Circulatory system Flashcards
why is a circulatory system necessary in mammals ?
-mammals have a small surface area to volume ratio
-circulatory system is necessary to transport materials to and from the large volume of metabolically active tissues
what type of circulation do mammals have?
-a double circulatory system
what is double circulation ?
-blood passes through the heart twice in one complete circuit of the body
what are the two circuits that blood passes through?
-pulmonary circuit
-systemic circuit
where does the pulmonary circuit supply blood to?
-the lungs
where does the systemic circuit supply blood to?
-organs and the rest of the body
what type of pressure is blood flowing in the pulmonary circulation and why?
-low pressure
-to allow time for gas exchange to occur in the lungs
what type of pressure is blood flowing in the systemic circulation and why?
-high pressure
-ensure that blood is pumped to all organs do deliver sufficient metabolites and remove waste
what are the three main types of blood vessels ?
-artery
-vein
-capillary
what is the job of each of the blood vessels?
-arteries carry oxygenated blood away from the heart at a high pressure to deliver to organs
-veins carry deoxygenated blood back to the heart and they contain valves
-capillaries connect arteries to veins to allow for the diffusion of gases
what do arteries subdivide into? what about veins?
-arteries sub divide into arterioles
-veins sub divide into venules
-arteries, arterioles, capillaries, venules, veins
how many layers of walls do arteries and veins have? what are each of these wall and what are they made out of ?
-3
-the inner layer is made of squamous endothelium
-the middle layer is made of smooth muscle and elastic fibres
-the tough outer layer is made of fibrous tissue
what is the structure of an artery ?
-thick wall
-thin outer layer of fibrous muscle
-thick middle of smooth muscle and elastic fibres
-inner squamous endothelium layer
-narrow lumen
-round shape
what is the structure of a vein?
-thin wall
-thin outer layer of fibrous muscle
-thin middle with some muscle and little elastic fibres
-inner layer squamous endothelium
-large lumen
-valves
-irregular oval shape
what is the structure of capillaries ?
-microscopic vessels
-one cell thick walls
-made of squamous endothelium
what is the blood pressure like in each of the blood vessels?
-arteries have a high blood pressure and have a pulse
-veins have a low blood pressure
-capillaries have a reduction in pressure across the capillary network
what are the adaptations of arteries
-elastic middle allows artery to stretch as blood pulses through
-as the elastic tissue recoils it helps to push blood along the artery
-muscle tissue in the middle layer can help with vasoconstriction and vasodilation which provides more or less blood to an organ depending on metabolic needs
what are the adaptations of veins
-large lumen offers little resistance to blood flow
-valves prevent the backflow of blood
-outer fibrous tissue offers protection
-inner squamous endothelium creates smooth surface which reduces friction
what are the adaptations of capillaries
-found in an extensive network which creates a large surface area for diffusion of materials
-thin permeable walls facilitates exchange of materials and provides a short diffusion distance
-red blood cells are close to the capillary walls which also reduces diffusion distance
what are the only veins that carry oxygenated blood ?
-the pulmonary veins carry oxygenated blood to the heart and the pulmonary artery carries deoxygenated blood away from the heart to the lungs
what are the vessels called that carry blood to and from the liver, intestines and kidneys?
-liver= hepatic artery/ vein
-intestines are connected to the liver via the hepatic portal vein
-kidneys= renal artery/ vein
what is the function of the heart?
-pumping blood around the body
the heart is myogenic what does this mean?
-the heart muscles can generate its own electrical impulses and so can contract independently
what is the job of the septum in the heart?
-it separates the left and right sides
what is the top and bottom chambers of the heart called?
-top= atrium
-bottom= ventricles
which ventricle wall is thicker the left or the right?
-the left is thicker because this is the chamber that is connected to the aorta and so needs to be able to pump at a high pressure
how does the heart maintain a high metabolic rate?
-coronary arteries supply oxygen and glucose to maintain metabolism
-the heart is also continually contracting
what is the job of the vena cava?
-returns blood from the body
what is the job of the right atrium?
-receives blood from the rest of the body
what does the right ventricle do?
-pumps blood to the lungs
what does the pulmonary artery do?
-carries deoxygenated blood to the lungs
what does the pulmonary vein do?
-carries oxygenated blood to the heart
what does the left atrium do?
-receives blood from the lungs
what does the left ventricle do?
-has thick muscular wall so it can pump blood around the body
what does the aorta do?
-carries oxygenated blood from the lungs
what do valves do?
-prevent the backflow of blood
