chapter 7 - the circulatory system

Question 1

function of blood

Answer 1

• transport: oxygen and nutrients to cells, carbon dioxide and waste away from cells
• protection: clotting prevents fluid loss, white blood cells prevent the body against disease
• regulation: helps maintain stable body temperature, pH, water and electrolyte levels

Question 2

what are the components of blood

Answer 2

• plasma

- formed elements (erythrocytes, leucocytes and platelets)

Question 3

explain what plasma is

Answer 3

• makes up 55% of blood volume
• 91% of plasma is water
• 9% is made up of dissolved substances (nutrients: monosaccharides, amino acids, fatty acid and glycerol) (gases: oxygen and carbon dioxide) (ions, hormones, wastes, salts)

Question 4

explain what white blood cells are

Answer 4

• leucocytes
• larger than rbc but there are much fewer
• remove dead or injured cells and invading micro organisms
• live for minutes (infection) to years (no infection)
• granulocytes: have a granular cytoplasm and a lobed nucleus
• monocytes and lymphocytes (spherical nucleus and a-granular cytoplasm)

Question 5

explain what red blood cells are

Answer 5

• erythrocytes
• biconcave discs (thicker edges - increased volume for haemoglobin molecules) (thinner middle - increases SA for oxygen exchange)
• no nucleus (allows for more haemoglobin for oxygen to attach to)
• produced in bone marrow, destroyed in liver and spleen
• live for approximately 120 days

Question 6

explain what platelets are

Answer 6

• thrombocytes
• very small cell fragments with no nucleus
• formed in red bone marrow
• important for normal blood clotting
• lasts for approximately 7 days

Question 7

what are arteries

Answer 7

• carry blood away from the heart (oxygenated except for pulmonary artery)
• contain smooth muscle and elastic fibres, thick and muscular
• walls extend and recoil
• doesn’t contract to pump (reduces diameter of artery wall)
• doesn’t contain valves (high blood pressure)
• vasoconstriction: reduces blood flow to an organ
• vasodilation: increases blood flow to an organ

Question 8

what are veins

Answer 8

• carry blood towards the heart (deoxygenated except for pulmonary vein)
• do not contain muscle, thin, inelastic walls
• contains valves to prevent backflow (low bp)
• cannot change diameter of the vessel

Question 9

what are arterioles

Answer 9

• tiny arteries (same characteristics)

- carry blood from arteries to capillaries

Question 10

what are venules

Answer 10

• tiny veins (same characteristics)

- carry blood away from capillaries to the veins

Question 11

what are capillaries

Answer 11

• carry blood between the cells
• microscopic blood vessels that form networks
• one cell layer thin (allows for easy exchange of gases and materials)
• carries both oxygenated and deoxygenated
• doesn’t have valves

Question 12

explain the transport of oxygen

Answer 12

• oxygen is not soluble in water, 3% is dissolved in plasma, 97% is carried in oxyhaemoglobin (oxygen + haemoglobin = HbO2)
• oxygenated blood: high oxyhaemoglobin
• deoxygenated blood: no oxyhaemoglobin

Question 13

explain the transport of carbon dioxide

Answer 13

• 8% dissolved in plasma
• 22% combined with the globin part of haemoglobin (carbaminohaemoglobin)
• 70% is carried in plasma as bicarbonate ions
  
  • CO2 + O2 –> H2CO3 –> HCO3 (bicarbonate ion)

Question 14

factors that allow for efficient exchange of gases

Answer 14

• moist
• large surface area
• thin (one cell layer thin)
• networks of capillaries

Question 15

explain the transport of nutrients and waste

Answer 15

• inorganic nutrients transported as ions (Na, Ca, K, Cl, I)
• organic nutrients required by the body (glucose, amino acids, vitamins, fatty acids and glycerol)
• wastes / metabolic wastes need to be removed (urea, creatinine, uric acid)

Question 16

what is the cardiac cycle

Answer 16

• a sequence of events that occur during one heart beat (both sides of the heart operate at the same time
• one heart beat is 0.8 seconds

Question 17

what is systole, atrial systole and ventricular systole

Answer 17

• pumping of blood (muscles contract)
• atria contract, blood is forced into ventricles (0.1 seconds)
• ventricles contract, blood is forced into arteries (0.3 seconds)

Question 18

what is diastole, atria diastole and ventricular diastole

Answer 18

• filling (muscles relax)
• both atria fill with blood (0.4 seconds)
• ventricles relax (fill with blood) (0.4 seconds)

Question 19

two things that affect blood flow

Answer 19

• output of blood from the heart (cardiac output)

- diameter of blood vessels supplying the tissues

Question 20

what is cardiac output

Answer 20

• stroke volume (mL) x heart rate (beats/min)
• stroke volume: volume of blood forced from a ventricle with each contraction
• heart rate: number of times the heart beats per minute

Question 21

how is cardiac output regulated

Answer 21

• sinistral node (SA node): works as a pacemaker (influenced by the nervous system)
• cardiovascular regulating centre: carries nerve impulses to SA node causing heart rate to speed up or slow down

Question 22

how is the diameter of blood vessels constricted during blood flow

Answer 22

• vasoconstriction and vasodilation (contraction and relaxation of artery walls to regulate blood flow)
• change of blood flow = change in diameter of blood vessels

Question 23

how is diameter of blood vessels regulated

Answer 23

• cardiac output and diameter changes of other BV

- factors influencing: cardiovascular regulating centre (brain, CNS) and hormones (adrenaline, epinephrine)

Question 24

steps that occur to (simple) injury of blood vessels

Answer 24

1 walls of blood vessels constrict
2 reduces blood flow
3 rough surface inside walls
4 platelets stick
5 attract other platelets
6 plug is formed
7 helps reduce blood flow
8 platelets release vasoconstrictors
9 stops bleeding

Question 25

steps that occur in blood clotting (coagulation), serious injuries to blood vessels

Answer 25

1 clotting factors
2 leads to a series of reactions
3 formation of fibrin (threads of insoluble protein)
4 formation of mesh work
5 trap blood cells, platelets and plasma (clot)
6 clot retraction (occurs slowly)
7 network of threads contract (become closer, denser and stronger)
8 pull edges of damaged BV together
9 serum is squeezed out
10 clot dries / forms a scab
11 prevents entry of micro-organisms

Question 26

what is the lymphatic system

Answer 26

• network of lymph capillaries joined to lymph vessels and nodes
• function: collect some of the fluid that escapes from the blood capillaries and return it to the circulatory system

Question 27

what are lymph vessels

Answer 27

• blood leaks out of capillaries due to high blood pressure in arteries
• lymph vessels returns the blood through venous ends (veins) or the lymphatic system

Question 28

similarities and differences between blood capillaries and lymph capillaries

Answer 28

• BC: circulate and carry blood around the body, smaller and less permeable
• LC: one way only (blind ends), circulates blood away from tissues, larger, more permeable

Question 29

what area lymph nodes

Answer 29

• occur along lymphatic vessels
• structure: bean shaped (1-25mm), contain lymphoid tissue (macrophages, lymphocytes, plasma cells, crisscrossed network of fibres)
• function: lymph enters through vessels - filters - leaves to next node - eventually drains into blood capillaries