Lecture 16, 23 Oct 2003 Chapter 12, Circulation Vertebrate Physiology ECOL 437
Lecture 18, 30 Oct 2003 Chapter 12, Circulation (con’t) Chapter 13, Respiration, Gas Exchange,...
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Transcript of Lecture 18, 30 Oct 2003 Chapter 12, Circulation (con’t) Chapter 13, Respiration, Gas Exchange,...
Lecture 18, 30 Oct 2003Chapter 12, Circulation (con’t)
Chapter 13, Respiration, Gas Exchange, Acid-Base Balance
Vertebrate PhysiologyECOL 437
University of ArizonaFall 2003
instr: Kevin Boninet.a.: Bret Pasch
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Vertebrate Physiology 437
1. Circulation (CH12)
2. Blood-Gas Chemistry (CH13)
3. Announcements...
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14-34, Vander 2001
See (12-32)
Thursday, 30 October -- the ARLDN's 2003 Edmund A. ArbasLecturer, Prof. Peter M. Narins from the Dept. of Physiological Science atUCLA, will give his public lecture in Economics 110 at 4:00 pm. The titleof his lecture is "Science on Seven: Adventures of an ExpeditionaryBiologist."
Narins is renowned for his elegant work on hearing and auditorycommunication in frogs and is a world leader in neuroethology, animalbehavior, and auditory neurophysiology. He is also a legendary fieldbiologist, having led 39 expeditions to remote and exotic field sites onseven continents over the last quarter century. A masterfully clear and very entertaining speaker, he has won the most prestigious teaching awards atUCLA.
2b
Name that student:
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Drew StasiakChem Minor
Elena CostinMCB
Gabriel ReinhardtMCB
Hemodynamics in Vessels
Vander 2001
14-11, Vander 2001
Flow depends primarily on pressure gradient and resistance
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Hemodynamics- Poiseuille’s Law:
Flow rate
8L
Q = (P1 – P2)r4
Pressure Gradient
radius4
length
viscosity
Use to approximate flow
Small change in radius large change in flow rate
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Hemodynamics- From Poiseuille’s Law:
Resistance
Q
R = (P1 – P2)
Pressure Gradient
radius4
Flow rate
viscosity
Small change in radius large change resistance
= 8L
r4
length
Modifiable if vessel distensible under pressure
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(12-25)
Summed resistance reduces pressure…
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(12-23)
Total Flow Rate same all along Circulatory System
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River
Lake
River
(12-24)
Shapes of curves slightly different because of RBCs (viscosity) and fact that they tend to flow in middle of lumen
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Peripheral Circulation
- Endothelium lining vessels- Middle layer with smooth muscle (esp. arteries)- Outer fibrous layer
Capillaries with ~ only Endothelium
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(12-26)
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Peripheral Circulation
Compliance vs. Elasticity
~ Veins vs. Arteries
Volume Reservoir vs. Pressure Reservoir
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Volume Reservoir vs. Pressure Reservoir
14-34, Vander 2001
(12-27)~Constant P and Q at Capillaries!
See (12-32)
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Venous System
- low pressure (11 mm Hg or less)
- thin walled veins with less muscle
- more compliant and less elastic
- valves
- blood moved by skeletal muscle (and smooth)- breathing creates vacuum (low pressure) in chest to aid blood flow to heart
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Microcirculation
- endothelium in capillaries is permeable1. continuous
2. Fenestrated (kidney, gut)
3. Sinusoidal (liver, bone)
Less permeable
- Movement across walls, between walls, in vesicles
More permeable
- Bulk Flow…
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Bulk Flow…
Fluid Pressurevs.Osmotic Pressure
(12-38)
Filtration > UptakeLymph System to return excess fluid
Faster than diffusion
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Bulk Flow… - Edema
- No RBCs; therefore not red
Lymph System
- Starvation
- Lungs
- Kidneys
- Drains interstitial spaces- has valves and smooth musculature
- empties into thoracic duct at vena cavae- transport system for large hormones and fats into blood stream- filariasis, elephantiasis- Reptiles and Amphibians with lymph hearts
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Giraffe example pgs. 504-505
Why does blood in the lower extremities of aquatic
organisms not pool as it may do in legs of humans, giraffes,
etc.?
FISH:
Blood tends to pool in tail b/c inertia and compression waves when swimming
-Veins in middle of body-Accessory caudal (tail) heart in some species
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Circulatory System Regulation1. Feed Brain and Heart First
2. Next Feed Tissues in Need3. Maintain volume, prevent edema, etc.Baroreceptors
Chemoreceptors
Mechanoreceptors
Thermoreceptors
Info. integrated at Medullary Cardiovascular Center medulla oblongata and
pons
Depressor Center Parasympathetic Effectors
Pressor Center Sympathetic Effectors
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Circulatory System RegulationBaroreceptors increase AP firing rate when BP increases
Sensed at carotid sinus, aortic arch, subclavian, common carotid, pulmonary
Usually leads to Sympathetic suppression to decrease BP
(12-43)
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Circulatory System Regulation
Arterial Chemoreceptors in carotid and aortic bodies(More details when discuss
ventilation)
e.g., low O2, high CO2, low pH leads to bradycardia and peripheral vasoconstriction (diving and not inflating lungs)
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What about when not diving?
Circulatory System Regulation
Cardiac Mechanoreceptors and Chemoreceptors
Alter heart rate AND blood volume
e.g., ANP (Atrial Natruiretic Peptide) released in response to stretch
- leads to increased Na+ excretion and therefore greater urine output
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Circulatory System RegulationExtrinsic vs. Local Control
Neuronal or HormonalMost arterioles with sympathetic innervationAlso respond to circulating catecholamines:-At high levels, alpha adrenoreceptors are stimulated vasoconstriction (to increase BP)
-At low levels, beta2 adrenoreceptors are stimulated vasodilation (to increase flow to tissue)-Response depends on tissue type, receptor type(s), level of catecholamines (epi, norepi), etc.
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Circulatory System RegulationExtrinsic vs. Local Control
Neuronal or HormonalNeuropeptide Y
- Acts by reducing IP3 levels
-decreases coronary blood flow-decreases heart contractility
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Circulatory System RegulationExtrinsic vs. Local Control
stretch
temp.O2
CO2
pHadenosineK+
Decreased O2 levels with opposite effect in lungs
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Circulatory System RegulationExtrinsic vs. Local Control
(12-45)
-Vasodilation-Relaxation
-Viagra acts by blocking breakdown of cGMP
NO (nitric oxide)
Released from vascular endothelium:
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Circulatory System RegulationExtrinsic vs. Local Control
-Vasodilation
Histamine
Released in response to injury of connective tissue and leukocytes:
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Chapter 13
Gas exchange
Acid-base balance
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Gas composition in air O CO N
% of dry air 21 0.03 78
pp at 760 mm Hg 159 0.23 594
380mmHg (at 6000m) 79.6 0.11 297
Solubility in water (ml/L) 34 1,019 17
2 2 2
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End
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