Respiratory System Flashcards
What is respiration?
process of bringing oxygen to all body cells and carrying carbon dioxide in opposite direction
2 steps: external and internal respiration
External respiration
in the lungs
Internal respiration
all over the body
What are the secondary functions of the respiratory system?
voice production, body temperature regulation, acid base balance regulation, and sense of smell
Phonation (voice production)
begins in the larynx aka the voice box
Vocal cords
= vocal folds
-made of fibrous c.t. bands
-stretch across lumen of the larynx
-vibrate as air passes over them
-produce basic sound of animal’s voice
How does the respiration system help body regulate temperature?
utilizes superficial blood vessels lining nasal passages
-inhaled air is warmed to prevent hypothermia
-panting increases evaporation of fluids to cool circulating blood
Acid base balance
- important homeostatic mechanism of body
-necessary for normal chemical reactions in cells
*the respiratory system influences amount of CO2 in blood by rate of breathing
The more CO2,
the lower the blood PH (more acidic)
-we can adjust the rate and volume of breathing to influence this
Where are the receptors for sense of smell located?
sensory epithelium
-located high in nasal passages
-most animals have highly sensitive smell and less sensitive sight
Pheromones
chemical substance produced by an animal that can act like an external hormone capable of affecting the behavior of another animal in the same species
ex: flehmen response
Upper Respiratory Tract
all structures outside the lungs
-nostrils
-pharynx
-larynx
-trachea
Lower Respiratory Tract
all structures within the lungs
-bronchi
-bronchioles
-alveolar ducts
-alveoli
Nasal passages
b/w nares and pharynx
Nares
external openings of respiratory tube/nostrils
Nasal Septum
midline
Turbinates (nasal conchae)
divide each nasal passageway into 3 main passageways:
1. ventral nasal meatus
2. middle nasal meatus
3. dorsal nasal meatus
Main function of the nasal passage:
is to condition inhaled air
-warming
-humidifying
-filtering
Sinuses
-outpouchings of the nasal passages
-named for skull bones that house them
Pharynx
common passageway for respiratory and digestive systems
Pharynx division at rostral end
nasopharynx (respiratory)
oropharynx (digestive)
Pharynx division at caudal end
esophagus (digestive)
larynx (respiratory)
Larynx
-connects pharynx with the trachea
-supported by hyoid bone
-made up of cartilage segments: epiglottis and arytenoid cartilages
Epiglottis
- most rostral of cartilages
- covers larynx opening during swallowing
Vocal cords attached to
arytenoid cartilages; together form boundaries of the glottis
-muscles attached to cartilages adjust tension in cords
False vocal cords
-in non-ruminant animals
-second set of c.t bands
-aka vestibular folds
Functions of the larynx
- part of the upper airway
-voice production
-prevention of inhalation of foreign matter
-control of airflow to and from the lungs
Trachea (Windpipe)
-fibrous tissue and smooth muscle held open by cartilage rings
-extends from larynx into thorax where it divides; bifurcation of the trachea
Trachea rings
- c shaped along length of trachea that prevent collapse during inhalation
-ciliated lining, mucous layer
*birds have complete cartilage rings
Collapsed trachea
-unknown cause
-narrow space b/w ends of several C shaped tracheal rings are wider than normal
-animal inhales the widened area of smooth muscles get sucked down into lumen and partially blocks it
Bronchial tree
autonomic nervous system controls diameter of tubes by adjusting muscle fibers in their walls
-bronchodilation
-bronchoconstriction
Alveoli
- tiny, thin walled sacs surrounded by capillaries
-sacs lined with a line layer of fluid the contains a surfactant
*external respiration takes place in alveoli
-simple squamous epithelium
Surfactant
reduces surface area which prevents collapse
Asthma
most common in cats
-allergic condition typically chronic and progressive
Lungs
- cone shaped
-light spongy
-base lies directly on cranial surface of diaphragm
-area b/w = mediastinum
Lungs are subdivided into lobes
externally by visible grooves and clefts
internally by major branches of bronchi
Left vs Right Lung
-same basic pattern among species
Left: 3 lobes (cranial, middle, caudal)
Right: 4 lobes (cranial, middle, caudal, accessory)
*exception = horse
Hilus
small, well defined area on medial side
-air, blood, lymph, and nerves enter and leave the lung
Pulmonary Circulation
- deO2 blood enters lungs (from right ventricle of heart through pulmonary artery)
-follow bronchial tree and subdivide
-capillary networks around alveoli (where CO2 and O2 are exchanged)
Diaphragm
- thin sheet of skeletal muscle
-forms caudal boundary of thorax
-acts as respiratory muscle: flattens when muscle contracts and enlarges volume of thorax
Negative Intrathoracic Pressure
-partial vacuum exists w/in thorax (pulls lungs tightly out against thoracic wall)
-allows lungs to follow movements of thoracic wall and diaphragm
-aids in return of blood to the heart
(veins have no muscular pump to facilitate process)
Inspiration
= inhalation
-process of drawing air into the lungs
-results from enlargement of volume of thorax (lungs follow enlargement passively, air is drawn into lungs)
Main inspiratory muscles are
diaphragm and external intercostal muscles
Expiration
= exhalation
-pushing are out of lungs
-size of thorax decreased, lungs are compressed, air is pushed out through respiratory passageways
Main expiratory muscles are
internal intercostal muscles and abdominal muscles
Tidal volume
volume of air inspired and expired during one breath
-smaller at rest
Minute volume
volume of air inspired and expired during one min
Residual volume
volume of air remaining in lungs after maximum expiration
Clinical significance Tidal Volume
the reservoir bag should hold about 5x the tidal volume
Inhaled air
high O2
low CO2
Blood entering capillary
low O2
high CO2
Simple diffusion of gas molecules during Inspiration
high level of O2 in air diffuses into blood where level is lower
high level of CO2 in blood diffuses into air where level is lower
Partial Pressure of Gases
pressure of each individual gas
Breathing controlled by area
in medulla oblongata of the brain stem
-directs timing and strength of resp muscle contraction
Mechanical Control System for breathing
-operates through stretch receptors in lungs
-preset/ autonomic system
-net effect is normal, rhythmic, resting breathing baseline pattern
Chemical Control System for Breathing
-system affects breathing pattern only when something is out of balance
-chemical receptors monitor blood located in carotid artery, aorta, and brain stem
-monitors: CO2 content, pH, O2 content
Hypercapnia / Hypoventilation
increased CO2 in the blood
-decreases blood pH (acidosis)
-tiggers respiratory center to increase rate and depth of respiration
Hypocapnia / Hyperventilation
decreased CO2 in blood
-increases blood pH (alkalosis)
-triggers respiratory center to decrease rate and depth of respiration
Slight hypoxia (not enough O2 in blood)
respiratory center signaled to increase rate and depth of breathing
Severe hypoxia
neurons of respiratory system become so depressed that impulses cant be sent to respiratory muscles
-can cause breathing to decrease or stop completely
