Download document

Function of Respiration
Lesson 3
RESPIRATORY SYSTEM
• PRIMARY function: BREATHING (for gas
exchange):
1. uptake oxygen needed by the cells
2. release carbon dioxide produced by the cells
(remove waste, pH balance of blood)
• Also used to produce SOUND
Why do we need to breath oxygen? Think
of your previous digestive unit!
cellular respiration:
glucose + oxygen = carbon dioxide and water
HUMAN ADAPTATIONS
• For efficient gas exchange to occur:
1. Water must be present at the respiratory
surface.
Adaptation:
Human lung located within the body cavity
which contains a lot of water and air is
moistened when it enters lungs.
(Compare this to worm, fish, frog, insect…)
Types of respiration in animals
Types of respiration in animals
• Outer skin
– Earthworm
• Gills
– Fish
• Treacheal System
– Insects
• Lungs
– Land animals
http://www.youtube.com/watch?v=HV60yTvy3Mk
http://www.youtube.com/watch?v=XEIRlw5rCUk
Why is this scenario physiologically
impossible?
HUMAN ADAPTATIONS
2. The respiratory surface must be large
Adaptation:
Spread out on a flat surface the gasexchange surface is how big?
a) Half of a basketball court
b) Half of a tennis court
c) Ping pong table
Learning Check
• Pg 444, Q 1-6
The Human Respiratory System
Nasal cavity
Path taken by air
Path taken by food
The Human Respiratory System
Part
Function
Nasal
Point of entry
passages Filter, warm,
moisten air
Oral
Cavity
Special Features
Mucus, hairs,
many capillaries,
sinus cavities,
turbinates
Warm and moisten Alternate space
air
for gas exchange,
no filtration
The Human Respiratory System
Nasal Cavity
Path taken by air
Path taken by food
Pharynx
Epiglottis
Esophagus
The Human Respiratory System
Part
Pharynx
Function
connects nasal and oral
cavity to larynx
Epiglottis A flap that prevents food
from entering the lungs by
blocking the glottis (opening
of trachea)
Special Features
Cilia in top portion
move food
towards mouth to
be swallowed
Small, flexible
The Human Respiratory System
Larynx
Nasal Cavity
Path taken by air
Path taken by food
Pharynx
Epiglottis
Esophagus
Trachea
Upper
Respiratory
Tract
The Human Respiratory System
Part
Function
Special
Features
Larynx
Contains the vocal
cords – for sound,
“voice box”
“Adam’s Apple”
two flaps of
cartilage, vibrate
when air passes
through
Trachea Passage of air into 2
bronchi, “windpipe”
filter particles up to
mouth
~12cm long
-Semicircular
cartilage rings to
prevent collapse Cilia and mucus
The Human Respiratory System
Larynx
Nasal Cavity
Path taken by air
Path taken by food
Pharynx
Epiglottis
Esophagus
Trachea
Bronchi
Bronchioles
Upper
Respiratory
Tract
The Human Respiratory System
Part
Bronchus
Function
Each carries air into lungs
and splits into many
bronchioles
Bronchiole Many branches carry air to
alveoli
Able to change diameter
to regulate air flow
Special Features
Full cartilage rings
for support
Many branched
tubes, Smallest
passageways, to
increase surface
area
Smooth muscle
walls
NO cartilage rings
The Human Respiratory System
Larynx
Nasal Cavity
Path taken by air
Upper
Path taken by food Respiratory
Pharynx
Tract
Epiglottis
Esophagus
Trachea
Bronchi
Bronchioles
Lower
Respiratory
Alveoli
Tract
Diaphragm
The Human Respiratory System
Part
Function
Special
Features
Alveoli
(singular:
alveolus)
Site of external
respiration (gas exchange)
~150 million very thin tiny
sacs (large surface area)
Single cell layer
thick, surrounded
by capillaries
Coated with
“surfactant” (a
lipoprotein) to
prevent sticking
Dome shaped,
thin, muscular
Diaphragm Increases and decreases
volume of chest cavity
The Human Respiratory System
Part
Function
Pleural
Membrane
Surrounds
lungs and
lines chest
cavity,
reduces
friction
Special
Features
Filled with
fluid that
reduces
friction during
inhalation
Mechanics of Breathing
Mechanics of
Breathing
Breathing
• Inspiration: the act of taking air INTO the
lungs, occurs when pressure inside the
lungs is LOWER than pressure outside the
lungs (i.e. atmospheric pressure)
• Expiration: the act of breathing OUT,
occurs when pressure inside the lungs is
GREATER than pressure outside the
lungs (atmospheric)
Breathing Movements
• The body uses muscles to change the
VOLUME of the thoracic cavity.
