heart elastic arteries muscular arteries arterioles capillaries veins 1) arteries (away) 2)...
TRANSCRIPT
Heart
ElasticArteries
MuscularArteries
Arterioles
Capillaries
Veins
1) Arteries (away)
2) Capillaries
3) Veins (toward)
Vessel Types:
Blood Vessel - Anatomy:
Venules
Structure and function - arterial system.
• 1/3 Conducting– The aorta & major branches
• Thickest• Largest• Elastic tubes
– Arteriosclerosis – Atherosclerosis (thickening) = turbulent flow– Balloon or burst (aneurysm)
Arterial System
• 2/3 Distributing – Delivery to organs – More active constriction – Less distensible
• Renal/urine - NFP
• 3/3 Arterioles• Flow determined by arteriole diameter• Constricted = bypassed• Dilated = local flow
Capillary Flow Control
• Precapillary sphincter– Cuff of smooth muscle fibers
» Open = flow
» Closed = shunt
Venous System.
– ↑ diameter– walls gradually ↔
• Venules→Veins– Larger lumens than corresponding
arteries» Reservoirs » 65% body’s blood supply
– VALVES for backflow» Most abundant in limbs - gravity
Vein Valve:
Blood Vessels:
Heart
Arteries Arterioles
Capillaries
VenulesVeins
• Carry blood away from heart
• Thick-walled:
• Smooth muscle / elastic fibers
• Withstand high pressure
Arteries
Blood Vessels:
Heart
Arteries Arterioles
Capillaries
VenulesVeins
• Control distribution of blood flow
• Smooth muscle expands / contracts
• Under hormone / NS control
Arterioles
Blood Vessels:
Heart
Arteries Arterioles
Capillaries
VenulesVeins
• Nutrients / waste exchanged with cells:
• Vessel wall one-cell thick
• Blood flow very slow
• Materials exit / enter via diffusion
Capillaries
Blood Vessels:
Heart
Arteries Arterioles
Capillaries
VenulesVeins
• Carry blood towards the heart
• Thin-walled; large diameter
• 65% blood volume in veins
Veins
Blood Vessels:
Heart
Arteries Arterioles
Capillaries
VenulesVeins
• Carry blood towards the heart
• Thin-walled; large diameter
• 65% blood volume in veins
Veins
• Low pressure system
• Blood return to heart assisted by:
1) Valves
2) Skeletal muscle pumps
Blood Vessels• Major arteries.
• Aorta – Ascending, arch, thoracic, abdominal
• Brachiocephalic• Ext. & Int. carotid• Pulmonary• Axillary, brachial, radial, ulnar • Femoral, post. tibial
– Major veins• Superior VC• Ext. & int. jugular• Pulmonary• Brachiocephalics• Internal & external iliac• Femoral..
Heart - Flow Through Heart:
Myocardial Infarction::
• Prolonged blockage of coronary vessels
Circuitsof the
CirculatorySystem:
Major branches - coronary
Coronary Vessels
Step 1:
• Depolarization wave initiated by sinoatrial node (SA Node)
Sequence of ExcitationHeart Physiology:
• Impulse to atrioventricular node (AV Node) where briefly delayed
Step 2:
Sequence of ExcitationHeart Physiology:
Step 3:
• Impulse to atrioventricular bundle and into bundle branches
Step 4:
• Impulse spreads throughout ventricles along Purkinje fibers
IntrinsicConduction
System:
Controlof heart rate: