437lect19 ch20-24 2005
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Lecture 19, 25 Oct 2005Chapter 20-24
Circulation, Oxygen and Carbon Dioxide Transport
Vertebrate PhysiologyECOL 437 (aka MCB 437, VetSci 437)
University of ArizonaFall 2005
instr: Kevin Boninet.a.: Kristen Potter
2
1. Circulatory System 2. Respiration
Text:Chapters 23 & 24(skip the invert material if you like)Then chapters 21 & 22(skim Chapter 20)
14-25, Vander 2001
3Knut Schmidt_Nielsen 1997
Gravityand BP
4
(Eckert, 12-4)To
Lungs
From body
To BodyviaAORTA
FromLungs
Mammalian Heart
Chordae tendinae
5
(Eckert, 12-8)
(Q,R,S masks atrial repolarization)6
(Eckert, 12-8)
P
Q, R, S
T
2
714-25, Vander 2001
WiggersDiagram
Valves open/close where pressure curves cross
760 mmHg = 1 atm= 9.8 m blood
1:2
8
Sherwood 1997
Atrial Kick
Heart filled ~same with increased HR
9
Sherwood 1997
Vander 2001
Frank-Starling Curve
Systole = Ventricular Emptying
Diastole = Ventricular Filling (rest)
10
Cardiac Output:
CO = cardiac output (ml/min from 1 ventricle)
SV = stroke volume (ml/beat from 1 ventricle)
= EDV – ESV (end-diastolic – end-systolic volume)
HR = heart rate (beats/min)
CO = HR x SV
- Heart can utilize different types of energy sources (unlike brain)
MABP = CO x TPRMABP = DP + 1/3(SP-DP)
11
Knut Schmidt-Nielsen 1997
Exercise
OxygenConsumptionX 20
Cardiac Output 6x
12
Cardiac Output Control
Sympathetic speeds heart rateand increases contractility
1. Norepinephrine binds to beta1 adrenergic receptors
2. Increases cAMP levels and phosphorylation
3. Activates cation channels (Na+) and increases HR
4. Epi and Norepi activate alpha and beta1adrenoreceptors which increase contractility and rate of signal conduction across heart
3
13Vander 2001
How increase contractility?
More Ca2+
14
HR control
Parasympathetic vs. Sympathetic
(Eckert, 12-5)
15
HR control
Parasympathetic slows heart rate
-Innervate Atria (Vagus nerve = Xth cranial nerve)
-Cholinergic (ACh)
-Alter SA node pacemaker potential by ⇑ K+ permeability
⇓ Ca2+ permeability
Parasympathetic innervation of AV node slows passage of signal between atria and ventricles
16
Peripheral Circulation
- Endothelium lining vessels- Middle layer with smooth muscle (esp. arteries)- Outer fibrous layer
Capillaries with ~ only Endothelium
17
(Eckert,12-26)
18
Peripheral Circulation
Compliance vs. Elasticity
~ Veins vs. Arteries
Volume Reservoir vs. Pressure Reservoir
4
19
Volume Reservoir vs. Pressure Reservoir
14-34, Vander 2001
(Eckert, 12-27)~Constant P and Q at Capillaries! 20
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
21
Microcirculation
- endothelium in capillaries is permeable
1. continuous
2. Fenestrated (kidney, gut)
3. Sinusoidal (liver, bone)
Less permeable
- Movement across walls, between walls, in vesicles
More permeable
- Bulk Flow…
22
Bulk Flow…
Fluid Pressurevs.Osmotic Pressure
(Eckert,12-38)
Filtration > Uptake
Lymph System to return excess fluid
Faster than diffusion
23
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
24
Circulatory System Regulation
1. Feed Brain and Heart First2. Next Feed Tissues in Need3. Maintain volume, prevent edema, etc.
BaroreceptorsChemoreceptorsMechanoreceptorsThermoreceptors
Info. integrated at Medullary Cardiovascular Centermedulla oblongata and pons
Depressor Center Parasympathetic Effectors
Pressor Center Sympathetic Effectors
5
25
Circulatory System Regulation
Baroreceptors 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
(Eckert, 12-43)
26
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)
What about when not diving?
27
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+ excretionand therefore greater urine output
28
Circulatory System Regulation
Extrinsic vs. Local Control
Neuronal or Hormonal
Most arterioles with sympathetic innervation
Also 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.