• This alters the PRESSURE inside the
lungs
• An increase in volume = decrease in
pressure (and vice versa)
Respiratory Muscles
• Diaphragm: dome shaped
sheet of muscle separating
thoracic and abdominal
cavities.
• Intercostal muscles:
muscles of the ribcage
– External intercostals:
outer surface, pull ribs
up
– Internal intercostals:
inner surface, pull ribs
down
Mechanics of INSPIRATION
• Diaphragm CONTRACTS and FLATTENS (moves
downwards)
• Intercostals CONTRACT and move ribcage UPWARDS
• Pleural membrane pulls on lungs
• Result:
– Lung volume:
INCREASED
– Pressure inside the lungs:
DECREASED
– AIR MOVES IN
Mechanics of EXPIRATION
•
•
•
•
Diaphragm RELAXES and RETURNS to DOME shape
Intercostals RELAX and move ribcage DOWNWARDS
Pleural Membrane no longer pulling on lungs
Result:
– Lung volume:
DECREASED
– Pressure inside the lungs:
INCREASES
– AIR MOVES OUT
• *Internal intercostals can pull
ribs in further to force exhalation
Respiration and Gas Exchange
• Once inside the lungs, air is exchanged with the
gases in the bloodstream.
• External Respiration: The exchange of O2 and
CO2 between air and blood (occurs in the lungs).
• The alveoli are surrounded by tiny blood vessels
(capillaries); both have walls that are only a
single cell layer thick to allow for diffusion of
gases.
Respiration and Gas Exchange
• the gases are exchanged due to differences in
CONCENTRATION.
– O2 in inhaled air > O2 in blood of capillaries in lungs.
– CO2 in inhaled air < CO2 in blood of capillaries in lungs.
• So in external respiration,
– O2 diffuses from the alveoli to the capillaries and
– CO2 diffuses from the capillaries to the alveoli.
Respiration and Gas Exchange
• Once in the bloodstream, oxygen travels
throughout the body.
• Internal Respiration: The exchange of O2 and
CO2 between blood and the cells of the
surrounding tissue (occurs in the body tissues).
• As blood passes body cells O2 diffuses from the
capillaries to the tissue and CO2 diffuses from
the tissue to the capillaries.
Lung Capacities
• The full capacity of your lungs is not used up
under normal conditions - consider yawning, or
blowing out a candle, or exercising.
• A spirometer is used to measure lung capacities
and produces a spirograph
Lung Capacities
• Tidal Volume: volume of air inhaled and
exhaled in a normal breathing movement
Lung Capacities
• Inspiratory Reserve Volume: the additional
volume of air that can be taken in, beyond a
regular or tidal inhalation.
• Inspiratory Capacity: total volume of air that
can be taken in
– (TV + IRV)
IRV
Lung Capacities
• Expiratory Reserve Volume: the
additional volume that can be forced out of
lungs
• Vital Capacity: the total volume of gas
that can be moved in or out of the lungs
– TV + IRV + ERV = VC
IRV
ERV
Lung Capacities
• Residual Volume: the amount of gas that
remains in the lungs and passageways of
the respiratory system even after full
exhalation (prevents collapse, no value for
gas exchange)
Learning Check
• Pg 447, Q 7-12