Respiratory System
Chapter 5
Respiratory System
 Function:
 Takes
oxygen from the air
 Places it in the bloodstream
 Removes carbon dioxide
Respiratory System

Structures
 Nose

lined with mucous membrane and fine hairs
 acts as a filter
 moistens and warm the entering air
Respiratory System
 Structures
Nostrils
 Large
Nasal
amounts of air
Chamber
Mouth
 Brings
in air
Respiratory System
 Structures
Pharynx
 Passageway
for
Food
Water
Air
Controlled
by epiglottis
Respiratory System

Structures
 Epiglottis

flap of cartilage that automatically covers the
opening of the larynx during swallowing and keeps
food from entering the larynx
Respiratory System
 Larynx
Voice
box (Adam’s apple)
Prevents material from
entering lungs.
 Trachea
Large
tube
Made of rigid cartilaginous
rings
Respiratory System
 Bronchi
Branch
out
further
 Lungs
Gas
exchange
Respiratory System

Bronchi: two branches from the trachea, which
conducts air into the lungs, where it divides and
subdivides (referred to as a bronchial tree).
 bronchioles:
smallest subdivision of the bronchial
tree

Alveolus: air sacs at the end of the bronchioles

oxygen and carbon dioxide are exchanged through
alveolar walls and capillaries
Respiratory System

Alveoli
 Surrounded
by
blood vessels
 Carbon dioxide is
removed from blood
 Oxygen is absorbed
into blood
Respiratory System

Lungs: 2 sponge-like organs in the thoracic
cavity
 pleura:
membrane covering each lung and lining the
thoracic cavity
Respiratory System
 Diaphragm
 Large
muscle under the lungs
 When contracted, rib cage expands
and air comes in
 When the diaphragm relaxes, air is
forced out
Mechanisms of Breathing

Inspiration
 Air
taken into the lungs
 Chest volume increase


Intercostal muscles
(between the ribs)
contract to raise the ribs
Diaphragm contracts
towards the abdomen
 Pressure
on lungs
lowers>allows air to
flow in
Mechanisms of Breathing

Expiration
 Forces
air out
 Chest volume
decreases



Intercostal muscles
relax, ribs lower
Diaphragm relaxes,
arches towards chest
Elastic tissues recoil &
air is pushed out
Normal Respiration Rates
Animal
Cat
Dog
Sheep
Cow
Horse
Human
Guinea Pig
Hamster
Rate (bpm)
26
22
19
30
12
12
90
74
Mechanisms of Breathing
Brain controls the normal rate of
respiration
 Many factors influence rate:

 Temperature
 Stress
 Activity
 Carbon
Dioxide
Mechanisms of Breathing

Carbon Dioxide
 When
muscles are active, release more CO2
 Receptors detect increase in CO2
 Brain signals for faster respiration
 Bronchioles dilate so more air to the alveoli
Mechanisms of Breathing

Small changes in CO2 change respiration
rate

Oxygen levels don’t influence unless they
fall very low
Clinical Practice

Cyanosis
 When
oxygen levels
fall too low, blood gets
much darker, and
looks blue through
tissue
Clinical Practice
Pneumonia: inflammation in the lungs
 Usually caused by bacterial or viral
infection

Clinical Practice

Heaves
 Disease
in horses
 Confused with pneumonia, but not infectious
 Begins slowly and is long-lasting
 Coughing, nasal discharge, labored breathing,
tire easily