Transcript Respiration

Two kinds:

Cellular Respiration: mitochondria --> ATP...
(Chapter 7)
◦ Uses O2 to turn glucose into energy (by-product is
CO2)

Organismal Respiration: exchange of gases
between cells and environment (Chapter 47)
◦ Involves the exchange of O2 CO2 between
cells/blood/lungs
2

Earliest animals simply diffused O2 through their skin

Insects = use "tracheae" (cuticle-lined tubules in abdomen)
good for small animals only

First evolved respiratory organs were GILLS; probably arose
as a feeding device, originally
◦ Thin, one cell thick membranes; folded, layered (high surface area);
increase respiratory surface; bring more blood in contact w/ O2
◦ "Counter Current Exchange": circulatory vessels are arranged so
blood is pumped through in opposite direction of water flow (O2).
Maximizes O2 pickup.

LUNGS- internal cavities, also made of many thin, folded air
sacs for lots of surface area (better gas exchange)
◦ More efficient than gills (21% O2/Air, 0.5% O2 in Water)
◦ Fish must process more H2O to get the same amount of O2 as in Air
(Energy-Consuming)
3
 STEP
1: "Bulk-flow" of air into lungs
(thin, close to blood vessels)
 STEP 2: Diffusion of O2 across
membrane into blood animation
 STEP 3: passage of O2 from blood
into tissues
 STEP 4: Diffusion of O2 into
individual cells
4

Oxygen enters the blood/tissues/cells enters blood
via diffusion (from areas of high concentration to low)

If there’s more O2 in the air we breathe, it should
diffuse into your red blood cells

Gas Exchange depends upon pressure and
concentration differences between atmosphere and
bloodstream

changes in the partial pressures of oxygen and
carbon dioxide affect diffusion: animation

Atmospheric pressure (mm Hg) affects O2 diffusion
into blood/tissues (higher altitude, lower pressure)

How does this affect our breathing at altitude?
5








Nasal passages
(mucus,cilia)
Pharynx
Epiglottis
Larynx
Trachea
R&L bronchi
Bronchioles
Alveoli (alveolus) are
tiny air sacs with thin
walls (surrounded by
capillaries)
◦ gases exchanged through
capillary/alveolar walls via
diffusion
A thin Pleural Membrane
encases lungs, secretes
lubricants (mucus)
6
7






Smooth Muscles can dilate/constrict the bronchi,
bronchioles
Asthma is a chronic disease that affects your
airways
the inside walls of your airways become inflamed
(swollen) and clogged with mucus
The inflammation makes the airways very sensitive,
and they tend to react strongly to things that you
are allergic to or find irritating.
When the airways react, they get narrower, and less
air flows through to your lung tissue.
This causes symptoms like wheezing (a whistling
sound when you breathe), coughing, chest
tightness, and trouble breathing, especially at night
and in the early morning.
8


Breathing- due to pressure changes w/in
thoracic cavity
muscles:
◦ Diaphragm
 relaxes--> rises
 contracts--> lowers
◦ Abdominals/ Intercostals raise and lower the
ribcage to adjust volume of thoracic cavity

http://health.howstuffworks.com/adam-200020.htm

Inspiration -vs- Expiration
◦ breathing animation
9
A. HEMOGLOBIN –

respiratory pigment

oxygen-carrying protein molecule w/ central iron (Fe)
atom
◦ Mollusks & Arthropods: “hemocyanin”, blue w/ O2


heme carried on RBC, can carry 4 Oxygen molecules each
(O2 not very soluble in plasma)
Most CO2 is carried in the plasma as (1) carbon anhydrase
(in RBC); or (2) carbonic acid; or (3) bicarbonate ion (HCO3)
B. MYOGLOBIN- respiratory pigment found is skeletal muscle
 has higher O2 affinity than hemoglobin
 O2 reserve for muscles under stress
 "Diving Reflex" in marine mammals
10



Respiration is under control of brainstem
(medulla)
Involuntary, but can be brought under voluntary
control temporarily
Many "sensors" located throughout body that
give feedback to brain resp. centers
◦ sensors sensitive to CO2, O2, H+ levels
◦ stretch sensors in lungs & chest
◦ chemoreceptors in Carotid Arteries detect blood pH
ex: low pH (acidic) = high CO2 levels, breathing becomes
faster/deeper
Practice! online quizzes:
Respiratory system anatomy
http://msjensen.cehd.umn.edu/webanatomy_arc
hive/wa_respiratory/wa_resps_1.html
11