the respiratory system chapter 10. organs of the respiratory system nose pharynx larynx trachea...
DESCRIPTION
Accessory Structures Thorax DiaphragmTRANSCRIPT
The Respiratory
System
Chapter 10
Organs of the Respiratory System
• Nose• Pharynx• Larynx• Trachea• Bronchi• Lungs
Accessory Structures
• Thorax• Diaphragm
The Nose
The Nose (naso or rhino)
• Acts as entrance for air and exit for carbon dioxide
• Lined with a ciliated epithelial mucus membrane
• Filters dust and foreign material• Warms & moistens entering air• Has olfactory receptors
Nostrils (Nares)
• Paired openings that vary in pliability and expandability to accommodate an increased need for oxygen.
• The horse has pliable and expandable nostrils because mouth breathing is not characteristic.
Pharynx (Throat)• A musculomembranous saclike structure• Upper portion is attached to the base of the
skull and the lower portion with the esophagus
• Connects with the nasal chambers, mouth, larynx and eustachian tubes
The pharynx is divided into three parts:•Nasopharynx – opens into the Eustachian tubes•Oropharynx – opens into the mouth•Laryngopharynx – opens into the larynx & esophagus
The pharynx is used as passageway for both air and
food. Depending on the species it may also have a role in
vocalization.
Larynx (Voice Box)
• Located just below the pharynx• Serves as a passage for air• The epiglottis is a lid-like
structure that prevents food from entering the airway during swallowing
The larynx plays an important role in creating sound. Air passes through the
glottis during expiration causing a vibration, and producing a sound.
Trachea (Windpipe)
• A tube formed of smooth muscle with numerous C shaped rings of cartilage embedded in the tissue
• These rings prevent collapse of the structure.
The end of the trachea separates
into smaller airways called
the primary bronchi.
The Bronchi
• Lined with a ciliated mucous membrane & C-shaped cartilage rings, which become complete as the bronchi enter the lungs
• They then divide into smaller secondary branches, then bronchioles, then alveolar ducts
The Bronchi
The alveolar ducts terminate into alveolar sacs:
Small, squamous epithelium lined spaces that allow the lungs to achieve the primary function of oxygen and carbon dioxide
exchange.
As the bronchioles get smaller, the cartilage rings begin to
disappear. There are no rings in the alveolar ducts, sacs or
alveoli.
The Lungs
• The primary structures of the respiratory system
• Occupy almost the entire thoracic space
• Each contains millions of alveoli and capillaries
Membranes in the Lungs
• Visceral pleura - Serous membrane that encases the lungs
• Parietal pleura – Lines the thoracic cavity
These membranes reduce friction during respiration.
The space between these membranes is called the pleural
cavity or potential space.
Thorax (Chest Cavity)
Lined with a membrane similar to the covering of the lungs, that lubricates both surfaces during respiration
The pleural membrane divides the chest into 3 parts:•Right pleural cavity•Left pleural cavity•Mediastinum
The mediastinum contains the heart, thymus, esophagus, trachea, bronchi, nerves, arteries,
veins and lymphatic vessels.
• A dome-shaped musculomembranous partition separating the thoracic and abdominal cavity
• Attaches to the lumbar and abdominal cavities at the lumbar vertebra, lower ribs and sternum
The Diaphragm
Normal feline chest
Diaphragmatic Hernia
The diaphragm is the primary muscle of respiration.
•Inspiration: Contracts, flattens and lowers, increasing thoracic capacity.•Expiration: Relaxes and returns to its normal position
Respiratory Process
The respiratory cycle is divided into three parts:•Inspiration•Expiration•Rest
Respiration• Involves the
exchange of oxygen and carbon dioxide wastes
• Tissue does not store oxygen and takes in only the oxygen it needs.
During exercise the oxygen requirement can more than double. Flow of air in and out of the lungs
depends on changes in the thoracic cavity. Inspiration and expiration are in accordance with pressure differences between the atmosphere and
air in the lungs
Tidal volume (TV):The amount of air inhaled during
ordinary respiration
Inspiratory reserve volume (IRV):The amount of air that can be
forcibly inhaled beyond the normal amount
Expiratory reserve volume (ERV):The volume of air that can be
forcibly expelled beyond normal expiration
Some air will always be trapped in the alveoli no matter how forcibly
an animal exhales due to intrathoracic pressure.
Residual Volume (RV):Air remaining in the lungs after
forced expiration
Minimal volume:Air remaining in the alveoli of a
collapsed lung
Vital capacity (VC):The largest amount of air that can be moved in and out of the lungs.The sum of the total of inspiratory
and expiratory reserve volumes plus tidal volume
There are several nerves from the brain that pass down the chest wall and diaphragm to control
respiration…
Vagus nerve:Originates in the brain and sends
branches to the larynx, heart, bronchi, esophagus, stomach, liver
and abdomen.
Phrenic nerve:Originates in the cervical spine
and passes to the diaphragm
Thoracic nerve:Originates in the thoracic spinal cord, these are the nerves of the
muscles of the thorax
Next up…
The GI Tract