chapter 13 part a

Chapter 13

The Respiratory System

1.     Organs of the system

a.    Nose

b.    Pharynx

c.    Larynx

d.    Trachea

e.    Bronchi

f.    Lungs/alveoli(us)

2.    Functions of the system

a.    Gas exchange between blood and external environment- occurs in the alveoli of the lungs

b.    Specific functions in parts of the system: passageways to the lungs purify, humidify, and warm the incoming air

3.    Nose

a.    External visible

b.    Nares- air enters the nose through the external nostrils= nares

c.    Nasal cavity- interior of the nose, nasal cavity is divided by a nasal septum

                                          i.    Olfactory receptors are located in the mucosa on the superior surface

                                        ii.    Respiratory mucosa lines the rest of the cavity. Moisten air and trap incoming foreign particles

                                       iii.    Conchae- on the lateral walls

1.     Increase the surface area

                                       iv.    Palate separates the nasal cavity from the oral cavity. Anterior hard palate(bone), posterior soft palate(muscle).

                                         v.    Sinuses are cavities within bones surrounding the nasal cavity.  Sinuses are located in the following bones…

1.     Frontal bone

2.    Sphenoid bone

3.    Ethmoid bone

4.    Maxillary bone

5.    Functions

a.    Weight –lighten the skull…not solid bone

b.    Resonance- act as resonance chambers of speech

c.    Produce mucus- drains into the nasal cavity

4.    Pharynx- muscular passage from nasal cavity or larynx. Three regions of the pharynx…

a.    Nasopharynx- superior region behind nasal cavity

b.    Oropharynx- middle region behind mouth

c.    Laryngopharynx inferior region attached to larynx

d.    The oropharynx and laryngopharynx are common passageways for air and food.

e.    Eustacean = auditory=pharyngotympanic tubes

f.    Tonsils

                                          i.    Pharyngeal

                                        ii.    Palatine

                                       iii.    Lingual

5.    Larynx

a.    Routes air and food into proper channels

b.    Plays a role in speech

c.    Made of eight rigid hyaline cartilages and a spoon shaped flap of elastic cartilage(epiglottis)

d.    Cartilage

                                          i.    Thyroid-largest of the hyaline cartilage, protrudes anteriorly (adams apple)

                                        ii.    Epiglottis – we already know. Protects the superior opening of the larynx. Routes food to the esophagus and air toward the trachea. When swallowing, the epiglottis rises and forms lid over the opening of the larynx.

e.    Vocal folds-true vocal cords

                                          i.    Vibrate with expelled air to create sound(speech)

                                        ii.    Glottis-opening between vocal cords

6.    Trachea

a.    Four inch long tube that connects larynx with bronchi

b.    C-shaped hyaline cartilage reinforces walls

c.    Ciliated mucosa-lining

                                          i.    Beat continuously in the opposite direction of incoming air

                                        ii.    Mucus loaded with dust and other debris is expelled away from the lungs

7.    Main bronchi(us)

a.    Division of the trachea

b.    Enters the lung at the hilum (medial depression)

c.    Subdivide into smaller and smaller branches

d.    The right bronchus is wider, shorter, and straighter than the left

8.    Lungs

a.    Anatomy

                                          i.    Location-occupy most of the thoracic cavity

                                        ii.    Mediastinum is where the heart occupies central portion (middle portion)

                                       iii.    Apex is near the clavicle (superior portion)

                                       iv.    Base rests on the diaphragm (inferior portion)

                                         v.    Lobes divide each lung by fissures

1.     Right –three lobes

2.    Left – two lobes

b.    Coverings

                                          i.    Serosa covers the outer surface of the lungs

                                        ii.    Visceral(pulmonary) pleura covers the lung surface

                                       iii.    Parietal pleura lines the wall of the thoracic cavity

                                       iv.    Pleural fluid fills the area between layers of pleura to allow gliding

                                         v.    These two pleural layers resist being pulled apart

c.    Bronchial tree

                                          i.    Bronchi divisions- all but the smallest of these passageways have reinforcing cartilage in their walls: primary bronchi, secondary bronchi, tertiary bronchi…

                                        ii.    Bronchioles

                                       iii.    Terminal bronchioles

                                       iv.    Respiratory zone

1.     Alveolar ducts

2.    Alveolar sacs

3.    Alveoli(air sacs)-where gas is exchanged

a.    Respiratory membrane = air/blood barrier

                                                                                          i.    Epithelium(squamous)- lines alveolar walls

                                                                                        ii.    Alveolar pores connect neighboring air sacs

                                                                                       iii.    Blood(pulmonary) capillaries cover external surfaces of alveoli

                                                                                       iv.    On one side of the membrane is air and on the other side is blood flowing past

b.    Gas exchange – the ultimate goal

9.    Gas exchange via diffusion only

a.    Oxygen

b.    Carbon dioxide

c.    Macrophages

d.    Surfactant

10.  Events of respiration

a.    Breathing

b.    External respiration

                                          i.    Oxygen

                                        ii.    Carbon dioxide

c.    Respiratory gas transport

d.    Internal respiration