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level: Blood vessels

Questions and Answers List

level questions: Blood vessels

QuestionAnswer
What are arteries- they carry blood from the heart to the rest of the body. - their walls are thick, muscular and have elastic tissue to stretch and recoil as the heart beats, which helps maintain the high pressure
What are arterioles- they have a layer of smooth muscle and less elastic tissue - this allows them to expand or contract, controlling the amount of blood flowing
What are capillaries- they are the smallest of the blood vessels - substances like glucose and oxygen are exchanged between cells and capillaries - their walls are one cell thick
What are venules- they join together to form veins
What are veins- they take blood back to the heart under low pressure - they have a wider lumen, less elastic and muscle tissue - they contain valves, which prevent back flow
How does blood flow through veins- blood flows with the help of contractions of the body muscles surrounding them
What is tissue fluid- the fluid that surrounds cells in tissue - it's made from substances that leaves the blood, for example: oxygen, water and nutrients
What does tissue fluid not contain- red blood cells and big proteins
How is tissue fluid formed from plasma- at the start of the capillary bed, the hydrostatic pressure inside the capillaries is greater than the hydrostatic pressure in the tissue fluid - this difference in hydrostatic pressure forces fluid out of the capillaries and into the spaces around the cells, forming tissue fluid - after tissue fluid leaves, the hydrostatic pressure reduces in the capillaries (being much lower at the end nearest to the venules)
Describe pressure filtration- as water leaves the capillaries, the concentration of plasma proteins in the capillaries increases, and the water potential decreases - plasma proteins in the capillaries generate a form of pressure called oncotic pressure - as water potential in the capillaries is lower than the tissue fluid, some water re-enters the capillaries from the tissue fluid at the venule end by osmosis
What are lymph vesselsexcess tissue fluid