Chapter 18.7 Anatomy of the Blood and Lymphatic Vessels-Cardiovascular System Flashcards
What do Arteries and Arterioles need to be able to do?
expand with high pressure caused by contraction of heart
What do Arteries and Arterioles contain?
elastic layer and smooth muscle layer
Why do Vasoconstriction and vasodilation need for arteries and arterioles?
to regulate blood flow
What are Arteries and Arterioles controlled by?
ANS
What are veins and venules?
They are Vessels that return blood to heart
Why are walls of veins thinner than arteries?
because blood pressure is lower than that in arteries
What are unidirectional valves that veins have do?
They prevent backward flow of blood
What does skeletal pump do as muscle contract?
they apply pressure to veins that run between them
What does unidirectional valves control
direction of flow
What do one-way valves that veins have do?
They prevent backflow of blood
What are Varicose veins?
veins that have become dilated and twisted because of incompetent (leaky) valves
What percentage of adult go through varicose veins and where are they usually?
About 15% of adults suffer from this condition, mainly in lower limbs
What are Capillaries ?
where oxygen and food molecules are transferred from blood to body’s cells
What are capilaries only composed of?
endothelial cells
How close are most cells in body to capillary?
no more than 100 mm from a capillary
Where is blood pressure far lower in? capilaries or arteries?
Blood pressure is far lower in capillaries than in arteries
Based on physiological needs of tissues, how would Capillary beds regulate?
Capillary beds can be opened or closed with precapillary sphincters
How much fluid does body lose each day due to capillary exchange and why does this occur?
body loses about 4 litres of fluid each day and this is because cardiovascular system is very leaky
What should body use to collect and recycle fluid
Body should use second circulatory system = lymphatic system
What is interstitial fluid compared to lymph?
it is fluid in between cells
What is lymph compared to interstitial fluid?
fluid in between cells that enters lymphatic vessels
Where does lymph ultimately re-enter?
bloodstream
What is Peristalsis?
smooth muscle in lymphatic vessel walls exerts slow contractions
What does Valves prevent?
backflow of lymph
