Circulatory System Flashcards
What are the functions of the circulatory system
maintain conc grad, enable hormone signalling, mediate inflammatory response
What is part of the circulatory system
heart, blood and blood vessels
Describe the circuits of circulatory flow
systemic, pulmonary
Describe the systemic circuit
moves to heart, parallel pathways
Describe the pulmonary circuit
single pathway from right to left side of heart
What system do arteries form
distribution system
What system do arteries and venules form
diffusion and filtration systems
What system do veins form
collection system
Describe the tunica interna
endothelial cells rest on basement membrane
Describe the tunica media
combination of smooth muscle cells, elastic fibres
Describe the tunica externa
collagen fibres, elastic fibres, external layer
What innervates arteries
efferent nerves of sympathetic nervous system
Describe the correlation between artery walls and lumen size
artery wall thickness increases as lumen size decreases
Describe the characteristics of the aorta
high compliance, elastic recoil
How are smooth muscle cells arranged in medium sized arteries
circumferentially
What are medium sized arteries capable of
greater vasoconstriction and vasodilation
What are arterioles
small arteries - lots of smooth muscle cells
What do arterioles enable
regulation of blood flow into capillary networks
When does vasoconstriction of arterioles occur
when noradrenaline is released from sympathetic nerve
What is the effect of noradrenaline on arterioles
activates a1 adrenoreceptors
What causes vasodilation of arterioles
reduced release of noradrenaline
Describe capillaries
small terminal vessels
Where are sinusoidal capillaries located
bone marrow
What are capillaries composed of
endothelial cells, basement membrane
What are capillaries essential for
exchange of substances between blood and interstitial fluid
What are the three groups of capillaries
continuous, fenestrated, sinusoidal
Describe venules
porous
What is the function of venules
exchange site for nutrients and waste
What do the thin walls of venules allow
expansion, blood reservoirs
Describe muscular venules
thin smooth muscle cell layer
Describe veins
less muscular and elastic
What is the function of veins
store blood
Describe large veins
more muscular than venules and smaller veins
What can defective leaky valves in veins cause
back flow, varicose veins
What do large veins possess
valves
What are the functions of the lymphatic system
drain excess interstitial fluid, transport dietary lipids, immune response
How is the lymph formed
excess fluid and protein enters lymphatic vessels
What is a lymph oedema
damage to lymphatic system
What are the symptoms of a lymph oedema
ineffective drainage, excessive fluid build up
