Transcript AP resp

Respiration
Respiration
• Physiological process by which oxygen
moves into internal environment and
carbon dioxide moves out
• Oxygen is needed for aerobic respiration
• Carbon dioxide is produced by same
• Respiratory System works with the
circulatory system to deliver oxygen and
remove carbon dioxide
Pressure Gradients
• Concentration gradients for gases
• Gases diffuse down their pressure
gradients
• Gases enter and leave the body by
diffusing down pressure gradients
across respiratory membranes
Fick’s Law
• Describes the rate at which a substance
(such as oxygen) will diffuse across a
membrane (such as a respiratory
surface)
• Rate is proportional to the pressure
gradient across the membrane and to
the surface area of the membrane
Surface-to-Volume Ratio
• As animal size increases, surface-tovolume ratio decreases
• Small, flattened animals can use the
body surface as their respiratory surface
• Larger animals have special structures
to increase respiratory surface, such as
gills or lungs
A. single celled organisms use simple
diffusion
B. Simple aquatic organisms use their skin
with blood vessels close by
C. Advanced aquatic organisms use
evaginated structures with blood vessels
near by.
D. Few aquatic organisms i.e. sea cucumbers
invaginate their respiratory surfaces
E. Land animals invaginated their respiratory
surfaces to prevent them from desiccation. Lungs
are associated with blood for gas exchange
F. Insects invaginate with a tracheal system that
are tubes branched inside the body without an
association with a circulatory system.
Aquatic Animals-
Because Oxygen in water is app. .004%
compared with 21% in the air, aquatic
animals have a difficult time with gas
exchange.
Most aquatic animals evolved
respiratory organs that are found on
the outside of the body called gills.
Gills are usually folded membranes
or layered membranes (increase
surface area)associated with a
circulatory system.
Blood vessels are very close to the
surface of the gills
Meeting the 4 basic needs
1. Gills are folded or layered to
increase surface area
2. Evagination in water insures moist
membranes
3. Some organisms have developed a
circulatory system to insure all cells
receive oxygen
4. Most gills have a protective
covering- operculum, mantel or
pedicellaria
Fish Gills
• Most commonly
internal
• Water is drawn in
through mouth and
water
flows in
through
mouth
FISH GILL
water flows
over gills,
then out
passed over gills
Figure 40.6
Page 710
The gills are layered like pages of a
book. One set of gills is layered on
top of one another. The water move
through the mouth and then over the
gills out the operculum. The water
is moving in the opposite direction
of the blood. This is the counter
current exchange system. It allows
for maximum exchange of gases.
Countercurrent Flow
• Blood flow runs in the
opposite direction of
water flow over the
filaments
• This enhances
movement of oxygen
from water to blood
respiratory surface
direction of
water flow
oxygenated blood
back toward body
direction of
blood flow
oxygen-poor blood
from deep in body
Figure 40.6
Page 710
Terrestrial animals must prevent
desiccation.
Gases must be exchanged across
moist surfaces. Also must be
protected as surfaces are very
delicate.
Most land animals invaginated their
respiratory surfaces into lungs,
tracheal systems or book lungs.
Earthworms- skin acts like respiratory
organ. Must stay moist or will die.
Spiders and other arachnids have book
lungs. Look more like invaginated gills
Insects-Tracheal systems - Tubes of
trachea leading from the outside of the
body inward The openings are called
spiracles. The trachea are extensively
branched into tracheoles which takes air
directly to individual cells.
Lungssac structures-->very complicated,
subdivide membranes to increase
surface area
Vertebrate Lungs
• Originated in some
fishes as
outpouching from
gut wall
• Allow gas exchange
in oxygen-poor
aquatic habitats and
on land
salamander
reptile
Figure 40.8
Page 711
Vertebrate Lungs
Amphibians have lungs which are like
simple sacs but they also have the ability
to respire through their moist skin
Frogs breathe via positive pressure
breathing- that is air is forced to the lung
Note- Homeotherms (warm blooded)
need more oxygen/body weight than
poikilotherms (cold blooded)
Birds have well developed lungs and air
sacs that allow for unidirectional flow of
air in the lungs and *better efficiency of
obtaining oxygen
Avian Respiration
• Lungs are inelastic
air
sacs
and connect to a
series of air sacs
air
sacs
lung
• Air is drawn
continually through
each lung
Figure 40.9
Page 711
air
sacs
Birds breathe via negativepressure breathing- that is air is
drawn in by increasing the volume
of the lungs
Human Respiratory System
Pharynx (Throat)
Epiglottis
Larynx (Voice Box)
Trachea (Windpipe)
Pleural Membrane
Bronchiole
Alveoli
Intercostal Muscle
Diaphragm
Figure 40.10
Page 712
Glottis- opening to larynx
Epiglottis- flap of skin to prevent foreign
particles in the trachea
Larynx- cartilage like tube contains vocal
cords
Trachea- air duct leading from larynx to
thoracic cavity
Epithelial lining is cilliated. This
cillia beats in waves to prevent
foreign particles from entering the
lungs.
Trachea also has cartilage rings to
prevent it from collapsing.
The trachea branches into 2 tubes
leading to the lungs called bronchi.
These continue to branch until it ends
at a sac like structure called an
alveolus.
Alveolus- one cell thick and
surrounded by a capillary bed.
Thoracic Cavity
Pleura covers the lungs (2 layers).
Parietal pleura covers the inside of
the thoracic cavity.
Visceral pleura covers the lungs
themselves.
In between is pleural fluid that allow
the lungs and cavity to slide past
one another
Gas Laws
Gases will diffuse evenly in a given
volume going from a higher [ ] to a lower[ ]
Boyle's Law
P1V1=P2V2 at a constant temperature a
volume of gas varies inversely with its
pressure PV=K
Breathing
• Moves air into and out of lungs
• Occurs in a cyclic pattern called
the respiratory cycle
• One respiratory cycle consists of
inhalation and exhalation
Respiratory Cycle
Involves 3 types of pressure
1. Atmospheric- pressure exerted by the
surrounding air 760 mmHg
2. intrapulmonic- pressure of air within
bronchial tubes- This fluctuates above
and below atmospheric pressure because
of the air moving in and out with the
changing volume of the lungs
3. intrapleural- pressure between the two
layers of pleural- During normal breathing
this is subatmospheric because the lungs
have a tendency to recoil (called
compliance) which increases the V of
pleural cavity increase V decrease P
inspiration (air into lungs)
1. diaphragm contracts
2. external intercostal muscles contract
Both contracted
Diaphragm is lowered increasing the V of
lungs
Intercostal muscles- raises the ribs,
pushes the sternum forward also increases
V of lungs
1. The parietal pleura pulls with the
enlarged thoracic cavity lowering the
pressure
2. Because of the fluid between the two
layers visceral pleura and the lung expands
with the enlarging thoracic cavity
3. Lung increase V and now P decreases
and air will flow into the lungs
Expiration (air out of lungs) (passive)- The
muscles relax or recoil decrease V thoracic
cavity and lungs
Thereby increase of P and air flows out
Inhalation
• Diaphragm flattens
• External intercostal
muscles contract
• Volume of thoracic
cavity increases
• Lungs expand
• Air flows down pressure
gradient into lungs
Figure 40.12
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Normal (Passive) Exhalation
• Muscles of
inhalation relax
• Thoracic cavity
recoils
• Lung volume
decreases
• Air flows down
pressure gradient
and out of lungs
Figure 40.12
Page 714
Active Exhalation
• Muscles in the abdomen and the
internal intercostal muscles contract
• This decreases thoracic cavity volume
more than passive exhalation
• A greater volume of air must flow out to
equalize intrapulmonary pressure with
atmospheric pressure
Control of Breathing
• Medulla oblongata sets main rhythm;
centers in pons fine-tune it
• Magnitude of breathing depends on
concentration of oxygen and H+
• Brain detects H+, increases breathing
• Carotid bodies and aortic bodies detect
drop in oxygen, increase breathing
intercostal nerves - intercostal muscles
Stimulation of these nerves is both
voluntary and involuntary
Respiratory center upper part of the
medulla- a drop in pH (blood) stimulates
respiratory center which stimulates the
respiratory nerves.
A drop in pH in the blood can result from
an increase of CO2-carbonic acid
Cutaway View of Alveolus
red blood cell
air space
inside
alveolus
(see next slide)
pore for airflow
between alveoli
Figure 40.16
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Respiratory Membrane
• Area between an
alveolus and a
pulmonary capillary
• Oxygen and
carbon dioxide
diffuse across
easily
alveolar
epithelium
capillary
endothelium
fused
basement
membranes
of both
epithelial
tissues
Figure 40.16
Page 715
Oxygen Transport
• Most oxygen is carried bound to
hemoglobin in red blood cells
• Hemoglobin has a great affinity for
oxygen when it is at high partial
pressure (in pulmonary capillaries)
• Lower affinity for oxygen in tissues,
where partial pressure is low
Bicarbonate Formation
CO2 + H2O
H2CO3
carbonic acid
HCO3– + H+
bicarbonate
• Most carbon dioxide is transported as
bicarbonate
• Some binds to hemoglobin
• Small amount dissolves in blood
Bronchitis
• Irritation of the ciliated epithelium that
lines the bronchiole walls
• Air pollutants, smoking, or allergies can
be the cause
• Excess mucus causes coughing, can
harbor bacteria
• Chronic bronchitis scars and constricts
airways
Emphysema
• An irreversible breakdown in alveolar
walls
• Lungs become inelastic
• May be caused by a genetic defect
• Most often caused by smoking
Humans at High Altitude
• Permanent residents of high areas have
– More vascularized lungs
– Larger ventricles in heart
– More mitochondria in muscle
• Acclimatization
– Changes in rate of breathing, heart output
– Kidney secretes erythropoietin; red cell
production increases
Carbon Monoxide (CO)
• Colorless, odorless gas
• Competes with oxygen for binding sites
in hemoglobin
• Binding capacity is at least 200 times
greater than oxygen’s
• Exposure impairs oxygen delivery