Chapter 15 Respiratory System

Question 1

Respiration

Answer 1

 Process of bringing oxygen to all body cells and carrying carbon dioxide in opposite direction
 2 steps
*External respiration
*Internal respiration

Question 2

External and Internal Respiration

Answer 2

 External respiration – exchange of O2 and CO2 between inhaled air and pulmonary capillaries
* Occurs in the lungs
 Internal respiration – exchange of O2 and CO2 between blood in systemic capillaries and all cells and tissues of the body
* Occurs in the body tissues

Question 3

Respiratory System Functions

Answer 3

 Primary function: bring O2 into the body and CO2 out of it
* Respiratory system works together with the cardiovascular system
 Secondary functions
*Phonation (voice production)
* Regulation of body temperature
* Regulation of acid-base balance
*Sense of smell

Question 4

Voice Production

Answer 4

= Phonation
 Begins in larynx = voice box
 Vocal cords = vocal folds
*Stretch across lumen of larynx
*Vibrate as air passes over them
*Produce basic sound of animal’s voice

Question 5

Body Temperature Regulation (respiratory)

Answer 5

 Involves many body systems
 Utilizes superficial blood vessels lining nasal passages
*Inhaled air is warmed to prevent hypothermia
*Panting increases evaporation of fluids to cool circulating blood

Question 6

Acid-Base Balance respiration

Answer 6

 Important homeostatic mechanism of the animal body
 Necessary for normal chemical reactions in cells
 Respiratory system influences amount of CO2 in blood by the rate of breathing
* The more CO2, the lower the blood pH
* Normal pH of blood = 7.4 (range 7.35-7.45)

Question 7

The Sense of Smell

Answer 7

= Olfactory Sense
 Receptors for sense of smell located in sensory epithelium
* Located high in nasal passages

Question 8

The Respiratory Tract

Answer 8

 Lungs and system of tubes that connect lungs to the outside world
* Upper respiratory tract
—All structures outside the lungs
* Lower respiratory tract
—All structures within the lungs

Question 9

Fix this card

Answer 9

 Trace a molecule of O2 from the air to bloodstream of animal
* Upper Respiratory Tract
* Lower Respiratory Tract

Question 10

Upper Respiratory Tract

Answer 10

Outside of lungs
 Nostrils
 Nasal Cavity
*Passages
 Pharynx
 Epiglottis
 Larynx
 Trachea
*Bifurcation

Question 11

Nose and Nasal Passages

Answer 11

 External openings of respiratory tube = nostrils = nares
 Nasal passages lie between nares and pharynx
 Midline is called the nasal septum

Question 12

Nasal Passages

Answer 12

 Lining:
*Pseudostratified columnar epithelium, cilia, mucus, blood vessels
 Main function is to condition inhaled air
* Warming
* Humidifying
* Filtering

Question 13

Nasal Passage Functions

Answer 13

 Inhaled air warmed by blood flowing through blood vessels just beneath nasal epithelium
 Inhaled air humidified by mucus and other fluids on epithelial surface
 Inhaled air filtered as it passes through winding passages produced by turbinates
*Particles trapped in mucous layer
* Cilia move mucus and trapped foreign material upward to pharynx, mouth

Question 14

Nasal Turbinates

Answer 14

(Nasal Conchae)
Divide each nasal passage into 3 main passageways
 Thin, scroll-like bones covered with nasal epithelium
 Dorsal and ventral

Question 15

Another Important Nasal Passages Function

Answer 15

 Olfactory sense
 Sensory neurons leading to olfactory nerve (cranial nerve I)

Question 16

Pharynx = Throat

Answer 16

 Common passageway for respiratory and digestive systems
 Divided at rostral end by soft palate:
* Nasopharynx (respiratory)
* Oropharynx (digestive)
 Opens at caudal end into:
* Esophagus (digestive)
* Larynx (respiratory)

Question 17

Larynx

Answer 17

( Voice Box)
 Connects pharynx with the trachea
 Supported by hyoid bone
 Made mainly of cartilage segments:
* Epiglottis (1)
* Artenoid cartilages (2)
* Thyroid cartilage (1)
* Cricoid cartilage (1)

Question 18

Larynx

Answer 18

short, irregular tube connecting pharynx with the trachea

Question 19

Epiglottis

Answer 19

single, leaf shaped; projects forward from the ventral portion of the larynx
* During swallowing, the epiglottis is pulled back to cover the opening of the larynx
* Most rostral of the cartilages

