2.5

Question 1

what does the Cardiovascular system consist of?

Answer 1

•heart
•blood
•blood vessels

Question 2

what is the function of the Cardiovascular system?

Answer 2

•to exchange substances between different structures in the body and to exchange substances between the body and its environment

Question 3

describe blood circulation

Answer 3

•oxygenated blood leaves the heart through the arteries which branch off into capillaries

•oxygen diffuses into respiring cells from the capillaries which then unite to form veins which return deoxygenated blood back to the heart

•blood decreases in pressure as it moves away from the heart

Question 4

what is the central cavity of a blood vessel called?
(blood vessels)

Answer 4

•central lumen

Question 5

what is the name of the cells the central lumen is lined with?
(blood vessels)

Answer 5

•endothelium cells

Question 6

what is the endothelium surrounded with?
(blood vessels)

Answer 6

•layers of tissue which varies in composition depending on which blood vessels it is found in

Question 7

in what direction do the arteries carry blood and at what pressure?
(arteries)

Answer 7

•arteries carry blood away from the heart at a high pressure

Question 8

describe the size of artery walls and lumen
(arteries)

Answer 8

•they have thick walls
(to withstand the high pressure)

•they have a narrow lumen

Question 9

what happens when the heart contracts?
(arteries)

Answer 9

•surges of high-pressure blood move into the arteries

•the elastic walls of the arteries stretch and recoil to accommodate the surge of blood after each contraction of the heart
(can be felt as a pulse)

•these fibres recoil between beats which maintains the high pressure of blood in the arteries

Question 10

in what direction do the veins carry blood and at what pressure?
(veins)

Answer 10

•veins carry blood back to heart at a low pressure

Question 11

what is the size of vein walls and central lumen?
(veins)

Answer 11

•they have thin walls

•they have a wide central lumen

Question 12

what is a special feature of veins and what does it do?
(veins)

Answer 12

•veins have valves that prevent back flow of blood as blood moves at a low pressure against gravity

Question 13

describe the size of capillary walls and their central lumen

Answer 13

•they have very thin walls
(only one cell thick endothelium)

•they have a narrow central lumen

Question 14

what is the function of capillaries?

Answer 14

•capillaries allow exchange if substances between the blood and tissues through their thin walls (rapid diffusion)

Question 15

what can the smooth muscle surrounding arteries do?
(arteries)

Answer 15

•contract or relax to control blood flow to capillaries depending on the body’s requirements

Question 16

what is vasodilation?

Answer 16

•vasodilation is the RELAXATION of smooth muscle to INCREASE the diameter of the central lumen and INCREASE blood flow to the capillaries

Question 17

what is vasoconstriction?
(arteries)

Answer 17

•vasoconstriction is the CONTRACTION of smooth muscle to DECREASE the diameter of the central lumen and DECREASE blood flow to the capillaries

Question 18

what is the blood made up of?

Answer 18

•red blood cells
•white blood cells
•plasma
•platelets (bathed in plasma)

Question 19

what is plasma?

Answer 19

•plasma is a watery yellow fluid that contains many dissolved substances

Question 20

what are the dissolved substances found in plasma?

Answer 20

•glucose
•amino acids
•respiratory gases
•plasma proteins

Question 21

describe a capillary network

Answer 21

•blood is carried away from the heart to tissues in arteries which branch off into arterioles which further branch of into capillary networks

•and run in between cells of the body tissues

Question 22

where do capillary networks run?

Answer 22

•run in between cells of the body tissues

Question 23

what is pressure filtration?

Answer 23

•when the blood in the arterioles is at a higher pressure than blood in the capillaries it causes pressure filtration

Question 24

what does pressure filtration cause?

Answer 24

•pressure filtration causes plasma to pass through capillary walls into the space surrounding the cells

•the plasma is now called tissue fluid and it bathes the cells

Question 25

tissue fluid and blood plasma are similar in composition. what id one difference between them?

Answer 25

•plasma proteins are too large to be filtered through the capillary walls

Question 26

what does tissue fluid supply cells with?

Answer 26

•glucose •oxygen •other substances that diffuse into cells

Question 27

what substances diffuse out of cells and into tissue fluid? why?

Answer 27

•carbon dioxide and other metabolic waste substances diffuse out of the cells and into the tissue fluid to be EXCRETED

Question 28

what happens to most of the tissue fluid?

Answer 28

•most of the tissue fluid returns to the blood capillaries to become part of plasma again

Question 29

what happens to EXCESS tissue fluid?

Answer 29

•excess tissue fluid is absorbed by lymphatic vessels and is now called a LYMPH

Question 30

what happens to the lymph after going through the lymphatic system?

Answer 30

•after going through the lymphatic system, the lymph is eventually returned to the circulatory system