Unit II: Transport Cardiovascular System II
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Transcript of Unit II: Transport Cardiovascular System II
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Unit II: TransportCardiovascular System II
Chapter 18: pp 657-671
Chapter 17: pp 595-619
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• Amount ejected by ventricle in 1 minute
• Cardiac reserve: with fitness, with disease
Maximum for trained athletesexercising at peak levels
Normal rangeof cardiacoutput duringheavy exercise
Average resting cardiac output
Some forms ofheart failure
Cardiacoutput
(L/min)
0
5
10
15
20
25
30
35
40
HR: 75 beats/min SV: 80 mL/beat CO: 6000 mL/min=x
Cardiac Output (CO)
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Cardiac Output (CO)
Body temperature
ANSHormones
Muscular contractions
Blood volume
Peripheral blood flow
Venous return ↑ = ↑ SV
EDV
Influences the efficiency of contractions
ESV
↑ Filling time = ↑ ESV
↑ afterload = ↓ pumping efficiencyand ↑ESV
Vasodilation
Vasoconstriction
↑ contractility = ↓ ESV
ANS Hormones
STROKE VOLUME (SV) = EDV – ESVHEART RATE (HR)
CARDIAC OUTPUT (CO) = HR x SV
Factors affecting heart rate (HR) Factors affecting stroke volume (SV)
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Heart Rate
• Pulse:
– infants have HR of 120 bpm or more
– young adult females avg. 72 - 80 bpm
– young adult males avg. 64 to 72 bpm
– HR rises again in the elderly
• Tachycardia:
– stress, anxiety, drugs, heart disease or body temp.
• Bradycardia:
– in sleep and endurance trained athletes
Bradycardia Tachycardia
Normal range ofresting heart
rates
60 bpm 100 bpm
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• Tunica interna: repels blood cells and platelets
– simple squamous endothelium overlying a basement membrane
• Tunica media: smooth muscle, collagen, elastic tissue
• Tunica externa: loose connective tissue
Tunica externa
Tunica media
Tunica intima
Endothelium
Smooth muscle
Vein
The structureof the wall ofa vein
LM x 60
Vein
Artery
Anatomy of Blood Vessels
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Arteries
3 Categories by Size:• Conducting (elastic) arteries
– pulmonary, aorta & common carotid
• Distributing (muscular) arteries– Brachial, femoral and splenic
• Resistance (small) arteries
– Arterioles
Capillaries
Arterioles
Distributing/Muscular Arteries
Conducting/Elastic Arteries
Internal elastic layerTunica intimaTunica mediaTunica externa
Tunica intimaTunica mediaTunica externa
Smooth muscle cellsEndothelium
Endothelial cells
Basal lamina
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Veins
• thinner tunica media
• 3 Categories by Size:
– Small veins
• venules
– Medium veins
• Radial, ulnar veins
• valves prevent backflow
– Large veins
– Vena cava, pulmonary, jugular
Large Veins
Medium-sized Veins
Venules
Capillaries
Basal lamina
Endothelial cells
Pores
EndotheliumTunica externa
Tunica externaTunica mediaTunica intima
Tunica externaTunica mediaTunica intima
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Filtration Predominates
No Net Movement
Reabsorption Predominates
24 L/day 20.4 L/day
ArterioleVenule KEY
CHP (Capillaryhydrostatic pressure)BCOP (Blood colloidosmotic pressure)NFP (Net filtrationpressure)
35 25 25 25 2518mm mmmmmmmmmmHg HgHgHgHgHg
NFP = +10 mm Hg NFP = 0
NFP = –7 mm Hg
Capillary
CHP > BCOP CHP = BCOP BCOP > CHP
Capillaries• Smallest blood vessels
• Only vessels that allow exchange of materials
• Anatomy:
– simple squamous endothelium with basement membrane
– walls: 0.2-0.4 µm thick; lumen: 5-9 µm diameter
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Capillary Beds
•Metarterioles
– connect arterioles to capillaries
•Thoroughfare channel
– connect capillaries to venule
•Perfusion
– precapillary sphincter
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Gap betweenadjacent cells
Basal laminaEndothelial cell
Nucleus
Types of Capillaries
• Continuous – (4nm)
– endothelial cells have tight junctions
• Fenestrated – (20-100nm)
– organs that require rapid absorption or filtration
– Ex. kidneys, small intestine
• Sinusoids – (30-40nm)
Basal laminaEndothelial cell
Nucleus
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Circulatory Routes• Most common route
– heart arteries arterioles capillaries venules veins heart
• Portal system
• hypothalamus – pituitary
• in kidneys
• intestines – liver
• Anastomoses
• Arteriovenous anastomosis
• Ears, fingers, toes, palms
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Blood Pressure
• Force that blood exerts against a vessel wall
• Measured at brachial artery of arm
• Systolic pressure and diastolic pressure
• Normal value, young adult: 120/75 mm Hg
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Blood Pressure
• Importance of arterial elasticity
– expansion and recoil maintains steady flow of blood throughout cardiac cycle, smoothes out pressure fluctuations and stress on small arteries
• BP rises with age: arteries less distensible
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Leastresistance,greatest flowat center
Greatest resistance,slowest flow near surfaces
Internal surface area = 2
Internal surface area = 1
Resistance to flow = 1Flow = 1
Resistance to flow = 2Flow = ½
Blood Pressure
BP determined by:
• cardiac output
• blood volume
• peripheral resistance
– Blood viscosity
– Vessel length
– Vessel radius (vasomotion)
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R. Common carotidR. Subclavian
Brachiocephalictrunk
AxillaryAscending aorta
Brachial
Radial
Ulnar
Femoral
Aortic archDescending aortaDiaphragm
Renal
Common iliac
Arteries
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Veins
External jugularInternal jugularSubclavian
Brachiocephalic
AxillaryBrachial
Radial
Ulnar
Femoral
Superior vena cava
Diaphragm
Inferior vena cavaRenal
Common iliac
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Fetal Development and Circulation
• Fetus = from 8 weeks until birth
• Fetal circulation– umbilical-placental circuit– circulatory shunts
• ductus venosus• foramen ovale• ductus arteriosus
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Foramen ovale
Ductus arteriosus
Pulmonarytrunk
Inferior vena cava
Ductus venosus
Umbilical arteries
Umbilical vein
Umbilicalcord
Placenta
Aorta
Liver
Blood Circulation Before Birth