functions:

• used to intake and expel air

• site of oxygen and carbon dioxide exchange with the blood

• maintains acid and base balance

• speech

• smell and taste senses

• traps and expel pathogens

nose and nasal cavities

• olfactory nerve - sense of smell

• palates- separate nasal and oral cavities

• nasal cavity-

  • warms and moistens inhaled air

  • uses mucus and cilia to trap dust and pathogens

    → removed by sneezing or swallowing

pharynx : throat; small muscular passageway

• three regions:

  • nasopharynx - air

  • orapharyx and laryngopharynx - both food water and air

larynx: 9 pieces of cartilage

• closes off the trachea when food is swallowed (epiglottis)

• produces sound (vocal cords)

• air passage between pharynx and trachea

lower respiratory tract:

• trachea

  • rigid tube supported by rings of cartilage (doesnt collapse)

  • brings air into lungs

• bronchi

  • at the end of trachea, right and left branches of bronchi enter each lung

  • each primary bronchi subdivides into smaller bronchi

• alveoli

  • bronchioles divide into structures called alveoli

  • gas exchange in blood occurs in the alveoli

    → each alveolus is encased by capillaries

    → to facilitate diffusion between alveoli and capillaries, both have thin walls

gas exchange: gasses diffuse from high to low concentration

lungs:

• large, spongy organs that have an opening for bronchi

• role is to expand and contract to facilitate breathing

• no muscle tissue

• depend on nearby muscle in ribs and diaphragm to expand and contract

respiratory muscle:

• intercostals

  • located between ribs

  • pull ribs up and out when contracted

• diaphragm

  • main breathing muscle

  • located under lungs

  • flattens and enlarges the thoracic cavity when contracted (relaxed=dome)

pulmonary ventilation = breathing

• inspiration (breathe in) and expiration (breathe out)

  • both depends on

    → respiratory muscles (lungs have no muscle tissue)

    → difference between air pressure within the lungs and outside the body

inspiration

• air is inhaled

• muscles contract ; diaphragm is flattened, muscles in ribs pull up and out

• this causes expansion in thoracic cavity (more space)

• as a result, low pressure in lungs and high pressure outside

• air flows from high to low pressure; fills lungs

expiration

• muscles relax

• diaphragm bulges upward; rib muscles stop pulling

• this causes a reduction in size in thoracic cavity (less space)

• as a result, high pressure in lungs and low pressure outside

• air flows from high to low pressure; lungs empty ; air is exhaled

pleura

• because lungs expand and contract, its important that friction is reduced

• therefore, lungs surrounded with a lining called pleura

• pleura is filled with serous fluid. this fluid

  • reduces friction

  • maintains pressure needed for breathing

• pleura consists of two linings with a fluid filled space between then

visceral pleura

• covers the surface of lungs

parietal pleura

• lines the thoracic cavity

pleural cavity

• filled with serous fluid, called pleural fluid

• lubricates to reduce friction

• maintains pressure for breathing

• the pressure in pleural cavity allows lung to expand

neural control of breathing

• stimulation to breathe comes from the autonomic nervous system

medulla oblongata

• contains a respiratory center that causes the intercostal and diaphragm to contract

pons

• contains two centers that can influence breathing rhythms

factors that influence breathing

• co2 (main regulator)- high levels signals medulla to high breathing

• oxygen levels- low oxygen signals medulla to high breathing

• hydrogen ions/ ph- low ph signals medulla to high breathing

• stretch- lungs stretching inhibits signals for inhalation

• pain and emotion- limbic system affects breathing in response to emotions

resistance and air flow- like blood flood, greater resistance means less airflow

diameter of bronchioles

• bronchiole dialation- larger diameter and more airflow

• bronchiole constriction- smaller diameter and less airflow

pulmonary compliance

• elasticity of lung tissue allows more airflow

measurement of ventilation

• breathing through a spirometer gives information about lung capacity

• if lungs showing increased resistance and decrease capacity, this can indicate disease

inspiratory reserve volume

• amount of air inhaled during max effort

vital capacity

• amount of air of that can be inhaled and exhaled with max effort

total lung capacity

• vital capacity + residual volume

tidal volume

• amount of air inhaled and exhaled during normal breathing; “quiet breathing”

expiratory reserve volume

• amount of air exhaled during max effort

residual volume

• amount of air that always remains in lungs after exhalation