chapter 8- transport in animals Flashcards
what are the 5 types of blood vessels
arteries, arterioles, capillaries, venules and veins
what arteries dont carry oxygenated blood
placental and pulmonary
what is the role of elastic fibres in blood vessels
to stretch and recoil providing flexibility, made of elastin (fibrous protein)
blood vessels are not tissues
but organs
how can you tell the difference between arteries and veins on a micrograph
arteries retain their shape (remains circular) and have thick musclular wall and veins collapse a bit
what is the role of smooth muscle in blood vessels
to contract and relax to change the size of the lumen
what is the role of collagen in blood vessels
to provide structural support, maintain shape and lumen
what type of protein is collagen
fibrous
what is tissue
a group of the same cells or similar cells that provide the same function
what is the inner layer of an artiery and a vein called
endothelium of tunica intima
what is the layer called in veins and arteries where the elastic and collagenous fibres are
the connective tissue
what is the “middle layer” called in arteries and beins
tunica media
what is the outside layer called in arteries and veins
tunica adventitia/externa
what is the role of arteries
to carry blood at high pressure from the heart ventricles to the tissues of the body and the lungs
what are the 3 structures of arteries that are special
narrow lumen (relative to the wall thickness)
a thick wall containing an outer layer of collagen
an inner layer of muscle and elastic fibres
what is the function of a narrow lumen in arteries
to maintain a high blood pressure (80-120mmHG)
what is the function of a thick wall containing an outer layer of collagen in arteries
to prevent the artery from rupturing under the high pressure
what is the function of an inner layer of muscles and elastic fibres in arteries
to maintain pulse flow and controlling the diameter of the lumen, muscle also offers support to withstand pressure but not s much as collagen, the elastic fibres recoil to smooth out the pulse
explain how muscle fibres in arteries contorl the flow of blood
they help to form a rigid arterial wall that is capable of withstanding a high blood pressure without rupturing , can also contract to narrow the lumen which increases the pressure between pumps and helps to maintain bp throughout the cardiac cycle
what are pulses
when blood is expelled from the heart upon ventricular systole it flows through the arteries in repeated surges called pulses at a high pressure
what is the difference in the size of the lumens in arteries and veinss
arteries have a narrow lumen relative to the arterial wall and veins have a large lumen relative to the venular wall
why is the pressure in capillaries low
high pressure is dissipated by extensive branching of vessels and narrowing of the lumen
what are the 3 features of capillaries
vary narrow diameter
thin walls only 1 cell thick
walls are leaky (gaps in the endothelium)
what is the function of a very narrow diameter in capillaries
reduces blood flow (erythrocytes 7.5-8micrometres so they go single file) to allow time and sa for exchange between blood and surrounding cells to take place more efficiently.