm of the diaphragm

Yawning

Buildup of CO2 in the blood

Respiratory Center

Medullary rhythmicity area (medulla oblongata)

Dorsal respiratory group

Basic rhythm of breathing

Ventral respiratory group

Generate impulses that increase respiratory movement when necessary

Pneumotaxic area

Pontine respiratory group, Transmits impulses to the dorsal respiratory group and controls breathing rate

Factors Affecting Breathing

Decreased blood oxygen concentration stimulates peripheral chemoreceptors in the carotid and aortic bodies which then stimulate the respiratory center, Motor impulses travel from the respiratory center to the diaphragm and external intercostal muscles, Contraction of these muscles causes lungs to expand, Expansion stimulates stretch receptors in the lungs, Inhibitory impulses from receptors to the respiratory center prevent overinflation of the lungs

Central Chemoreceptors

Are sensitive to carbon dioxide and blood pH, Carbon dioxide combines with water to form acid which ionizes releasing hydrogen ions and bicarbonate ions, Increase in carbon dioxide and decrease in pH results in stimulation of the respiratory center

Reflect accumulation of environmental influences, Reflect the effects of aging in other organ systems, Cilia less active, Mucus thickens, Swallowing, gagging, and coughing reflexes slow, Macrophages in lungs lose efficiency, Increased susceptibility to respiratory infections, Bronchial walls thin and collapse 

Life Span Changes