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A-Level Biology B > 4.4 Circulation > Flashcards

4.4 Circulation Flashcards

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1
Q

give 4 features of mass transport systems

A
  • system of vessels that carry substances
  • making sure substances move in the right direction
  • moving materials fast to supply the needs of the organism
  • suitable transport medium
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2
Q

describe a single circulatory system

A

heart pumps deoxygenated blood to the organs of gas exchange, where blood takes in oxygen and gives up carbon dioxide at the same time
blood then travels to the rest of the body, giving up oxygen to cells before returning to the heart

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3
Q

describe a double circulatory system

A

circulation that involves 2 systems; pulmonary and sytemic circulation

pulmonary circulation - deoxygenated blood travels from the heart to lungs and returns to heart as deoxygenated blood

systemic circulation - oxygenated blood leaves heart and flows around body, returning deoxygenated blood back to the heart

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4
Q

give functions of the cardiovascular system

A 
delivers materials needed by body cells
carries away waste products
carries hormones
forms part of the defense system
distributes heat
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5
Q

describe function of plasma

A

transports food products, nutrients, hormones etc
maintains body temperature
acts as a buffer to pH changes
contains platelets

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6
Q

describe what erythrocytes are

A

red blood cells
contain haemoglobin which binds to oxygen
no nucleus and biconcave shape gives a large sa:v ratio to aid oxygen diffusion and able to pack in more haemoglobin

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7
Q

describe what leucocytes are

A

white blood cells
defend body against infection
several types: neutrophils, monocytes, eosinophils and lymphocytes

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8
Q

give function of neutrophils and monocytes

A

engulf and digest pathogens by phagocytosis

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9
Q

give function of eosinophils

A

involved in allergic reaction responses + protection against viruses and parasites

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10
Q

give function of lymphocytes

A

natural killer cells
vital to immune system
formation of antibodies

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11
Q

describe function of arteries and how it is adapted for the function

A

carries blood away from heart towards body cells.
has external layer of tough tissue
artery wall has elastic fibres and smooth muscle
smooth lining = easy blood flow
lumen is small = carries high pressure blood
lots of elastic fibres = stretches to accomodate high volumes of blood

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12
Q

describe function of capillaries and how it is adapted for the function

A 
branch between cells
small vessels
blood travels slow - more diffusion
blood is oxygenated
thin walls allow rapid diffusion (epithelial cells)
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13
Q

describe function of veins and how it is adapted for the fucntion

A

carries blood back to the heart
carries low pressure blood
has a large lumen

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14
Q

describe the events in the cardiac cycle

A
  1. vena cava transports deoxygenated blood from the body to right atrum
2. right atrium fills with blood
tricuspid valves open
atrium contracts
blood enters right ventricles
semi-lunar valves prevent backflow
  1. right ventricles contract
    blood flows into pulmonary artery
    travels to lungs
    tricuspid valves close
  2. oxygenated blood enters left side of heart by pulmonary veins
    blood retuns to left atrium
    atrium contracts and blood flows into left ventricle
    bicuspid valves prevent backflow
  3. left ventricle pumps blood into aorta
    aorta carried blood to rest of body
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15
Q

describe the process of controlling the heart beat

A
  1. heartbeat starts in sinoatrial node
    SAN sends impulses across atria walls causing them to contract
    annulus fibrosus (tissue between atria and ventricles) prevents impulse from spreading to ventricles - causes delay
  2. impulses reach atrioventricular node
    impulse passed via Bundle of His to the ventricles
  3. bundle of His splits into 2 branches
    impulse carried into Purkyne tissue
    carries impulse down septum + through ventricles
  4. impulse causes ventricular contraction from apex upwards, squeezing blood out of the heart.
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16
Q

give the equation of carbon dioxide dissolving in blood + reacting with water. name the enzyme controlling this reaction.

A

O2 (aq) + H2O « H2CO3 « HCO3- + H+

carbonic anhydrase controls the reaction

17
Q

where is most carbon dioxide carried?

A
  • in solution in plasma
  • combines with haemoglobin to form carbaminohaemoglobin
  • transported in cytoplasm of red blood cells as hydrogencarbonate ions
18
Q

describe what happens in the blood when there is a high concentration of carbon dioxide

A

at high concentration of CO2, carbonic anhydrase catalyses the formation of carbonic acid

19
Q

describe what happens in the lungs when there is low concentration of carbon dioxide

A

at low CO2 concentration, carbonic anhydrase catalyses reverse reaction + frees carbon dioxide out of blood and into the lungs

20
Q

what ions are formed when carbonic acid dissociates?

A

H+ and HCO3- ions

21
Q

in the formation of blood clots, platelets release serotonin + thromboplastin. give the function of both.

A

serotonin- causes the smooth muscle of blood vessel to contract which cuts off blood flow to damaged area
thromboplastin - enzyme that leads to the formation of clots

22
Q

describe the blood clotting cascade

A
  1. thrombocytes (platelets) stick to exposed collagen fibres, forming a plug.
    thrombocytes become activated + releasing clotting factors through thromboplastins
  2. thromboplastins convert prothrombin (inactive plasma protein0 into thrombin (active plasma protein)
    requires Ca2+ and vitamin K
    catalysed by thrombokinase
  3. thrombin catalyses the conversion of soluble fibrinogen into soluble fibrin
    fibrin forms a mesh that traps red blood cells and strengthens platelet plug, forming a clot
  4. blood clot is eventually reabsorbed by fibrinolysis
    controlled by enzyme plasmin
23
Q

define atherosclerosis

A

condition in which yellow fatty deposits build up on arttey linings, causing them to narrow

24
Q

describe how an atheroma is formed

A
  1. slight damage to endothelial cells lining the artery can lead to a build-up of lipids
  2. blood platelets form a cap over the fatty plaque which narrows the artery
  3. any further damages causes clot formation which can block the whole artery and have fatal consequences
25
Q

why does atherosclerosis usually occur in arteries?

A

blood in arteries flows fast under high pressure = more strain on endothelium lining
in veins, pressure is low so damage is less likely

26
Q

describe the stages of atherosclerosis

A
  1. body’s inflammatory system begins + white blood cells arrive at site of damage
    cells accumulate chemicals from blood e.g cholesterol
  2. this leads to an atheroma forming on endothelial lining
  3. fibrous tissue + calcium salts build up around atheroma, forming a hardened plaque
  4. hardened area means part of the artery wall hardens so it is less elastic than it should be
27
Q

what are the effects of atherosclerosis?

A

lumen of artery becomes smaller
this increases blood pressure so it is harder to pump blood
raised blood pressure = more endothelial damage = more plaques
=increased blood pressure

28
Q

consequences of atherosclerosis

A 
aneurysms
raised blood pressure
stroke
angina
myocardial infarction
29
Q

identify the non-modifiable risks of atherosclerosis

A

genes
age
gender

30
Q

identify the modifiable risk factors of atherosclerosis

A 
smoking
exercise
weight
stress
diet

A-Level Biology B (43 decks)

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