Question 20

Larynx Functions

Answer 20

 Voice Production
* Vocal cords – two connective tissue bands attached to the arytenoid cartilages
* Together form boundaries of the glottis
* Stretched across lumen of larynx parallel to each other
* Vocal cords vibrate as air passes over them
 Vocal cords – like a guitar
* Muscles attached to cartilages adjust tension in cords
* Complete relaxation opens the glottis wide; no sound
* Lessening the tension produces lower-pitched sounds
* Tightening the tension produces higher-pitched sounds

Question 21

Swallowing

Answer 21

 Breathing stops, opening into larynx (glottis) is covered by epiglottis, material to be swallowed moves to rear of pharynx, esophagus opens
 After swallowing, larynx is reopened and breathing resumes

Question 22

Trachea

Answer 22

= Windpipe
 Short, wide tube
* Fibrous tissue and smooth muscle held open by cartilage rings
–C-shaped rings spaced along length of trachea prevent collapse during inhalation
–Ciliated lining
–Mucous layer
 Extends from larynx into thorax where it divides
*Bifurcation of the trachea

Question 23

Structures of the Lower Respiratory Tract –

Answer 23

The Bronchial Tree
 Bronchi
 Bronchioles
(bronchial tree)
 Alveolar ducts
 Alveoli
 Autonomic nervous system controls diameter of tubes by adjusting muscle fibers in their walls
*Bronchodilation
*Bronchoconstriction

Question 24

The Alveoli

Answer 24

 Tiny, thin-walled sacs surrounded by capillaries
 Sacs lined with a thin layer of fluid that contains a surfactant
 External respiration takes place in alveoli
* Oxygen and carbon dioxide exchanged between blood and air

Question 25

The Lungs

Answer 25

Subdivided into lobes
* Distinguished externally by visible grooves and clefts
* Distinguished internally by major branches of bronchi
 Same basic pattern among species
* 3 lobes in left lung (cranial, middle, caudal)
* 4 lobes in right lung (cranial, middle, caudal, accessory)
* Exception: the horse
 Hilus = small, well-defined area on medial side
* air, blood, lymph, and nerves enter and leave the lung

Question 26

Pulmonary Circulation

Answer 26

 Deoxygenated blood enters lungs
* From right ventricle of heart through pulmonary artery
 Vessels follow bronchial tree and subdivide
 Capillary networks around alveoli
* CO2 and O2 are exchanged

Question 27

Thoracic Cavity

Answer 27

Thorax = Thoracic Cavity = Chest Cavity
 Area bounded by
* Thoracic vertebrae, ribs and intercostal muscles, and sternum
 Main contents
* Lungs, heart, large blood vessels, nerves, trachea, esophagus, lymphatic vessels, and lymph nodes

Question 28

Diaphragm

Answer 28

 Thin sheet of skeletal muscle
 Forms caudal boundary of thorax
 Acts as respiratory muscle
*Bases of lungs lie directly on its cranial surface
* Dome-shaped in relaxed state
* Flattens when muscle contracts and enlarges volume of thorax

Question 29

Negative Intra-thoracic Pressure

Answer 29

 Partial vacuum exists within thorax
*Pulls lungs tightly out against thoracic wall
 Allows lungs to follow movements of thoracic wall and diaphragm
*Inspiration and expiration
 Aids in return of blood to the heart
*Veins have no muscular pump to facilitate process

Question 30

Inspiration

Answer 30

= 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
* Diaphragm and external intercostal muscles

Question 31

Expiration

Answer 31

= Exhalation
 Process of pushing air out of the lungs
 Opposite of inspiration
*Size of thorax is decreased
* Lungs are compressed
*Air is pushed out through respiratory passageways
 Main expiratory muscles
*Internal intercostal muscles and abdominal muscles

Question 32

Respiratory Volumes

Answer 32

Standardized terms for describing quantity of air involved in respiration
 Tidal volume – volume in a normal breath - most animals 5 cc per pound
 Minute volume – volume of air an animal breathes in and out in 1 minute
* Multiply tidal volume X respiratory rate
 Residual volume – volume of air remaining in the lungs after a maximum exhale (expiration)

