announcements 6 vfs passed! we will have “lectures” after exam friday 17 th last day for wet...
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Announcements• 6 VFs passed!• We will have “lectures” after exam• Friday 17th last day for wet experiments
–can appeal for one more experiment• Thursday 30th last day of VFs
– show me TA practice receipts...
3
Gas Exchange
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CO2 from tissue
CO2 + H2O HCO3– + H+
Cl–
HCO3–
Red blood cell
Plasma
Transported in plasma
Carbonic anhydrase
Binds to hemoglobin
At the tissue (the capillary bed by active muscle)
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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)
The Heart: Structure
-Structure four chambers and two-layered sac (pericardium).
Two atria: collection chambers
Two ventricles: thick walled pumps
Sinoatrial node
Atrioventricular node
Conducting fibers
Left ventricle
Left atriumRight
atrium
Right ventricle
-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)
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
Sinoatrial node
Atrioventricular node
Conducting fibers
Left ventricle
Left atriumRight
atrium
Right ventricle
0 0.1
Electrical activity in atria
SA node activates atria
AV node delay
Electrical activity
in ventricles
Ventricles recover
0.2
Time (seconds)
0.3 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.
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QuickTime™ and aSorenson Video decompressorare needed to see this picture.
QuickTime™ and aSorenson Video decompressorare needed to see this picture.
QuickTime™ and aSorenson Video decompressorare needed to see this picture.
QuickTime™ and aSorenson Video decompressorare 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
Right Atrium
Right Ventricle
Left Atrium
Left 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
27
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.
28
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.
29
When you hold your breath, which of the following blood gas changes first leads to the urge to
breathe?
a)rising O2b)falling O2c)rising CO2d)falling CO2e)rising CO2 and falling O2