Circulatory system

Question 1

why is a circulatory system necessary in mammals ?

Answer 1

-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

Question 2

what type of circulation do mammals have?

Answer 2

-a double circulatory system

Question 3

what is double circulation ?

Answer 3

-blood passes through the heart twice in one complete circuit of the body

Question 4

what are the two circuits that blood passes through?

Answer 4

-pulmonary circuit
-systemic circuit

Question 5

where does the pulmonary circuit supply blood to?

Answer 5

-the lungs

Question 6

where does the systemic circuit supply blood to?

Answer 6

-organs and the rest of the body

Question 7

what type of pressure is blood flowing in the pulmonary circulation and why?

Answer 7

-low pressure
-to allow time for gas exchange to occur in the lungs

Question 8

what type of pressure is blood flowing in the systemic circulation and why?

Answer 8

-high pressure
-ensure that blood is pumped to all organs do deliver sufficient metabolites and remove waste

Question 9

what are the three main types of blood vessels ?

Answer 9

-artery
-vein
-capillary

Question 10

what is the job of each of the blood vessels?

Answer 10

-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

Question 11

what do arteries subdivide into? what about veins?

Answer 11

-arteries sub divide into arterioles
-veins sub divide into venules
-arteries, arterioles, capillaries, venules, veins

Question 12

how many layers of walls do arteries and veins have? what are each of these wall and what are they made out of ?

Answer 12

-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

Question 13

what is the structure of an artery ?

Answer 13

-thick wall
-thin outer layer of fibrous muscle
-thick middle of smooth muscle and elastic fibres
-inner squamous endothelium layer
-narrow lumen
-round shape

Question 14

what is the structure of a vein?

Answer 14

-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

Question 15

what is the structure of capillaries ?

Answer 15

-microscopic vessels
-one cell thick walls
-made of squamous endothelium

Question 16

what is the blood pressure like in each of the blood vessels?

Answer 16

-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

Question 17

what are the adaptations of arteries

Answer 17

-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

Question 18

what are the adaptations of veins

Answer 18

-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

Question 19

what are the adaptations of capillaries

Answer 19

-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

Question 20

what are the only veins that carry oxygenated blood ?

Answer 20

-the pulmonary veins carry oxygenated blood to the heart and the pulmonary artery carries deoxygenated blood away from the heart to the lungs

Question 21

what are the vessels called that carry blood to and from the liver, intestines and kidneys?

Answer 21

-liver= hepatic artery/ vein
-intestines are connected to the liver via the hepatic portal vein
-kidneys= renal artery/ vein

Question 22

what is the function of the heart?

Answer 22

-pumping blood around the body

Question 23

the heart is myogenic what does this mean?

Answer 23

-the heart muscles can generate its own electrical impulses and so can contract independently

Question 24

what is the job of the septum in the heart?

Answer 24

-it separates the left and right sides

Question 25

what is the top and bottom chambers of the heart called?

Answer 25

-top= atrium
-bottom= ventricles

Question 26

which ventricle wall is thicker the left or the right?

Answer 26

-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

Question 27

how does the heart maintain a high metabolic rate?

Answer 27

-coronary arteries supply oxygen and glucose to maintain metabolism
-the heart is also continually contracting

Question 28

what is the job of the vena cava?

Answer 28

-returns blood from the body

Question 29

what is the job of the right atrium?

Answer 29

-receives blood from the rest of the body

Question 30

what does the right ventricle do?

Answer 30

-pumps blood to the lungs

Question 31

what does the pulmonary artery do?

Answer 31

-carries deoxygenated blood to the lungs

Question 32

what does the pulmonary vein do?

Answer 32

-carries oxygenated blood to the heart

Question 33

what does the left atrium do?

Answer 33

-receives blood from the lungs

Question 34

what does the left ventricle do?

Answer 34

-has thick muscular wall so it can pump blood around the body

Question 35

what does the aorta do?

Answer 35

-carries oxygenated blood from the lungs

Question 36

what do valves do?

Answer 36

-prevent the backflow of blood