Question 33

Alveolar Gas Exchange

Answer 33

 Inhaled air:
* High O2
—in air diffuses into blood where level is lower
* Low CO2
 Blood entering capillary:
* Low O2
* High CO2
–in blood diffuses into air where level is lower

All occurs passively through diffusion

Question 34

Trace molecule of air

Answer 34

(upper respiratory tract)
1- Into Nose
2- Nasal Cavity
– moistened, warmed and filtered
3- Pharynx (throat)
– common passageway for digestion and respiration
4 - epiglottis
5. larynx
6. trachea
(lower respiratory tract)
7. Bronchus
8. Bronchial tree
9. Alveolar duct (bronchioles)
10. Alveolus

Question 35

Alveolus

Answer 35

A network of capillaries where blood becomes oxygenated

Question 36

Alveolar Gas Exchange -Expiration

Answer 36

 Exhaled air:
* Higher CO2
* Lower O2

Question 37

Respiratory Center

Answer 37

 Breathing controlled by area in medulla oblongata of the brain stem
* Directs timing and strength of respiratory muscle contraction
 Individual control centers for inspiration, expiration, and breath-holding
 Breathing can be consciously controlled for brief periods of time

Question 38

Mechanical Control System for Breathing

Answer 38

 Operates through stretch receptors in lungs
 A preset and automatic system
* Nerve impulses sent to respiratory center indicate when lungs inflate to certain point
* Muscle contractions that produce inspiration are stopped
* Muscle contractions to produce expiration are initiated
* Another set of nerve impulses is sent when lungs deflate to a certain point
* Expiration is stopped; process of inspiration is begun
 Net effect is normal, rhythmic, resting breathing baseline pattern

Question 39

Chemical Control System for Breathing

Answer 39

 System affects breathing pattern only when something is out of balance
* Makes adjustments to maintain homeostasis
 Chemical receptors monitor blood
* Located in carotid artery and aorta, and the brain stem
 Characteristics monitored
* CO2 content
* The pH
* O2 content

Question 40

CO2 Variations in the Blood

Answer 40

 Blood level of CO2 and blood pH usually linked
 Increased CO2
in blood
* Decreases blood pH
* Triggers respiratory center to increase rate and
depth of respiration
 Decreased CO2 in blood
*Increases blood pH
*Excess = respiratory alkalosis
* Triggers respiratory center to decrease rate and depth of respiration

Question 41

Oxygen Variations in the Blood

Answer 41

– Hypoxia
 Effects of variations not as clear-cut as with CO2
 Slight hypoxia
* Respiratory center signaled to increase rate and depth of breathing
 Severe hypoxia
* Neurons of respiratory system become so depressed that impulses cannot be sent to respiratory muscles
* Can cause breathing to decrease or stop completely

Question 42

Stenotic Nares

Answer 42

 Stenotic nares is part of the brachycephalic syndrome of short-nosed dogs. Breeds such as Boxers, Bulldogs, Cavalier King Charles Spaniels, Pugs, Boston Terriers, Shih Tzus, Lhasa Apsos, etc. are all considered brachycephalic breeds. Stenotic nares means the nostrils are pinched or narrow. This makes it more difficult to breathe and causes snorting and snoring in these animals. It is a congenital trait.

Question 43

Elongated Soft Palate

Answer 43

 In dogs with an elongated soft palate, the palate overlaps the epiglottis to a considerable degree, partially obstructing the animal’s airway during breathing. This is manifested by snorting, snoring, strider, gurgling and gagging. The obstruction is worse with exercise

Question 44

Brachycephalic Breed issues

Answer 44

Short muzzle
stenotic nares
Elongated soft palate

Question 45

choanae

Answer 45

The mouth and nasal chambers are linked by the choanae, internal nares that open from the nasal chambers into the roof of the mouth in birds.

Question 46

syrinx

Answer 46

Produces sound in birds instead of larynx
An enlargement of the trachea above the sternum

Question 47

Bird respiratory

Answer 47

*Mesobronchi -A bird’s two main-stem bronchi divide and contain no cartilaginous rings.
*The mesobronchi divide into four to six secondary ventrobronchi.
*The ventrobronchi divide to become the parabronchi that connect to air capillaries, where gas exchange occurs.
*Air sacs comprise the majority of the volume of the avian respiratory system.
—small membranous sacs that act as a storage site for air, aid in thermoregulation, and help provide buoyancy to water birds