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3
Gas Exchange
QuickTime™ and a
Video decompressor
are needed to see this picture.
At the tissue (the capillary bed by active muscle)
HCO3–
CO2 from
tissue
Cl–
Transported in
plasma
HCO3– + H+
CO2 + H2O
Carbonic
anhydrase
Binds to
hemoglobin
Red blood cell
Plasma
Q uickTim e™ and a
TI FF ( Uncom pr essed) decom pr essor
ar e needed t o see t his pict ur e.
The Heart: Structure
-Structure four chambers and two-layered sac (pericardium).
Two atria: collection chambers
Two ventricles: thick walled pumps
Four valves: prevent backflow, flaps of connective tissue
AV Atrioventricular valves between each atrium and ventricle
SL Semilunar valves between ventricles and departing arteries
(when they slam closed they create heart sounds)
Sinoatrial
node
Atrioventricular
node
Conducting
fibers
Right
atrium
Right
ventricle
Left
atrium
Left
ventricle
The Heart: Control
-Cardiac cells: myogenic (self-excitable) in syncytium
Controlled by sinoatrial (SA) node, the pacemaker.
1st: Atrial electrical wave -> two atria contract
2nd: wave at atrioventricular (AV) node, delayed 0.1s
3rd: Common bundle & Purkinje fibers to Ventricles
-Regulation of SA and AV nodes:
Nervous: Sympathetic : Parasympathetic (vagus)
Hormones: Epi, ACh, Temperature, Exercise, pH
these also effect blood vessels (constrict or relax PR)
Sinoatrial
node
Atrioventricular
node
Conducting
fibers
Right
atrium
Right
ventricle
Left
atrium
Left
ventricle
SA node
activates
atria
AV
node
delay
Electrical
activity
in atria
0
Electrical
activity
in ventricles
0.1
Ventricles recover
0.2
0.3
Time (seconds)
0.4
0.5
Be the HEART and Depolarize
The Heart: Function
-Function pump blood; create pressure gradient.
Contraction and relaxation =cardiac cycle
During systole, muscle contracts and pumps
During diastole, muscle relaxes and chambers fill
Sounds “Lub” AV, “Dub” SL, “ssssshh” murmur.
QuickTime™ and a
Animation decompressor
are needed to see this picture.
QuickTime™ and a
Sorenson Video decompressor
are needed to see this picture.
QuickTime™ and a
Sorenson Video decompressor
are needed to see this picture.
QuickTime™ and a
Sorenson Video decompressor
are needed to see this picture.
QuickTime™ and a
Sorenson Video decompressor
are needed to see this picture.
Properties of the Heart that
Clinicians Examine
•
•
•
•
•
Size/Volume
Structure
Pressure Generation
Electrical Activity
Efficiency
Properties of the Heart that
Clinicians Examine
• Size/Volume
• Structure
• Pressure Generation
• Electrical Activity
• Efficiency
Size/Volume
Left Atrium
Right Atrium
Left Ventricle
Right Ventricle
When Things Aren’t Quite Right
After some time with this Atrial
Septal Defect - how would the
Chest X-ray change?
Hypertension is similar
Left Ventricle
Blood returning to the mammalian
heart in a pulmonary vein drains first
into the
a)vena cava.
b)left atrium.
c)right atrium.
d)left ventricle.
e)right ventricle.
27
Compared with the interstitial fluid
that bathes active muscle cells, blood
reaching these cells in arteries has a
a)higher PO2.
b)higher PCO2.
c)greater bicarbonate
concentration.
d)lower pH.
e)lower osmotic pressure.
28
When you hold your breath, which of
the following blood gas changes first
leads to the urge to breathe?
a)rising O2
b)falling O2
c)rising CO2
d)falling CO2
e)rising CO2 and falling O2
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