29
Circulatory System Regulation
Extrinsic vs. Local Control
stretch
temp.O2CO2pHadenosineK+
Decreased O2 levels with opposite effect in lungs
30
Circulatory System Regulation
Extrinsic vs. Local Control
(Eckert, 12-45)
-Vasodilation-Relaxation
-Viagra acts by blocking breakdown of cGMP
NO (nitric oxide)
Released fromvascular endothelium:
6
31
Circulatory System Regulation
Extrinsic vs. Local Control
-Vasodilation
Histamine
Released in response to injury of connective tissue and leukocytes:
32
(Hill et al., 2004Fig 23.11)
33
Hemodynamics in Vessels
Vander 2001
14-11, Vander 2001
Flow depends primarily on pressure gradient and resistance
34
Hemodynamics
- Poiseuille’s Law:
Flow rate
8Lη
Q = (P1 – P2)πr4
Pressure Gradient
radius4
length viscosity
Use to approximate flow
Small change in radius large change in flow rate
35
Hemodynamics
- From Poiseuille’s Law:
Resistance
Q
R = (P1 – P2)
Pressure Gradient
radius4
Flow rate
viscosity
Small change in radius large change resistance
= 8Lη
πr4
length
Modifiable if vessel distensible under pressure36
(Eckert, 12-25)
Summed resistance reduces pressure…
7
37
(Eckert, 12-23)Total Flow Rate same all along Circulatory System
River
Lake
River
38(Eckert, 12-24)
Shapes of curves slightly different because of RBCs (viscosity)
39
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
40Hill et al., 2004, Fig. 21.1
41
Lung Anatomy
Nonrespiratory-Trachea ->-Bronchi ->-Bronchioles ->
Respiratory-Terminal bronchioles ->-Respiratory bronchioles ->-Alveoli
-Cilia and Mucus
(Eckert, 13-21)
42
(Eckert, 13-22)
-Gas Diffusion Barriers:
8
43Hill et al., 2004, Fig. 20.4 44Hill et al., 2004, Fig. 20.4
45
Lung Ventilation
-Small mammals with greater per gram O2 needs and therefore greater per gram respiratory surface area
-Dead Space (anatomic and physiological)
Swan (Eckert, 13-24)
46(Eckert, 13-23)
Lung Ventilation
47
Mammalian Ventilation
-lungs are elastic bags
-suspended in pleural cavity within thoracic cage (ribs and diaphragm define, fluid lines)
-low volume pleural “space” between lung and thoracic wall
-negative pressure to inflate lungs (increase volume)
-pneumothorax
48
Mammalian Ventilation (Eckert, 13-28)
9
49
Mammalian Ventilation
(Eckert, 13-30)
-expiration usually passive
50Knut Schmidt_Nielsen 1997
MammalianLung
Alveoli and Capillaries
RBC (not to scale)
51Knut Schmidt_Nielsen 1997
Bird Lung Ventilation
Unidirectional!!
52
Bird Ventilation
(Eckert,13-32)
-lung volume changes very little, air sacs instead
Unidirectional
(Eckert,13-32)
53
Knut Schmidt_Nielsen 1972
Bird LungParabronchi
Mammal LungAlveoli
54
Frog Ventilation
(Eckert, 13-33)
-Positive pressure ventilation
1. Into mouth (buccal cavity)
2. Close nares, open glottis and force air into lungs by raising buccalfloor
10
55
Pulmonary Surfactants-Reduce liquid surface tension in alveoli
-Lipoproteins
-keep alveoli from getting stuck closedAtelectasis = collapsed lung
-premature babies may need artificial surfactant
-Allows for compliance and low-cost expansion of lung
56Knut Schmidt_Nielsen 1972
Panting Dogs?
57Knut Schmidt_Nielsen 1997
Fish Gill
58Hill et al., 2004, Fig. 20.3
59Hill et al., 2004, Fig. 21.10 60Knut Schmidt_Nielsen 1997
Relative Gill Surface Area in Fishes
11
61
Knut Schmidt_Nielsen 1997
Fish Gill
-breathing in water
-need much higher ventilation rate
-unidirectional
-pump water across gills (or ram ventilation)
62
GILLS – breathing in water
-need much higher ventilation rate
-unidirectional
-pump water across gills (or ram ventilation)
(Eckert, 13-40)
Floor of Mouth (buccal cavity)
63Knut Schmidt_Nielsen 1997
Lake Titicaca Frog
(Bolivian Navy; Peru-Bolivia border)
64
Hill et al., 2004, Fig. 21.8Gas ExchangeAcrossSkin
65Hill et al., 2004, Fig. 21.7 66Hill et al., 2004, Fig. 21.7
12
67
Rate and Depth Regulation -Primarily via CO2changes (central)
-O2 controls respiration in aquatic vertebrates
(Eckert, 13-46)
-Innervate MedullaryRespiratory Center(phrenic nerve to diaphragm and intercostals)
-Peripheral ChemoreceptorsPO2, PCO2, pH
-Emotions, sleep, light, temperature, speech, volition, etc.
68
Rate and Depth Regulation
(Eckert, 13-48)
-Central Chemoreceptors
Long term
69(Eckert, 13-45)
To Diaphragm
alveolar
70
Hering-Breuer reflex
-Stimulation of stretch receptors inhibits medullaryinspiratory center
-Prevent overinflation
-Ectotherms often breathe intermittently
71
(Eckert, 13-45)
1
1
2
2
To Diaphragm
72Hill et al., 2004, Fig. 20.5
Oxygen Partial Pressure
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